Página 1 dos resultados de 46 itens digitais encontrados em 0.461 segundos

Renal redox-sensitive signaling, but not blood pressure, is attenuated by Nox1 knockout in angiotensin II-dependent chronic hypertension

YOGI, Alvaro; MERCURE, Chantal; TOUYZ, Joshuah; CALLERA, Glaucia E.; MONTEZANO, Augusto C. I.; ARANHA, Anna B.; TOSTES, Rita C.; REUDELHUBER, Timothy; TOUYZ, Rhian M.
Fonte: LIPPINCOTT WILLIAMS & WILKINS Publicador: LIPPINCOTT WILLIAMS & WILKINS
Tipo: Artigo de Revista Científica
Português
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We demonstrated previously that, in mice with chronic angiotensin II-dependent hypertension, gp91phoxcontaining NADPH oxidase is not involved in the development of high blood pressure, despite being important in redox signaling. Here we sought to determine whether a gp91phox homologue, Nox1, may be important in blood pressure elevation and activation of redox-sensitive pathways in a model in which the renin-angiotensin system is chronically upregulated. Nox1-deficient mice and transgenic mice expressing human renin (TTRhRen) were crossed, and 4 genotypes were generated: control, TTRhRen, Nox1-deficient, and TTRhRen Nox1-deficient. Blood pressure and oxidative stress (systemic and renal) were increased in TTRhRen mice (P < 0.05). This was associated with increased NADPH oxidase activation. Nox1 deficiency had no effect on the development of hypertension in TTRhRen mice. Phosphorylation of c-Src, mitogen-activated protein kinases, and focal adhesion kinase was significantly increased 2-to 3-fold in kidneys from TTRhRen mice. Activation of c-Src, p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, and focal adhesion kinase but not of extracellular signal regulated kinase 1/2 or extracellular signal regulated kinase 5, was reduced in TTRhRen/Nox1-deficient mice (P < 0.05). Expression of procollagen III was increased in TTRhRen and TTRhRen/Nox1-deficient mice versus control mice...

Evidence for premature aging due to oxidative stress in iPSCs from Cockayne syndrome

Andrade, Luciana Nogueira de Sousa; Nathanson, Jason L.; Yeo, Gene W.; Menck, Carlos Frederico Martins; Muotri, Alysson Renato
Fonte: OXFORD UNIV PRESS; OXFORD Publicador: OXFORD UNIV PRESS; OXFORD
Tipo: Artigo de Revista Científica
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Cockayne syndrome (CS) is a human premature aging disorder associated with neurological and developmental abnormalities, caused by mutations mainly in the CS group B gene (ERCC6). At the molecular level, CS is characterized by a deficiency in the transcription-couple DNA repair pathway. To understand the role of this molecular pathway in a pluripotent cell and the impact of CSB mutation during human cellular development, we generated induced pluripotent stem cells (iPSCs) from CSB skin fibroblasts (CSB-iPSC). Here, we showed that the lack of functional CSB does not represent a barrier to genetic reprogramming. However, iPSCs derived from CSB patients fibroblasts exhibited elevated cell death rate and higher reactive oxygen species (ROS) production. Moreover, these cellular phenotypes were accompanied by an up-regulation of TXNIP and TP53 transcriptional expression. Our findings suggest that CSB modulates cell viability in pluripotent stem cells, regulating the expression of TP53 and TXNIP and ROS production.; UCSD; UCSD; Emerald Foundation; Emerald Foundation; National Institutes of Health [1-DP2-OD006495-01]; National Institutes of Health; California Institute for Regenerative Medicine (CIRM); California Institute for Regenerative Medicine (CIRM) [TR2-01814]; CAPES (Coordenacao de Aperfeicoamento de Nivel Superior); CAPES (Coordenacao de Aperfeicoamento de Nivel Superior) [BEX 4428/08-0]; FAPESP-CEPID (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo); FAPESPCEPID (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo); CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)

