Journal articles on the topic 'DgkA Proteins'
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1
YAMADA, Keiko, Fumio SAKANE, Norio MATSUSHIMA, and Hideo KANOH. "EF-hand motifs of α, β and γ isoforms of diacylglycerol kinase bind calcium with different affinities and conformational changes." Biochemical Journal 321, no. 1 (January 1, 1997): 59–64. http://dx.doi.org/10.1042/bj3210059.
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The three diacylglycerol kinase isoenzymes (DGKα, DGKβ and DGKγ) cloned so far contain in common a tandem repeat of EF-hand motifs. However, the Ca2+ dependences of the DGK activities are known to be variable between isoenzymes, and the Ca2+-binding activities of these motifs have not been tested except for those present in DGKα. We therefore attempted to define the intrinsic properties of EF-hands occurring in the DGK isoenzymes. For this purpose we bacterially expressed and purified the EF-hand motifs (termed DKE forms) of the three DGKs. Equilibrium dialysis with the purified DKE forms showed that all of the expressed proteins could bind approx. 2 mol of Ca2+ per mol. However, the apparent dissociation constant (Kd) for calcium binding to α-DKE (9.9 µM) was an order of magnitude greater than those estimated for β-DKE (0.89 µM) and γ-DKE (0.40 µM). Experiments with 2-p-toluidinylnaphthalene 6-sulphonate, a probe for hydrophobic regions of proteins, showed that the binding of Ca2+ to β-DKE resulted in the exposure of hydrophobic amino acids, whereas hydrophobic regions of α-DKE and γ-DKE were masked by the addition of Ca2+. Taken together, these results indicate that DGKα, DGKβ and DGKγ possess EF-hand structures with intrinsic properties different from each other with respect to affinities for Ca2+ and Ca2+-induced conformational changes.
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Gharbi, Severine I., Esther Rincón, Antonia Avila-Flores, Pedro Torres-Ayuso, María Almena, María Angeles Cobos, Juan Pablo Albar, and Isabel Mérida. "Diacylglycerol kinase ζ controls diacylglycerol metabolism at the immunological synapse." Molecular Biology of the Cell 22, no. 22 (November 15, 2011): 4406–14. http://dx.doi.org/10.1091/mbc.e11-03-0247.
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Diacylglycerol (DAG) generation at the T cell immunological synapse (IS) determines the correct activation of antigen-specific immune responses. DAG kinases (DGKs) α and ζ act as negative regulators of DAG-mediated signals by catalyzing DAG conversion to phosphatidic acid (PA). Nonetheless, the specific input of each enzyme and their spatial regulation during IS formation remain uncharacterized. Here we report recruitment of endogenous DGKα and DGKζ to the T cell receptor (TCR) complex following TCR/CD28 engagement. Specific DGK gene silencing shows that PA production at the activated complex depends mainly on DGKζ, indicating functional differences between these proteins. DGKζ kinase activity at the TCR is enhanced by phorbol-12-myristate-13-acetate cotreatment, suggesting DAG-mediated regulation of DGKζ responsiveness. We used GFP-DGKζ and -DGKα chimeras to assess translocation dynamics during IS formation. Only GFP-DGKζ translocated rapidly to the plasma membrane at early stages of IS formation, independent of enzyme activity. Finally, use of a fluorescent DAG sensor confirmed rapid, sustained DAG accumulation at the IS and allowed us to directly correlate membrane translocation of active DGKζ with DAG consumption at the IS. This study highlights a DGKζ-specific function for local DAG metabolism at the IS and offers new clues to its mode of regulation.
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Li, Dianfan, Valerie E. Pye, and Martin Caffrey. "Experimental phasing for structure determination using membrane-protein crystals grown by the lipid cubic phase method." Acta Crystallographica Section D Biological Crystallography 71, no. 1 (January 1, 2015): 104–22. http://dx.doi.org/10.1107/s1399004714010360.
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Despite the marked increase in the number of membrane-protein structures solved using crystals grown by the lipid cubic phase orin mesomethod, only ten have been determined by SAD/MAD. This is likely to be a consequence of the technical difficulties associated with handling proteins and crystals in the sticky and viscous hosting mesophase that is usually incubated in glass sandwich plates for the purposes of crystallization. Here, a four-year campaign aimed at phasing thein mesostructure of the integral membrane diacylglycerol kinase (DgkA) fromEscherichia coliis reported. Heavy-atom labelling of this small hydrophobic enzyme was attempted by pre-labelling, co-crystallization, soaking, site-specific mercury binding to genetically engineered single-cysteine mutants and selenomethionine incorporation. Strategies and techniques for special handling are reported, as well as the typical results and the lessons learned for each of these approaches. In addition, an assay to assess the accessibility of cysteine residues in membrane proteins for mercury labelling is introduced. The various techniques and strategies described will provide a valuable reference for future experimental phasing of membrane proteins where crystals are grown by the lipid cubic phase method.
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Topham, Matthew K., and Stephen M. Prescott. "Diacylglycerol Kinase ζ Regulates Ras Activation by a Novel Mechanism." Journal of Cell Biology 152, no. 6 (March 12, 2001): 1135–44. http://dx.doi.org/10.1083/jcb.152.6.1135.
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Guanine nucleotide exchange factors (GEFs) activate Ras by facilitating its GTP binding. Ras guanyl nucleotide-releasing protein (GRP) was recently identified as a Ras GEF that has a diacylglycerol (DAG)-binding C1 domain. Its exchange factor activity is regulated by local availability of signaling DAG. DAG kinases (DGKs) metabolize DAG by converting it to phosphatidic acid. Because they can attenuate local accumulation of signaling DAG, DGKs may regulate RasGRP activity and, consequently, activation of Ras. DGKζ, but not other DGKs, completely eliminated Ras activation induced by RasGRP, and DGK activity was required for this mechanism. DGKζ also coimmunoprecipitated and colocalized with RasGRP, indicating that these proteins associate in a signaling complex. Coimmunoprecipitation of DGKζ and RasGRP was enhanced in the presence of phorbol esters, which are DAG analogues that cannot be metabolized by DGKs, suggesting that DAG signaling can induce their interaction. Finally, overexpression of kinase-dead DGKζ in Jurkat cells prolonged Ras activation after ligation of the T cell receptor. Thus, we have identified a novel way to regulate Ras activation: through DGKζ, which controls local accumulation of DAG that would otherwise activate RasGRP.
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Abramovici, Hanan, Parmiss Mojtabaie, Robin J. Parks, Xiao-Ping Zhong, Gary A. Koretzky, Matthew K. Topham, and Stephen H. Gee. "Diacylglycerol Kinase ζ Regulates Actin Cytoskeleton Reorganization through Dissociation of Rac1 from RhoGDI." Molecular Biology of the Cell 20, no. 7 (April 2009): 2049–59. http://dx.doi.org/10.1091/mbc.e07-12-1248.
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Activation of Rac1 GTPase signaling is stimulated by phosphorylation and release of RhoGDI by the effector p21-activated kinase 1 (PAK1), but it is unclear what initiates this potential feed-forward mechanism for regulation of Rac activity. Phosphatidic acid (PA), which is produced from the lipid second messenger diacylglycerol (DAG) by the action of DAG kinases (DGKs), is known to activate PAK1. Here, we investigated whether PA produced by DGKζ initiates RhoGDI release and Rac1 activation. In DGKζ-deficient fibroblasts PAK1 phosphorylation and Rac1–RhoGDI dissociation were attenuated, leading to reduced Rac1 activation after platelet-derived growth factor stimulation. The cells were defective in Rac1-regulated behaviors, including lamellipodia formation, membrane ruffling, migration, and spreading. Wild-type DGKζ, but not a kinase-dead mutant, or addition of exogenous PA rescued Rac activation. DGKζ stably associated with PAK1 and RhoGDI, suggesting these proteins form a complex that functions as a Rac1-selective RhoGDI dissociation factor. These results define a pathway that links diacylglycerol, DGKζ, and PA to the activation of Rac1: the PA generated by DGKζ activates PAK1, which dissociates RhoGDI from Rac1 leading to changes in actin dynamics that facilitate the changes necessary for cell motility.
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Tabet, Ricardos, Enora Moutin, Jérôme A. J. Becker, Dimitri Heintz, Laetitia Fouillen, Eric Flatter, Wojciech Krężel, et al. "Fragile X Mental Retardation Protein (FMRP) controls diacylglycerol kinase activity in neurons." Proceedings of the National Academy of Sciences 113, no. 26 (May 27, 2016): E3619—E3628. http://dx.doi.org/10.1073/pnas.1522631113.
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Fragile X syndrome (FXS) is caused by the absence of the Fragile X Mental Retardation Protein (FMRP) in neurons. In the mouse, the lack of FMRP is associated with an excessive translation of hundreds of neuronal proteins, notably including postsynaptic proteins. This local protein synthesis deregulation is proposed to underlie the observed defects of glutamatergic synapse maturation and function and to affect preferentially the hundreds of mRNA species that were reported to bind to FMRP. How FMRP impacts synaptic protein translation and which mRNAs are most important for the pathology remain unclear. Here we show by cross-linking immunoprecipitation in cortical neurons that FMRP is mostly associated with one unique mRNA: diacylglycerol kinase kappa (Dgkκ), a master regulator that controls the switch between diacylglycerol and phosphatidic acid signaling pathways. The absence of FMRP in neurons abolishes group 1 metabotropic glutamate receptor-dependent DGK activity combined with a loss of Dgkκ expression. The reduction of Dgkκ in neurons is sufficient to cause dendritic spine abnormalities, synaptic plasticity alterations, and behavior disorders similar to those observed in the FXS mouse model. Overexpression of Dgkκ in neurons is able to rescue the dendritic spine defects of the Fragile X Mental Retardation 1 gene KO neurons. Together, these data suggest that Dgkκ deregulation contributes to FXS pathology and support a model where FMRP, by controlling the translation of Dgkκ, indirectly controls synaptic proteins translation and membrane properties by impacting lipid signaling in dendritic spine.
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SAKANE, Fumio, Masahiro KAI, Ikuo WADA, Shin-ichi IMAI, and Hideo KANOH. "The C-terminal part of diacylglycerol kinase α lacking zinc fingers serves as a catalytic domain." Biochemical Journal 318, no. 2 (September 1, 1996): 583–90. http://dx.doi.org/10.1042/bj3180583.
