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del Nogal M, Troyano N, Calleros L, Griera M, Rodriguez-Puyol M, Rodriguez-Puyol D, Ruiz-Torres MP. Hyperosmolarity induced by high glucose promotes senescence in human glomerular mesangial cells. Int J Biochem Cell Biol 2014; 54:98-110. [DOI: 10.1016/j.biocel.2014.07.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 07/07/2014] [Accepted: 07/10/2014] [Indexed: 02/06/2023]
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Min HK, Sookoian S, Pirola CJ, Cheng J, Mirshahi F, Sanyal AJ. Metabolic profiling reveals that PNPLA3 induces widespread effects on metabolism beyond triacylglycerol remodeling in Huh-7 hepatoma cells. Am J Physiol Gastrointest Liver Physiol 2014; 307:G66-76. [PMID: 24763554 PMCID: PMC4080161 DOI: 10.1152/ajpgi.00335.2013] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
PNPLA3 was recently associated with the susceptibility to nonalcoholic fatty liver disease, a common cause of chronic liver disease characterized by abnormal triglyceride accumulation. Although it is established that PNPLA3 has both triacylglycerol lipase and acylglycerol O-acyltransferase activities, is still unknown whether the gene has any additional role in the modulation of the human liver metabolome. To uncover the functional role of PNPLA3 on liver metabolism, we performed high-throughput metabolic profiling of PNPLA3 siRNA-silencing and overexpression of wild-type and mutant Ile148Met variants (isoleucine/methionine substitution at codon 148) in Huh-7 cells. Metabolomic analysis was performed by using GC/MS and LC/MS platforms. Silencing of PNPLA3 was associated with a global perturbation of Huh-7 hepatoma cells that resembled a catabolic response associated with protein breakdown. A significant decrease in amino- and γ-glutamyl-amino acids and dipeptides and a significant increase in cysteine sulfinic acid, myo-inositol, lysolipids, sphingolipids, and polyunsaturated fatty acids were observed. Overexpression of the PNPLA3 Met148 variant mirrored many of the metabolic changes observed during gene silencing, but in the opposite direction. These findings were replicated by the exploration of canonical pathways associated with PNPLA3 silencing and Met148 overexpression. Overexpression of the PNPLA3 Met148 variant was associated with a 1.75-fold increase in lactic acid, suggesting a shift to anaerobic metabolism and mitochondrial dysfunction. Together, these results suggest a critical role of PNPLA3 in the modulation of liver metabolism beyond its classical participation in triacylglycerol remodeling.
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Affiliation(s)
- Hae-Ki Min
- 1Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia; and
| | - Silvia Sookoian
- 2Department of Clinical and Molecular Hepatology and Molecular Genetics and Biology of Complex Diseases, Institute of Medical Research, IDIM, University of Buenos Aires-National Scientific and Technical Research Council (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Carlos J. Pirola
- 2Department of Clinical and Molecular Hepatology and Molecular Genetics and Biology of Complex Diseases, Institute of Medical Research, IDIM, University of Buenos Aires-National Scientific and Technical Research Council (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Jianfeng Cheng
- 1Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia; and
| | - Faridoddin Mirshahi
- 1Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia; and
| | - Arun J. Sanyal
- 1Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia; and
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Overduin J, Tylee TS, Frayo RS, Cummings DE. Hyperosmolarity in the small intestine contributes to postprandial ghrelin suppression. Am J Physiol Gastrointest Liver Physiol 2014; 306:G1108-16. [PMID: 24789208 PMCID: PMC4059977 DOI: 10.1152/ajpgi.00072.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Plasma levels of the orexigenic hormone ghrelin are suppressed by meals with an efficacy dependent on their macronutrient composition. We hypothesized that heterogeneity in osmolarity among macronutrient classes contributes to these differences. In three studies, the impact of small intestinal hyperosmolarity was examined in Sprague-Dawley rats. In study 1, isotonic, 2.5×, and 5× hypertonic solutions of several agents with diverse absorption and metabolism properties were infused duodenally at a physiological rate (3 ml/10 min). Jugular vein blood was sampled before and at 30, 60, 90, 120, 180, 240, and 300 min after infusion. Plasma ghrelin was suppressed dose dependently and most strongly by glucose. Hyperosmolar infusions of lactulose, which transits the small intestine unabsorbed, and 3-O-methylglucose (3-O-MG), which is absorbed like glucose but remains unmetabolized, also suppressed ghrelin. Glucose, but not lactulose or 3-O-MG, infusions increased plasma insulin. In study 2, intestinal infusions of hyperosmolar NaCl suppressed ghrelin, a response that was not attenuated by coinfusion with the neural blocker lidocaine. In study 3, we reconfirmed that the low-osmolar lipid emulsion Intralipid suppresses ghrelin more weakly than isocaloric (but hypertonic) glucose. Importantly, raising Intralipid's osmolarity to that of the glucose solution by nonabsorbable lactulose supplementation enhanced ghrelin suppression to that seen after glucose. Hyperosmolar ghrelin occurred particularly during the initial 3 postinfusion hours. We conclude that small intestinal hyperosmolarity 1) is sufficient to suppress ghrelin, 2) may combine with other postprandial mechanisms to suppress ghrelin, 3) might contribute to altered ghrelin regulation after gastric bypass surgery, and 4) may inform dietary modifications for metabolic health.
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Affiliation(s)
- Joost Overduin
- University of Washington School of Medicine, Seattle, Washington; and Veterans Affairs Puget Sound Health Care System Seattle, Washington
| | - Tracy S. Tylee
- University of Washington School of Medicine, Seattle, Washington; and Veterans Affairs Puget Sound Health Care System Seattle, Washington
| | - R. Scott Frayo
- University of Washington School of Medicine, Seattle, Washington; and Veterans Affairs Puget Sound Health Care System Seattle, Washington
| | - David E. Cummings
- University of Washington School of Medicine, Seattle, Washington; and Veterans Affairs Puget Sound Health Care System Seattle, Washington
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In vitro increase of mean corpuscular volume difference (dMCV) as a marker for serum hypertonicity in dogs. Res Vet Sci 2014; 96:442-6. [PMID: 24656345 DOI: 10.1016/j.rvsc.2014.03.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 01/19/2014] [Accepted: 03/01/2014] [Indexed: 11/21/2022]
Abstract
Spurious increase in erythrocyte mean corpuscular volume (MCV) on automated cell analyzers is a well-characterized lab error in hypertonic patients. A difference between automated and manual MCV (dMCV) greater than 2 fl has been shown to predict hypertonicity in humans. The purpose of this study was to investigate dMCV as a marker for serum hypertonicity in dogs and to examine the relationship between dMCV and three methods of estimating serum tonicity: measured (OsMM), calculated (OsMC), and calculated effective (OsMCE) osmolalities. OsMC, OsMCE, and dMCV were calculated from routine blood values and OsMM was directly measured in 121 dogs. The dMCV of hypertonic dogs was significantly larger than that of normotonic dogs for all three osmolality methods. dMCV predicted hypertonicity as estimated by OsMM better than it predicted hypertonicity as estimated by OsMC and OsMCE. A cutoff of 2.96 fl yielded the best sensitivity (76%) and specificity (71%) for hypertonicity estimated by OsMM.
