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1
Tokarska-Schlattner, Malgorzata, Nour Zeaiter, Valérie Cunin, Stéphane Attia, Cécile Meunier, Laurence Kay, Amel Achouri et al. "Multi-Method Quantification of Acetyl-Coenzyme A and Further Acyl-Coenzyme A Species in Normal and Ischemic Rat Liver". International Journal of Molecular Sciences 24, n. 19 (6 ottobre 2023): 14957. http://dx.doi.org/10.3390/ijms241914957.
Testo completoAbstract (sommario):
Thioesters of coenzyme A (CoA) carrying different acyl chains (acyl-CoAs) are central intermediates of many metabolic pathways and donor molecules for protein lysine acylation. Acyl-CoA species largely differ in terms of cellular concentrations and physico-chemical properties, rendering their analysis challenging. Here, we compare several approaches to quantify cellular acyl-CoA concentrations in normal and ischemic rat liver, using HPLC and LC-MS/MS for multi-acyl-CoA analysis, as well as NMR, fluorimetric and spectrophotometric techniques for the quantification of acetyl-CoAs. In particular, we describe a simple LC-MS/MS protocol that is suitable for the relative quantification of short and medium-chain acyl-CoA species. We show that ischemia induces specific changes in the short-chain acyl-CoA relative concentrations, while mild ischemia (1–2 min), although reducing succinyl-CoA, has little effects on acetyl-CoA, and even increases some acyl-CoA species upstream of the tricarboxylic acid cycle. In contrast, advanced ischemia (5–6 min) also reduces acetyl-CoA levels. Our approach provides the keys to accessing the acyl-CoA metabolome for a more in-depth analysis of metabolism, protein acylation and epigenetics.
2
Han, Lijuan, Ling Zhao, Yong Zhou, Chao Yang, Teng Xiong, Lin Lu, Yusheng Deng et al. "Altered metabolome and microbiome features provide clues in understanding irritable bowel syndrome and depression comorbidity". ISME Journal 16, n. 4 (8 novembre 2021): 983–96. http://dx.doi.org/10.1038/s41396-021-01123-5.
Testo completoAbstract (sommario):
AbstractIrritable bowel syndrome (IBS) is one of the functional gastrointestinal disorders characterized by chronic and/or recurrent symptoms of abdominal pain and irregular defecation. Changed gut microbiota has been proposed to mediate IBS; however, contradictory results exist, and IBS-specific microbiota, metabolites, and their interactions remain poorly understood. To address this issue, we performed metabolomic and metagenomic profiling of stool and serum samples based on discovery (n = 330) and validation (n = 101) cohorts. Fecal metagenomic data showed moderate dysbiosis compared with other diseases, in contrast, serum metabolites showed significant differences with greater power to distinguish IBS patients from healthy controls. Specifically, 726 differentially abundant serum metabolites were identified, including a cluster of fatty acyl-CoAs enriched in IBS. We further identified 522 robust associations between differentially abundant gut bacteria and fecal metabolites, of which three species including Odoribacter splanchnicus, Escherichia coli, and Ruminococcus gnavus were strongly associated with the low abundance of dihydropteroic acid. Moreover, dysregulated tryptophan/serotonin metabolism was found to be correlated with the severity of IBS depression in both fecal and serum metabolomes, characterized by a shift in tryptophan metabolism towards kynurenine production. Collectively, our study revealed serum/fecal metabolome alterations and their relationship with gut microbiome, highlighted the massive alterations of serum metabolites, which empower to recognize IBS patients, suggested potential roles of metabolic dysregulation in IBS pathogenesis, and offered new clues to understand IBS depression comorbidity. Our study provided a valuable resource for future studies, and would facilitate potential clinical applications of IBS featured microbiota and/or metabolites.
3
IGAL, R. Ariel, Ping WANG e Rosalind A. COLEMAN. "Triacsin C blocks de novo synthesis of glycerolipids and cholesterol esters but not recycling of fatty acid into phospholipid: evidence for functionally separate pools of acyl-CoA". Biochemical Journal 324, n. 2 (1 giugno 1997): 529–34. http://dx.doi.org/10.1042/bj3240529.