Evaluation of a protein deficient diet in rats through blood oxidative stress biomarkers

Prada, F. J A; Macedo, D. V.; De Mello, Maria Alice Rostom
Tipo: Artigo de Revista Científica Formato: 213-228
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Protein malnutrition leads to functional impairment in several organs, which is not fully restored with nutritional recovery. Little is known about the role of oxidative stress in the genesis of these alterations. This study was designed to assess the sensitivity of blood oxidative stress biomarkers to a dietary protein restriction. Male Wistar rats were divided into two groups, according to the diet fed from weaning (21 days) to 60 day old: normal protein (17% protein) and low protein (6% protein). Serum protein, albumin, free fatty acid and liver glycogen and lipids were evaluated to assess the nutritional status. Blood glutathione reductase (GR) and catalase (CAT) activities, plasma total sulfhydryl groups concentration (TSG) as well as plasma thiobarbituric acid reactive substances (TBARs) and reactive carbonyl derivatives (RCD) were measured as biomarkers of the antioxidant system and oxidative damage, respectively. The glucose metabolism in soleus muscle was also evaluated as an index of stress severity imposed to muscular mass by protein malnutrition. No difference was observed in muscle glucose metabolism or plasma RCD concentration between both groups. However, our results showed that the low protein group had higher plasma TBARs (62%) concentration and lower TSG (44%) concentration than control group...

Expressed Sequence Tag-Based Gene Expression Analysis under Aluminum Stress in Rye1[w]

Milla, Miguel A. Rodriguez; Butler, Ed; Huete, Alicia Rodriguez; Wilson, Cindy F.; Anderson, Olin; Gustafson, J. Perry
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: text
Publicado em /12/2002 Português
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To understand the mechanisms responsible for aluminum (Al) toxicity and tolerance in plants, an expressed sequence tag (EST) approach was used to analyze changes in gene expression in roots of rye (Secale cereale L. cv Blanco) under Al stress. Two cDNA libraries were constructed (Al stressed and unstressed), and a total of 1,194 and 774 ESTs were generated, respectively. The putative proteins encoded by these cDNAs were uncovered by Basic Local Alignment Search Tool searches, and those ESTs showing similarity to proteins of known function were classified according to 13 different functional categories. A total of 671 known function genes were used to analyze the gene expression patterns in rye cv Blanco root tips under Al stress. Many of the previously identified Al-responsive genes showed expression differences between the libraries within 6 h of Al stress. Certain genes were selected, and their expression profiles were studied during a 48-h period using northern analysis. A total of 13 novel genes involved in cell elongation and division (tonoplast aquaporin and ubiquitin-like protein SMT3), oxidative stress (glutathione peroxidase, glucose-6-phosphate-dehydrogenase, and ascorbate peroxidase), iron metabolism (iron deficiency-specific proteins IDS3a...

Lethal oxidative damage and mutagenesis are generated by iron in delta fur mutants of Escherichia coli: protective role of superoxide dismutase.

Touati, D; Jacques, M; Tardat, B; Bouchard, L; Despied, S
Tipo: text
Publicado em /05/1995 Português
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The Escherichia coli Fur protein, with its iron(II) cofactor, represses iron assimilation and manganese superoxide dismutase (MnSOD) genes, thus coupling iron metabolism to protection against oxygen toxicity. Iron assimilation is triggered by iron starvation in wild-type cells and is constitutive in fur mutants. We show that iron metabolism deregulation in fur mutants produces an iron overload, leading to oxidative stress and DNA damage including lethal and mutagenic lesions. fur recA mutants were not viable under aerobic conditions and died after a shift from anaerobiosis to aerobiosis. Reduction of the intracellular iron concentration by an iron chelator (ferrozine), by inhibition of ferric iron transport (tonB mutants), or by overexpression of the iron storage ferritin H-like (FTN) protein eliminated oxygen sensitivity. Hydroxyl radical scavengers dimethyl sulfoxide and thiourea also provided protection. Functional recombinational repair was necessary for protection, but SOS induction was not involved. Oxygen-dependent spontaneous mutagenesis was significantly increased in fur mutants. Similarly, SOD deficiency rendered sodA sodB recA mutants nonviable under aerobic conditions. Lethality was suppressed by tonB mutations but not by iron chelation or overexpression of FTN. Thus...