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55
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Jimenez V. Dealing with environmental challenges: mechanisms of adaptation in Trypanosoma cruzi. Res Microbiol 2014; 165:155-65. [PMID: 24508488 DOI: 10.1016/j.resmic.2014.01.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 01/27/2014] [Indexed: 10/25/2022]
Abstract
Protozoan parasites have a significant impact upon global health, infecting millions of people around the world. With limited therapeutic options and no vaccines available, research efforts are focused upon unraveling cellular mechanisms essential for parasite survival. During its life cycle, Trypanosoma cruzi, the causal agent of Chagas disease, is exposed to multiple external conditions and different hosts. Environmental cues are linked to the differentiation process allowing the parasite to complete its life cycle. Successful transmission depends on the ability of the cells to trigger adaptive responses and cope with stressors while regulating proliferation and transition to different life stages. This review focuses upon different aspects of the stress response in T. cruzi, proposing new hypotheses regarding cross-talk and cross-tolerance with respect to environmental changes and discussing open questions and future directions.
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Affiliation(s)
- Veronica Jimenez
- Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, 800 N State College Blvd, McCarthy Hall 307, 92831 Fullerton, CA, USA.
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FXYD2c Plays a Potential Role in Modulating Na+/K+-ATPase Activity in HK-2 Cells Upon Hypertonic Challenge. J Membr Biol 2013; 247:93-105. [DOI: 10.1007/s00232-013-9615-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 11/08/2013] [Indexed: 01/07/2023]
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57
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Sama RRK, Ward CL, Kaushansky LJ, Lemay N, Ishigaki S, Urano F, Bosco DA. FUS/TLS assembles into stress granules and is a prosurvival factor during hyperosmolar stress. J Cell Physiol 2013; 228:2222-31. [PMID: 23625794 DOI: 10.1002/jcp.24395] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 04/17/2013] [Indexed: 12/14/2022]
Abstract
FUsed in Sarcoma/Translocated in LipoSarcoma (FUS/TLS or FUS) has been linked to several biological processes involving DNA and RNA processing, and has been associated with multiple diseases, including myxoid liposarcoma and amyotrophic lateral sclerosis (ALS). ALS-associated mutations cause FUS to associate with stalled translational complexes called stress granules under conditions of stress. However, little is known regarding the normal role of endogenous (non-disease linked) FUS in cellular stress response. Here, we demonstrate that endogenous FUS exerts a robust response to hyperosmolar stress induced by sorbitol. Hyperosmolar stress causes an immediate re-distribution of nuclear FUS to the cytoplasm, where it incorporates into stress granules. The redistribution of FUS to the cytoplasm is modulated by methyltransferase activity, whereas the inhibition of methyltransferase activity does not affect the incorporation of FUS into stress granules. The response to hyperosmolar stress is specific, since endogenous FUS does not redistribute to the cytoplasm in response to sodium arsenite, hydrogen peroxide, thapsigargin, or heat shock, all of which induce stress granule assembly. Intriguingly, cells with reduced expression of FUS exhibit a loss of cell viability in response to sorbitol, indicating a prosurvival role for endogenous FUS in the cellular response to hyperosmolar stress.
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Affiliation(s)
- Reddy Ranjith K Sama
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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58
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Gokhale NA, Zaremba A, Janoshazi AK, Weaver JD, Shears SB. PPIP5K1 modulates ligand competition between diphosphoinositol polyphosphates and PtdIns(3,4,5)P3 for polyphosphoinositide-binding domains. Biochem J 2013; 453:413-26. [PMID: 23682967 PMCID: PMC3931004 DOI: 10.1042/bj20121528] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We describe new signalling consequences for PPIP5K1 (diphosphoinositol pentakisphosphate kinase type 1)-mediated phosphorylation of InsP6 and 5-InsP7 to 1-InsP7 and InsP8. In NIH 3T3 cells, either hyperosmotic stress or receptor activation by PDGF (platelet-derived growth factor) promoted translocation of PPIP5K1 from the cytoplasm to the plasma membrane. The PBD1 (polyphosphoinositide-binding domain) in PPIP5K1 recapitulated that translocation. Mutagenesis of PBD1 to reduce affinity for PtdIns(3,4,5)P3 prevented translocation. Using surface plasmon resonance, we found that PBD1 association with vesicular PtdIns(3,4,5)P3 was inhibited by InsP6 and diphosphoinositol polyphosphates. However, the inhibition by PPIP5K1 substrates (IC50: 5-InsP7=5 μM and InsP6=7 μM) was substantially more potent than that of the PPIP5K1 products (IC50: InsP8=32 μM and 1-InsP7=43 μM). This rank order of ligand competition with PtdIns(3,4,5)P3 was also exhibited by the PH (pleckstrin homology) domains of Akt (also known as protein kinase B), GRP1 (general receptor for phosphoinositides 1) and SIN1 (stress-activated protein kinase-interaction protein 1). We propose that, in vivo, PH domain binding of InsP6 and 5-InsP7 suppresses inappropriate signalling ('noise') from stochastic increases in PtdIns(3,4,5)P3. That restraint may be relieved by localized depletion of InsP6 and 5-InsP7 at the plasma membrane following PPIP5K1 recruitment. We tested this hypothesis in insulin-stimulated L6 myoblasts, using mTOR (mechanistic/mammalian target of rapamycin)-mediated phosphorylation of Akt on Ser473 as a readout for SIN1-mediated translocation of mTORC (mTOR complex) 2 to the plasma membrane [Zoncu, Efeyan and Sabatini (2011) Nat. Rev. Mol. Cell Biol. 12, 21-35]. Knockdown of PPIP5K1 expression was associated with a 40% reduction in Ser473 phosphorylation. A common feature of PtdIns(3,4,5)P3-based signalling cascades may be their regulation by PPIP5K1.