Testo completoAbstract (sommario):
The trafficking of acyl-CoAs within cells is poorly understood. In order to determine whether newly synthesized acyl-CoAs are equally available for the synthesis of all glycerolipids and cholesterol esters, we incubated human fibroblasts with [14C]oleate, [3H]arachidonate or [3H]glycerol in the presence or absence of triacsin C, a fungal metabolite that is a competitive inhibitor of acyl-CoA synthetase. Triacsin C inhibited de novo synthesis from glycerol of triacylglycerol, diacylglycerol and cholesterol esters by more than 93%, and the synthesis of phospholipid by 83%. However, the incorporation of oleate or arachidonate into phospholipids appeared to be relatively unimpaired when triacsin was present. Diacylglycerol acyltransferase and lysophosphatidylcholine acyltransferase had similar dependences on palmitoyl-CoA in both liver and fibroblasts; thus it did not appear that acyl-CoAs, when present at low concentrations, would be preferentially used to acylate lysophospholipids. We interpret these data to mean that, when fatty acid is not limiting, triacsin blocks the acylation of glycerol 3-phosphate and diacylglycerol, but not the reacylation of lysophospholipids. Two explanations are possible: (1) different acyl-CoA synthetases exist that vary in their sensitivity to triacsin; (2) an independent mechanism channels acyl-CoA towards phospholipid synthesis when little acyl-CoA is available. In either case, the acyl-CoAs available to acylate cholesterol, glycerol 3-phosphate, lysophosphatidic acid and diacylglycerol and those acyl-CoAs that are used by lysophospholipid acyltransferases and by ceramide N-acyltransferase must reside in two non-mixing acyl-CoA pools or, when acyl-CoAs are limiting, they must be selectively channelled towards specific acyltransferase reactions.
4
Pons, Roser, e Darryl C. De Vivo. "Primary and Secondary Carnitine Deficiency Syndromes". Journal of Child Neurology 10, n. 2_suppl (novembre 1995): 2S8–2S24. http://dx.doi.org/10.1177/0883073895010002s03.
Testo completoAbstract (sommario):
The objective of this article is to review primary and secondary causes of carnitine deficiency, emphasizing recent advances in our knowledge of fatty acid oxidation. It is now understood that the cellular metabolism of fatty acids requires the cytosolic carnitine cycle and the mitochondrial β-oxidation cycle. Carnitine is central to the translocation of the long chain acyl-CoAs across the inner mitochondrial membrane. The mitochondrial β-oxidation cycle is composed of a newly described membrane-bound system and the classic matrix compartment system. Very long chain acyl-CoA dehydrogenase and the trifunctional enzyme complex are embedded in the inner mitochondrial membrane, and metabolize the long chain acyl-CoAs. The chain shortened acyl-CoAs are further degraded by the well-known system in the mitochondrial matrix. Numerous metabolic errors have been described in the two cycles of fatty acid oxidation; all are transmitted as autosomal recessive traits. Primary or secondary carnitine deficiency is present in all these clinical conditions except carnitine palmitoyltransferase type I and the classic adult form of carnitine palmitoyltransferase type II deficiency. The sole example of primary carnitine deficiency is the genetic defect involving the active transport across the plasmalemmal membrane. This condition responds dramatically to oral carnitine therapy. The secondary carnitine deficiencies respond less obviously to carnitine replacement. These conditions are managed by high carbohydrate, low fat frequent feedings, and vitamin/cofactor supplementation (eg, carnitine, glycine, and riboflavin). Medium chain triglycerides may be useful in the dietary management of patients with inborn errors of the cytosolic carnitine cycle or the mitochondrial membrane-bound long chain specific β-oxidation system. (J Child Neurol 1995;10(Suppl):2S8-2S24).
5
Yu, Wenfeng, Xiquan Liang, Regina E. Ensenauer, Jerry Vockley, Lawrence Sweetman e Horst Schulz. "Leaky β-Oxidation of atrans-Fatty Acid". Journal of Biological Chemistry 279, n. 50 (4 ottobre 2004): 52160–67. http://dx.doi.org/10.1074/jbc.m409640200.
Testo completoAbstract (sommario):
The degradation of elaidic acid (9-trans-octadecenoic acid), oleic acid, and stearic acid by rat mitochondria was studied to determine whether the presence of atransdouble bond in place of acisdouble bond or no double bond affects β-oxidation. Rat mitochondria from liver or heart effectively degraded the coenzyme A derivatives of all three fatty acids. However, with elaidoyl-CoA as a substrate, a major metabolite accumulated in the mitochondrial matrix. This metabolite was isolated and identified as 5-trans-tetradecenoyl-CoA. In contrast, little or none of the corresponding metabolites were detected with oleoyl-CoA or stearoyl-CoA as substrates. A kinetic study of long-chain acyl-CoA dehydrogenase (LCAD) and very long-chain acyl-CoA dehydrogenase revealed that 5-trans-tetradecenoyl-CoA is a poorer substrate of LCAD than is 5-cis-tetradecenoyl-CoA, while both unsaturated acyl-CoAs are poor substrates of very long-chain acyl-CoA dehydrogenase when compared with myristoyl-CoA. Tetradecenoic acid and tetradecenoylcarnitine were detected by gas chromatography/mass spectrometry and tandem mass spectrometry, respectively, when rat liver mitochondria were incubated with elaidoyl-CoA but not when oleoyl-CoA was the substrate. These observations support the conclusion that 5-trans-tetradecenoyl-CoA accumulates in the mitochondrial matrix, because it is less efficiently dehydrogenated by LCAD than is itscisisomer and that the accumulation of this β-oxidation intermediate facilitates its hydrolysis and conversion to 5-trans-tetradecenoylcarnitine thereby permitting a partially degraded fatty acid to escape from mitochondria. Analysis of this compromised but functional process provides insight into the operation of β-oxidation in intact mitochondria.
