Littérature scientifique sur le sujet « Vacuolar acidification »
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Articles de revues sur le sujet "Vacuolar acidification"
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Yamashiro, C. T., P. M. Kane, D. F. Wolczyk, R. A. Preston et T. H. Stevens. « Role of vacuolar acidification in protein sorting and zymogen activation : a genetic analysis of the yeast vacuolar proton-translocating ATPase ». Molecular and Cellular Biology 10, no 7 (juillet 1990) : 3737–49. http://dx.doi.org/10.1128/mcb.10.7.3737-3749.1990.
Texte intégralRésumé :
Vacuolar acidification has been proposed to play a key role in a number of cellular processes, including protein sorting, zymogen activation, and maintenance of intracellular pH. We investigated the significance of vacuolar acidification by cloning and mutagenizing the gene for the yeast vacuolar proton-translocating ATPase 60-kilodalton subunit (VAT2). Cells carrying a vat2 null allele were viable; however, these cells were severely defective for growth in medium buffered at neutral pH. Vacuoles isolated from cells bearing the vat2 null allele were completely devoid of vacuolar ATPase activity. The pH of the vacuolar lumen of cells bearing the vat2 mutation was 7.1, compared with the wild-type pH of 6.1, as determined by a flow cytometric pH assay. These results indicate that the vacuolar proton-translocating ATPase complex is essential for vacuolar acidification and that the low-pH state of the vacuole is crucial for normal growth. The vacuolar acidification-defective vat2 mutant exhibited normal zymogen activation but displayed a minor defect in vacuolar protein sorting.
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Yamashiro, C. T., P. M. Kane, D. F. Wolczyk, R. A. Preston et T. H. Stevens. « Role of vacuolar acidification in protein sorting and zymogen activation : a genetic analysis of the yeast vacuolar proton-translocating ATPase. » Molecular and Cellular Biology 10, no 7 (juillet 1990) : 3737–49. http://dx.doi.org/10.1128/mcb.10.7.3737.
Texte intégralRésumé :
Vacuolar acidification has been proposed to play a key role in a number of cellular processes, including protein sorting, zymogen activation, and maintenance of intracellular pH. We investigated the significance of vacuolar acidification by cloning and mutagenizing the gene for the yeast vacuolar proton-translocating ATPase 60-kilodalton subunit (VAT2). Cells carrying a vat2 null allele were viable; however, these cells were severely defective for growth in medium buffered at neutral pH. Vacuoles isolated from cells bearing the vat2 null allele were completely devoid of vacuolar ATPase activity. The pH of the vacuolar lumen of cells bearing the vat2 mutation was 7.1, compared with the wild-type pH of 6.1, as determined by a flow cytometric pH assay. These results indicate that the vacuolar proton-translocating ATPase complex is essential for vacuolar acidification and that the low-pH state of the vacuole is crucial for normal growth. The vacuolar acidification-defective vat2 mutant exhibited normal zymogen activation but displayed a minor defect in vacuolar protein sorting.
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Morano, K. A., et D. J. Klionsky. « Differential effects of compartment deacidification on the targeting of membrane and soluble proteins to the vacuole in yeast ». Journal of Cell Science 107, no 10 (1 octobre 1994) : 2813–24. http://dx.doi.org/10.1242/jcs.107.10.2813.
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Lysosomal/vacuolar protein targeting is dependent on compartment acidification. In yeast, sorting of soluble vacuolar proteins such as carboxypeptidase Y is sensitive to acute changes in vacuolar pH. In contrast, the vacuolar membrane protein alkaline phosphatase is missorted only under conditions of chronic deacidification. We have undertaken a temporal analysis to define further the relationship between compartment acidification and sorting of soluble and membrane vacuolar proteins. Depletion of either the Vma3p or Vma4p subunits of the yeast vacuolar ATPase over time resulted in loss of vacuolar ATPase activity and vacuolar acidification. A kinetic delay in processing of carboxypeptidase Y occurred concomitant with these physiological changes while transport of alkaline phosphatase remained unaffected. Carboxypeptidase S, another vacuolar hydrolase that transits through the secretory pathway as an integral membrane protein, displayed a pH sensitivity similar to that of soluble vacuolar proteins. These results indicate that compartment acidification is tightly coupled to efficient targeting of proteins to the vacuole and that there may be multiple distinct mechanisms for targeting of vacuolar membrane proteins.
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Chen, Shuliang, Maureen Tarsio, Patricia M. Kane et Miriam L. Greenberg. « Cardiolipin Mediates Cross-Talk between Mitochondria and the Vacuole ». Molecular Biology of the Cell 19, no 12 (décembre 2008) : 5047–58. http://dx.doi.org/10.1091/mbc.e08-05-0486.