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Affiliation(s)
- Nikhil A. Gokhale
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC 27709, U.S.A
| | - Angelika Zaremba
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC 27709, U.S.A
| | - Agnes K. Janoshazi
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC 27709, U.S.A
| | - Jeremy D. Weaver
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC 27709, U.S.A
| | - Stephen B. Shears
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC 27709, U.S.A
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59
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Tang CH, Lee TH. Freshwater Acclimation Induces Stress Responses and Expression of Branchial Na+/K+-ATPase and Proliferating Cell Nuclear Antigen inTakifugu niphobles. ACTA ACUST UNITED AC 2013; 319:409-21. [PMID: 23776130 DOI: 10.1002/jez.1804] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 02/18/2013] [Accepted: 04/17/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Cheng-Hao Tang
- Institute of Marine Biotechnology, National Dong Hwa University, Pingtung, Taiwan
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60
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Kalujnaia S, Gellatly SA, Hazon N, Villasenor A, Yancey PH, Cramb G. Seawater acclimation and inositol monophosphatase isoform expression in the European eel (Anguilla anguilla) and Nile tilapia (Orechromis niloticus). Am J Physiol Regul Integr Comp Physiol 2013; 305:R369-84. [PMID: 23739342 DOI: 10.1152/ajpregu.00044.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inositol monophosphatase (IMPA) is responsible for the synthesis of inositol, a polyol that can function as an intracellular osmolyte helping re-establish cell volume when exposed to hypertonic environments. Some epithelial tissues in euryhaline teleosts such as the eel and tilapia encounter considerable hyperosmotic challenge when fish move from freshwater (FW) to seawater (SW) environments; however, the roles played by organic osmolytes, such as inositol, have yet to be determined. Syntenic analysis has indicated that, as a result of whole genome- and tandem-duplication events, up to six IMPA isoforms can exist within teleost genomes. Four isoforms are homologs of the mammalian IMPA1 gene, and two isoforms are homologs of the mammalian IMPA2 gene. Although the tissue-dependent isoform expression profiles of the teleost isoforms appear to be species-specific, it was primarily mRNA for the IMPA1.1 isoform that was upregulated in epithelial tissues after fish were transferred to SW (up to 16-fold in eel and 90-fold in tilapia). Although up-regulation of IMPA1.1 expression was evident in many tissues in the eel, more substantial increases in IMPA1.1 expression were found in tilapia tissues, where SW acclimation resulted in up to 2,000-fold increases in protein expression, 16-fold increases in enzyme activity and 15-fold increases in tissue inositol contents. Immunohistochemical studies indicated that the tissue and cellular distribution of IMPA1.1 protein differed slightly between eels and tilapia; however, in both species the basal epithelial cell layers within the skin and fin, and the branchial epithelium and interstitial cells within the kidney, exhibited high levels of IMPA1.1 protein expression.
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Affiliation(s)
- Svetlana Kalujnaia
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom
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61
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Tang CH, Lee TH. Early response of protein quality control in gills is associated with survival of hypertonic shock in Mozambique tilapia. PLoS One 2013; 8:e63112. [PMID: 23690986 PMCID: PMC3653892 DOI: 10.1371/journal.pone.0063112] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 03/28/2013] [Indexed: 12/01/2022] Open
Abstract
The protein quality control (PQC) mechanism is essential for cell function and viability. PQC with proper biological function depends on molecular chaperones and proteases. The hypertonicity-induced protein damage and responses of PQC mechanism in aquatic organisms, however, are poorly understood. In this study, we examine the short-term effects of different hypertonic shocks on the levels of heat shock proteins (HSPs, e.g., HSP70 and HSP90), ubiquitin-conjugated proteins and protein aggregation in gills of the Mozambique tilapia (Oreochromis mossambicus). Following transfer from fresh water (FW) to 20‰ hypertonicity, all examined individuals survived to the end of experiment. Moreover, the levels of branchial HSPs and ubiquitin-conjugated proteins significantly increased at 3 and 24 h post-transfer, respectively. Up-regulation of HSPs and ubiquitin-conjugated proteins was sufficient to prevent the accumulation of aggregated proteins. However, the survival rate of tilapia dramatically declined at 5 h and all fish died within 7 h after direct transfer to 30‰ hypertonicity. We presumed that this result was due to the failed activation of gill PQC system, which resulted in elevating the levels of aggregated proteins at 3 and 4 h. Furthermore, in aggregated protein fractions, the amounts of gill Na+/K+-ATPase (NKA) remained relatively low when fish were transferred to 20‰ hypertonicity, whereas abundant NKA was found at 4 h post-transfer to 30‰ hypertonicity. This study demonstrated that the response of PQC in gills is earlier than observable changes in localization of ion-secreting transport proteins upon hypertonic challenge. To our knowledge, this is the first study to investigate the regulation of PQC mechanism in fish and characterize its important role in euryhaline teleost survival in response to hypertonic stress.
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Affiliation(s)
- Cheng-Hao Tang
- Institute of Marine Biotechnology, National Dong Hwa University, Pingtung, Taiwan
- National Museum of Marine Biology and Aquarium, Pingtung, Taiwan
| | - Tsung-Han Lee
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan
- Department of Biological Science and Technology, China Medical University, Taichung, Taiwan
- * E-mail:
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62
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Casali CI, Weber K, Favale NO, Tome MCF. Environmental hyperosmolality regulates phospholipid biosynthesis in the renal epithelial cell line MDCK. J Lipid Res 2013; 54:677-691. [PMID: 23269393 PMCID: PMC3617943 DOI: 10.1194/jlr.m031500] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 12/14/2012] [Indexed: 12/29/2022] Open
Abstract
Hyperosmolality is a key signal for renal physiology. On the one hand, it contributes to the differentiation of renal medullary structures and to the development of the urinary concentrating mechanism. On the other, it is a stress factor. In both cases, hyperosmolality activates processes that require an adequate extension of cellular membranes. In the present work, we examined whether hyperosmolality regulates phospholipid biosynthesis, which is needed for the membrane biogenesis in the renal epithelial cell line Madin-Darby canine kidney (MDCK). Because phospholipids are the structural determinants of all cell membranes, we evaluated their content, synthesis, and regulation in MDCK cultures subjected to different hyperosmotic concentrations of NaCl, urea, or both. Hyperosmolality increased phospholipid content in a concentration-dependent manner. Such an effect was exclusively due to changes in NaCl concentration and occurred at the initial stage of hyperosmolar treatment concomitantly with the expression of the osmoprotective protein COX-2. The hypertonic upregulation of phosphatidylcholine (PC) synthesis, the main constituent of all cell membranes, involved the transcriptional activation of two main regulatory enzymes, choline kinase (CK) and cytidylyltransferase α (CCTα) and required ERK1/2 activation. Considering that physiologically, renal medullary cells are constantly exposed to high and variable NaCl, these findings could contribute to explaining how renal cells could maintain cellular integrity even in a nonfavorable environment.