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Varner, Erika L., Sophie Trefely, David Bartee, Eliana von Krusenstiern, Luke Izzo, Carmen Bekeova, Roddy S. O'Connor et al. "Quantification of lactoyl-CoA (lactyl-CoA) by liquid chromatography mass spectrometry in mammalian cells and tissues". Open Biology 10, n. 9 (settembre 2020): 200187. http://dx.doi.org/10.1098/rsob.200187.
Testo completoAbstract (sommario):
Lysine lactoylation is a recently described protein post-translational modification (PTM). However, the biochemical pathways responsible for this acylation remain unclear. Two metabolite-dependent mechanisms have been proposed: enzymatic histone lysine lactoylation derived from lactoyl-coenzyme A (lactoyl-CoA, also termed lactyl-CoA), and non-enzymatic lysine lactoylation resulting from acyl-transfer via lactoyl-glutathione. While the former has precedent in the form of enzyme-catalysed lysine acylation, the lactoyl-CoA metabolite has not been previously quantified in mammalian systems. Here, we use liquid chromatography–high-resolution mass spectrometry (LC-HRMS) together with a synthetic standard to detect and validate the presence of lactoyl-CoA in cell and tissue samples. Conducting a retrospective analysis of data from previously analysed samples revealed the presence of lactoyl-CoA in diverse cell and tissue contexts. In addition, we describe a biosynthetic route to generate 13 C 3 15 N 1 -isotopically labelled lactoyl-CoA, providing a co-eluting internal standard for analysis of this metabolite. We estimate lactoyl-CoA concentrations of 1.14 × 10 −8 pmol per cell in cell culture and 0.0172 pmol mg −1 tissue wet weight in mouse heart. These levels are similar to crotonyl-CoA, but between 20 and 350 times lower than predominant acyl-CoAs such as acetyl-, propionyl- and succinyl-CoA. Overall our studies provide the first quantitative measurements of lactoyl-CoA in metazoans, and provide a methodological foundation for the interrogation of this novel metabolite in biology and disease.
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Xia, Chuanwu, Zhuji Fu, Kevin P. Battaile e Jung-Ja P. Kim. "Crystal structure of human mitochondrial trifunctional protein, a fatty acid β-oxidation metabolon". Proceedings of the National Academy of Sciences 116, n. 13 (8 marzo 2019): 6069–74. http://dx.doi.org/10.1073/pnas.1816317116.
Testo completoAbstract (sommario):
Membrane-bound mitochondrial trifunctional protein (TFP) catalyzes β-oxidation of long chain fatty acyl-CoAs, employing 2-enoyl-CoA hydratase (ECH), 3-hydroxyl-CoA dehydrogenase (HAD), and 3-ketothiolase (KT) activities consecutively. Inherited deficiency of TFP is a recessive genetic disease, manifesting in hypoketotic hypoglycemia, cardiomyopathy, and sudden death. We have determined the crystal structure of human TFP at 3.6-Å resolution. The biological unit of the protein is α2β2. The overall structure of the heterotetramer is the same as that observed by cryo-EM methods. The two β-subunits make a tightly bound homodimer at the center, and two α-subunits are bound to each side of the β2dimer, creating an arc, which binds on its concave side to the mitochondrial innermembrane. The catalytic residues in all three active sites are arranged similarly to those of the corresponding, soluble monofunctional enzymes. A structure-based, substrate channeling pathway from the ECH active site to the HAD and KT sites is proposed. The passage from the ECH site to the HAD site is similar to those found in the two bacterial TFPs. However, the passage from the HAD site to the KT site is unique in that the acyl-CoA intermediate can be transferred between the two sites by passing along the mitochondrial inner membrane using the hydrophobic nature of the acyl chain. The 3′-AMP-PPi moiety is guided by the positively charged residues located along the “ceiling” of the channel, suggesting that membrane integrity is an essential part of the channel and is required for the activity of the enzyme.