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Cardiolipin (CL) is an anionic phospholipid with a dimeric structure predominantly localized in the mitochondrial inner membrane, where it is closely associated with mitochondrial function, biogenesis, and genome stability ( Daum, 1985 ; Janitor and Subik, 1993 ; Jiang et al., 2000 ; Schlame et al., 2000 ; Zhong et al., 2004 ). Previous studies have shown that yeast mutant cells lacking CL due to a disruption in CRD1, the structural gene encoding CL synthase, exhibit defective colony formation at elevated temperature even on glucose medium ( Jiang et al., 1999 ; Zhong et al., 2004 ), suggesting a role for CL in cellular processes apart from mitochondrial bioenergetics. In the current study, we present evidence that the crd1Δ mutant exhibits severe vacuolar defects, including swollen vacuole morphology and loss of vacuolar acidification, at 37°C. Moreover, vacuoles from crd1Δ show decreased vacuolar H+-ATPase activity and proton pumping, which may contribute to loss of vacuolar acidification. Deletion mutants in RTG2 and NHX1, which mediate vacuolar pH and ion homeostasis, rescue the defective colony formation phenotype of crd1Δ, strongly suggesting that the temperature sensitivity of crd1Δ is a consequence of the vacuolar defects. Our results demonstrate the existence of a novel mitochondria-vacuole signaling pathway mediated by CL synthesis.
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Raymond, C. K., I. Howald-Stevenson, C. A. Vater et T. H. Stevens. « Morphological classification of the yeast vacuolar protein sorting mutants : evidence for a prevacuolar compartment in class E vps mutants. » Molecular Biology of the Cell 3, no 12 (décembre 1992) : 1389–402. http://dx.doi.org/10.1091/mbc.3.12.1389.
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The collection of vacuolar protein sorting mutants (vps mutants) in Saccharomyces cerevisiae comprises of 41 complementation groups. The vacuoles in these mutant strains were examined using immunofluorescence microscopy. Most of the vps mutants were found to possess vacuolar morphologies that differed significantly from wild-type vacuoles. Furthermore, mutants representing independent vps complementation groups were found to share aberrant morphological features. Six distinct classes of vacuolar morphology were observed. Mutants from eight vps complementation groups were defective both for vacuolar segregation from mother cells into developing buds and for acidification of the vacuole. Another group of mutants, represented by 13 complementation groups, accumulated a novel organelle distinct from the vacuole that contained a late-Golgi protein, active vacuolar H(+)-ATPase complex, and soluble vacuolar hydrolases. We suggest that this organelle may represent an exaggerated endosome-like compartment. None of the vps mutants appeared to mislocalize significant amounts of the vacuolar membrane protein alkaline phosphatase. Quantitative immunoprecipitations of the soluble vacuolar hydrolase carboxypeptidase Y (CPY) were performed to determine the extent of the sorting defect in each vps mutant. A good correlation between morphological phenotype and the extent of the CPY sorting defect was observed.
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Raymond, C. K., P. J. O'Hara, G. Eichinger, J. H. Rothman et T. H. Stevens. « Molecular analysis of the yeast VPS3 gene and the role of its product in vacuolar protein sorting and vacuolar segregation during the cell cycle. » Journal of Cell Biology 111, no 3 (1 septembre 1990) : 877–92. http://dx.doi.org/10.1083/jcb.111.3.877.
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vps3 mutants of the yeast Saccharomyces cerevisiae are impaired in the sorting of newly synthesized soluble vacuolar proteins and in the acidification of the vacuole (Rothman, J. H., and T. H. Stevens. Cell. 47:1041-1051; Rothman, J. H., C. T. Yamashiro, C. K. Raymond, P. M. Kane, and T. H. Stevens. 1989. J. Cell Biol. 109:93-100). The VPS3 gene, which was cloned using a novel selection procedure, encodes a low abundance, hydrophilic protein of 117 kD that most likely resides in the cytoplasm. Yeast strains bearing a deletion of the VPS3 gene (vps3-delta 1) are viable, yet their growth rate is significantly reduced relative to wild-type cells. Temperature shift experiments with strains carrying a temperature conditional vps3 allele demonstrate that cells rapidly lose the capacity to sort the vacuolar protein carboxypeptidase Y upon loss of VPS3 function. Vacuolar morphology was examined in wild-type and vps3-delta 1 yeast strains by fluorescence microscopy. The vacuoles in wild-type yeast cells are morphologically complex, and they appear to be actively partitioned between mother cells and buds during an early phase of bud growth. Vacuolar morphology in vps3-delta 1 mutants is significantly altered from the wild-type pattern, and the vacuolar segregation process seen in wild-type strains is defective in these mutants. With the exception of a vacuolar acidification defect, the phenotypes of vps3-delta 1 strains are significantly different from those of mutants lacking the vacuolar proton-translocating ATPase. These data demonstrate that the acidification defect in vps3-delta 1 cells is not the primary cause of the pleiotropic defects in vacuolar function observed in these mutants.