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Affiliation(s)
- Cecilia I. Casali
- Department of Biological Sciences, School of Pharmacy and Biochemistry, University of Buenos Aires, IQUIFIB–CONICET, Ciudad Autónoma de Buenos Aires (C1113AAD), Argentina
| | - Karen Weber
- Department of Biological Sciences, School of Pharmacy and Biochemistry, University of Buenos Aires, IQUIFIB–CONICET, Ciudad Autónoma de Buenos Aires (C1113AAD), Argentina
| | - Nicolás O. Favale
- Department of Biological Sciences, School of Pharmacy and Biochemistry, University of Buenos Aires, IQUIFIB–CONICET, Ciudad Autónoma de Buenos Aires (C1113AAD), Argentina
| | - María C. Fernández Tome
- Department of Biological Sciences, School of Pharmacy and Biochemistry, University of Buenos Aires, IQUIFIB–CONICET, Ciudad Autónoma de Buenos Aires (C1113AAD), Argentina
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63
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Kim YH, Kim DH, Hwang J, Kim HS, Lim GY, Ryoo ZY, Choi SU, Lee S. The inclusion of fetal bovine serum in gelatin/PCL electrospun scaffolds reduces short-term osmotic stress in HEK 293 cells caused by scaffold components. J Appl Polym Sci 2013. [DOI: 10.1002/app.39052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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64
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Nunes P, Ernandez T, Roth I, Qiao X, Strebel D, Bouley R, Charollais A, Ramadori P, Foti M, Meda P, Féraille E, Brown D, Hasler U. Hypertonic stress promotes autophagy and microtubule-dependent autophagosomal clusters. Autophagy 2013; 9:550-67. [PMID: 23380587 DOI: 10.4161/auto.23662] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Osmotic homeostasis is fundamental for most cells, which face recurrent alterations of environmental osmolality that challenge cell viability. Protein damage is a consequence of hypertonic stress, but whether autophagy contributes to the osmoprotective response is unknown. Here, we investigated the possible implications of autophagy and microtubule organization on the response to hypertonic stress. We show that hypertonicity rapidly induced long-lived protein degradation, LC3-II generation and Ptdlns3K-dependent formation of LC3- and ATG12-positive puncta. Lysosomotropic agents chloroquine and bafilomycin A 1, but not nutrient deprivation or rapamycin treatment, further increased LC3-II generation, as well as ATG12-positive puncta, indicating that hypertonic stress increases autophagic flux. Autophagy induction upon hypertonic stress enhanced cell survival since cell death was increased by ATG12 siRNA-mediated knockdown and reduced by rapamycin. We additionally showed that hypertonicity induces fast reorganization of microtubule networks, which is associated with strong reorganization of microtubules at centrosomes and fragmentation of Golgi ribbons. Microtubule remodeling was associated with pericentrosomal clustering of ATG12-positive autolysosomes that colocalized with SQSTM1/p62 and ubiquitin, indicating that autophagy induced by hypertonic stress is at least partly selective. Efficient autophagy by hypertonic stress required microtubule remodeling and was DYNC/dynein-dependent as autophagosome clustering was enhanced by paclitaxel-induced microtubule stabilization and was reduced by nocodazole-induced tubulin depolymerization as well as chemical (EHNA) or genetic [DCTN2/dynactin 2 (p50) overexpression] interference of DYNC activity. The data document a general and hitherto overlooked mechanism, where autophagy and microtubule remodeling play prominent roles in the osmoprotective response.
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Affiliation(s)
- Paula Nunes
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland
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65
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5′-Untranslated region of heat shock protein 70 mRNA drives translation under hypertonic conditions. Biochem Biophys Res Commun 2013; 431:321-5. [DOI: 10.1016/j.bbrc.2012.12.100] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 12/25/2012] [Indexed: 11/22/2022]
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66
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New insights into roles of acidocalcisomes and contractile vacuole complex in osmoregulation in protists. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 305:69-113. [PMID: 23890380 DOI: 10.1016/b978-0-12-407695-2.00002-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
While free-living protists are usually subjected to hyposmotic environments, parasitic protists are also in contact with hyperosmotic habitats. Recent work in one of these parasites, Trypanosoma cruzi, has revealed that its contractile vacuole complex, which usually collects and expels excess water as a mechanism of regulatory volume decrease after hyposmotic stress, has also a role in cell shrinking when the cells are submitted to hyperosmotic stress. Trypanosomes also have an acidic calcium store rich in polyphosphate (polyP), named the acidocalcisome, which is involved in their response to osmotic stress. Here, we review newly emerging insights on the role of acidocalcisomes and the contractile vacuole complex in the cellular response to hyposmotic and hyperosmotic stresses. We also review the current state of knowledge on the composition of these organelles and their other roles in calcium homeostasis and protein trafficking.
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67
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Stookey JD, Brass B, Holliday A, Arieff A. What is the cell hydration status of healthy children in the USA? Preliminary data on urine osmolality and water intake. Public Health Nutr 2012; 15:2148-56. [PMID: 22281298 PMCID: PMC10271274 DOI: 10.1017/s1368980011003648] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Accepted: 12/13/2011] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Hyperosmotic stress on cells limits many aspects of cell function, metabolism and health. International data suggest that schoolchildren may be at risk of hyperosmotic stress on cells because of suboptimal water intake. The present study explored the cell hydration status of two samples of children in the USA. DESIGN Cross-sectional study describing the urine osmolality (an index of hyperosmotic cell shrinkage) and water intake of convenience samples from Los Angeles (LA) and New York City (NYC). SETTING Each participant collected a urine sample at an outpatient clinic on the way to school on a weekday morning in spring 2009. Each was instructed to wake, eat, drink and do as usual before school, and complete a dietary record form describing the type and amounts of all foods and beverages consumed after waking, before giving the sample. SUBJECTS The children (9-11 years) in LA (n 337) and NYC (n 211) considered themselves healthy enough to go to school on the day they gave the urine sample. RESULTS Elevated urine osmolality (>800 mmol/kg) was observed in 63 % and 66 % of participants in LA and NYC, respectively. In multivariable-adjusted logistic regression models, elevated urine osmolality was associated with not reporting intake of drinking water in the morning (LA: OR = 2·1, 95 % CI 1·2, 3·5; NYC: OR = 1·8, 95 % CI 1·0, 3·5). Although over 90 % of both samples had breakfast before giving the urine sample, 75 % did not drink water. CONCLUSIONS Research is warranted to confirm these results and pursue their potential health implications.