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All mammalian diacylglycerol kinase (DGK) isoenzymes so far cloned consist of four conserved regions, namely C1, C2 (tandem EF-hand structures), C3 (tandem cysteine-rich zinc finger sequences) and the C-terminal C4 domains. To determine the catalytic domain we expressed in COS-7 cells various truncation mutants of pig DGKα and assessed their enzyme activities. We found that the C4 domain lacking the whole N-terminal region including the zinc fingers possessed DGK activity that was dependent on the concentrations of diacylglycerol and ATP very similarly, as did the wild-type DGKα. Furthermore the DGK activity of the wild-type DGK and that expressed by the C4 domain were similarly activated by anionic amphiphiles such as phosphatidylserine, phosphatidylinositol and deoxycholate. It was also shown that a DGK mutant consisting of the zinc fingers and the C4 domain has enzymological properties very similar to those expressed by the C4 domain alone. We also confirmed that the intact DGKs α, β and γ expressed in COS-7 cells displayed no detectable phorbol ester binding. These results show that the C4 domain of DGK is the catalytic region that is responsible for the enzyme activities sensitive to different activators. We cannot exclude the possibility that the N-terminal portion including the zinc fingers can still interact with diacylglycerol and activators without affecting the enzyme activity measured in vitro. However, it is quite likely that the DGK zinc fingers do not serve as diacylglycerol-binding sites, in contrast with those present in other proteins such as protein kinases C and n-chimaerin. Site-directed mutagenesis of all six putative ATP binding sites (Lys248, Lys383, Lys395, Lys483, Lys492, and Lys554) did not significantly affect the enzyme activity. We therefore suggest that DGK does not contain a typical P-loop of ATP binding sites.
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Baldanzi, Gianluca, Beatrice Ragnoli, and Mario Malerba. "Potential role of diacylglycerol kinases in immune-mediated diseases." Clinical Science 134, no. 13 (July 1, 2020): 1637–58. http://dx.doi.org/10.1042/cs20200389.
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Abstract The mechanism promoting exacerbated immune responses in allergy and autoimmunity as well as those blunting the immune control of cancer cells are of primary interest in medicine. Diacylglycerol kinases (DGKs) are key modulators of signal transduction, which blunt diacylglycerol (DAG) signals and produce phosphatidic acid (PA). By modulating lipid second messengers, DGK modulate the activity of downstream signaling proteins, vesicle trafficking and membrane shape. The biological role of the DGK α and ζ isoforms in immune cells differentiation and effector function was subjected to in deep investigations. DGK α and ζ resulted in negatively regulating synergistic way basal and receptor induced DAG signals in T cells as well as leukocytes. In this way, they contributed to keep under control the immune response but also downmodulate immune response against tumors. Alteration in DGKα activity is also implicated in the pathogenesis of genetic perturbations of the immune function such as the X-linked lymphoproliferative disease 1 and localized juvenile periodontitis. These findings suggested a participation of DGK to the pathogenetic mechanisms underlying several immune-mediated diseases and prompted several researches aiming to target DGK with pharmacologic and molecular strategies. Those findings are discussed inhere together with experimental applications in tumors as well as in other immune-mediated diseases such as asthma.
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Prescott, Stephen, and Matthew Topham. "Diacylglycerol Kinases: Regulation and Signaling Roles." Thrombosis and Haemostasis 88, no. 12 (2002): 912–18. http://dx.doi.org/10.1055/s-0037-1613333.
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SummaryDiacylglycerol kinases (DGKs) are thought to attenuate diacylglycerol signals by converting diacylglycerol to phosphatidic acid. The nine mammalian diacylglycerol kinases that have been identified are widely expressed, but each isoform has a unique tissue and subcellular distribution. The activity of DGKs is regulated by mechanisms that can modify their access to diacylglycerol, affect their activity, or alter their ability to bind to other proteins. Although little is known of the specific function of DGKs in platelets, they likely influence actin reorganization and other signaling events requiring diacylglycerol.
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Nagaya, Hisao, Ikuo Wada, Yan-Jun Jia, and Hideo Kanoh. "Diacylglycerol Kinase δ Suppresses ER-to-Golgi Traffic via Its SAM and PH Domains." Molecular Biology of the Cell 13, no. 1 (January 2002): 302–16. http://dx.doi.org/10.1091/mbc.01-05-0255.
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We report here that the anterograde transport from the endoplasmic reticulum (ER) to the Golgi was markedly suppressed by diacylglycerol kinase δ (DGKδ) that uniquely possesses a pleckstrin homology (PH) and a sterile α motif (SAM) domain. A low-level expression of DGKδ in NIH3T3 cells caused redistribution into the ER of the marker proteins of the Golgi membranes and the vesicular-tubular clusters (VTCs). In this case DGKδ delayed the ER-to-Golgi traffic of vesicular stomatitis virus glycoprotein (VSV G) and also the reassembly of the Golgi apparatus after brefeldin A (BFA) treatment and washout. DGKδ was demonstrated to associate with the ER through its C-terminal SAM domain acting as an ER-targeting motif. Both of the SAM domain and the N-terminal PH domain of DGKδ were needed to exert its effects on ER-to-Golgi traffic. Kinase-dead mutants of DGKδ were also effective as the wild-type enzyme, suggesting that the catalytic activity of DGK was not involved in the present observation. Remarkably, the expression of DGKδ abrogated formation of COPII-coated structures labeled with Sec13p without affecting COPI structures. These findings indicate that DGKδ negatively regulates ER-to-Golgi traffic by selectively inhibiting the formation of ER export sites without significantly affecting retrograde transport.
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Ishikawa, Ko, Chihiro Chubachi, Saeko Tochigi, Naomi Hoshi, Seiji Kojima, Mamoru Hyodo, Yoshihiro Hayakawa, Tadaomi Furuta, Kota Kera, and Nobuyuki Uozumi. "Functional characterization of multiple PAS domain-containing diguanylate cyclases in Synechocystis sp. PCC 6803." Microbiology 166, no. 7 (July 1, 2020): 659–68. http://dx.doi.org/10.1099/mic.0.000929.
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Bis-(3′–5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) is a second messenger known to control a variety of bacterial processes. The model cyanobacterium, Synechocystis sp. PCC 6803, has a score of genes encoding putative enzymes for c-di-GMP synthesis and degradation. However, most of them have not been functionally characterized. Here, we chose four genes in Synechocystis (dgcA–dgcD), which encode proteins with a GGDEF, diguanylate cyclase (DGC) catalytic domain and multiple Per-ARNT-Sim (PAS) conserved regulatory motifs, for detailed analysis. Purified DgcA, DgcB and DgcC were able to catalyze synthesis of c-di-GMP from two GTPs in vitro. DgcA had the highest activity, compared with DgcB and DgcC. DgcD did not show detectable activity. DgcA activity was specific for GTP and stimulated by the divalent cations, magnesium or manganese. Full activity of DgcA required the presence of the multiple PAS domains, probably because of their role in protein dimerization or stability. Synechocystis mutants carrying single deletions of dgcA–dgcD were not affected in their growth rate or biofilm production during salt stress, suggesting that there was functional redundancy in vivo. In contrast, overexpression of dgcA resulted in increased biofilm formation in the absence of salt stress. In this study, we characterize the enzymatic and physiological function of DgcA–DgcD, and propose that the PAS domains in DgcA function in maintaining the enzyme in its active form.
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Sakane, Fumio, Fumi Hoshino, and Chiaki Murakami. "New Era of Diacylglycerol Kinase, Phosphatidic Acid and Phosphatidic Acid-Binding Protein." International Journal of Molecular Sciences 21, no. 18 (September 16, 2020): 6794. http://dx.doi.org/10.3390/ijms21186794.
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Diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DG) to generate phosphatidic acid (PA). Mammalian DGK consists of ten isozymes (α–κ) and governs a wide range of physiological and pathological events, including immune responses, neuronal networking, bipolar disorder, obsessive-compulsive disorder, fragile X syndrome, cancer, and type 2 diabetes. DG and PA comprise diverse molecular species that have different acyl chains at the sn-1 and sn-2 positions. Because the DGK activity is essential for phosphatidylinositol turnover, which exclusively produces 1-stearoyl-2-arachidonoyl-DG, it has been generally thought that all DGK isozymes utilize the DG species derived from the turnover. However, it was recently revealed that DGK isozymes, except for DGKε, phosphorylate diverse DG species, which are not derived from phosphatidylinositol turnover. In addition, various PA-binding proteins (PABPs), which have different selectivities for PA species, were recently found. These results suggest that DGK–PA–PABP axes can potentially construct a large and complex signaling network and play physiologically and pathologically important roles in addition to DGK-dependent attenuation of DG–DG-binding protein axes. For example, 1-stearoyl-2-docosahexaenoyl-PA produced by DGKδ interacts with and activates Praja-1, the E3 ubiquitin ligase acting on the serotonin transporter, which is a target of drugs for obsessive-compulsive and major depressive disorders, in the brain. This article reviews recent research progress on PA species produced by DGK isozymes, the selective binding of PABPs to PA species and a phosphatidylinositol turnover-independent DG supply pathway.
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Kawasaki, Takumi, Takeshi Kobayashi, Takehiko Ueyama, Yasuhito Shirai, and Naoaki Saito. "Regulation of clathrin-dependent endocytosis by diacylglycerol kinase δ: importance of kinase activity and binding to AP2α." Biochemical Journal 409, no. 2 (December 21, 2007): 471–79. http://dx.doi.org/10.1042/bj20070755.
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DGKδ (diacylglycerol kinase δ), which phosphorylates DAG (diacylglycerol) and converts it into PA (phosphatidic acid), has an important role in signal transduction. In the present study, we have demonstrated the molecular mechanism of DGKδ-mediated regulation of clathrin-dependent endocytosis that controls the internalization, recycling and degradation of receptors. Involvement of DGKδ in the regulation of clathrin-dependent endocytosis was previously proposed following genome-wide RNAi (RNA interference) screening. Clathrin-coated pits are mainly formed by clathrin and AP-2 (adaptor protein 2) complex. These proteins assemble a polyhedral lattice at the membrane and gather several endocytic accessory proteins. As the intracellular localization of DGKδ2 overlapped with clathrin-coated pits, we predicted the possible regulation of clathrin-dependent endocytosis by DGKδ2 and its interaction with some endocytosis-regulatory proteins. DGKδ2 contained the DXF-type binding motifs, and DGKδ2 bound to AP2α, a subunit of the AP-2 complex. DGKδ2 interacted with the platform subdomain in the AP2α ear domain via F369DTFRIL and D746PF sequences in the catalytic domain of DGKδ2. For further insight into the role for DGKδ2 in clathrin-dependent endocytosis, we measured the transferrin and EGF (epidermal growth factor) uptake-expressing wild-type or mutant DGKδ2 under knockdown of endogenous DGKδ. Mutants lacking binding ability to AP2α as well as kinase-negative mutants could not compensate for the uptake of transferrin inhibited by siRNA (small interfering RNA) treatment, whereas overexpression of wild-type DGKδ2 completely recovered the transferrin uptake. These results demonstrate that binding between DGKδ2 and AP2α is involved in the transferrin internalization and that DGK activity is also necessary for the regulation of the endocytic process.