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Rothman, J. H., C. T. Yamashiro, C. K. Raymond, P. M. Kane et T. H. Stevens. « Acidification of the lysosome-like vacuole and the vacuolar H+-ATPase are deficient in two yeast mutants that fail to sort vacuolar proteins. » Journal of Cell Biology 109, no 1 (1 juillet 1989) : 93–100. http://dx.doi.org/10.1083/jcb.109.1.93.
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Organelle acidification plays a demonstrable role in intracellular protein processing, transport, and sorting in animal cells. We investigated the relationship between acidification and protein sorting in yeast by treating yeast cells with ammonium chloride and found that this lysosomotropic agent caused the mislocalization of a substantial fraction of the newly synthesized vacuolar (lysosomal) enzyme proteinase A (PrA) to the cell surface. We have also determined that a subset of the vpl mutants, which are deficient in sorting of vacuolar proteins (Rothman, J. H., and T. H. Stevens. 1986. Cell. 47:1041-1051; Rothman, J. H., I. Howald, and T. H. Stevens. EMBO [Eur. Mol. Biol. Organ.] J. In press), failed to accumulate the lysosomotropic fluorescent dye quinacrine within their vacuoles, mimicking the phenotype of wild-type cells treated with ammonium. The acidification defect of vpl3 and vpl6 mutants correlated with a marked deficiency in vacuolar ATPase activity, diminished levels of two immunoreactive subunits of the protontranslocating ATPase (H+-ATPase) in purified vacuolar membranes, and accumulation of the intracellular portion of PrA as the precursor species. Therefore, some of the VPL genes are required for the normal function of the yeast vacuolar H+-ATPase complex and may encode either subunits of the enzyme or components required for its assembly and targeting. Collectively, these findings implicate a critical role for acidification in vacuolar protein sorting and zymogen activation in yeast, and suggest that components of the yeast vacuolar acidification system may be identified by examining mutants defective in sorting of vacuolar proteins.
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Klionsky, D. J., H. Nelson, N. Nelson et D. S. Yaver. « Mutations in the yeast vacuolar ATPase result in the mislocalization of vacuolar proteins. » Journal of Experimental Biology 172, no 1 (1 novembre 1992) : 83–92. http://dx.doi.org/10.1242/jeb.172.1.83.
Texte intégralRésumé :
The vacuolar ATPase of the yeast Saccharomyces cerevisiae acidifies the vacuolar lumen and generates an electrochemical gradient across the vacuole membrane. We have investigated the role of compartment acidification of the vacuolar system in the sorting of vacuolar proteins. Strains with chromosomal disruptions of genes (delta vat) encoding the A (69 x 10(3) M(r)), B (57 x 10(3) M(r)) or c (16 x 10(3) M(r)) subunits of the vacuolar ATPase accumulate and secrete precursor forms of the soluble vacuolar hydrolases carboxypeptidase Y and proteinase A. A kinetic analysis suggests that these precursor proteins accumulate in, and are secreted from, the Golgi complex or post-Golgi vesicles. In addition, subcellular fractionation shows that vacuolar hydrolase-invertase hybrid proteins are inefficiently localized to the vacuole in delta vat strains. This result suggests that the vat mutations cause a steady-state defect in vacuolar protein sorting. The vat mutations also affect the sorting of vacuolar membrane proteins. Precursor forms of alkaline phosphatase are accumulated in vat mutant cells, but to a lesser extent than is seen for the soluble vacuolar hydrolases. This finding, coupled with the insensitivity of alkaline phosphatase to the ATPase inhibitor bafilomycin A1, suggests that vacuolar membrane protein sorting is less sensitive to changes in lumenal pH when compared with the targeting of soluble vacuolar proteins. These results indicate that acidification of the vacuolar system is important for efficient sorting of soluble proteins to the vacuole.
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Banta, L. M., J. S. Robinson, D. J. Klionsky et S. D. Emr. « Organelle assembly in yeast : characterization of yeast mutants defective in vacuolar biogenesis and protein sorting. » Journal of Cell Biology 107, no 4 (1 octobre 1988) : 1369–83. http://dx.doi.org/10.1083/jcb.107.4.1369.