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Affiliation(s)
- Jodi D Stookey
- Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA.
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68
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Fujisawa M, Tokuda M, Morimoto-Yamashita Y, Tatsuyama S, Arany S, Sugiyama T, Kitamura C, Shibukawa Y, Torii M. Hyperosmotic Stress Induces Cell Death in an Odontoblast-lineage Cell Line. J Endod 2012; 38:931-5. [DOI: 10.1016/j.joen.2012.03.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 03/23/2012] [Accepted: 03/27/2012] [Indexed: 10/28/2022]
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69
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Veley KM, Haswell ES. Plastids and pathogens: mechanosensitive channels and survival in a hypoosmotic world. PLANT SIGNALING & BEHAVIOR 2012; 7:668-71. [PMID: 22580705 PMCID: PMC3442863 DOI: 10.4161/psb.19991] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
In bacteria, MscS-type mechanosensitive channels serve to protect cells from lysis as they swell during extreme osmotic stress. We recently showed that two MscS homologs from Arabidopsis thaliana serve a similar purpose in the epidermal plastids of the leaf, indicating that the plant cell cytoplasm can present a dynamic osmotic challenge to the plastid. MscS homologs are predicted to be targeted to both plastids and mitochondrial envelopes and have been found in the genomes of intracellular pathogens. Here we discuss the implications of these observations, and propose that MS channels provide an essential mechanism for osmotic adaptation to both intracellular and the extracellular environments.
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70
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71
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Shen CF, Kamen A. Hyperosmotic pressure on HEK 293 cells during the growth phase, but not the production phase, improves adenovirus production. J Biotechnol 2012; 157:228-36. [DOI: 10.1016/j.jbiotec.2011.11.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 11/16/2011] [Accepted: 11/22/2011] [Indexed: 01/09/2023]
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72
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Mavrogonatou E, Kletsas D. Differential response of nucleus pulposus intervertebral disc cells to high salt, sorbitol, and urea. J Cell Physiol 2011; 227:1179-87. [DOI: 10.1002/jcp.22840] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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73
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Li ZH, Alvarez VE, De Gaudenzi JG, Sant'Anna C, Frasch ACC, Cazzulo JJ, Docampo R. Hyperosmotic stress induces aquaporin-dependent cell shrinkage, polyphosphate synthesis, amino acid accumulation, and global gene expression changes in Trypanosoma cruzi. J Biol Chem 2011; 286:43959-43971. [PMID: 22039054 DOI: 10.1074/jbc.m111.311530] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The protist parasite Trypanosoma cruzi has evolved the ability to transit between completely different hosts and to replicate in adverse environments. In particular, the epimastigote form, the replicative stage inside the vector, is subjected to nutritional and osmotic stresses during its development. In this work, we describe the biochemical and global gene expression changes of epimastigotes under hyperosmotic conditions. Hyperosmotic stress resulted in cell shrinking within a few minutes. Depending on the medium osmolarity, this was followed by lack of volume recovery for at least 2 h or by slow recovery. Experiments with inhibitors, or with cells in which an aquaporin gene (TcAQP1) was knocked down or overexpressed, revealed its importance for the cellular response to hyperosmotic stress. Furthermore, the adaptation to this new environment was shown to involve the regulation of the polyphosphate polymerization state as well as changes in amino acid catabolism to generate compatible osmolytes. A genome-wide transcriptional analysis of stressed parasites revealed down-regulation of genes belonging to diverse functional categories and up-regulation of genes encoding trans-sialidase-like and ribosomal proteins. Several of these changes were confirmed by Northern blot analyses. Sequence analysis of the 3'UTRs of up- and down-regulated genes allowed the identification of conserved structural RNA motifs enriched in each group, suggesting that specific ribonucleoprotein complexes could be of great importance in the adaptation of this parasite to different environments through regulation of transcript abundance.
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Affiliation(s)
- Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Vanina E Alvarez
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602; Instituto de Investigaciones Biotecnólogicas, Universidad Nacional de General San Martin/Consejo Nacional de Investigaciones Científicas y Técnicas, 1650 San Martin, Buenos Aires, Argentina
| | - Javier G De Gaudenzi
- Instituto de Investigaciones Biotecnólogicas, Universidad Nacional de General San Martin/Consejo Nacional de Investigaciones Científicas y Técnicas, 1650 San Martin, Buenos Aires, Argentina
| | - Celso Sant'Anna
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Alberto C C Frasch
- Instituto de Investigaciones Biotecnólogicas, Universidad Nacional de General San Martin/Consejo Nacional de Investigaciones Científicas y Técnicas, 1650 San Martin, Buenos Aires, Argentina
| | - Juan J Cazzulo
- Instituto de Investigaciones Biotecnólogicas, Universidad Nacional de General San Martin/Consejo Nacional de Investigaciones Científicas y Técnicas, 1650 San Martin, Buenos Aires, Argentina
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602.
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74
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Human antiquitin: structural and functional studies. Chem Biol Interact 2010; 191:165-70. [PMID: 21185811 DOI: 10.1016/j.cbi.2010.12.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 12/17/2010] [Accepted: 12/18/2010] [Indexed: 11/21/2022]
Abstract
Antiquitin (ALDH7) is a member of the aldehyde dehydrogenase superfamily which oxidizes various aldehydes to form the corresponding carboxylic acids. Human antiquitin (ALDH7A1) is believed to play a role in detoxification, osmoregulation and more specifically, in lysine metabolism in which alpha-aminoadipic semialdehyde is identified as the specific, physiological substrate of the enzyme. In the present study, the structural basis for the substrate specificity was studied by site-directed mutagenesis. Kinetic analysis on wild-type human antiquitin and its mutants E121A and R301A demonstrated the importance of Glu121 and Arg301 in the binding as well as the turnover of alpha-aminoadipic semialdehyde. On the functional aspect, in addition to the already diversified physiological functions of antiquitin, the recent demonstration of its presence in the nucleus suggests that it may also play a role in cell growth and cell cycle progression. In this investigation, the expression level of antiquitin was monitored in synchronized WRL68 and HEK293 cell culture systems. It was found that the protein was up-regulated during G(1)-S phase transition. Immunofluorescence staining of the synchronized cells demonstrated an increased expression and accumulation of antiquitin in the nucleus during the G(1)-S phase transition. Knockdown of antiquitin using shRNA transfection also resulted in changes in the levels of several key cell cycle-regulating proteins.