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Bozelli, José Carlos, William Jennings, Stephanie Black, Yu Heng Hou, Darius Lameire, Preet Chatha, Tomohiro Kimura, et al. "Membrane curvature allosterically regulates the phosphatidylinositol cycle, controlling its rate and acyl-chain composition of its lipid intermediates." Journal of Biological Chemistry 293, no. 46 (September 20, 2018): 17780–91. http://dx.doi.org/10.1074/jbc.ra118.005293.
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Signaling events at membranes are often mediated by membrane lipid composition or membrane physical properties. These membrane properties could act either by favoring the membrane binding of downstream effectors or by modulating their activity. Several proteins can sense/generate membrane physical curvature (i.e. shape). However, the modulation of the activity of enzymes by a membrane's shape has not yet been reported. Here, using a cell-free assay with purified diacylglycerol kinase ϵ (DGKϵ) and liposomes, we studied the activity and acyl-chain specificity of an enzyme of the phosphatidylinositol (PI) cycle, DGKϵ. By systematically varying the model membrane lipid composition and physical properties, we found that DGKϵ has low activity and lacks acyl-chain specificity in locally flat membranes, regardless of the lipid composition. On the other hand, these enzyme properties were greatly enhanced in membrane structures with a negative Gaussian curvature. We also found that this is not a consequence of preferential binding of the enzyme to those structures, but rather is due to a curvature-mediated allosteric regulation of DGKϵ activity and acyl-chain specificity. Moreover, in a fine-tuned interplay between the enzyme and the membrane, DGKϵ favored the formation of structures with greater Gaussian curvature. DGKϵ does not bear a regulatory domain, and these findings reveal the importance of membrane curvature in regulating DGKϵ activity and acyl-chain specificity. Hence, this study highlights that a hierarchic coupling of membrane physical property and lipid composition synergistically regulates membrane signaling events. We propose that this regulatory mechanism of membrane-associated enzyme activity is likely more common than is currently appreciated.
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Tako, Elad. "The Linoleic Acid: Dihomo-γ-Linolenic Acid Ratio (LA: DGLA)- an Emerging Biomarker of Zinc Status." Current Developments in Nutrition 4, Supplement_2 (May 29, 2020): 1842. http://dx.doi.org/10.1093/cdn/nzaa067_069.
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Abstract Objectives Assessment of erythrocyte linoleic: dihomo-γ-linolenic acid (LA: DGLA) ratio as a biomarker of Zn status, and structure and function of cecal microbiota following the consumption of a Zn-biofortified wheat diet. Methods The efficacy of the LA: DGLA ratio to predict the Zn status of subjects consuming a wheat-based diet, a representative diet of the target Zn-deficient populations, was evaluated in-vivo (Gallus gallus). Two groups (n = 15) were fed two different diets, a “high-Zn” diet (46.5 ppm Zn) and a “low-Zn” diet (32.8 ppm Zn), for 6 weeks. Dietary Zn-intake, body-weight, serum zinc, intestinal microbiome, expression of zinc related proteins, and the erythrocyte fatty acid profile were assessed (LA: DGLA ratio). Results Serum and tissues Zn concentrations were greater in the high-Zn group (P < 0.05). Duodenal expression of Zn transporters demonstrated a higher mean value in the tissues collected from the birds fed a low-Zn diet (n = 15, P < 0.05). Hepatic ∆6-desaturase expression showed a higher mean value in birds fed high-Zn diets (P < 0.05). LA: DGLA ratio was higher (P < 0.05) in the low-Zn group of birds at all-time points. Even though both groups of birds were fed Zn-deficient diets, with only 14 ppm differential in dietary Zn content, still the LA: DGLA ratio differentiated clearly between the groups, which demonstrates the sensitivity of the biomarker to change in accordance with dietary Zn intake. Conclusions Recent evidence demonstrate the potential of the LA: DGLA ratio to be used as an additional biomarker of Zn status in humans. To date, research shows that the LA: DGLA ratio corresponds to dietary Zn manipulations, both in animal model and humans. Funding Sources N/A.
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Raina, Rupesh, Nina Vijayvargiya, Amrit Khooblall, Manasa Melachuri, Shweta Deshpande, Divya Sharma, Kashin Mathur, Manav Arora, Sidharth Kumar Sethi, and Sonia Sandhu. "Pediatric Atypical Hemolytic Uremic Syndrome Advances." Cells 10, no. 12 (December 18, 2021): 3580. http://dx.doi.org/10.3390/cells10123580.
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Atypical hemolytic uremic syndrome (aHUS) is a rare disorder characterized by dysregulation of the alternate pathway. The diagnosis of aHUS is one of exclusion, which complicates its early detection and corresponding intervention to mitigate its high rate of mortality and associated morbidity. Heterozygous mutations in complement regulatory proteins linked to aHUS are not always phenotypically active, and may require a particular trigger for the disease to manifest. This list of triggers continues to expand as more data is aggregated, particularly centered around COVID-19 and pediatric vaccinations. Novel genetic mutations continue to be identified though advancements in technology as well as greater access to cohorts of interest, as in diacylglycerol kinase epsilon (DGKE). DGKE mutations associated with aHUS are the first non-complement regulatory proteins associated with the disease, drastically changing the established framework. Additional markers that are less understood, but continue to be acknowledged, include the unique autoantibodies to complement factor H and complement factor I which are pathogenic drivers in aHUS. Interventional therapeutics have undergone the most advancements, as pharmacokinetic and pharmacodynamic properties are modified as needed in addition to their as biosimilar counterparts. As data continues to be gathered in this field, future advancements will optimally decrease the mortality and morbidity of this disease in children.
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Zeppenfeld, Tim, Christina Larisch, Joseph W. Lengeler, and Knut Jahreis. "Glucose Transporter Mutants of Escherichia coli K-12 with Changes in Substrate Recognition of IICBGlc and Induction Behavior of theptsG Gene." Journal of Bacteriology 182, no. 16 (August 15, 2000): 4443–52. http://dx.doi.org/10.1128/jb.182.16.4443-4452.2000.
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ABSTRACT In Escherichia coli K-12, the major glucose transporter with a central role in carbon catabolite repression and in inducer exclusion is the phosphoenolpyruvate-dependent glucose:phosphotransferase system (PTS). Its membrane-bound subunit, IICBGlc, is encoded by the gene ptsG; its soluble domain, IIAGlc, is encoded by crr, which is a member of the pts operon. The system is inducible by d-glucose and, to a lesser degree, byl-sorbose. The regulation of ptsG transcription was analyzed by testing the induction of IICBGlctransporter activity and of a single-copy Φ(ptsGop-lacZ) fusion. Among mutations found to affect directly ptsGexpression were those altering the activity of adenylate cyclase (cyaA), the repressor DgsA (dgsA; also called Mlc), the general PTS proteins enzyme I (ptsI) and histidine carrier protein HPr (ptsH), and the IIAGlc and IIBGlc domains, as well as several authentic and newly isolated UmgC mutations. The latter, originally thought to map in the repressor gene umgC outside theptsG locus, were found to represent ptsGalleles. These affected invariably the substrate specificity of the IICBGlc domain, thus allowing efficient transport and phosphorylation of substrates normally transported very poorly or not at all by this PTS. Simultaneously, all of these substrates became inducers for ptsG. From the analysis of the mutants, fromcis-trans dominance tests, and from the identification of the amino acid residues mutated in the UmgC mutants, a new regulatory mechanism involved in ptsG induction is postulated. According to this model, the phosphorylation state of IIBGlc modulates IICGlc which, directly or indirectly, controls the repressor DgsA and hence ptsGexpression. By the same mechanism, glucose uptake and phosphorylation also control the expression of the pts operon and probably of all operons controlled by the repressor DgsA.
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Mérida, Isabel, Antonia Ávila-Flores, and Ernesto Merino. "Diacylglycerol kinases: at the hub of cell signalling." Biochemical Journal 409, no. 1 (December 11, 2007): 1–18. http://dx.doi.org/10.1042/bj20071040.
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DGKs (diacylglycerol kinases) are members of a unique and conserved family of intracellular lipid kinases that phosphorylate DAG (diacylglycerol), catalysing its conversion into PA (phosphatidic acid). This reaction leads to attenuation of DAG levels in the cell membrane, regulating a host of intracellular signalling proteins that have evolved the ability to bind this lipid. The product of the DGK reaction, PA, is also linked to the regulation of diverse functions, including cell growth, membrane trafficking, differentiation and migration. In multicellular eukaryotes, DGKs provide a link between lipid metabolism and signalling. Genetic experiments in Caenorhabditis elegans, Drosophila melanogaster and mice have started to unveil the role of members of this protein family as modulators of receptor-dependent responses in processes such as synaptic transmission and photoreceptor transduction, as well as acquired and innate immune responses. Recent discoveries provide new insights into the complex mechanisms controlling DGK activation and their participation in receptor-regulated processes. After more than 50 years of intense research, the DGK pathway emerges as a key player in the regulation of cell responses, offering new possibilities of therapeutic intervention in human pathologies, including cancer, heart disease, diabetes, brain afflictions and immune dysfunctions.
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Tesena, Parichart, Amornthep Kingkaw, Narumon Phaonakrop, Sittiruk Roytrakul, Paviga Limudomporn, Wanwipa Vongsangnak, and Attawit Kovitvadhi. "Faecal Proteomics and Functional Analysis of Equine Melanocytic Neoplasm in Grey Horses." Veterinary Sciences 9, no. 2 (February 21, 2022): 94. http://dx.doi.org/10.3390/vetsci9020094.
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Equine melanocytic neoplasm (EMN) is a common disease in older grey horses. The purpose of this study was to examine the potential proteins throughout EMN stages from faecal proteomic outlining using functional analysis. Faecal samples were collected from the rectum of 25 grey horses divided into three groups; normal group without EMN (n = 10), mild EMN (n = 6) and severe EMN (n = 9). Based on the results, 5910 annotated proteins out of 8509 total proteins were assessed from proteomic profiling. We observed differentially expressed proteins (DEPs) between the normal group and the EMN group, and 109 significant proteins were obtained, of which 28 and 81 were involved in metabolic and non-metabolic functions, respectively. We found 10 proteins that play a key role in lipid metabolism, affecting the tumour microenvironment and, consequently, melanoma progression. Interestingly, FOSL1 (FOS like 1, AP-1 transcription factor subunit) was considered as a potential highly expressed protein in a mild EMN group involved in melanocytes cell and related melanoma. Diacylglycerol kinase (DGKB), TGc domain-containing protein (Tgm2), structural maintenance of chromosomes 4 (SMC4) and mastermind-like transcriptional coactivator 2 (MAML2) were related to lipid metabolism, facilitating melanoma development in the severe-EMN group. In conclusion, these potential proteins can be used as candidate biomarkers for the monitoring of early EMN, the development of EMN, further prevention and treatment.
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Sitaram, Uyemura, Malarkannan, and Riese. "Beyond the Cell Surface: Targeting Intracellular Negative Regulators to Enhance T cell Anti-Tumor Activity." International Journal of Molecular Sciences 20, no. 23 (November 20, 2019): 5821. http://dx.doi.org/10.3390/ijms20235821.