Nitric oxide and oxidative stress (H2O2) control mammalian iron metabolism by different pathways.

Pantopoulos, K; Weiss, G; Hentze, M W
Tipo: text
Publicado em /07/1996 Português
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Several cellular mRNAs are regulated posttranscriptionally by iron-responsive elements (IREs) and the cytosolic IRE-binding proteins IRP-1 and IRP-2. Three different signals are known to elicit IRP-1 activity and thus regulate IRE-containing mRNAs: iron deficiency, nitric oxide (NO), and the reactive oxygen intermediate hydrogen peroxide (H2O2). In this report, we characterize the pathways for IRP-1 regulation by NO and H2O2 and examine their effects on IRP-2. We show that the responses of IRP-1 and IRP-2 to NO remarkably resemble those elicited by iron deficiency: IRP-1 induction by NO and by iron deficiency is slow and posttranslational, while IRP-2 induction by these inductive signals is slow and requires de novo protein synthesis. In contrast, H2O2 induces a rapid posttranslational activation which is limited to IRP-1. Removal of the inductive signal H2O2 after < or = 15 min of treatment (induction phase) permits a complete IRP-1 activation within 60 min (execution phase) which is sustained for several hours. This contrasts with the IRP-1 activation pathway by NO and iron depletion, in which NO-releasing drugs or iron chelators need to be present during the entire activation phase. Finally, we demonstrate that biologically synthesized NO regulates the expression of IRE-containing mRNAs in target cells by passive diffusion and that oxidative stress endogenously generated by pharmacological modulation of the mitochondrial respiratory chain activates IRP-1...

DROSOPHILA HOLOCARBOXYLASE SYNTHETASE IS A CHROMOSOMAL PROTEIN REQUIRED FOR NORMAL HISTONE BIOTINYLATION, GENE TRANSCRIPTION PATTERNS, LIFESPAN AND HEAT TOLERANCE12

Camporeale, Gabriela; Giordano, Ennio; Rendina, Rosaria; Zempleni, Janos; Eissenberg, Joel C.
Tipo: text
Publicado em /11/2006 Português
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Posttranslational modifications of histones play important roles in chromatin structure and genomic stability. Distinct lysine residues in histones are targets for covalent binding of biotin, catalyzed by holocarboxylase synthetase (HCS) and biotinidase (BTD). Histone biotinylation has been implicated in heterochromatin structures, DNA repair, and mitotic chromosome condensation. To test whether HCS and BTD deficiency alters histone biotinylation, and to characterize phenotypes associated with HCS and BTD deficiency, HCS- and BTD-deficient flies were generated by RNA interference (RNAi). Expression of HCS and BTD decreased by 65–90% in RNAi-treated flies, as judged by mRNA abundance, BTD activity, and abundance of HCS protein. Decreased expression of HCS and BTD caused decreased biotinylation of K9 and K18 in histone H3. This was associated with altered expression of 201 genes in HCS-deficient flies. Lifespan of HCS- and BTD-deficient flies decreased by up to 32% compared to wild-type controls. Heat tolerance decreased by up to 55% in HCS-deficient flies compared to controls, as judged by survival times; effects of BTD deficiency were minor. Consistent with this observation, HCS deficiency was associated with altered expression of 285 heat-responsive genes. HCS and BTD deficiency did not affect cold tolerance...

c-Jun Downregulation by HDAC3-Dependent Transcriptional Repression Promotes Osmotic Stress-Induced Cell Apoptosis