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Lone, Museer A., Andreas J. Hülsmeier, Essa M. Saied, Gergely Karsai, Christoph Arenz, Arnold von Eckardstein e Thorsten Hornemann. "Subunit composition of the mammalian serine-palmitoyltransferase defines the spectrum of straight and methyl-branched long-chain bases". Proceedings of the National Academy of Sciences 117, n. 27 (23 giugno 2020): 15591–98. http://dx.doi.org/10.1073/pnas.2002391117.
Testo completoAbstract (sommario):
Sphingolipids (SLs) are chemically diverse lipids that have important structural and signaling functions within mammalian cells. SLs are commonly defined by the presence of a long-chain base (LCB) that is normally formed by the conjugation ofl-serine and palmitoyl-CoA. This pyridoxal 5-phosphate (PLP)-dependent reaction is mediated by the enzyme serine-palmitoyltransferase (SPT). However, SPT can also metabolize other acyl-CoAs, in the range of C14to C18, forming a variety of LCBs that differ by structure and function. Mammalian SPT consists of three core subunits: SPTLC1, SPTLC2, and SPTLC3. Whereas SPTLC1 and SPTLC2 are ubiquitously expressed, SPTLC3 expression is restricted to certain tissues only. The influence of the individual subunits on enzyme activity is not clear. Using cell models deficient in SPTLC1, SPTLC2, and SPTLC3, we investigated the role of each subunit on enzyme activity and the LCB product spectrum. We showed that SPTLC1 is essential for activity, whereas SPTLC2 and SPTLC3 are partly redundant but differ in their enzymatic properties. SPTLC1 in combination with SPTLC2 specifically formed C18, C19, and C20 LCBs while the combination of SPTLC1 and SPTLC3 yielded a broader product spectrum. We identifiedanteiso-branched-C18 SO (meC18SO) as the primary product of the SPTLC3 reaction. The meC18SO was synthesized fromanteiso-methyl-palmitate, in turn synthesized from a precursor metabolite generated in the isoleucine catabolic pathway. The meC18SO is metabolized to ceramides and complex SLs and is a constituent of human low- and high-density lipoproteins.
9
Carrer, Alessandro, Joshua L. D. Parris, Sophie Trefely, Ryan A. Henry, David C. Montgomery, AnnMarie Torres, John M. Viola et al. "Impact of a High-fat Diet on Tissue Acyl-CoA and Histone Acetylation Levels". Journal of Biological Chemistry 292, n. 8 (11 gennaio 2017): 3312–22. http://dx.doi.org/10.1074/jbc.m116.750620.
Testo completoAbstract (sommario):
Cellular metabolism dynamically regulates the epigenome via availability of the metabolite substrates of chromatin-modifying enzymes. The impact of diet on the metabolism-epigenome axis is poorly understood but could alter gene expression and influence metabolic health. ATP citrate-lyase produces acetyl-CoA in the nucleus and cytosol and regulates histone acetylation levels in many cell types. Consumption of a high-fat diet (HFD) results in suppression of ATP citrate-lyase levels in tissues such as adipose and liver, but the impact of diet on acetyl-CoA and histone acetylation in these tissues remains unknown. Here we examined the effects of HFD on levels of acyl-CoAs and histone acetylation in mouse white adipose tissue (WAT), liver, and pancreas. We report that mice consuming a HFD have reduced levels of acetyl-CoA and/or acetyl-CoA:CoA ratio in these tissues. In WAT and the pancreas, HFD also impacted the levels of histone acetylation; in particular, histone H3 lysine 23 acetylation was lower in HFD-fed mice. Genetic deletion of Acly in cultured adipocytes also suppressed acetyl-CoA and histone acetylation levels. In the liver, no significant effects on histone acetylation were observed with a HFD despite lower acetyl-CoA levels. Intriguingly, acetylation of several histone lysines correlated with the acetyl-CoA: (iso)butyryl-CoA ratio in liver. Butyryl-CoA and isobutyryl-CoA interacted with the acetyltransferase P300/CBP-associated factor (PCAF) in liver lysates and inhibited its activity in vitro. This study thus provides evidence that diet can impact tissue acyl-CoA and histone acetylation levels and that acetyl-CoA abundance correlates with acetylation of specific histone lysines in WAT but not in the liver.