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It is well established that extracellular proteins that negatively regulate T cell function, such as Cytotoxic T-Lymphocyte-Associated protein 4 (CTLA-4) and Programmed Cell Death protein 1 (PD-1), can be effectively targeted to enhance cancer immunotherapies and Chimeric Antigen Receptor T cells (CAR-T cells). Intracellular proteins that inhibit T cell receptor (TCR) signal transduction, though less well studied, are also potentially useful therapeutic targets to enhance T cell activity against tumor. Four major classes of enzymes that attenuate TCR signaling include E3 ubiquitin kinases such as the Casitas B-lineage lymphoma proteins (Cbl-b and c-Cbl), and Itchy (Itch), inhibitory tyrosine phosphatases, such as Src homology region 2 domain-containing phosphatases (SHP-1 and SHP-2), inhibitory protein kinases, such as C-terminal Src kinase (Csk), and inhibitory lipid kinases such as Src homology 2 (SH2) domain-containing inositol polyphosphate 5-phosphatase (SHIP) and Diacylglycerol kinases (DGKs). This review describes the mechanism of action of eighteen intracellular inhibitory regulatory proteins in T cells within these four classes, and assesses their potential value as clinical targets to enhance the anti-tumor activity of endogenous T cells and CAR-T cells.
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Lastovetsky, Olga A., Maria L. Gaspar, Stephen J. Mondo, Kurt M. LaButti, Laura Sandor, Igor V. Grigoriev, Susan A. Henry, and Teresa E. Pawlowska. "Lipid metabolic changes in an early divergent fungus govern the establishment of a mutualistic symbiosis with endobacteria." Proceedings of the National Academy of Sciences 113, no. 52 (December 12, 2016): 15102–7. http://dx.doi.org/10.1073/pnas.1615148113.
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The recent accumulation of newly discovered fungal–bacterial mutualisms challenges the paradigm that fungi and bacteria are natural antagonists. To understand the mechanisms that govern the establishment and maintenance over evolutionary time of mutualisms between fungi and bacteria, we studied a symbiosis of the fungus Rhizopus microsporus (Mucoromycotina) and its Burkholderia endobacteria. We found that nonhost R. microsporus, as well as other mucoralean fungi, interact antagonistically with endobacteria derived from the host and are not invaded by them. Comparison of gene expression profiles of host and nonhost fungi during interaction with endobacteria revealed dramatic changes in expression of lipid metabolic genes in the host. Analysis of the host lipidome confirmed that symbiosis establishment was accompanied by specific changes in the fungal lipid profile. Diacylglycerol kinase (DGK) activity was important for these lipid metabolic changes, as its inhibition altered the fungal lipid profile and caused a shift in the host–bacterial interaction into an antagonism. We conclude that adjustments in host lipid metabolism during symbiosis establishment, mediated by DGKs, are required for the mutualistic outcome of the Rhizopus–Burkholderia symbiosis. In addition, the neutral and phospholipid profiles of R. microsporus provide important insights into lipid metabolism in an understudied group of oleaginous Mucoromycotina. Lastly, our study revealed that the DGKs involved in the symbiosis form a previously uncharacterized clade of DGK domain proteins.
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Okada, Masashi, Yasukazu Hozumi, Tohru Ichimura, Toshiaki Tanaka, Hiroshi Hasegawa, Masakazu Yamamoto, Nobuya Takahashi, et al. "Interaction of nucleosome assembly proteins abolishes nuclear localization of DGKζ by attenuating its association with importins." Experimental Cell Research 317, no. 20 (December 2011): 2853–63. http://dx.doi.org/10.1016/j.yexcr.2011.09.014.
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Becker, Ann-Katrin, Tim Zeppenfeld, Ariane Staab, Sabine Seitz, Winfried Boos, Teppei Morita, Hiroji Aiba, Kerstin Mahr, Fritz Titgemeyer, and Knut Jahreis. "YeeI, a Novel Protein Involved in Modulation of the Activity of the Glucose-Phosphotransferase System in Escherichia coli K-12." Journal of Bacteriology 188, no. 15 (August 1, 2006): 5439–49. http://dx.doi.org/10.1128/jb.00219-06.
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ABSTRACT The membrane-bound protein EIICBGlc encoded by the ptsG gene is the major glucose transporter in Escherichia coli. This protein is part of the phosphoenolpyruvate:glucose-phosphotransferase system, a very important transport and signal transduction system in bacteria. The regulation of ptsG expression is very complex. Among others, two major regulators, the repressor Mlc and the cyclic AMP-cyclic AMP receptor protein activator complex, have been identified. Here we report identification of a novel protein, YeeI, that is involved in the regulation of ptsG by interacting with Mlc. Mutants with reduced activity of the glucose-phosphotransferase system were isolated by transposon mutagenesis. One class of mutations was located in the open reading frame yeeI at 44.1 min on the E. coli K-12 chromosome. The yeeI mutants exhibited increased generation times during growth on glucose, reduced transport of methyl-α-d-glucopyranoside, a substrate of EIICBGlc, reduced induction of a ptsG-lacZ operon fusion, and reduced catabolite repression in lactose/glucose diauxic growth experiments. These observations were the result of decreased ptsG expression and a decrease in the amount of EIICBGlc. In contrast, overexpression of yeeI resulted in higher expression of ptsG, of a ptsG-lacZ operon fusion, and of the autoregulated dgsA gene. The effect of a yeeI mutation could be suppressed by introducing a dgsA deletion, implying that the two proteins belong to the same signal transduction pathway and that Mlc is epistatic to YeeI. By measuring the surface plasmon resonance, we found that YeeI (proposed gene designation, mtfA) directly interacts with Mlc with high affinity.
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Graham, Kate L., Peter Halasz, Yan Tan, Marilyn J. Hewish, Yoshikazu Takada, Erich R. Mackow, Martyn K. Robinson, and Barbara S. Coulson. "Integrin-Using Rotaviruses Bind α2β1 Integrin α2 I Domain via VP4 DGE Sequence and Recognize αXβ2 and αVβ3 by Using VP7 during Cell Entry." Journal of Virology 77, no. 18 (September 15, 2003): 9969–78. http://dx.doi.org/10.1128/jvi.77.18.9969-9978.2003.
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ABSTRACT Integrins α2β1, αXβ2, and αVβ3 have been implicated in rotavirus cell attachment and entry. The virus spike protein VP4 contains the α2β1 ligand sequence DGE at amino acid positions 308 to 310, and the outer capsid protein VP7 contains the αXβ2 ligand sequence GPR. To determine the viral proteins and sequences involved and to define the roles of α2β1, αXβ2, and αVβ3, we analyzed the ability of rotaviruses and their reassortants to use these integrins for cell binding and infection and the effect of peptides DGEA and GPRP on these events. Many laboratory-adapted human, monkey, and bovine viruses used integrins, whereas all porcine viruses were integrin independent. The integrin-using rotavirus strains each interacted with all three integrins. Integrin usage related to VP4 serotype independently of sialic acid usage. Analysis of rotavirus reassortants and assays of virus binding and infectivity in integrin-transfected cells showed that VP4 bound α2β1, and VP7 interacted with αXβ2 and αVβ3 at a postbinding stage. DGEA inhibited rotavirus binding to α2β1 and infectivity, whereas GPRP binding to αXβ2 inhibited infectivity but not binding. The truncated VP5* subunit of VP4, expressed as a glutathione S-transferase fusion protein, bound the expressed α2 I domain. Alanine mutagenesis of D308 and G309 in VP5* eliminated VP5* binding to the α2 I domain. In a novel process, integrin-using viruses bind the α2 I domain of α2β1 via DGE in VP4 and interact with αXβ2 (via GPR) and αVβ3 by using VP7 to facilitate cell entry and infection.
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Timoszuk, Magdalena, Katarzyna Bielawska, and Elżbieta Skrzydlewska. "Evening Primrose (Oenothera biennis) Biological Activity Dependent on Chemical Composition." Antioxidants 7, no. 8 (August 14, 2018): 108. http://dx.doi.org/10.3390/antiox7080108.
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Evening primrose (Oenothera L.) is a plant belonging to the family Onagraceae, in which the most numerous species is Oenothera biennis. Some plants belonging to the genus Oenothera L. are characterized by biological activity. Therefore, studies were conducted to determine the dependence of biological activity on the chemical composition of various parts of the evening primrose, mainly leaves, stems, and seeds. Common components of all parts of the Oenothera biennis plants are fatty acids, phenolic acids, and flavonoids. In contrast, primrose seeds also contain proteins, carbohydrates, minerals, and vitamins. Therefore, it is believed that the most interesting sources of biologically active compounds are the seeds and, above all, evening primrose seed oil. This oil contains mainly aliphatic alcohols, fatty acids, sterols, and polyphenols. Evening primrose oil (EPO) is extremely high in linoleic acid (LA) (70–74%) and γ-linolenic acid (GLA) (8–10%), which may contribute to the proper functioning of human tissues because they are precursors of anti-inflammatory eicosanoids. EPO supplementation results in an increase in plasma levels of γ-linolenic acid and its metabolite dihomo-γ-linolenic acid (DGLA). This compound is oxidized by lipoxygenase (15-LOX) to 15-hydroxyeicosatrienoic acid (15-HETrE) or, under the influence of cyclooxygenase (COX), DGLA is metabolized to series 1 prostaglandins. These compounds have anti-inflammatory and anti-proliferative properties. Furthermore, 15-HETrE blocks the conversion of arachidonic acid (AA) to leukotriene A4 (LTA4) by direct inhibition of 5-LOX. In addition, γ-linolenic acid suppresses inflammation mediators such as interleukin 1β (IL-1β), interleukin 6 (IL-6), and cytokine - tumor necrosis factor α (TNF-α). The beneficial effects of EPO have been demonstrated in the case of atopic dermatitis, psoriasis, Sjögren’s syndrome, asthma, and anti-cancer therapy.
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Takahashi, Nobuya, Yasukazu Hozumi, Toshiaki Tanaka, Masashi Okada, Ken Iseki, Kiyoshi Hayasaka, and Kaoru Goto. "Cellular expression and localization of DGKζ-interacting NAP1-like proteins in the brain and functional implications under hypoxic stress." Histochemistry and Cell Biology 142, no. 5 (June 4, 2014): 461–71. http://dx.doi.org/10.1007/s00418-014-1226-x.
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Quon, Evan, Aleksa Nenadic, Mohammad F. Zaman, Jesper Johansen, and Christopher T. Beh. "ER-PM membrane contact site regulation by yeast ORPs and membrane stress pathways." PLOS Genetics 18, no. 3 (March 3, 2022): e1010106. http://dx.doi.org/10.1371/journal.pgen.1010106.