Xia, Yan; Wang, Ji; Liu, Ta-Jen; Alfred Yung, W. K.; Hunter, Tony; Lu, Zhimin
Tipo: text
Publicado em 26/01/2007 Português
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c-Jun, a major transcription factor in the activating protein 1 (AP-1) family of regulatory proteins, is activated by many physiologic and pathologic stimuli. However, whether c-jun is regulated by epigenetic modification of chromatin structure is not clear. We showed here that c-jun was transcriptionally repressed in response to osmotic stress via a truncated HDAC3 generated by caspase-7–dependent cleavage at aspartic acid 391. The activation of caspase-7, which is independent of cytochrome c release and activation of caspase-9 and caspase-12, depends on activation of caspase-8, which in turn requires MEK2 activity and secretion of FAS ligand. The cell apoptosis induced by the truncated HDAC3 or enhanced by c-Jun deficiency during osmotic stress was suppressed by exogenous expression of c-Jun, indicating that the downregulation of c-Jun by HDAC3-dependent transcriptional repression plays a role in regulating cell survival and apoptosis.

Light-Induced Energy Dissipation in Iron-Starved Cyanobacteria: Roles of OCP and IsiA Proteins[W]

Wilson, Adjélé; Boulay, Clémence; Wilde, Annegret; Kerfeld, Cheryl A.; Kirilovsky, Diana
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: text
Publicado em /02/2007 Português
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In response to iron deficiency, cyanobacteria synthesize the iron stress–induced chlorophyll binding protein IsiA. This protein protects cyanobacterial cells against iron stress. It has been proposed that the protective role of IsiA is related to a blue light–induced nonphotochemical fluorescence quenching (NPQ) mechanism. In iron-replete cyanobacterial cell cultures, strong blue light is known to induce a mechanism that dissipates excess absorbed energy in the phycobilisome, the extramembranal antenna of cyanobacteria. In this photoprotective mechanism, the soluble Orange Carotenoid Protein (OCP) plays an essential role. Here, we demonstrate that in iron-starved cells, blue light is unable to quench fluorescence in the absence of the phycobilisomes or the OCP. By contrast, the absence of IsiA does not affect the induction of fluorescence quenching or its recovery. We conclude that in cyanobacteria grown under iron starvation conditions, the blue light–induced nonphotochemical quenching involves the phycobilisome OCP–related energy dissipation mechanism and not IsiA. IsiA, however, does seem to protect the cells from the stress generated by iron starvation, initially by increasing the size of the photosystem I antenna. Subsequently...

p31 Deficiency Influences Endoplasmic Reticulum Tubular Morphology and Cell Survival?

Uemura, Takefumi; Sato, Takashi; Aoki, Takehiro; Yamamoto, Akitsugu; Okada, Tetsuya; Hirai, Rika; Harada, Reiko; Mori, Kazutoshi; Tagaya, Mitsuo; Harada, Akihiro
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: text
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p31, the mammalian orthologue of yeast Use1p, is an endoplasmic reticulum (ER)-localized soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor (SNARE) that forms a complex with other SNAREs, particularly syntaxin 18. However, the role of p31 in ER function remains unknown. To determine the role of p31 in vivo, we generated p31 conditional knockout mice. We found that homozygous deletion of the p31 gene led to early embryonic lethality before embryonic day 8.5. Conditional knockout of p31 in brains and mouse embryonic fibroblasts (MEFs) caused massive apoptosis accompanied by upregulation of ER stress-associated genes. Microscopic analysis showed vesiculation and subsequent enlargement of the ER membrane in p31-deficient cells. This type of drastic disorganization in the ER tubules has not been demonstrated to date. This marked change in ER structure preceded nuclear translocation of the ER stress-related transcription factor C/EBP homologous protein (CHOP), suggesting that ER stress-induced apoptosis resulted from disruption of the ER membrane structure. Taken together, these results suggest that p31 is an essential molecule involved in the maintenance of ER morphology and that its deficiency leads to ER stress-induced apoptosis.