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75
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Shears SB, Gokhale NA, Wang H, Zaremba A. Diphosphoinositol polyphosphates: what are the mechanisms? ACTA ACUST UNITED AC 2010; 51:13-25. [PMID: 21035493 DOI: 10.1016/j.advenzreg.2010.09.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Accepted: 09/17/2010] [Indexed: 12/30/2022]
Abstract
In countries where adulthood is considered to be attained at age eighteen, 2011 can be the point at which the diphosphoinositol polyphosphates might formally be described as "coming of age", since these molecules were first fully defined in 1993 (Menniti et al., 1993; Stephens et al., 1993b). But from a biological perspective, these polyphosphates cannot quite be considered to have matured into the status of being independently-acting intracellular signals. This review has discussed several of the published proposals for mechanisms by which the diphosphoinositol polyphosphates might act. We have argued that all of these hypotheses need further development.We also still do not know a single molecular mechanism by which a change in the levels of a particular diphosphoinositol polyphosphate can be controlled. Yet, despite all these gaps in our understanding, there is an enduring anticipation that these molecules have great potential in the signaling field. Reflecting our expectations of all teenagers, it should be our earnest hope that in the near future the diphosphoinositol polyphosphates will finally grow up.
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Affiliation(s)
- Stephen B Shears
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.
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76
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Galetti M, Alfieri RR, Cavazzoni A, La Monica S, Bonelli M, Fumarola C, Mozzoni P, De Palma G, Andreoli R, Mutti A, Mor M, Tiseo M, Ardizzoni A, Petronini PG. Functional characterization of gefitinib uptake in non-small cell lung cancer cell lines. Biochem Pharmacol 2010; 80:179-87. [DOI: 10.1016/j.bcp.2010.03.033] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 03/25/2010] [Accepted: 03/26/2010] [Indexed: 02/06/2023]
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77
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Kalujnaia S, McVee J, Kasciukovic T, Stewart AJ, Cramb G. A role for inositol monophosphatase 1 (IMPA1) in salinity adaptation in the euryhaline eel (Anguilla anguilla). FASEB J 2010; 24:3981-91. [PMID: 20547660 DOI: 10.1096/fj.10-161000] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study investigated the expression and tissue distribution of inositol monophosphatase (IMPA1) and characterized its role in salinity adaptation in the eel. The coding sequence of eel IMPA1 was determined and confirmed to be orthologous to the mammalian gene/enzyme by phylogenetic analysis and structural modeling. Quantitative real-time PCR and Western blot techniques indicated up to 17-fold increases in mRNA expression and 2-fold increases in protein abundance in major osmoregulatory tissues following transfer of fish to seawater (SW). This was accompanied by up to 5-fold increases in enzyme activity, and 1.8- and 3-fold increases in inositol contents within the gill and kidney, respectively. Immunohistological studies revealed that IMPA1 protein expression predominated in SW-acclimated fish within basal epithelial/epidermal layers of the gill, esophagus, intestine, skin, and fins. SW transfer also induced a 10-fold increase in inositol content in the fin. IMPA1 immunoreactivity was also identified in chondrocytes within the cartilagenous matrix of the gills and fins, as well as in clusters of interstitial cells surrounding the kidney tubules. The observed increases in expression of IMPA1 highlight a protective role for inositol within various eel tissues following SW acclimation. This constitutes an adaptive mechanism in teleost fish naturally exposed to hypertonic environments.
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Affiliation(s)
- Svetlana Kalujnaia
- School of Medicine, University of St Andrews, St Andrews, Fife, KY16 9TF, UK
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78
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Brocker C, Lassen N, Estey T, Pappa A, Cantore M, Orlova VV, Chavakis T, Kavanagh KL, Oppermann U, Vasiliou V. Aldehyde dehydrogenase 7A1 (ALDH7A1) is a novel enzyme involved in cellular defense against hyperosmotic stress. J Biol Chem 2010; 285:18452-63. [PMID: 20207735 DOI: 10.1074/jbc.m109.077925] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Mammalian ALDH7A1 is homologous to plant ALDH7B1, an enzyme that protects against various forms of stress, such as salinity, dehydration, and osmotic stress. It is known that mutations in the human ALDH7A1 gene cause pyridoxine-dependent and folic acid-responsive seizures. Herein, we show for the first time that human ALDH7A1 protects against hyperosmotic stress by generating osmolytes and metabolizing toxic aldehydes. Human ALDH7A1 expression in Chinese hamster ovary cells attenuated osmotic stress-induced apoptosis caused by increased extracellular concentrations of sucrose or sodium chloride. Purified recombinant ALDH7A1 efficiently metabolized a number of aldehyde substrates, including the osmolyte precursor, betaine aldehyde, lipid peroxidation-derived aldehydes, and the intermediate lysine degradation product, alpha-aminoadipic semialdehyde. The crystal structure for ALDH7A1 supports the enzyme's substrate specificities. Tissue distribution studies in mice showed the highest expression of ALDH7A1 protein in liver, kidney, and brain, followed by pancreas and testes. ALDH7A1 protein was found in the cytosol, nucleus, and mitochondria, making it unique among the aldehyde dehydrogenase enzymes. Analysis of human and mouse cDNA sequences revealed mitochondrial and cytosolic transcripts that are differentially expressed in a tissue-specific manner in mice. In conclusion, ALDH7A1 is a novel aldehyde dehydrogenase expressed in multiple subcellular compartments that protects against hyperosmotic stress by generating osmolytes and metabolizing toxic aldehydes.