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Yeast vacuole protein targeting (vpt) mutants exhibit defects in the sorting and processing of multiple vacuolar hydrolases. To evaluate the impact these vpt mutations have on the biogenesis and functioning of the lysosome-like vacuole, we have used light and electron microscopic techniques to analyze the vacuolar morphology in the mutants. These observations have permitted us to assign the vpt mutants to three distinct classes. The class A vpt mutants (26 complementation groups) contain 1-3 large vacuoles that are morphologically indistinguishable from those in the parental strain, suggesting that only a subset of the proteins destined for delivery to this compartment is mislocalized. One class A mutant (vpt13) is very sensitive to low pH and exhibits a defect in vacuole acidification. Consistent with a potential role for vacuolar pH in protein sorting, we found that bafilomycin A1, a specific inhibitor of the vacuolar ATPase, as well as the weak base ammonium acetate and the proton ionophore carbonyl cyanide m-chlorophenylhydrazone, collapse the pH gradient across the vacuolar membrane and cause the missorting and secretion of two vacuolar hydrolases in wild-type cells. Mutants in the three class B vpt complementation groups exhibit a fragmented vacuole morphology. In these mutants, no large normal vacuoles are observed. Instead, many (20-40) smaller vacuole-like organelles accumulate. The class C vpt mutants, which constitute four complementation groups, exhibit extreme defects in vacuole biogenesis. The mutants lack any organelle resembling a normal vacuole but accumulate other organelles including vesicles, multilamellar membrane structures, and Golgi-related structures. Heterozygous class C zygotes reassemble normal vacuoles rapidly, indicating that some of the accumulated aberrant structures may be intermediates in vacuole formation. These class C mutants also exhibit sensitivity to osmotic stress, suggesting an osmoregulatory role for the vacuole. The vpt mutants should provide insights into the normal physiological role of the vacuole, as well as allowing identification of components required for vacuole protein sorting and/or vacuole assembly.
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Steele-Mortimer, Olivia, Maryse St-Louis, Martin Olivier et B. Brett Finlay. « Vacuole Acidification Is Not Required for Survival ofSalmonella enterica Serovar Typhimurium within Cultured Macrophages and Epithelial Cells ». Infection and Immunity 68, no 9 (1 septembre 2000) : 5401–4. http://dx.doi.org/10.1128/iai.68.9.5401-5404.2000.
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ABSTRACT Phagosome acidification is an important component of the microbicidal response by infected eukaryotic cells. Thus, intracellular pathogens that reside within phagosomes must either block phagosome acidification or be able to survive at low pH. In this work, we studied the effect of phagosomal acidification on the survival of intracellular Salmonella enterica serovar Typhimurium in different cell types. Bafilomycin A1, a specific inhibitor of the vacuolar proton-ATPases, was used to block acidification of salmonella-containing vacuoles. We found that in several epithelial cell lines, treatment with bafilomycin A1 had no effect on intracellular survival or replication. Furthermore, although acidification was essential for Salmonella intracellular survival in J774 cultured macrophages, as reported previously (13), it is not essential in other macrophage cell lines. These data suggest that vacuolar acidification may play a role in intracellular survival of salmonellae only under certain conditions and in specific cell types.
Thèses sur le sujet "Vacuolar acidification"
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Kriegel, Anne [Verfasser], et Karin [Akademischer Betreuer] Schumacher. « Vacuolar acidification relies on the combined activity of endomembrane proton pumps / Anne Kriegel ; Betreuer : Karin Schumacher ». Heidelberg : Universitätsbibliothek Heidelberg, 2016. http://d-nb.info/1180613961/34.
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Rousselle, Anthony. « Role of the (Pro)renin Receptor [(P)RR/ATP6ap2] in Osteoclast and Macrophage Physiology ». Doctoral thesis, Humboldt-Universität zu Berlin, 2017. http://dx.doi.org/10.18452/18599.
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Vor zehn Jahren wurde der (Pro)Renin-Rezeptor [(P)RR] entdeckt und als neuer Bestandteil des Renin-Angiotensin-Systems beschrieben. Neuere Studien ergaben, dass der (P)RR mit der vakuolären H+-ATPase (V-ATPase) assoziiert sein kann, weshalb er auch V-ATPase associated protein 2 (ATP6ap2) genannt wird.
In Osteoklasten befinden sich V-ATPase hauptsächlich an der zur Knochenoberfläche gerichteten Plasmamembran und transportieren Protonen in den extrazellulären Raum. Mäuse mit genetischer Deletion verschiedener V-ATPase-Untereinheiten charakterisiert durch einen Anstieg von Knochenmasse (Osteopetrose). In der vorliegenden Arbeit fanden wir heraus, dass (P)RR stark in reifen Osteoklasten in vitro und in vivo exprimiert wird. Mäuse mit genetischer Deletion des (P)RR in Osteoklasten wurden durch einen komplexen Knochen-Phänotyp mit reduzierter Knochendichte charakterisiert. (P)RR-defiziten Osteoklasten wiesen vermehrte Differenzierung und/oder Aktivität in vitro und in vivo auf. Wir postulieren deshalb, dass der (P)RR die in der Plasmamembran lokalisierten V-ATPase nicht direkt reguliert, sondern mit der physiologischen Aktivität der Osteoklasten durch andere Mechanismen interferiert.