XBP-1 deficiency in the nervous system protects against amyotrophic lateral sclerosis by increasing autophagy

Hetz, Claudio; Thielen, Peter; Matus, Soledad; Nassif, Melissa; Court, Felipe; Kiffin, Roberta; Martinez, Gabriela; Cuervo, Ana María; Brown, Robert H.; Glimcher, Laurie H.
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: text
Publicado em 01/10/2009 Português
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Mutations in superoxide dismutase-1 (SOD1) cause familial amyotrophic lateral sclerosis (fALS). Recent evidence implicates adaptive responses to endoplasmic reticulum (ER) stress in the disease process via a pathway known as the unfolded protein response (UPR). Here, we investigated the contribution to fALS of X-box-binding protein-1 (XBP-1), a key UPR transcription factor that regulates genes involved in protein folding and quality control. Despite expectations that XBP-1 deficiency would enhance the pathogenesis of mutant SOD1, we observed a dramatic decrease in its toxicity due to an enhanced clearance of mutant SOD1 aggregates by macroautophagy, a cellular pathway involved in lysosome-mediated protein degradation. To validate these observations in vivo, we generated mutant SOD1 transgenic mice with specific deletion of XBP-1 in the nervous system. XBP-1-deficient mice were more resistant to developing disease, correlating with increased levels of autophagy in motoneurons and reduced accumulation of mutant SOD1 aggregates in the spinal cord. Post-mortem spinal cord samples from patients with sporadic ALS and fALS displayed a marked activation of both the UPR and autophagy. Our results reveal a new function of XBP-1 in the control of autophagy and indicate critical cross-talk between these two signaling pathways that can provide protection against neurodegeneration.

Dual and opposing roles of the unfolded protein response regulated by IRE1? and XBP1 in proinsulin processing and insulin secretion

Lee, Ann-Hwee; Heidtman, Keely; Hotamisligil, Gökhan S.; Glimcher, Laurie H.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: text
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As a key regulator of the unfolded protein response, the transcription factor XBP1 activates genes in protein secretory pathways and is required for the development of certain secretory cells. To elucidate the function of XBP1 in pancreatic ?-cells, we generated ?-cell-specific XBP1 mutant mice. Xbp1f/f;RIP-cre mice displayed modest hyperglycemia and glucose intolerance resulting from decreased insulin secretion from ?-cells. Ablation of XBP1 markedly decreased the number of insulin granules in ?-cells, impaired proinsulin processing, increased the serum proinsulin:insulin ratio, blunted glucose-stimulated insulin secretion, and inhibited cell proliferation. Notably, XBP1 deficiency not only compromised the endoplasmic reticulum stress response in ?-cells but also caused constitutive hyperactivation of its upstream activator, IRE1?, which could degrade a subset of mRNAs encoding proinsulin-processing enzymes. Hence, the combined effects of XBP1 deficiency on the canonical unfolded protein response and its negative feedback activation of IRE1? caused ?-cell dysfunction in XBP1 mutant mice. These results demonstrate that IRE1? has dual and opposing roles in ?-cells, and that a precisely regulated feedback circuit involving IRE1? and its product XBP1s is required to achieve optimal insulin secretion and glucose control.

Hematopoietic Cells from Ube1L-Deficient Mice Exhibit an Impaired Proliferation Defect under the Stress of Bone Marrow Transplantation

Cong, Xiuli; Yan, Ming; Yin, Xiaoyan; Zhang, Dong-Er
Tipo: text
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Following bone marrow transplantation, donor stem cells are recruited from their quiescent status to promote the rapid reconstitution in recipients. This dynamic process is tightly regulated by a complex of internal and external signals. Protein modification by the ubiquitin like modifier ISG15 (ISGylation) is strongly induced by Type I Interferons (IFNs). There are higher levels of Type I IFNs and protein ISGylation in the bone marrow of recipients shortly after transplantation. In order to clarify the physiological function of protein ISGylation, we generated a mouse model that lacks protein ISGylation due to deficiency of ISG15 conjugating enzyme Ube1L (Ube1L?/?). In this report, we focused on the analysis of the hematopoietic system in Ube1L?/? mice in steady-state hematopoiesis and its potential protective role during bone marrow reconstitution. Here we demonstrated that In Ube1L?/? mice, steady-state hematopoiesis was unperturbed. However, transplantation experiment revealed a 50% reduction in repopulation potential of Ube1L-deficient cells at 3 weeks posttransplantation, but no differences at 6 and 12 weeks. A competitive transplantation experiment magnified and extended this phenotype. Cell cycle analysis revealed that under the condition with high levels of IFNs and protein ISGylation...