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In yeast, at least seven proteins (Ice2p, Ist2p, Scs2/22p, Tcb1-Tcb3p) affect cortical endoplasmic reticulum (ER) tethering and contact with the plasma membrane (PM). In Δ-super-tether (Δ-s-tether) cells that lack these tethers, cortical ER-PM association is all but gone. Yeast OSBP homologue (Osh) proteins are also implicated in membrane contact site (MCS) assembly, perhaps as subunits for multicomponent tethers, though their function at MCSs involves intermembrane lipid transfer. Paradoxically, when analyzed by fluorescence and electron microscopy, the elimination of the OSH gene family does not reduce cortical ER-PM association but dramatically increases it. In response to the inactivation of all Osh proteins, the yeast E-Syt (extended-synaptotagmin) homologue Tcb3p is post-transcriptionally upregulated thereby generating additional Tcb3p-dependent ER-PM MCSs for recruiting more cortical ER to the PM. Although the elimination of OSH genes and the deletion of ER-PM tether genes have divergent effects on cortical ER-PM association, both elicit the Environmental Stress Response (ESR). Through comparisons of transcriptomic profiles of cells lacking OSH genes or ER-PM tethers, changes in ESR expression are partially manifested through the induction of the HOG (high-osmolarity glycerol) PM stress pathway or the ER-specific UPR (unfolded protein response) pathway, respectively. Defects in either UPR or HOG pathways also increase ER-PM MCSs, and expression of extra “artificial ER-PM membrane staples” rescues growth of UPR mutants challenged with lethal ER stress. Transcriptome analysis of OSH and Δ-s-tether mutants also revealed dysregulation of inositol-dependent phospholipid gene expression, and the combined lethality of osh4Δ and Δ-s-tether mutations is suppressed by overexpression of the phosphatidic acid biosynthetic gene, DGK1. These findings establish that the Tcb3p tether is induced by ER and PM stresses and ER-PM MCSs augment responses to membrane stresses, which are integrated through the broader ESR pathway.
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González-Mancha, Natalia, and Isabel Mérida. "Interplay Between SNX27 and DAG Metabolism in the Control of Trafficking and Signaling at the IS." International Journal of Molecular Sciences 21, no. 12 (June 15, 2020): 4254. http://dx.doi.org/10.3390/ijms21124254.
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Recognition of antigens displayed on the surface of an antigen-presenting cell (APC) by T-cell receptors (TCR) of a T lymphocyte leads to the formation of a specialized contact between both cells named the immune synapse (IS). This highly organized structure ensures cell–cell communication and sustained T-cell activation. An essential lipid regulating T-cell activation is diacylglycerol (DAG), which accumulates at the cell–cell interface and mediates recruitment and activation of proteins involved in signaling and polarization. Formation of the IS requires rearrangement of the cytoskeleton, translocation of the microtubule-organizing center (MTOC) and vesicular compartments, and reorganization of signaling and adhesion molecules within the cell–cell junction. Among the multiple players involved in this polarized intracellular trafficking, we find sorting nexin 27 (SNX27). This protein translocates to the T cell–APC interface upon TCR activation, and it is suggested to facilitate the transport of cargoes toward this structure. Furthermore, its interaction with diacylglycerol kinase ζ (DGKζ), a negative regulator of DAG, sustains the precise modulation of this lipid and, thus, facilitates IS organization and signaling. Here, we review the role of SNX27, DAG metabolism, and their interplay in the control of T-cell activation and establishment of the IS.
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Savenkova, N. D., D. O. Ivanov, O. V. Lubimova, V. N. Barsukova, E. A. Pankov, E. P. Fedotova, and E. M. Dmitrieva. "The use of the drug Elizaria – a biosimilar of the original eculizumab in atypical hemolytic-uremic syndrome due to mutation of the С3 gene in children: clinical observation and literature review." Nephrology (Saint-Petersburg) 27, no. 1 (March 8, 2023): 92–101. http://dx.doi.org/10.36485/1561-6274-2023-27-1-92-101.
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This article presents the features of atypical haemolytic-uremic syndrome (ORPHA 544472) in children. Atypical haemolytic-uremic syndrome (aHUS) is defined by a triad: haemolytic anaemia, thrombocytopenia and acute kidney injury in pediatric and adult patients. The OMIM catalogue presents the phenotypic series of aHUS with mutations of the C3, CFB, CFH, CFHR1, CFHR3, DGKE, MCP, THBD genes. Atypical haemolytic-uremic syndrome is often associated with gene mutations in proteins and activators that regulate complement. We report the case of a girl who had a manifestation of aHUS at 8 years 5 months of age and a severe relapse at 8 years 10 months of age. The relapse was characterised by manifestations of haemolytic anaemia, thrombocytopenia, acute renal damage, severe arterial hypertension, high lactate dehydrogenase and membrane attack complex levels and low C3 component. After 5 courses of haemodialysis, 3 haemodiafiltration, diuresis increased and biochemical parameters improved. We presented with ASUS in a child associated with a p.Cys1101Tyr C3 gene mutation. We used a complement inhibitor, Elizaria®, a biosimilar to the original drug eculizumab, to treat a child with atypical haemolytic-uremic syndrome due to the C3 gene mutation. The complement system inhibitor therapy with Elizaria preserved the health and life of a sick girl with a severe relapse of aHUS.
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Ptiček, Petra, and Ana Milardović. "Hemolytic Uremic Syndrome in Children." Medicina Fluminensis 59, no. 3 (September 1, 2023): 241–50. http://dx.doi.org/10.21860/medflum2023_306341.
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Hemolitičko-uremijski sindrom (HUS) je klinički sindrom koji karakterizira istodobna pojava trombocitopenije i mikroangiopatske hemolitičke anemije uz akutnu bubrežnu ozljedu. Znatnu ulogu u patogenezi bolesti ima nekontrolirana aktivacija sustava komplementa. Prema najnovijoj klasifikaciji razlikuju se nasljedni i stečeni HUS. Za oko 90 % slučajeva HUS-a odgovorna je shiga toksin-producirajuća E. coli (STEC), dok je otprilike polovica ostalih slučajeva uzrokovana mutacijama gena za komponente i regulatorne proteine sustava komplementa. Nasljedni oblik HUS-a može biti povezan i s mutacijama gena THBD, PLG i DGKE ili s poremećenim metabolizmom kobalamina C. Skupini stečenih HUS-eva, posredovanih infekcijama, pripadaju i oni uzrokovani drugim mikroorganizmima kao što su Streptococcus pneumoniae, Shigella dysenteriae, virus influence i HIV. S druge strane, neinfektivni uzroci stečenih HUS-eva mogu biti neželjene posljedice uslijed uzimanja lijekova i posebna stanja poput autoimunih bolesti, stanja nakon transplantacije organa i tkiva te malignih bolesti, ali i protutijela na komponente komplementa. Povrh mokraćnog, HUS može zahvatiti i ostale organske sustave. Dijagnoza HUS-a je klinička i potvrđuje se laboratorijski, a nakon postavljanja dijagnoze određuje se etiologija bolesti. Terapijski postupci, koji se provode prilikom liječenja HUS-a, najvećim su dijelom potporne mjere. Specifični postupci koji se koriste za liječenje HUS-a posredovanog poremećajima komplementa, jesu ekulizumab, plazmafereza i infuzije svježe smrznute plazme te transplantacija bubrega ili simultana transplantacija bubrega i jetre.
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Nair, Vidhya A., Lara J. Bou Malhab, and Wael M. Abdel-Rahman. "Characterization of the Molecular Alterations Induced by the Prolonged Exposure of Normal Colon Mucosa and Colon Cancer Cells to Low-Dose Bisphenol A." International Journal of Molecular Sciences 23, no. 19 (October 1, 2022): 11620. http://dx.doi.org/10.3390/ijms231911620.
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Colorectal cancer is a common cancer with a poor prognosis in both males and females. The influence of bisphenol A (BPA), a widely used environmental contaminant, in colon cancer development and progression is not well identified, in spite of the fact that the most common mode of exposure to BPA is ingestion. The aim of this work is to elucidate the carcinogenic effects of BPA in the colon in vitro. We analyzed BPA’s effects on human colon epithelial (HCoEpiC) and colon cancer (HCT116) cells. BPA exerted cytotoxic effects and augmented the 5FU cytotoxicity on both cell lines at high doses, while it did not show this effect at low doses. Therefore, we focused on studying the effects of low-dose (0.0043 nM) exposure on normal colonic epithelial cells for a long period of time (two months), which is more consistent with environmental exposure levels and patterns. BPA increased cellular invasiveness through collagen and the ability to anchorage-independent cell growth, as measured by colony formation in soft agar, which could support oncogenicity. To gain insights into the mechanism of these actions, we performed transcriptomic analysis using next-generation sequencing, which revealed 340 differentially expressed transcripts by BPA in HCT116 and 75 in HCoEpiC. These transcripts belong in many cancer-related pathways such as apoptosis, cell proliferation, signal transduction, and angiogenesis. Some of the significant genes (FAM83H, CXCL12, PITPNA, HMOX1, DGKZ, NR5A2, VMP1, and ID1) were confirmed by quantitative RT-PCR. Furthermore, BPA induced the phosphorylation of protein kinases such as JNK1/2/3, GSK-3α/β, AMPKα1, AKT1/2/3, AMPKα2, HSP27, β-catenin, STAT2, Hck, Chk2, FAK, and PRAS40 in HCoEpiC, as well as GSK-3α/β, p53, AKT1/2/3, p70 S6 kinase, and WNK1 in HCT116. The majority of these proteins are involved in potential carcinogenic pathways. Taken together, these data suggest that BPA plays a role in colon carcinogenesis, and they provide insights into the molecular mechanisms of colon epithelial cell transformation by BPA. Increasing exposure to environmental toxins such as BPA can explain the increasing incidence of colorectal cancer.
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Li, Jianping, Yang Shen, Yanke Chen, Zhengfeng Zhang, Shaojie Ma, Qianfen Wan, Qiong Tong, Clemens Glaubitz, Maili Liu, and Jun Yang. "Structure of membrane diacylglycerol kinase in lipid bilayers." Communications Biology 4, no. 1 (March 5, 2021). http://dx.doi.org/10.1038/s42003-021-01802-1.
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AbstractDiacylglycerol kinase (DgkA) is a small integral membrane protein, responsible for the ATP-dependent phosphorylation of diacylglycerol to phosphatidic acid. Its structures reported in previous studies, determined in detergent micelles by solution NMR and in monoolein cubic phase by X-ray crystallography, differ significantly. These differences point to the need to validate these detergent-based structures in phospholipid bilayers. Here, we present a well-defined homo-trimeric structure of DgkA in phospholipid bilayers determined by magic angle spinning solid-state NMR (ssNMR) spectroscopy, using an approach combining intra-, inter-molecular paramagnetic relaxation enhancement (PRE)-derived distance restraints and CS-Rosetta calculations. The DgkA structure determined in lipid bilayers is different from the solution NMR structure. In addition, although ssNMR structure of DgkA shows a global folding similar to that determined by X-ray, these two structures differ in monomeric symmetry and dynamics. A comparative analysis of DgkA structures determined in three different detergent/lipid environments provides a meaningful demonstration of the influence of membrane mimetic environments on the structure and dynamics of membrane proteins.