Macrophagen sind speziell auf die Immunabwehr ausgerichtete Fresszellen (Phagozyten). Phagozytose ist ein wesentlicher Zellprozess der die V-ATPase in Lysosomen braucht um die eingeschlossenen Pathogen zu zerstören. Wir generierten transgene Ratten mit konditionellen knockdown von (P)RR unter Nutzung eines Doxyzyclin-induzierten shRNA-Expressionssystems. Eine effiziente (P)RR-Depletion in Makrophagen wurde durch Behandlung mit Doxyzyclin in vivo im Trinkwasser und in vitro im Kulturmedium erreicht. Die vorliegende Arbeit zeigt, dass die Verschiebung des vesikulären pHs erst ziemlich spät nach (P)RR-Depletion auftritt. Wir fanden heraus, dass (P)RR-Depletion weder Phagozytose noch Endozytose beeinträchtigte, sondern für das Recycling des Transferrin-Rezeptors zur Plasmamembran wichtig ist.A decade ago, the (pro)renin receptor [(P)RR] was discovered and depicted as a new component of the renin-angiotensin system. However, recent studies have put in evidence that the (P)RR associate with and regulate the vacuolar H+-ATPase (V-ATPase), hence its other name vacuolar H+-ATPase associated protein 2 (ATP6ap2). In osteoclasts, V-ATPases are mainly located at the plasma membrane facing the bone surface and extrude protons into the extracellular space. Mice with genetic deletion of various V-ATPase subunits are characterized by an increase of bone mass (osteopetrosis). In this work, we found that the (P)RR is highly expressed in mature osteoclasts in vitro and in vivo. Mice with genetic deletion of the (P)RR in osteoclasts developed a complex bone phenotype characterized by a reduced bone density. Osteoclasts lacking (P)RR displayed increased differentiation and/or activity in vitro and in vivo. We therefore suggest that the (P)RR does not directly regulate V-ATPases located at the plasma membrane but rather interferes with osteoclast physiology through other mechanisms. Macrophages are professionalized phagocytes crucial for immune response. Phagocytosis is an essential cellular process, which requires lysosomal V-ATPases for degradation of engulfed pathogens. We generated transgenic rats with a conditional depletion of the (P)RR with the use of a doxycycline-induced shRNA expression system. Efficient (P)RR depletion in macrophages was accomplished by doxycycline treatment in vivo in drinking water and in vitro in culture medium. In this work, we found that the impairment of vesicular pH occurs lately after (P)RR deletion. Also, we found that (P)RR deletion did not impair neither phagocytosis nor endocytosis but rather perturbed the recycling of the transferrin receptor to the plasma membrane.
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Miles, Anna Louise. « V-ATPase regulation of Hypoxia Inducible transcription Factors ». Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283217.
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Metazoans have evolved conserved mechanisms to promote cell survival under low oxygen tensions by initiating a transcriptional cascade centered on the action of Hypoxia Inducible transcription Factors (HIFs). In aerobic conditions, HIFs are inactivated by ubiquitin-proteasome-mediated degradation of their a subunit, which is dependent on prolyl hydroxylation by 2-oxoglutarate (2-OG) and Fe(II)-dependent prolyl hydroxylases (PHDs). In hypoxia, HIF-$\alpha$ is no longer hydroxylated and is therefore stabilised, activating a global transcriptional response to ensure cell survival. Interestingly, HIFs can also be activated in aerobic conditions, however the mechanisms of this oxygen-independent regulation are poorly understood. Here, I have explored the role of the vacuolar H+-ATPase (V-ATPase), the major proton pump for acidifying intracellular vesicles and facilitating lysosomal degradation, in regulating HIF-$\alpha$ turnover. Unbiased forward genetic screens in near-haploid human cells identified that disruption of the V-ATPase leads to activation of HIFs in aerobic conditions. Rather than preventing the lysosomal degradation of HIF-$\alpha$, I found that V-ATPase inhibition indirectly affects the canonical proteasome-mediated degradation of HIF-$\alpha$ isoforms by altering the intracellular iron pool and preventing HIF-$\alpha$ prolyl hydroxylation. In parallel, I characterised two putative mammalian V-ATPase assembly proteins, TMEM199 and CCDC115, identified by the forward genetic screen and subsequent mass spectrometry analysis. I confirmed that both TMEM199 and CCDC115 are required for V-ATPase function, and established assays to determine how TMEM199 and CCDC115 associate with components of the core V-ATPase complex. Lastly, to measure how V-ATPase activity leads to changes in the labile iron pool, I developed an endogenous iron reporter using CRISPR-Cas9 knock-in technology. This approach confirmed that iron homeostasis is impaired during V-ATPase inhibition, and demonstrated that exogenous ferric iron can restore the labile iron pool in a transferrin-independent manner. Together my studies highlight a crucial link between V-ATPase activity, iron homeostasis, and the hypoxic response pathway.
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Piétrement, Christine. « Hétérogénéité physiologique de l'épithélium de l'épididyme : sécrétion de protons via la H+-ATPase vacuolaire dans les cellules claires et transport d'eau et de solutés via l'aquaporine 9 dans les cellules principales ». Reims, 2006. http://theses.univ-reims.fr/exl-doc/GED00000376.pdf.