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Affiliation(s)
- Chad Brocker
- Department of Pharmaceutical Sciences, University of Colorado Denver, Aurora, Colorado 80045, USA
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79
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Iñesta-Vaquera FA, Centeno F, del Reino P, Sabio G, Peggie M, Cuenda A. Proteolysis of the tumour suppressor hDlg in response to osmotic stress is mediated by caspases and independent of phosphorylation. FEBS J 2008; 276:387-400. [DOI: 10.1111/j.1742-4658.2008.06783.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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80
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Systemic multicompartmental effects of the gut microbiome on mouse metabolic phenotypes. Mol Syst Biol 2008; 4:219. [PMID: 18854818 PMCID: PMC2583082 DOI: 10.1038/msb.2008.56] [Citation(s) in RCA: 251] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 07/15/2008] [Indexed: 02/08/2023] Open
Abstract
To characterize the impact of gut microbiota on host metabolism, we investigated the multicompartmental metabolic profiles of a conventional mouse strain (C3H/HeJ) (n=5) and its germ-free (GF) equivalent (n=5). We confirm that the microbiome strongly impacts on the metabolism of bile acids through the enterohepatic cycle and gut metabolism (higher levels of phosphocholine and glycine in GF liver and marked higher levels of bile acids in three gut compartments). Furthermore we demonstrate that (1) well-defined metabolic differences exist in all examined compartments between the metabotypes of GF and conventional mice: bacterial co-metabolic products such as hippurate (urine) and 5-aminovalerate (colon epithelium) were found at reduced concentrations, whereas raffinose was only detected in GF colonic profiles. (2) The microbiome also influences kidney homeostasis with elevated levels of key cell volume regulators (betaine, choline, myo-inositol and so on) observed in GF kidneys. (3) Gut microbiota modulate metabotype expression at both local (gut) and global (biofluids, kidney, liver) system levels and hence influence the responses to a variety of dietary modulation and drug exposures relevant to personalized health-care investigations.
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81
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Kloskowska E, Bruton JD, Winblad B, Benedikz E. The APP670/671 mutation alters calcium signaling and response to hyperosmotic stress in rat primary hippocampal neurons. Neurosci Lett 2008; 444:275-9. [DOI: 10.1016/j.neulet.2008.08.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 08/07/2008] [Accepted: 08/19/2008] [Indexed: 10/21/2022]
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82
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Choe KP, Strange K. Genome-wide RNAi screen and in vivo protein aggregation reporters identify degradation of damaged proteins as an essential hypertonic stress response. Am J Physiol Cell Physiol 2008; 295:C1488-98. [PMID: 18829898 DOI: 10.1152/ajpcell.00450.2008] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The damaging effects of hypertonic stress on cellular proteins are poorly defined, and almost nothing is known about the pathways that detect and repair hypertonicity-induced protein damage. To begin addressing these problems, we screened approximately 19,000 Caenorhabditis elegans genes by RNA interference (RNAi) feeding and identified 40 that are essential for survival during acute hypertonic stress. Half (20 of 40) of these genes encode proteins that function to detect, transport, and degrade damaged proteins, including components of the ubiquitin-proteasome system, endosomal sorting complexes, and lysosomes. High-molecular-weight ubiquitin conjugates increase during hypertonic stress, suggesting a global change in the ubiquitinylation state of endogenous proteins. Using a polyglutamine-containing fluorescent reporter, we demonstrate that cell shrinkage induces rapid protein aggregation in vivo and that many of the genes that are essential for survival during hypertonic stress function to prevent accumulation of aggregated proteins. High levels of urea, a strong protein denaturant, do not cause aggregation, suggesting that factors such as macromolecular crowding also contribute to protein aggregate formation during cell shrinkage. Acclimation of C. elegans to mild hypertonicity dramatically increases the osmotic threshold for protein aggregation, demonstrating that protein aggregation-inhibiting pathways are activated by osmotic stress. Our studies demonstrate that hypertonic stress induces protein damage in vivo and that detection and degradation of damaged proteins are essential mechanisms for survival under hypertonic conditions.
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Affiliation(s)
- Keith P Choe
- Vanderbilt Univ. Medical Center, S. Nashville, TN 37232-2520, USA
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83
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Yang L, Reece JM, Cho J, Bortner CD, Shears SB. The nucleolus exhibits an osmotically regulated gatekeeping activity that controls the spatial dynamics and functions of nucleolin. J Biol Chem 2008; 283:11823-31. [PMID: 18299322 PMCID: PMC2431058 DOI: 10.1074/jbc.m800308200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 02/15/2008] [Indexed: 12/17/2022] Open
Abstract
We demonstrate that physiologically relevant perturbations in the osmotic environment rheostatically regulate a gatekeeping function for the nucleolus that controls the spatial dynamics and functions of nucleolin. HeLa cells and U2-OS osteosarcoma cells were osmotically challenged with 100-200 mm sorbitol, and the intranuclear distribution of nucleolin was monitored by confocal microscopy. Nucleolin that normally resides in the innermost fibrillar core of the nucleolus, where it assists rDNA transcription and replication, was expelled within 30 min of sorbitol addition. The nucleolin was transferred into the nucleoplasm, but it distributed there non-uniformly; locally high levels accumulated in 4',6-diamidino-2-phenylindole-negative zones containing euchromatic (transcriptionally active) DNA. Inositol pyrophosphates also responded within 30 min of hyperosmotic stress: levels of bisdiphosphoinositol tetrakisphosphate increased 6-fold, and this was matched by decreased levels of its precursor, diphosphoinositol pentakisphosphate. Such fluctuations in inositol pyrophosphate levels are of considerable interest, because, according to previously published in vitro data, they regulate the degree of phosphorylation of nucleolin through a novel kinase-independent phosphotransferase reaction ( Saiardi, A., Bhandari, A., Resnick, R., Cain, A., Snowman, A. M., and Snyder, S. H. (2004) Science 306, 2101-2105 ). However, by pharmacologically intervening in inositol pyrophosphate metabolism, we found that it did not supervise the osmotically driven switch in the biological activities of nucleolin in vivo.