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Wu, Hao, Jingdan Liang, Lixia Gou, Qiulin Wu, Wei-Jun Liang, Xiufen Zhou, Ian J. Bruce, Zixin Deng e Zhijun Wang. "Recycling of Overactivated Acyls by a Type II Thioesterase during Calcimycin Biosynthesis in Streptomyces chartreusis NRRL 3882". Applied and Environmental Microbiology 84, n. 12 (13 aprile 2018): e00587-18. http://dx.doi.org/10.1128/aem.00587-18.
Testo completoAbstract (sommario):
ABSTRACT Type II thioesterases typically function as editing enzymes, removing acyl groups that have been misconjugated to acyl carrier proteins during polyketide secondary metabolite biosynthesis as a consequence of biosynthetic errors. Streptomyces chartreusis NRRL 3882 produces the pyrrole polyether ionophoric antibiotic, and we have identified the presence of a putative type II thioesterase-like sequence, calG, within the biosynthetic gene cluster involved in the antibiotic's synthesis. However, targeted gene mutagenesis experiments in which calG was inactivated in the organism did not lead to a decrease in calcimycin production but rather reduced the strain's production of its biosynthetic precursor, cezomycin. Results from in vitro activity assays of purified, recombinant CalG protein indicated that it was involved in the hydrolysis of cezomycin coenzyme A (cezomycin-CoA), as well as other acyl CoAs, but was not active toward 3-S-N-acetylcysteamine (SNAC; the mimic of the polyketide chain-releasing precursor). Further investigation of the enzyme's activity showed that it possessed a cezomycin-CoA hydrolysis Km of 0.67 mM and a kcat of 17.77 min−1 and was significantly inhibited by the presence of Mn2+ and Fe2+ divalent cations. Interestingly, when S. chartreusis NRRL 3882 was cultured in the presence of inorganic nitrite, NaNO2, it was observed that the production of calcimycin rather than cezomycin was promoted. Also, supplementation of S. chartreusis NRRL 3882 growth medium with the divalent cations Ca2+, Mg2+, Mn2+, and Fe2+ had a similar effect. Taken together, these observations suggest that CalG is not responsible for megasynthase polyketide precursor chain release during the synthesis of calcimycin or for retaining the catalytic efficiency of the megasynthase enzyme complex as is supposed to be the function for type II thioesterases. Rather, our results suggest that CalG is a dedicated thioesterase that prevents the accumulation of cezomycin-CoA when intracellular nitrogen is limited, an apparently new and previously unreported function of type II thioesterases. IMPORTANCE Type II thioesterases (TEIIs) are generally regarded as being responsible for removing aberrant acyl groups that block polyketide production, thereby maintaining the efficiency of the megasynthase involved in this class of secondary metabolites' biosynthesis. Specifically, this class of enzyme is believed to be involved in editing misprimed precursors, controlling initial units, providing key intermediates, and releasing final synthetic products in the biosynthesis of this class of secondary metabolites. Our results indicate that the putative TEII CalG present in the calcimycin (A23187)-producing organism Streptomyces chartreusis NRRL 3882 is not important either for the retention of catalytic efficiency of, or for the release of the product compound from, the megasynthase involved in calcimycin biosynthesis. Rather, the enzyme is involved in regulating/controlling the pool size of the calcimycin biosynthetic precursor, cezomycin, by hydrolysis of its CoA derivative. This novel function of CalG suggests a possible additional activity for enzymes belonging to the TEII protein family and promotes better understanding of the overall biosynthetic mechanisms involved in the production of this class of secondary metabolites.
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Ozols, Juris. "Degradation of Hepatic Stearyl CoA Δ9-Desaturase". Molecular Biology of the Cell 8, n. 11 (novembre 1997): 2281–90. http://dx.doi.org/10.1091/mbc.8.11.2281.