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L’@épididyme est l’organe où les spermatozoïdes deviennent matures et où ils sont stockés dans un état quiescent. La lumière de l’épididyme est limitée par un épithélium hétérogène composé de deux principaux types cellulaires aux fonctions distinctes et complémentaires. Un pH intra-luminal acide par rapport au plasma est créé par la réabsorption des bicarbonates par les cellules principales dans les parties proximales, et par la sécrétion de protons, par les cellules claires via la H+-ATPase vacuolaire, dans les zones distales. Les cellules principales interviennent dans les mouvements d’eau et de solutés, via l’aquaporine 9, régulant la concentration du sperme. Nous montrons la spécificité de la composition en sous-unités, et en isoformes, de la H+-ATPase vacuolaire exprimée à la membrane apicale des cellules claires et en intracellulaire dans les deux types cellulaires. Nous montrons que la réabsorption du glycérol par l’aquaporine 9 est stimulée par l’AMP cyclique. Cette stimulation pourrait être en relation avec les interactions, que nous mettons en évidence, de l’aquaporine 9 avec NHERF1, et de l’aquaporine 9 avec CFTR. Au delà de l’intérêt d’une meilleure connaissance de la physiologie de l’épididyme, ce travail permet d’aborder la physiopathologie de la stérilité dans la mucoviscidose, et des phénomènes cellulaires généraux : la relation structure/fonction de la H+-ATPase vacuolaire et la régulation de l’aquaporine 9@Sperm are stored in a dormant state and become mature in the epididymis. The epididymis épithélium is heterogenous, and is composed of two main cell types with distinct but complementary functions. Acidic pH compared to plasma is established through bicarbonate reabsorption in the proximal epididymis by principal cells, and in the distal parts by clear cells. Protons secretion occurs in clear cells via the vacuolar H+-ATPase. Principal cells are involved in water and solute movements, via aquaporin 9, and regulate sperm concentration. Here we show the specificity of the vacuolar H+-ATPase subunit and isoform combination, expressed in the clear cells apical plasma membrane and in the cytosol of both cell types cytosol. We show cAMP stimulation of the aquaporin 9-dependent glycerol reabsorption. This stimulation might be related to the interaction between aquaporine 9 and NHERF1 and between aquaporine 9 and CFTR, which we revealed as part of this work. Through this study on epididymis physiology, the question of cystic fibrosis sterility is studied but general cellular functions are also explored : structure/function of the vacuolar H+-ATPase, and regulation of aquaporin 9
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Piétrement, Christine Rieu Philippe. « Hétérogénéité physiologique de l'épithélium de l'épididyme : sécrétion de protons via la H+-ATPase vacuolaire dans les cellules claires et transport d'eau et de solutés via l'aquaporine 9 dans les cellules principales ». S.n. : S.l, 2006. http://scdurca.univ-reims.fr/exl-doc/GED00000376.pdf.
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Brenot, Françoise. « Etude des mécanismes de contrôle et de régulation de l'endocytose chez Dictyostelium discoideum ». Grenoble 1, 1992. http://www.theses.fr/1992GRE10181.
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Ce travail a consiste en l'isolement de souches mutantes de l'amibe dictyostelium discoideum ax2 affectees dans l'endocytose et en leur caracterisation afin d'analyser les mecanismes de regulation impliques dans ce processus. Quinze mutants de dictyostelium ont ete obtenus par une selection basee sur leur resistance a la toxicite du methylene diphosphonate, qui penetre dans les amibes uniquement par pinocytose de phase fluide. Trois de ces mutants, etudies plus en detail, sont caracterises par une vitesse d'entree du marqueur de phase fluide et un volume apparent endocyte reduits de moitie par rapport a la souche ax2 ainsi qu'un contenu plus faible en enzymes lysosomales. La rmn du #3#1p revele la presence d'un compartiment endosomal precoce de ph acide (ph 4,3), suivi d'un compartiment tardif plus alcalin (ph 5,8-6,0) chez la souche ax2. Ce compartiment acide precoce est absent chez les 3 mutants. Le phenotype mutant est systematiquement associe a une deficience de l'acidification. Le fonctionnement subcellulaire a permis d'isoler des vesicules (acidosomes) caracterisees par la presence d'une atpase vacuolaire sensible a des concentrations faibles de nbd et de bafilomycine. Ces acidosomes sont depourvus de marqueurs de pinocytose comme d'enzymes lysosomales mais apparaissent comme des organites specialises dans l'acidification precoce des compartiments endocytaires par association transitoire avec les endosomes. Les acidosomes des 3 mutants montrent une reduction de l'activite atpasique vacuolaire et une diminution de la capacite d'acidification intravesiculaire qui est sensible a la presence des ions chlorures dans le milieu
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Saw, Ner Mu Nar. « The Roles of the Voa Subunit of the Vacuolar H+-ATPase in Dense-core Vesicle Acidification, Transmitter Uptake and Storage ». Thesis, 2011. http://hdl.handle.net/1807/31433.