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Chen, Xinyue, Yifei Liu, Junhua Jin, Hui Liu, Yanling Hao, Hongxing Zhang, and Yuanhong Xie. "YbfA Regulates the Sensitivity of Escherichia coli K12 to Plantaricin BM-1 via the BasS/BasR Two-Component Regulatory System." Frontiers in Microbiology 12 (August 17, 2021). http://dx.doi.org/10.3389/fmicb.2021.659198.
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Plantaricin BM-1, a class IIa bacteriocin produced by Lactobacillus plantarum BM-1, shows obvious antibacterial activity against Escherichia coli. However, the mechanism underlying the action of class IIa bacteriocins against gram-negative bacteria remains to be explored. The purpose of this study was to investigate the role of YbfA, a DUF2517 domain-containing protein, in the response of Escherichia coli K12 to plantaricin BM-1. The growth curve experiment and MIC experiment showed that the sensitivity of E. coli to plantaricin BM-1 was decreased by a ybfA null mutation. Electron microscopy showed that the ybfA null mutation reduced the surface rupture and contraction caused by plantaricin BM-1, and mitigated the effect of plantaricin BM-1 on the morphology of the E. coli cell membrane. Proteomics analysis showed that 323 proteins were differentially expressed in E. coli lacking the ybfA gene (P < 0.05); 118 proteins were downregulated, and 205 proteins were upregulated. The metabolic pathways containing the upregulated proteins mainly included outer membrane proteins, integral components of the plasma membrane, regulation of cell motility, and regulation of locomotion. The metabolic pathways involving the downregulated proteins mainly included outer membrane protein glycine betaine transport, amino-acid betaine transport, and transmembrane signaling receptor activity. The results of the proteomics analysis showed that the protein expression of the BasS/BasR two-component system was significantly increased (P < 0.05). Moreover, the expression levels of downstream proteins regulated by this two-component system were also significantly increased, including DgkA, FliC, and MlaE, which are involved in cell membrane structure and function, and RT-qPCR also confirmed this result. The growth curve showed that the sensitivity of E. coli to plantaricin BM-1 was significantly increased due to deletion of the BasS/BasR two-component system. Thus, deletion of ybfA in E. coli can increase the expression of the BasS/BasR two-component system and positively regulate the structure and function of the cell membrane to reduce the sensitivity to plantaricin BM-1. This will help to explore the mechanism of action of class IIa bacteriocins against gram-negative bacteria.
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Gaballa, Ahmed, Martin Wiedmann, and Laura M. Carroll. "More than mcr: canonical plasmid- and transposon-encoded mobilized colistin resistance genes represent a subset of phosphoethanolamine transferases." Frontiers in Cellular and Infection Microbiology 13 (June 8, 2023). http://dx.doi.org/10.3389/fcimb.2023.1060519.
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Mobilized colistin resistance genes (mcr) may confer resistance to the last-resort antimicrobial colistin and can often be transmitted horizontally. mcr encode phosphoethanolamine transferases (PET), which are closely related to chromosomally encoded, intrinsic lipid modification PET (i-PET; e.g., EptA, EptB, CptA). To gain insight into the evolution of mcr within the context of i-PET, we identified 69,814 MCR-like proteins present across 256 bacterial genera (obtained by querying known MCR family representatives against the National Center for Biotechnology Information [NCBI] non-redundant protein database via protein BLAST). We subsequently identified 125 putative novel mcr-like genes, which were located on the same contig as (i) ≥1 plasmid replicon and (ii) ≥1 additional antimicrobial resistance gene (obtained by querying the PlasmidFinder database and NCBI’s National Database of Antibiotic Resistant Organisms, respectively, via nucleotide BLAST). At 80% amino acid identity, these putative novel MCR-like proteins formed 13 clusters, five of which represented putative novel MCR families. Sequence similarity and a maximum likelihood phylogeny of mcr, putative novel mcr-like, and ipet genes indicated that sequence similarity was insufficient to discriminate mcr from ipet genes. A mixed-effect model of evolution (MEME) indicated that site- and branch-specific positive selection played a role in the evolution of alleles within the mcr-2 and mcr-9 families. MEME suggested that positive selection played a role in the diversification of several residues in structurally important regions, including (i) a bridging region that connects the membrane-bound and catalytic periplasmic domains, and (ii) a periplasmic loop juxtaposing the substrate entry tunnel. Moreover, eptA and mcr were localized within different genomic contexts. Canonical eptA genes were typically chromosomally encoded in an operon with a two-component regulatory system or adjacent to a TetR-type regulator. Conversely, mcr were represented by single-gene operons or adjacent to pap2 and dgkA, which encode a PAP2 family lipid A phosphatase and diacylglycerol kinase, respectively. Our data suggest that eptA can give rise to “colistin resistance genes” through various mechanisms, including mobilization, selection, and diversification of genomic context and regulatory pathways. These mechanisms likely altered gene expression levels and enzyme activity, allowing bona fide eptA to evolve to function in colistin resistance.
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Bartoli, J., L. My, Lucid Belmudes, Yohann Couté, J. P. Viala, and E. Bouveret. "The Long Hunt for pssR—Looking for a Phospholipid Synthesis Transcriptional Regulator, Finding the Ribosome." Journal of Bacteriology 199, no. 14 (May 8, 2017). http://dx.doi.org/10.1128/jb.00202-17.
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ABSTRACT The phospholipid (PL) composition of bacterial membranes varies as a function of growth rate and in response to changes in the environment. While growth adaptation can be explained by biochemical feedback in the PL synthesis pathway, recent transcriptome studies have revealed that the expression of PL synthesis genes can also be tuned in response to various stresses. We previously showed that the BasRS two-component pathway controls the expression of the diacylglycerol kinase gene, dgkA, in Escherichia coli (A. Wahl, L. My, R. Dumoulin, J. N. Sturgis, and E. Bouveret, Mol Microbiol, 80:1260–1275, 2011, https://doi.org/10.1111/j.1365-2958.2011.07641.x ). In this study, we set up a strategy to identify the mutation responsible for the upregulation of pssA observed in the historical pssR1 mutant and supposedly corresponding to a transcriptional repressor (C. P. Sparrow and J. Raetz, J Biol Chem, 258:9963–9967, 1983). pssA encodes phosphatidylserine synthase, the first step of phosphatidylethanolamine synthesis. We showed that this mutation corresponded to a single nucleotide change in the anti-Shine-Dalgarno sequence of the 16S rRNA encoded by the rrnC operon. We further demonstrated that this mutation enhanced the translation of pssA. Though this effect appeared to be restricted to PssA among phospholipid synthesis enzymes, it was not specific, as evidenced by a global effect on the production of unrelated proteins. IMPORTANCE Bacteria adjust the phospholipid composition of their membranes to the changing environment. In addition to enzymatic regulation, stress response regulators control specific steps of the phospholipid synthesis pathway. We wanted to identify a potential regulator controlling the expression of the phosphatidylserine synthase gene. We showed that it was not the previously suggested hdfR gene and instead that a mutation in the anti-Shine-Dalgarno sequence of 16S RNA was responsible for an increase in pssA translation. This example underlines the fact that gene expression can be modulated by means other than specific regulatory processes.
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Kalachova, Tetiana, Eliška Škrabálková, Stéphanie Pateyron, Ludivine Soubigou-Taconnat, Nabila Djafi, Sylvie Collin, Juraj Sekereš, et al. "DIACYLGLYCEROL KINASE 5 Participates in Flagellin-Induced Signaling in Arabidopsis." Plant Physiology, July 28, 2022. http://dx.doi.org/10.1093/plphys/kiac354.
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Abstract Flagellin perception is a keystone of pattern-triggered immunity in plants. The recognition of this protein by a plasma membrane receptor complex is the beginning of a signaling cascade that includes protein phosphorylation and the production of reactive oxygen species (ROS). In both Arabidopsis (Arabidopsis thaliana) seedlings and suspension cells, we found that treatment with flg22, a peptide corresponding to the most conserved domain of bacterial flagellin, caused a rapid and transient decrease in the level of phosphatidylinositol 4,5-bisphosphate along with a parallel increase in phosphatidic acid (PA). In suspension cells, inhibitors of either phosphoinositide-dependent phospholipases C (PLC) or diacylglycerol kinases (DGKs) inhibited flg22-triggered PA production and the oxidative burst. In response to flg22, receptor-like kinase-deficient fls2, bak1 and bik1 mutants (FLAGELLIN SENSITIVE 2, BRASSINOSTEROID INSENSITIVE 1–associated kinase 1 and BOTRYTIS-INDUCED KINASE 1, respectively) produced less PA than wild-type (WT) plants, whereas this response did not differ in NADPH oxidase-deficient rbohD (RESPIRATORY BURST OXIDASE HOMOLOG D) plants. Among the DGK-deficient lines tested, the dgk5.1 mutant produced less PA and less ROS after flg22 treatment compared to WT seedlings. In response to flg22, dgk5.1 plants showed lower callose accumulation and impaired resistance to Pseudomonas syringae pv. tomato DC3000 hrcC-. Transcriptomics revealed that the basal expression of defense-related genes was altered in dgk5.1 seedlings compared to the WT. A GFP-DGK5 fusion protein localized to the plasma membrane, where RBOHD and PLC2 (proteins involved in plant immunity) are also located. The role of DGK5 and its enzymatic activity in flagellin signaling and fine-tuning of early immune responses in plant-microbe interactions is discussed.
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Nakano, Tomoyuki, and Kaoru Goto. "Diacylglycerol Kinase ε in Adipose Tissues: A Crosstalk Between Signal Transduction and Energy Metabolism." Frontiers in Physiology 13 (January 27, 2022). http://dx.doi.org/10.3389/fphys.2022.815085.
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Diacylglycerol (DG) is unique in lipid metabolism because it serves not only as an intermediate product for triglyceride synthesis, but also as a signaling molecule that activates proteins containing DG-responsive elements, such as protein kinase C. Consequently, DG acts as a hub between energy metabolism and intracellular signaling. Of DG metabolizing pathways, DG kinase (DGK) phosphorylates DG to produce phosphatidic acid, which also serves as a second messenger. Several lines of evidence suggest that DGK is deeply involved in metabolic diseases such as obesity and insulin resistance. Of DGK isozymes, DGKε is simplest in terms of structure, but it is characterized by substrate specificity toward arachidonoyl-DG. Recently, we have reported that DGKε deficiency promotes adipose tissue remodeling in mice during the course of high fat diet (HFD) feeding regimen including obesity, insulin resistance, and beige adipogenesis. DGKε ablation engenders altered expression of other lipid metabolizing enzymes, including adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and diacylglycerol acyltransferase (DGAT). Subcellular localization of DGKε in the endoplasmic reticulum suggests involvement of this isozyme in lipid energy homeostasis. This review presents current findings of DGKε in lipid-orchestrated pathophysiology, especially unique phenotypes of DGKε-knockout mice in the early and late stages of obesogenic conditions.