Testo completoAbstract (sommario):
Δ9-Desaturase is a key enzyme in the synthesis of desaturated fatty acyl-CoAs. Desaturase is an integral membrane protein induced in the endoplasmic reticulum by dietary manipulations and then rapidly degraded. The proteolytic machinery that specifically degrades desaturase and other short-lived proteins in the endoplasmic reticulum has not been identified. As the first step in identifying cellular factors involved in the degradation of desaturase, liver subcellular fractions of rats that had undergone induction of this enzyme were examined. In livers from induced animals, desaturase was present in the microsomal, nuclear (P-1), and subcellular fractions (P-2). Incubation of desaturase containing fractions at physiological pH and temperature led to the complete disappearance of the enzyme. Washing microsomes with a buffer containing high salt decreased desaturase degradation activity. N-terminal sequence analysis of desaturase freshly isolated from the P-1 fraction without incubation indicated the absence of three residues from the N terminus, but the mobility of this desaturase preparation on SDS-PAGE was identical to the microsomal desaturase, which contains a masked N terminus under similar purification procedures. Addition of concentrated cytosol or the high-salt wash fraction did not enhance the desaturase degradation in the washed microsomes. Extensive degradation of desaturase in the high-salt washed microsomes could be restored by supplementation of the membranes with the lipid and protein components essential for the reconstituted desaturase catalytic activity. Lysosomotrophic agents leupeptin and pepstatin A were ineffective in inhibiting desaturase degradation. The calpain inhibitor, N-acetyl-leucyl-leucyl-methional, or the proteosome inhibitor, Streptomyces metabolite, lactacystin, did not inhibit the degradation of desaturase in the microsomal or the P-1 and P-2 fractions. These results show that the selective degradation of desaturase is likely to be independent of the lysosomal and the proteosome systems. The reconstitution of complete degradation of desaturase in the high-salt–washed microsomes by the components essential for its catalytic activity reflects that the degradation of this enzyme may depend on a specific orientation of desaturase and intramembranous interactions between desaturase and the responsible protease.
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Chen, Keting, Liza E. Alexander, Umnia Mahgoub, Yozo Okazaki, Yasuhiro Higashi, Ann M. Perera, Lucas J. Showman et al. "Dynamic relationships among pathways producing hydrocarbons and fatty acids of maize silk cuticular waxes". Plant Physiology, 27 marzo 2024. http://dx.doi.org/10.1093/plphys/kiae150.
Testo completoAbstract (sommario):
Abstract The hydrophobic cuticle is the first line of defense between aerial portions of plants and the external environment. On maize (Zea mays L.) silks, the cuticular cutin matrix is infused with cuticular waxes, consisting of a homologous series of very long-chain fatty acids (VLCFAs), aldehydes, and hydrocarbons. Together with VLC fatty-acyl-CoAs (VLCFA-CoAs), these metabolites serve as precursors, intermediates and end-products of the cuticular wax biosynthetic pathway. To deconvolute the potentially confounding impacts of the change in silk microenvironment and silk development on this pathway, we profiled cuticular waxes on the silks of the inbreds B73 and Mo17, and their reciprocal hybrids. Multivariate interrogation of these metabolite abundance data demonstrates that VLCFA-CoAs and total free VLCFAs are positively correlated with the cuticular wax metabolome, and this metabolome is primarily affected by changes in the silk microenvironment and plant genotype. Moreover, the genotype effect on the pathway explains the increased accumulation of cuticular hydrocarbons with a concomitant reduction in cuticular VLCFA accumulation on B73 silks, suggesting that the conversion of VLCFA-CoAs to hydrocarbons is more effective in B73 than Mo17. Statistical modeling of the ratios between cuticular hydrocarbons and cuticular VLCFAs reveals a significant role of precursor chain length in determining this ratio. This study establishes the complexity of the product–precursor relationships within the silk cuticular wax-producing network by dissecting both the impact of genotype and the allocation of VLCFA-CoA precursors to different biological processes, and demonstrates that longer chain VLCFA-CoAs are preferentially utilized for hydrocarbon biosynthesis.
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Lee, Jennifer, Archana Vijayakumar, Phillip J. White, Yuping Xu, Olga Ilkayeva, Christopher J. Lynch, Christopher B. Newgard e Barbara B. Kahn. "BCAA Supplementation in Mice with Diet-induced Obesity Alters the Metabolome Without Impairing Glucose Homeostasis". Endocrinology 162, n. 7 (25 marzo 2021). http://dx.doi.org/10.1210/endocr/bqab062.
Testo completoAbstract (sommario):
Abstract Circulating branched chain amino acid (BCAA) levels are elevated in obese humans and genetically obese rodents. However, the relationship of BCAAs to insulin resistance in diet-induced obese mice, a commonly used model to study glucose homeostasis, is still ill-defined. Here we examined how high-fat high-sucrose (HFHS) or high-fat diet (HFD) feeding, with or without BCAA supplementation in water, alters the metabolome in serum/plasma and tissues in mice and whether raising circulating BCAA levels worsens insulin resistance and glucose intolerance. Neither HFHS nor HFD feeding raised circulating BCAA levels in insulin-resistant diet-induced obese mice. BCAA supplementation raised circulating BCAA and branched-chain α-keto acid levels and C5-OH/C3-DC acylcarnitines (AC) in muscle from mice fed an HFHS diet or HFD, but did not worsen insulin resistance. A set of short- and long-chain acyl CoAs were elevated by diet alone in muscle, liver, and white adipose tissue (WAT), but not increased further by BCAA supplementation. HFD feeding reduced valine and leucine oxidation in WAT but not in muscle. BCAA supplementation markedly increased valine oxidation in muscle from HFD-fed mice, while leucine oxidation was unaffected by diet or BCAA treatment. Here we establish an extensive metabolome database showing tissue-specific changes in mice on 2 different HFDs, with or without BCAA supplementation. We conclude that mildly elevating circulating BCAAs and a subset of ACs by BCAA supplementation does not worsen insulin resistance or glucose tolerance in mice. This work highlights major differences in the effects of BCAAs on glucose homeostasis in diet-induced obese mice versus data reported in obese rats and in humans.