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The Vo sector of the vacuolar H+-ATPase is a multi-subunit complex that forms a proteolipid pore. The largest subunit in this complex is the a subunit which has four isoforms (a1-a4). The isoform(s) critical for secretory vesicle acidification has yet to be identified. Using a cell line derived from rat pheochromocytoma in which Voa1 and/or Voa2 had been down-regulated this study revealed that Voa1, and to a lesser extent, Voa2 are critical for acidifying dense-core vesicles (DCVs). The acidification defects resulting from down-regulation of Voa1 and Voa1/ Voa2 were suppressed by the expression of knockdown-resistant Voa1. Defects in DCV acidification resulted in reductions in their transmitter uptake and storage. Lastly, Ca2+-dependent peptide secretion appeared normal in Voa1 and Voa1/ Voa2 knockdown cells. . This study demonstrated that Voa1 and Voa2 cooperatively regulate dense-core vesicle acidification as well as transmitter uptake/storage, while they may not be critical for dense-core vesicle exocytosis.
Chapitres de livres sur le sujet "Vacuolar acidification"
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Gluck, Stephen, Bahar Bastani, Raoul Nelson, Henry Purcell, Zhi-Qiang Wang, Kun Zhang, Michael Marushack et al. « Properties and Function of the Kidney Vacuolar H+ ATPase : a Versatile Proton Pump Responsible for Urinary Acidification ». Dans Nephrology, 435–43. Berlin, Heidelberg : Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-662-35158-1_38.
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Gluck, Stephen L., Raoul D. Nelson, Beth S. M. Lee, L. Shannon Holliday et Masahiro Iyori. « Properties of Kidney Plasma Membrane Vacuolar H+-ATPases : Proton Pumps Responsible for Bicarbonate Transport, Urinary Acidification, and Acid-Base Homeostasis ». Dans Organellar Proton-ATPases, 163–221. Berlin, Heidelberg : Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-662-22265-2_6.
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Fujishima, M., et M. Kawai. « Acidification in Digestive Vacuoles is an Early Event Required for Holospora Infection of Paramecium Nucleus ». Dans Eukaryotism and Symbiosis, 367–70. Berlin, Heidelberg : Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-60885-8_28.
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Libby Sherr, Goldie, et Chang-Hui Shen. « The Interplay of Key Phospholipid Biosynthetic Enzymes and the Yeast V-ATPase Pump and their Role in Programmed Cell Death ». Dans Regulation and Dysfunction of Apoptosis [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97886.
Texte intégralRésumé :
Exposure of the yeast Saccharomyces cerevisiae to environmental stress can influence cell growth, physiology and differentiation, and thus result in a cell’s adaptive response. During the course of an adaptive response, the yeast vacuoles play an important role in protecting cells from stress. Vacuoles are dynamic organelles that are similar to lysosomes in mammalian cells. The defect of a lysosome’s function may cause various genetic and neurodegenerative diseases. The multi-subunit V-ATPase is the main regulator for vacuolar function and its activity plays a significant role in maintaining pH homeostasis. The V-ATPase is an ATP-driven proton pump which is required for vacuolar acidification. It has also been demonstrated that phospholipid biosynthetic genes might influence vacuolar morphology and function. However, the mechanistic link between phospholipid biosynthetic genes and vacuolar function has not been established. Recent studies have demonstrated that there is a regulatory role of Pah1p, a phospholipid biosynthetic gene, in V-ATPase disassembly and activity. Therefore, in this chapter we will use Saccharomyces cerevisiae as a model to discuss how Pah1p affects V-ATPase disassembly and activity and how Pah1p negatively affect vacuolar function. Furthermore, we propose a hypothesis to describe how Pah1p influences vacuolar function and programmed cell death through the regulation of V-ATPase.
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Abe, Fumiyoshi, et Koki Horikoshi. « Vacuolar acidification under high hydrostatic pressure in Saccharomyces cerevisiae ». Dans High Pressure Bioscience and Biotechnology, Proceedings of the International Conference on High Pressure Bioscience and Biotechnology, 53–58. Elsevier, 1996. http://dx.doi.org/10.1016/s0921-0423(06)80010-9.
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Tripathi, Anuj, et Smita Misra. « Vacuolar ATPase (V-ATPase) Proton Pump and Its Significance in Human Health ». Dans Ion Transporters - From Basic Properties to Medical Treatment [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106848.
Texte intégralRésumé :
Vacuolar H + -ATPases (V-ATPase), is an ATP-dependent proton transporter that transports protons across intracellular and cellular plasma membranes. V-ATPase is a multi-protein complex, which functions as an ATP-driven proton pump and is involved in maintaining pH homeostasis. The V-ATPase is a housekeeping proton pump and is highly conserved during evolution. The proton-pumping activity of V-ATPases allows acidification of intracellular compartments and influences a diverse range of cellular and biological processes. Thus, V-ATPase aberrant overexpression, mis-localization, and mutations in the genes for subunits are associated with several human diseases. This chapter focuses on a detailed view of V-type ATPase, and how V-ATPase contributes to human health and disease.