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Kunz, Sandra, Anke Tribensky, Wieland Steinchen, Luis Oviedo-Bocanegra, Patricia Bedrunka, and Peter L. Graumann. "Cyclic di-GMP Signaling in Bacillus subtilis Is Governed by Direct Interactions of Diguanylate Cyclases and Cognate Receptors." mBio 11, no. 2 (March 10, 2020). http://dx.doi.org/10.1128/mbio.03122-19.
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ABSTRACT Bacillus subtilis contains two known cyclic di-GMP (c-di-GMP)-dependent receptors, YdaK and DgrA, as well as three diguanylate cyclases (DGCs): soluble DgcP and membrane-integral DgcK and DgcW. DgrA regulates motility, while YdaK is responsible for the formation of a putative exopolysaccharide, dependent on the activity of DgcK. Using single-molecule tracking, we show that a majority of DgcK molecules are statically positioned in the cell membrane but significantly less so in the absence of YdaK but more so upon overproduction of YdaK. The soluble domains of DgcK and of YdaK show a direct interaction in vitro, which depends on an intact I-site within the degenerated GGDEF domain of YdaK. These experiments suggest a direct handover of a second messenger at a single subcellular site. Interestingly, all three DGC proteins contribute toward downregulation of motility via the PilZ protein DgrA. Deletion of dgrA also affects the mobility of DgcK within the membrane and also that of DgcP, which arrests less often at the membrane in the absence of DgrA. Both, DgcK and DgcP interact with DgrA in vitro, showing that divergent as well as convergent direct connections exist between cyclases and their effector proteins. Automated determination of molecule numbers in live cells revealed that DgcK and DgcP are present at very low copy numbers of 6 or 25 per cell, respectively, such that for DgcK, a part of the cell population does not contain any DgcK molecule, rendering signaling via c-di-GMP extremely efficient. IMPORTANCE Second messengers are free to diffuse through the cells and to activate all responsive elements. Cyclic di-GMP (c-di-GMP) signaling plays an important role in the determination of the life style transition between motility and sessility/biofilm formation but involves numerous distinct synthetases (diguanylate cyclases [DGCs]) or receptor pathways that appear to act in an independent manner. Using Bacillus subtilis as a model organism, we show that for two c-di-GMP pathways, DGCs and receptor molecules operate via direct interactions, where a synthesized dinucleotide appears to be directly used for the protein-protein interaction. We show that very few DGC molecules exist within cells; in the case of exopolysaccharide (EPS) formation via membrane protein DgcK, the DGC molecules act at a single site, setting up a single signaling pool within the cell membrane. Using single-molecule tracking, we show that the soluble DGC DgcP arrests at the cell membrane, interacting with its receptor, DgrA, which slows down motility. DgrA also directly binds to DgcK, showing that divergent as well as convergent modules exist in B. subtilis. Thus, local-pool signal transduction operates extremely efficiently and specifically.
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Bimmer, Martin, Martin Reimer, Andreas Klingl, Christina Ludwig, Cordt Zollfrank, Wolfgang Liebl, and Armin Ehrenreich. "Analysis of cellulose synthesis in a high-producing acetic acid bacterium Komagataeibacter hansenii." Applied Microbiology and Biotechnology, March 17, 2023. http://dx.doi.org/10.1007/s00253-023-12461-z.
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Abstract Bacterial cellulose (BC) represents a renewable biomaterial with unique properties promising for biotechnology and biomedicine. Komagataeibacter hansenii ATCC 53,582 is a well-characterized high-yield producer of BC used in the industry. Its genome encodes three distinct cellulose synthases (CS), bcsAB1, bcsAB2, and bcsAB3, which together with genes for accessory proteins are organized in operons of different complexity. The genetic foundation of its high cellulose-producing phenotype was investigated by constructing chromosomal in-frame deletions of the CSs and of two predicted regulatory diguanylate cyclases (DGC), dgcA and dgcB. Proteomic characterization suggested that BcsAB1 was the decisive CS because of its high expression and its exclusive contribution to the formation of microcrystalline cellulose. BcsAB2 showed a lower expression level but contributes significantly to the tensile strength of BC and alters fiber diameter significantly as judged by scanning electron microscopy. Nevertheless, no distinct extracellular polymeric substance (EPS) from this operon was identified after static cultivation. Although transcription of bcsAB3 was observed, expression of the protein was below the detection limit of proteome analysis. Alike BcsAB2, deletion of BcsAB3 resulted in a visible reduction of the cellulose fiber diameter. The high abundance of BcsD and the accessory proteins CmcAx, CcpAx, and BglxA emphasizes their importance for the proper formation of the cellulosic network. Characterization of deletion mutants lacking the DGC genes dgcA and dgcB suggests a new regulatory mechanism of cellulose synthesis and cell motility in K. hansenii ATCC 53,582. Our findings form the basis for rational tailoring of the characteristics of BC. Key points • BcsAB1 induces formation of microcrystalline cellulose fibers. • Modifications by BcsAB2 and BcsAB3 alter diameter of cellulose fibers. • Complex regulatory network of DGCs on cellulose pellicle formation and motility.
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Cooke, Mariana, and Marcelo G. Kazanietz. "Overarching roles of diacylglycerol signaling in cancer development and antitumor immunity." Science Signaling 15, no. 729 (April 12, 2022). http://dx.doi.org/10.1126/scisignal.abo0264.
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Diacylglycerol (DAG) is a lipid second messenger that is generated in response to extracellular stimuli and channels intracellular signals that affect mammalian cell proliferation, survival, and motility. DAG exerts a myriad of biological functions through protein kinase C (PKC) and other effectors, such as protein kinase D (PKD) isozymes and small GTPase-regulating proteins (such as RasGRPs). Imbalances in the fine-tuned homeostasis between DAG generation by phospholipase C (PLC) enzymes and termination by DAG kinases (DGKs), as well as dysregulation in the activity or abundance of DAG effectors, have been widely associated with tumor initiation, progression, and metastasis. DAG is also a key orchestrator of T cell function and thus plays a major role in tumor immunosurveillance. In addition, DAG pathways shape the tumor ecosystem by arbitrating the complex, dynamic interaction between cancer cells and the immune landscape, hence representing powerful modifiers of immune checkpoint and adoptive T cell–directed immunotherapy. Exploiting the wide spectrum of DAG signals from an integrated perspective could underscore meaningful advances in targeted cancer therapy.
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Cai, Xiao, Chen Yang, Jin Chen, Weibo Gong, Faping Yi, Wei Liao, Rongzhong Huang, Liang Xie, and Jian Zhou. "Proteomic Insights Into Susceptibility and Resistance to Chronic-Stress-Induced Depression or Anxiety in the Rat Striatum." Frontiers in Molecular Biosciences 8 (October 5, 2021). http://dx.doi.org/10.3389/fmolb.2021.730473.
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Chronic stress is a key factor for the onset of anxiety and depression disorders. However, the stress-induced common and unique molecular basis of the two psychiatric disorders is not fully known and still needs to be explored. Previously, we employed a chronic mild stress (CMS) procedure to induce a rat model including depression-susceptible (Dep-Sus), anxiety-susceptible (Anx-Sus), and insusceptible (Insus) cohorts. In this work, we continuously analyze the striatal proteomes of the three stressed cohorts by the use of comparative proteomics and bioinformatics approaches. Through isobaric tags for relative and absolute quantitation (iTRAQ)-based analysis, 386 abnormally expressed proteins in total were identified. These deregulated proteins are involved in various biological functions and significant pathways that are potentially connected with resistance and susceptibility to CMS-caused anxious- or depressive-like behaviors and, hence, could act as suggestive protein targets. A further parallel reaction monitoring-based independent investigation shows that alterations in Pak5, Dgkg, Scn4b, Rb1cc1, and Acin1; Ggps1, Fntb, Nudt19, Ufd1, and Ndufab1; and Dnajb12, Hbb2, Ap2s1, Ip6k1, and Stk4 were specifically connected with Dep-Sus, Anx-Sus, or Insus groups, respectively, potentially indicating that identical CMS treatment results in the different changes in the striatal protein regulations. Overall, our current proteomics study of the striatum provides an important molecular foundation and comprehensive insights into common and specific deregulations correlated with pathophysiological mechanisms that underlie resistance and susceptibility to chronic stress–induced anxiety or depression.
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Niu, Rui-Ze, Wan-Qing Feng, Qing-Shan Yu, Lan-Lan Shi, Qing-Min Qin, and Jia Liu. "Integrated analysis of plasma proteome and cortex single-cell transcriptome reveals the novel biomarkers during cortical aging." Frontiers in Aging Neuroscience 15 (July 19, 2023). http://dx.doi.org/10.3389/fnagi.2023.1063861.
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BackgroundWith the increase of age, multiple physiological functions of people begin gradually degenerating. Regardless of natural aging or pathological aging, the decline in cognitive function is one of the most obvious features in the process of brain aging. Brain aging is a key factor for several neuropsychiatric disorders and for most neurodegenerative diseases characterized by onset typically occurring late in life and with worsening of symptoms over time. Therefore, the early prevention and intervention of aging progression are particularly important. Since there is no unified conclusion about the plasma diagnostic biomarkers of brain aging, this paper innovatively employed the combined multi-omics analysis to delineate the plasma markers of brain aging.MethodsIn order to search for specific aging markers in plasma during cerebral cortex aging, we used multi-omics analysis to screen out differential genes/proteins by integrating two prefrontal cortex (PFC) single-nucleus transcriptome sequencing (snRNA-seq) datasets and one plasma proteome sequencing datasets. Then plasma samples were collected from 20 young people and 20 elder people to verify the selected differential genes/proteins with ELISA assay.ResultsWe first integrated snRNA-seq data of the post-mortem human PFC and generated profiles of 65,064 nuclei from 14 subjects across adult (44–58 years), early-aging (69–79 years), and late-aging (85–94 years) stages. Seven major cell types were classified based on established markers, including oligodendrocyte, excitatory neurons, oligodendrocyte progenitor cells, astrocytes, microglia, inhibitory neurons, and endotheliocytes. A total of 93 cell-specific genes were identified to be significantly associated with age. Afterward, plasma proteomics data from 2,925 plasma proteins across 4,263 young adults to nonagenarians (18–95 years old) were combined with the outcomes from snRNA-seq data to obtain 12 differential genes/proteins (GPC5, CA10, DGKB, ST6GALNAC5, DSCAM, IL1RAPL2, TMEM132C, VCAN, APOE, PYH1R, CNTN2, SPOCK3). Finally, we verified the 12 differential genes by ELISA and found that the expression trends of five biomarkers (DSCAM, CNTN2, IL1RAPL2, CA10, GPC5) were correlated with brain aging.ConclusionFive differentially expressed proteins (DSCAM, CNTN2, IL1RAPL2, CA10, GPC5) can be considered as one of the screening indicators of brain aging, and provide a scientific basis for clinical diagnosis and intervention.