Endogenous HMGB1 contributes to ischemia-reperfusion-induced myocardial apoptosis by potentiating the effect of TNF-?/JNK

Xu, Hu; Yao, Yongwei; Su, Zhaoliang; Yang, Yunbo; Kao, Raymond; Martin, Claudio M.; Rui, Tao
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: text
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High-mobility group box 1 (HMGB1) is a nuclear protein that has been implicated in the myocardial inflammation and injury induced by ischemia-reperfusion (I/R). The purpose of the present study was to assess the role of HMGB1 in myocardial apoptosis induced by I/R. In vivo, myocardial I/R induced an increase in myocardial HMGB1 expression and apoptosis. Inhibition of HMGB1 (A-box) ameliorated the I/R-induced myocardial apoptosis. In vitro, isolated cardiac myocytes were challenged with anoxia-reoxygenation (A/R; in vitro correlate to I/R). A/R-challenged myocytes also generated HMGB1 and underwent apoptosis. Inhibition of HMGB1 attenuated the A/R-induced myocyte apoptosis. Exogenous HMGB1 had no effect on myocyte apoptosis. However, inhibition of HMGB1 attenuated myocyte TNF-? production after the A/R was challenged; surprisingly, HMGB1 itself did not induce myocyte TNF-? production. Exogenous TNF-? induced a moderate proapoptotic effect on the myocytes, an effect substantially potentiated by coadministration of HMGB1. It is generally accepted that apoptosis induced by TNF-? is regulated by the balance of activation of c-Jun NH2-terminal kinase (JNK) and NF-?B. Indeed, in the present study, TNF-? increased the phosphorylation status of JNK and p65...

Role of the Polarity Protein Scribble for Podocyte Differentiation and Maintenance

Hartleben, Björn; Widmeier, Eugen; Wanner, Nicola; Schmidts, Miriam; Kim, Sung Tae; Schneider, Lisa; Mayer, Britta; Kerjaschki, Dontscho; Miner, Jeffrey H.; Walz, Gerd; Huber, Tobias B.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: text
Publicado em 07/05/2012 Português
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The kidney filter represents a unique assembly of podocyte epithelial cells that tightly enwrap the glomerular capillaries with their complex foot process network. While deficiency of the polarity proteins Crumbs and aPKC result in impaired podocyte foot process architecture, the function of basolateral polarity proteins for podocyte differentiation and maintenance remained unclear. Here we report, that Scribble is expressed in developing podocytes, where it translocates from the lateral aspects of immature podocytes to the basal cell membrane and foot processes of mature podocytes. Immunogold electron microscopy reveals membrane associated localisation of Scribble predominantly at the basolateral site of foot processes. To further study the role of Scribble for podocyte differentiation Scribbleflox/flox mice were generated by introducing loxP-sites into the Scribble introns 1 and 8 and these mice were crossed to NPHS2.Cre mice and Cre deleter mice. Podocyte-specific Scribble knockout mice develop normally and display no histological, ultrastructural or clinical abnormalities up to 12 months of age. In addition, no increased susceptibility to glomerular stress could be detected in these mice. In contrast, constitutive Scribble knockout animals die during embryonic development indicating the fundamental importance of Scribble for embryogenesis. Like in podocyte-specific Scribble knockout mice...