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Affiliation(s)
- Ling Yang
- Inositol Signaling Group and
the Molecular Endocrinology Group,
NIEHS, National Institutes of Health, Department of Health and Human Services,
Research Triangle Park, North Carolina 27709 and
Reecent Technologies, LLC, Durham,
North Carolina 27713
| | - Jeff M. Reece
- Inositol Signaling Group and
the Molecular Endocrinology Group,
NIEHS, National Institutes of Health, Department of Health and Human Services,
Research Triangle Park, North Carolina 27709 and
Reecent Technologies, LLC, Durham,
North Carolina 27713
| | - Jaiesoon Cho
- Inositol Signaling Group and
the Molecular Endocrinology Group,
NIEHS, National Institutes of Health, Department of Health and Human Services,
Research Triangle Park, North Carolina 27709 and
Reecent Technologies, LLC, Durham,
North Carolina 27713
| | - Carl D. Bortner
- Inositol Signaling Group and
the Molecular Endocrinology Group,
NIEHS, National Institutes of Health, Department of Health and Human Services,
Research Triangle Park, North Carolina 27709 and
Reecent Technologies, LLC, Durham,
North Carolina 27713
| | - Stephen B. Shears
- Inositol Signaling Group and
the Molecular Endocrinology Group,
NIEHS, National Institutes of Health, Department of Health and Human Services,
Research Triangle Park, North Carolina 27709 and
Reecent Technologies, LLC, Durham,
North Carolina 27713
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84
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Fisher DI, McLennan AG. Correlation of intracellular diadenosine triphosphate (Ap3A) with apoptosis in Fhit-positive HEK293 cells. Cancer Lett 2007; 259:186-91. [PMID: 18006149 DOI: 10.1016/j.canlet.2007.10.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Revised: 10/08/2007] [Accepted: 10/08/2007] [Indexed: 11/24/2022]
Abstract
The pro-apoptotic Fhit tumor suppressor protein binds and hydrolyses diadenosine triphosphate (Ap3A) and diadenosine tetraphosphate (Ap4A) in vitro. We have measured the level of both these nucleotides in Fhit-positive HEK293 cells exposed to various apoptosis inducers. Cold shock, anti-Fas, cadmium ions and etoposide all increased the basal level of Ap4A of 0.500pmol/10(6)cells by about 50%. However, the corresponding increases in Ap3A from a basal 0.079pmol/10(6)cells correlated closely with the degree of apoptosis produced, up to a maximum of 0.510pmol/10(6)cells with etoposide. These results support the view that Ap3A is the in vivo Fhit ligand and that an inhibition of Fhit activity is a key element in Fhit-mediated apoptosis.
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Affiliation(s)
- David I Fisher
- Cell Regulation and Signalling Group, School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, UK
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85
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Choi JH, Williams J, Cho J, Falck JR, Shears SB. Purification, sequencing, and molecular identification of a mammalian PP-InsP5 kinase that is activated when cells are exposed to hyperosmotic stress. J Biol Chem 2007; 282:30763-75. [PMID: 17702752 PMCID: PMC2366029 DOI: 10.1074/jbc.m704655200] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian cells utilize multiple signaling mechanisms to protect against the osmotic stress that accompanies plasma membrane ion transport, solute uptake, and turnover of protein and carbohydrates (Schliess, F., and Haussinger, D. (2002) Biol. Chem. 383, 577-583). Recently, osmotic stress was found to increase synthesis of bisdiphosphoinositol tetrakisphosphate ((PP)2-InsP4), a high energy inositol pyrophosphate (Pesesse, X., Choi, K., Zhang, T., and Shears, S. B. (2004) J. Biol. Chem. 279, 43378-43381). Here, we describe the purification from rat brain of a diphosphoinositol pentakisphosphate kinase (PPIP5K) that synthesizes (PP)2-InsP4. Partial amino acid sequence, obtained by mass spectrometry, matched the sequence of a 160-kDa rat protein containing a putative ATP-grasp kinase domain. BLAST searches uncovered two human isoforms (PPIP5K1 (160 kDa) and PPIP5K2 (138 kDa)). Recombinant human PPIP5K1, expressed in Escherichia coli, was found to phosphorylate diphosphoinositol pentakisphosphate (PP-InsP5) to (PP)2-InsP4 (Vmax = 8.3 nmol/mg of protein/min; Km = 0.34 microM). Overexpression in human embryonic kidney cells of either PPIP5K1 or PPIP5K2 substantially increased levels of (PP)2-InsP4, whereas overexpression of a catalytically dead PPIP5K1(D332A) mutant had no effect. PPIP5K1 and PPIP5K2 were more active against PP-InsP5 than InsP6, both in vitro and in vivo. Analysis by confocal immunofluorescence showed PPIP5K1 to be distributed throughout the cytoplasm but excluded from the nucleus. Immunopurification of overexpressed PPIP5K1 from osmotically stressed HEK cells (0.2 M sorbitol; 30 min) revealed a persistent, 3.9 +/- 0.4-fold activation when compared with control cells. PPIP5Ks are likely to be important signaling enzymes.
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Affiliation(s)
- Jae H Choi
- Inositide Signaling Group Laboratory of Signal Transduction, NIEHS, National Institutes of Health, DHHS, North Carolina 27709, USA
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86
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Ricardo RA, Bassani RA, Bassani JWM. Osmolality- and Na+-dependent effects of hyperosmotic NaCl solution on contractile activity and Ca2+ cycling in rat ventricular myocytes. Pflugers Arch 2007; 455:617-26. [PMID: 17680266 DOI: 10.1007/s00424-007-0322-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 07/04/2007] [Accepted: 07/05/2007] [Indexed: 10/23/2022]
Abstract
Hypertonic NaCl solutions have been used for small-volume resuscitation from hypovolemic shock. We sought to identify osmolality- and Na(+)-dependent components of the effects of the hyperosmotic NaCl solution (85 mOsm/kg increment) on contraction and cytosolic Ca(2+) concentration ([Ca(2+)](i)) in isolated rat ventricular myocytes. The biphasic change in contraction and Ca(2+) transient amplitude (decrease followed by recovery) was accompanied by qualitatively similar changes in sarcoplasmic reticulum (SR) Ca(2+) content and fractional release and was mimicked by isosmotic, equimolar increase in extracellular [Na(+)] ([Na(+)](o)). Raising osmolality with sucrose, however, augmented systolic [Ca(2+)](i) monotonically without change in SR parameters and markedly decreased contraction amplitude and diastolic cell length. Functional SR inhibition with thapsigargin abolished hyperosmolality effects on [Ca(2+)](i). After 15-min perfusion, both hyperosmotic solutions slowed mechanical relaxation during twitches and [Ca(2+)](i) decline during caffeine-evoked transients, raised diastolic and systolic [Ca(2+)](i), and depressed systolic contractile activity. These effects were greater with sucrose solution, and were not observed after isosmotic [Na(+)](o) increase. We conclude that under the present experimental conditions, transmembrane Na(+) redistribution apparently plays an important role in determining changes in SR Ca(2+) mobilization, which markedly affect contractile response to hyperosmotic NaCl solutions and attenuate the osmotically induced depression of contractile activity.
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Affiliation(s)
- Rafael A Ricardo
- Departamento de Engenharia Biomédica/Faculdade de Engenharia Elétrica e de Computação, Universidade Estadual de Campinas, Campinas, SP, Brazil
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