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Sekiya, Motohiro, Kenta Kainoh, Takehito Sugasawa, Ryunosuke Yoshino, Takatsugu Hirokawa, Hiroaki Tokiwa, Shogo Nakano et al. "The transcriptional corepressor CtBP2 serves as a metabolite sensor orchestrating hepatic glucose and lipid homeostasis". Nature Communications 12, n. 1 (2 novembre 2021). http://dx.doi.org/10.1038/s41467-021-26638-5.
Testo completoAbstract (sommario):
AbstractBiological systems to sense and respond to metabolic perturbations are critical for the maintenance of cellular homeostasis. Here we describe a hepatic system in this context orchestrated by the transcriptional corepressor C-terminal binding protein 2 (CtBP2) that harbors metabolite-sensing capabilities. The repressor activity of CtBP2 is reciprocally regulated by NADH and acyl-CoAs. CtBP2 represses Forkhead box O1 (FoxO1)-mediated hepatic gluconeogenesis directly as well as Sterol Regulatory Element-Binding Protein 1 (SREBP1)-mediated lipogenesis indirectly. The activity of CtBP2 is markedly defective in obese liver reflecting the metabolic perturbations. Thus, liver-specific CtBP2 deletion promotes hepatic gluconeogenesis and accelerates the progression of steatohepatitis. Conversely, activation of CtBP2 ameliorates diabetes and hepatic steatosis in obesity. The structure-function relationships revealed in this study identify a critical structural domain called Rossmann fold, a metabolite-sensing pocket, that is susceptible to metabolic liabilities and potentially targetable for developing therapeutic approaches.
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Ussher, John Edward R., Timothy R. Koves, Jagdip S. Jaswal, Christopher B. Newgard, Jason R. Dyck, Deborah M. Muoio e Gary D. Lopaschuk. "Abstract 5381: Insulin-Stimulated Glucose Oxidation is Increased in Hearts from High Fat Diet-Induced Obese Mice Lacking Malonyl CoA Decarboxylase". Circulation 118, suppl_18 (28 ottobre 2008). http://dx.doi.org/10.1161/circ.118.suppl_18.s_539.
Testo completoAbstract (sommario):
OBJECTIVE - Diet-induced obesity (DIO) leads to an accumulation of intra-myocardial fatty acid metabolites that have been proposed to cause myocardial insulin resistance and dysfunction. Our goal was to determine the effect of DIO on myocardial fatty acid metabolite accumulation and how this is altered when mitochondrial fatty acid uptake is inhibited. This was achieved by using mice lacking malonyl CoA decarboxylase (MCD−/−), which have higher levels of malonyl CoA, an endogenous inhibitor of mitochondrial fatty acid uptake. METHODS - Wild type (WT) and MCD−/− mice were fed a low (4% kcal from lard) or high (60% kcal from lard) fat diet for 12 weeks to determine the effect of DIO on the intra-myocardial accumulation of long chain acylcarnitines, long chain acyl CoAs, triglycerides (TGs), and ceramides. A parallel feeding study was performed to assess myocardial function and energy metabolism in isolated working hearts in the absence/presence of insulin. RESULTS - We demonstrate that MCD−/− mice do not accumulate intramyocardial long chain acylcarnitines to the same extent as WT mice following DIO (0.56 ± 0.10 vs. 0.28 ± 0.07 pmol myristoylcarnitine/mg protein, P <0.05), but do accumulate similar amounts of long chain acyl CoAs (3.88 ± 0.34 vs. 4.35 ± 1.19 nmol/g wet weight). Interestingly, DIO only lead to an accumulation of TGs in the hearts of MCD−/− mice (3.29 ± 0.62 vs. 10.92 ± 3.72 μmol/g wet weight, P <0.05). Despite this elevation in TGs, MCD−/− mice showed increased insulin-stimulated glucose oxidation (2.46 ± 0.25 vs. 1.74 ± 0.18 fold increase, P <0.05) during aerobic isolated working heart perfusions and did not elicit any dysfunction. CONCLUSIONS - Our data reveal discordance between myocardial TG accumulation and glucose metabolism, suggesting that TG buffers against toxic lipids, and that inhibition of mitochondrial fatty acid oxidation does not cause myocardial dysfunction following DIO.