Regulation of unfolded protein response modulator XBP1s by acetylation and deacetylation

Wang, Feng-Ming; Ouyang, Hong-Jiao
Tipo: text
Publicado em 01/01/2011 Português
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X-box-binding protein 1 (XBP1) is a key modulator of unfolded protein response (UPR), which is involved in a wide range of pathological and physiological processes. The active/spliced form of XBP1 (XBP1s) messenger RNA is generated from unspliced form by IRE1 during UPR. However, post-translational modulation of XBP1s remains largely unknown. Here, we demonstrate that XBP1s is a target of acetylation and deacetylation mediated by p300 and SIRT1 respectively. p300 increases acetylation and protein stability of XBP1s, and enhances the transcriptional activity of XBP1s. SIRT1 deacetylates XBP1s and inhibits the transcriptional activity of XBP1s. Deficiency of SIRT1 enhances the XBP1s-mediated luciferase reporter activity in HEK293 cells and the upregulation of XBP1s target gene expression under ER stress in mouse embryonic fibroblasts (MEFs). Consistent with XBP1s favoring cell survival under ER stress, Sirt1?/? MEFs display a greater resistance to the ER stress-induced apoptotic cell death compared with Sirt1+/+ MEFs. Taken together, these results suggest that acetylation/deacetylation constitutes an important post-translational mechanism in controlling protein levels as well as transcriptional activity of XBP1s. This study provides a novel insight into molecular mechanisms by which SIRT1 regulates UPR signaling.

SOD2 deficiency in hematopoietic cells in mice results in reduced red blood cell deformability and increased heme degradation

Mohanty, Joy G.; Nagababu, Enika; Friedman, Jeffrey S.; Rifkind, Joseph M.
Tipo: text
Português
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Among the three types of super oxide dismutases (SODs) known, SOD2 deficiency is lethal in neonatal mice owing to cardiomyopathy caused by severe oxidative damage. SOD2 is found in red blood cell (RBC) precursors, but not in mature RBCs. To investigate the potential damage to mature RBCs resulting from SOD2 deficiency in precursor cells, we studied RBCs from mice in which fetal liver stem cells deficient in SOD2 were capable of efficiently rescuing lethally irradiated host animals. These transplanted animals lack SOD2 only in hematopoietically generated cells and live longer than SOD2 knockouts. In these mice, approximately 2.8% of their total RBCs in circulation are iron-laden reticulocytes, with numerous siderocytic granules and increased protein oxidation similar to that seen in sideroblastic anemia. We have studied the RBC deformability and oxidative stress in these animals and the control group by measuring them with a microfluidic ektacytometer and assaying fluorescent heme degradation products with a fluorimeter, respectively. In addition, the rate of hemoglobin oxidation in RBCs from these mice and the control group were measured spectrophotometrically. The results show that RBCs from these SOD2-deficient mice have reduced deformability...

A Deficiency of Herp, an Endoplasmic Reticulum Stress Protein, Suppresses Atherosclerosis in ApoE Knockout Mice by Attenuating Inflammatory Responses

Shinozaki, Shohei; Chiba, Tsuyoshi; Kokame, Koichi; Miyata, Toshiyuki; Kaneko, Eiji; Shimokado, Kentaro
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: text
Publicado em 28/10/2013 Português
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Herp was originally identified as an endoplasmic reticulum (ER) stress protein in vascular endothelial cells. ER stress is induced in atherosclerotic lesions, but it is not known whether Herp plays any role in the development of atherosclerosis. To address this question, we generated Herp- and apolipoprotein E (apoE)-deficient mice (Herp?/?; apoE?/? mice) by crossbreeding Herp?/? mice and apoE?/? mice. Herp was expressed in the endothelial cells and medial smooth muscle cells of the aorta, as well as in a subset of macrophages in the atherosclerotic lesions in apoE?/? mice, while there was no expression of Herp in the Herp?/?; apoE?/? mice. The doubly deficient mice developed significantly fewer atherosclerotic lesions than the apoE?/? mice at 36 and 72 weeks of age, whereas the plasma levels of cholesterol and triglycerides were not significantly different between the strains. The plasma levels of non-esterified fatty acids were significantly lower in the Herp?/?; apoE?/? mice when they were eight and 16 weeks old. The gene expression levels of ER stress response proteins (GRP78 and CHOP) and inflammatory cytokines (IL-1?, IL-6, TNF-? and MCP-1) in the aorta were significantly lower in Herp?/?; apoE?/? mice than in apoE?/? mice, suggesting that Herp mediated ER stress-induced inflammation. In fact...