Rapports d'organisations sur le sujet "Vacuolar acidification"
1
Nelson, Nathan, et Randy Schekman. Functional Biogenesis of V-ATPase in the Vacuolar System of Plants and Fungi. United States Department of Agriculture, septembre 1996. http://dx.doi.org/10.32747/1996.7574342.bard.
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The vacuolar H+-ATPase (V-ATPase) is one of the most fundamental enzymes in nature. It pumps protons into the vacuolar system of eukaryotic cells and provides the energy for numerous transport systems. Through our BARD grant we discovered a novel family of membrane chaperones that modulate the amount of membrane proteins. We also elucidated the mechanism by which assembly factors guide the membrane sector of V-ATPase from the endoplasmic reticulum to the Golgi apparatus. The major goal of the research was to understand the mechanism of action and biogenesis of V-ATPase in higher plants and fungi. The fundamental question of the extent of acidification in organelles of the vacuolar system was addressed by studying the V-ATPase of lemon fruit, constructing lemon cDNAs libraries and study their expression in mutant yeast cells. The biogenesis of the enzyme and its function in the Golgi apparatus was studied in yeast utilizing a gallery of secretory mutants available in our laboratories. One of the goals of this project is to determine biochemically and genetically how V-ATPase is assembled into the different membranes of a wide variety of organelles and what is the mechanism of its action.The results of this project advanced out knowledge along these lines.
2
Sadka, Avi, Mikeal L. Roose et Yair Erner. Molecular Genetic Analysis of Citric Acid Accumulation in Citrus Fruit. United States Department of Agriculture, mars 2001. http://dx.doi.org/10.32747/2001.7573071.bard.
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The acid content of the juice sac cells is a major determinant of maturity and fruit quality in citrus. Many citrus varieties accumulate acid in concentrations that exceed market desires, reducing grower income and consumer satisfaction. Pulp acidity is thought to be dependent on two mechanisms: the accumulation of citric acid in the vacuoles of the juice sac cells, and acidification of the vacuole. The major aim of the project was to direct effort toward understanding the mechanism of citric acid accumulation in the fruit. The following objectives were suggested: Measure the activity of enzymes likely to be involved in acid accumulation and follow their pattern of expression in developing fruit (Sadka, Erner). Identify and clone genes which are associated with high and low acid phenotypes and with elevated acid level (Roose, Sadka, Erner). Convert RAPD markers that map near a gene that causes low acid phenotype to specific co dominant markers (Roose). Use genetic co segregation to test whether specific gene products are responsible for low acid phenotype (Roose and Sadka). Objective 1 was fully achieved. Most of the enzymes of organic acid metabolism were cloned from lemon pulp. Their expression was studied during fruit development in low and high acid varieties. The activity and expression of citrate synthase, aconitase and NADP-isocitrate dehydrogenase (IDH) were studied in detail. The role that each enzyme plays in acid accumulation and decline was evaluated. As a result, a better understanding of the metabolic changes that contribute to acid accumulation was achieved. It was found that the activity of the mitochondrial aconitase is greatly reduced early in high-acid fruits, but not in acidless ones, suggesting that this enzyme plays an important role in acid accumulation. In addition, it was demonstrated that increases in the cytosolic forms of aconitase and NADP-IDH towards fruit maturation play probably a major role in acid decline. Our studies also demonstrated that the two mechanisms that contribute to fruit acidity, vacuolar acidification and citric acid accumulation, are independent, although they are tightly co-regulated. Additional, we demonstrated that sodium arsenite, which reduce fruit acidity, causes a transient inhibition in the activity of citrate synthase, but an induction in the gene expression. This part of the work has resulted in 4 papers. Objective 3 was also fully achieved. Using bulked segregant analysis, three random amplified polymorphic DNA (RAPD) markers were identified as linked to acitric, a gene controlling the acidless phenotype of pummelo 2240. One of them, which mapped 1.2 cM from acitric was converted into sequence characterized amplified region (SCAR marker, and into co dominant restriction length polymorphism (RFLP) marker. These markers were highly polymorphic among 59 citrus accessions, and therefore, they should be useful for selecting seedling progeny heterozygous for acitric in nearly all crosses between pummelo 2240 and other citrus genotypes. This part of the project resulted in one paper. Objective 4 was also fully achieved. Clones isolated by the Israeli group were sent to the American laboratory for co segregation analysis. However, none of them seemed to co segregate with the low acid phenotype. Both laboratories invested much effort in achieving the goals of Objective 2, namely the isolation of genes that are elevated in expression in low and high acid phenotypes, and in tissue cultures treated with arsenite (a treatment which reduces fruit acidity). However, conventional differential display and restriction fragment differential display analyses could not identify any differentially expressed genes. The isolation of such genes was the major aim of a continuation project, which was recently submitted.