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Dibble, Christian C., Samuel A. Barritt, Grace E. Perry, Evan C. Lien, Renee C. Geck, Sarah E. DuBois-Coyne, David Bartee et al. "PI3K drives the de novo synthesis of coenzyme A from vitamin B5". Nature, 27 luglio 2022. http://dx.doi.org/10.1038/s41586-022-04984-8.
Testo completoAbstract (sommario):
AbstractIn response to hormones and growth factors, the class I phosphoinositide-3-kinase (PI3K) signalling network functions as a major regulator of metabolism and growth, governing cellular nutrient uptake, energy generation, reducing cofactor production and macromolecule biosynthesis1. Many of the driver mutations in cancer with the highest recurrence, including in receptor tyrosine kinases, Ras, PTEN and PI3K, pathologically activate PI3K signalling2,3. However, our understanding of the core metabolic program controlled by PI3K is almost certainly incomplete. Here, using mass-spectrometry-based metabolomics and isotope tracing, we show that PI3K signalling stimulates the de novo synthesis of one of the most pivotal metabolic cofactors: coenzyme A (CoA). CoA is the major carrier of activated acyl groups in cells4,5 and is synthesized from cysteine, ATP and the essential nutrient vitamin B5 (also known as pantothenate)6,7. We identify pantothenate kinase 2 (PANK2) and PANK4 as substrates of the PI3K effector kinase AKT8. Although PANK2 is known to catalyse the rate-determining first step of CoA synthesis, we find that the minimally characterized but highly conserved PANK49 is a rate-limiting suppressor of CoA synthesis through its metabolite phosphatase activity. Phosphorylation of PANK4 by AKT relieves this suppression. Ultimately, the PI3K–PANK4 axis regulates the abundance of acetyl-CoA and other acyl-CoAs, CoA-dependent processes such as lipid metabolism and proliferation. We propose that these regulatory mechanisms coordinate cellular CoA supplies with the demands of hormone/growth-factor-driven or oncogene-driven metabolism and growth.
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Nolen, Rayna M., Lene H. Petersen, Karl Kaiser, Antonietta Quigg e David Hala. "In silico biomarker analysis of the adverse effects of perfluorooctane sulfonate (PFOS) exposure on the metabolic physiology of embryo-larval zebrafish". Frontiers in Systems Biology 4 (27 marzo 2024). http://dx.doi.org/10.3389/fsysb.2024.1367562.
Testo completoAbstract (sommario):
Perfluorooctane sulfonate (PFOS) is a ubiquitous pollutant in global aquatic ecosystems with increasing concern for its toxicity to aquatic wildlife through inadvertent exposures. To assess the likely adverse effects of PFOS exposure on aquatic wildlife inhabiting polluted ecosystems, there is a need to identify biomarkers of its exposure and toxicity. We used an integrated systems toxicological framework to identify physiologically relevant biomarkers of PFOS toxicity in fish. An in silico stoichiometric metabolism model of zebrafish (Danio rerio) was used to integrate available (published by other authors) metabolomics and transcriptomics datasets from in vivo toxicological studies with 5 days post fertilized embryo-larval life stage of zebrafish. The experimentally derived omics datasets were used as constraints to parameterize an in silico mathematical model of zebrafish metabolism. In silico simulations using flux balance analysis (FBA) and its extensions showed prominent effects of PFOS exposure on the carnitine shuttle and fatty acid oxidation. Further analysis of metabolites comprising the impacted metabolic reactions indicated carnitine to be the most highly represented cofactor metabolite. Flux simulations also showed a near dose-responsive increase in the pools for fatty acids and acyl-CoAs under PFOS exposure. Taken together, our integrative in silico results showed dyslipidemia effects under PFOS exposure and uniquely identified carnitine as a candidate metabolite biomarker. The verification of this prediction was sought in a subsequent in vivo environmental monitoring study by the authors which showed carnitine to be a modal biomarker of PFOS exposure in wild-caught fish and marine mammals sampled from the northern Gulf of Mexico. Therefore, we highlight the efficacy of FBA to study the properties of large-scale metabolic networks and to identify biomarkers of pollutant exposure in aquatic wildlife.