The Regulation of Coenzyme Q Biosynthesis in Eukaryotic Cells: All That Yeast Can Tell Us

González-Mariscal, Isabel; García-Testón, Elena; Padilla, Sergio; Martín-Montalvo, Alejandro; Pomares Viciana, Teresa; Vazquez-Fonseca, Luis; Gandolfo Domínguez, Pablo; Santos-Ocaña, Carlos
Fonte: S. Karger AG Publicador: S. Karger AG
Tipo: text
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Coenzyme Q (CoQ) is a mitochondrial lipid, which functions mainly as an electron carrier from complex I or II to complex III at the mitochondrial inner membrane, and also as antioxidant in cell membranes. CoQ is needed as electron acceptor in ?-oxidation of fatty acids and pyridine nucleotide biosynthesis, and it is responsible for opening the mitochondrial permeability transition pore. The yeast model has been very useful to analyze the synthesis of CoQ, and therefore, most of the knowledge about its regulation was obtained from the Saccharomyces cerevisiae model. CoQ biosynthesis is regulated to support 2 processes: the bioenergetic metabolism and the antioxidant defense. Alterations of the carbon source in yeast, or in nutrient availability in yeasts or mammalian cells, upregulate genes encoding proteins involved in CoQ synthesis. Oxidative stress, generated by chemical or physical agents or by serum deprivation, modifies specifically the expression of some COQ genes by means of stress transcription factors such as Msn2/4p, Yap1p or Hsf1p. In general, the induction of COQ gene expression produced by metabolic changes or stress is modulated downstream by other regulatory mechanisms such as the protein import to mitochondria, the assembly of a multi-enzymatic complex composed by Coq proteins and also the existence of a phosphorylation cycle that regulates the last steps of CoQ biosynthesis. The CoQ biosynthetic complex assembly starts with the production of a nucleating lipid such as HHB by the action of the Coq2 protein. Then...

PBP1a-Deficiency Causes Major Defects in Cell Division, Growth and Biofilm Formation by Streptococcus mutans

Wen, Zezhang T.; Bitoun, Jacob P.; Liao, Sumei
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: text
Publicado em 16/04/2015 Português
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Streptococcus mutans, a key etiological agent of human dental caries, lives almost exclusively on the tooth surface in plaque biofilms and is known for its ability to survive and respond to various environmental insults, including low pH, and antimicrobial agents from other microbes and oral care products. In this study, a penicillin-binding protein (PBP1a)-deficient mutant, strain JB467, was generated by allelic replacement mutagenesis and analyzed for the effects of such a deficiency on S. mutans’ stress tolerance response and biofilm formation. Our results so far have shown that PBP1a-deficiency in S. mutans affects growth of the deficient mutant, especially at acidic and alkaline pHs. As compared to the wild-type, UA159, the PBP1a-deficient mutant, JB467, had a reduced growth rate at pH 6.2 and did not grow at all at pH 8.2. Unlike the wild-type, the inclusion of paraquat in growth medium, especially at 2 mM or above, significantly reduced the growth rate of the mutant. Acid killing assays showed that the mutant was 15-fold more sensitive to pH 2.8 than the wild-type after 30 minutes. In a hydrogen peroxide killing assay, the mutant was 16-fold more susceptible to hydrogen peroxide (0.2%, w/v) after 90 minutes than the wild-type. Relative to the wild-type...