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Takic, Marija, Milica Zekovic, Brankica Terzic, Aleksandar Stojsavljevic, Mirjana Mijuskovic, Slavica Radjen, and Danijela Ristic-Medic. "Zinc Deficiency, Plasma Fatty Acid Profile and Desaturase Activities in Hemodialysis Patients: Is Supplementation Necessary?" Frontiers in Nutrition 8 (September 23, 2021). http://dx.doi.org/10.3389/fnut.2021.700450.
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Background: Desaturation and elongation are critical processes in endogenous metabolic fatty acid pathways. Zinc (Zn) is a cofactor for desaturases and elongases enzymes. There is limited evidence regarding the relationships between biomarkers of Zn status, nutritional intake, plasma phospholipid fatty acid profile and clinical outcomes among patients undergoing hemodialysis (HD).Objective: To examine the relationships between dietary and serum levels of Zn and Cu/Zn ratio and to explore associations of these micronutrients with PUFA profile and estimated desaturase and elongase enzyme activities in serum phospholipids among HD patients.Methods: This study included 40 adult patients undergoing hemodialysis treatment. Repeated 24-h recalls were applied for dietary intake assessment. Serum concentration of Zn and Cu were determined using inductively coupled plasma mass spectrometry and fatty acid composition by gas-liquid chromatography. Desaturase and elongase activities were calculated from product-precursor fatty acid ratios.Results: Inadequate dietary Zn intake was found in 55% of HD patients. They all had serum Zn concentration below the reference value of 60 μg/dL (mean 38.8 ± 7.72 μg/dL). Adequate zinc intake was accompanied with significantly higher intake of energy, total fats, SFA, MUFA and proteins. There was no correlation between Zn serum status and Zn intake estimates. Serum Cu/Zn ratio was high, (2.76 ± 0.68), directly and significantly associated with HD period, CRP, BMI, VFA, and inversely with Kt/V, albumin, iron, and iPTH. The n-6/n-3 ratio in plasma phospholipids was elevated (12.25 ± 3.45) and patients with inadequate Zn intake had lower n-3 PUFA intake and status compared to those with adequate intake. Serum Zn concentrations were inversely correlated with linoleic/dihomo-γ-linolenic acid ratio (LA/DGLA) (p = 0.037), related to D6-desaturase activity (p = 0.033) and directly with DGLA relative abundances (p = 0.024). Cu status was inversely associated with EPA level (p = 0.03) and estimates of elongase activity (p = 0.001). Furthermore, positive relationship was found between the Cu/Zn ratio and determined elongase value (p = 0.01).Conclusion: Findings of this study underpin the high prevalence of Zn deficiency and inadequate n-3 PUFA intake and status among subjects undergoing HD. The results obtained indicate that the assessment of Zn status should be a standard parameter of nutritional status screening in HD patients while emphasizing the importance of Cu/Zn determination. Although further research is warranted, Zn and-n-3 PUFA supplementation in HD patients might be beneficial for the prevention and attenuation of adverse health outcomes
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Emam, Mohamed, Khalil Eslamloo, Albert Caballero-Solares, Evandro Kleber Lorenz, Xi Xue, Navaneethaiyer Umasuthan, Hajarooba Gnanagobal, et al. "Nutritional immunomodulation of Atlantic salmon response to Renibacterium salmoninarum bacterin." Frontiers in Molecular Biosciences 9 (September 21, 2022). http://dx.doi.org/10.3389/fmolb.2022.931548.
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We investigated the immunomodulatory effect of varying levels of dietary ω6/ω3 fatty acids (FA) on Atlantic salmon (Salmo salar) antibacterial response. Two groups were fed either high-18:3ω3 or high-18:2ω6 FA diets for 8 weeks, and a third group was fed for 4 weeks on the high-18:2ω6 diet followed by 4 weeks on the high-18:3ω3 diet and termed “switched-diet”. Following the second 4 weeks of feeding (i.e., at 8 weeks), head kidney tissues from all groups were sampled for FA analysis. Fish were then intraperitoneally injected with either a formalin-killed Renibacterium salmoninarum bacterin (5 × 107 cells mL−1) or phosphate-buffered saline (PBS control), and head kidney tissues for gene expression analysis were sampled at 24 h post-injection. FA analysis showed that the head kidney profile reflected the dietary FA, especially for C18 FAs. The qPCR analyses of twenty-three genes showed that both the high-ω6 and high-ω3 groups had significant bacterin-dependent induction of some transcripts involved in lipid metabolism (ch25ha and lipe), pathogen recognition (clec12b and tlr5), and immune effectors (znrf1 and cish). In contrast, these transcripts did not significantly respond to the bacterin in the “switched-diet” group. Concurrently, biomarkers encoding proteins with putative roles in biotic inflammatory response (tnfrsf6b) and dendritic cell maturation (ccl13) were upregulated, and a chemokine receptor (cxcr1) was downregulated with the bacterin injection regardless of the experimental diets. On the other hand, an inflammatory regulator biomarker, bcl3, was only significantly upregulated in the high-ω3 fed group, and a C-type lectin family member (clec3a) was only significantly downregulated in the switched-diet group with the bacterin injection (compared with diet-matched PBS-injected controls). Transcript fold-change (FC: bacterin/PBS) showed that tlr5 was significantly over 2-fold higher in the high-18:2ω6 diet group compared with other diet groups. FC and FA associations highlighted the role of DGLA (20:3ω6; anti-inflammatory) and/or EPA (20:5ω3; anti-inflammatory) vs. ARA (20:4ω6; pro-inflammatory) as representative of the anti-inflammatory/pro-inflammatory balance between eicosanoid precursors. Also, the correlations revealed associations of FA proportions (% total FA) and FA ratios with several eicosanoid and immune receptor biomarkers (e.g., DGLA/ARA significant positive correlation with pgds, 5loxa, 5loxb, tlr5, and cxcr1). In summary, dietary FA profiles and/or regimens modulated the expression of some immune-relevant genes in Atlantic salmon injected with R. salmoninarum bacterin. The modulation of Atlantic salmon responses to bacterial pathogens and their associated antigens using high-ω6/high-ω3 diets warrants further investigation.
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González-Mancha, Natalia, Cristina Rodríguez-Rodríguez, Andrés Alcover, and Isabel Merida. "Sorting Nexin 27 Enables MTOC and Secretory Machinery Translocation to the Immune Synapse." Frontiers in Immunology 12 (January 12, 2022). http://dx.doi.org/10.3389/fimmu.2021.814570.
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Sorting nexin 27 (SNX27) association to the retromer complex mediates intracellular trafficking of cargoes containing PSD95/Dlg1/ZO-1 (PDZ)-binding C-terminal sequences from endosomes to the cell surface, preventing their lysosomal degradation. Antigen recognition by T lymphocyte leads to the formation of a highly organized structure named the immune synapse (IS), which ensures cell-cell communication and sustained T cell activation. At the neuronal synapse, SNX27 recycles PDZ-binding receptors and its defective expression is associated with synaptic dysfunction and cognitive impairment. In T lymphocytes, SNX27 was found localized at recycling endosomal compartments that polarized to the IS, suggesting a function in polarized traffic to this structure. Proteomic analysis of PDZ-SNX27 interactors during IS formation identify proteins with known functions in cytoskeletal reorganization and lipid regulation, such as diacylglycerol (DAG) kinase (DGK) ζ, as well as components of the retromer and WASH complex. In this study, we investigated the consequences of SNX27 deficiency in cytoskeletal reorganization during IS formation. Our analyses demonstrate that SNX27 controls the polarization towards the cell-cell interface of the PDZ-interacting cargoes DGKζ and the retromer subunit vacuolar protein sorting protein 26, among others. SNX27 silencing abolishes the formation of a DAG gradient at the IS and prevents re-localization of the dynactin complex component dynactin-1/p150Glued, two events that correlate with impaired microtubule organizing center translocation (MTOC). SNX27 silenced cells show marked alteration in cytoskeleton organization including a failure in the organization of the microtubule network and defects in actin clearance at the IS. Reduced SNX27 expression was also found to hinder the arrangement of signaling microclusters at the IS, as well as the polarization of the secretory machinery towards the antigen presenting cells. Our results broaden the knowledge of SNX27 function in T lymphocytes by showing a function in modulating IS organization through regulated trafficking of cargoes.
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Kim, Hyo-Eun, Kyung Mi Park, Dasom Lee, So-Ra Lee, Sang-Woon Kim, Tae Soon Hwang, and Kyung-Won Hong. "Direct-to-Consumer Genetic Test and Lifestyle Questionnaire Analysis of Body Mass Index and Body Fat Percentage in a Large Korean Population." Journal of Disease Markers 8, no. 1 (February 20, 2023). http://dx.doi.org/10.26420/jdismarkers.2023.1051.
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Background: Direct-to-Consumer (DTC) genetic testing provides genetic risk to consumers and motivates consumers to take care of their own customized health care. In 2018, we developed and provided a DTC genetic testing service (GENESTART™) in collaboration with Herbalife Korea Co. Ltd. Methods: The analyzed dataset consisted of the body fat percentage (BFP), body mass index (BMI), 31 genetic polymorphism genotypes, and responses to 19 questionnaire items of 24,447 individuals. The genetic main effects for BFP and BMI were examined by linear regression analysis, and the interaction effects were examined using a generalized linear model that controlled age and sex as covariates. Results: In the case of BFP, the sample average was 31.47% overall, 24.76% for men, and 32.79% for women, showing that men had an average BFP that was 8 percentage points lower than that of women. The average BMI was 25.38 overall, 26.45 for men, and 25.17 for women, showing that men had an average BMI of 1.2 kg/m2 higher than that of women. The FTO and MC4R genes, well-known obesity markers, showed a significant correlation with both phenotypes, and the BDNF gene, which is related to stress obesity, showed a highly significant association with BMI but only a weak association with BFP. Among the remaining genes, TRIB1, ABCA1, MYL2, G6PC, GCKR, GLIS3, CYP17A1, HECTD4, and NT5C2 genes showed significant associations with the obesity-related phenotypes. In this study, we found four interaction results for BFP (ABO and fruits, CYP1A2 and sugary foods, FTO and muscle exercise, MC4R and vitamins) and five interactions for BMI (MC4R and proteins, CSK and fruits, MC4R and calcium, DGKB and calcium, CSK and water). Conclusions: This study is expected to enable the provision of personalized and accurate solutions for BFP and BMI management to customers who have undergone genetic testing.