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Wong M.G.,University of Sydney | Perkovic V.,University of Sydney | Woodward M.,University of Sydney | Chalmers J.,University of Sydney | And 11 more authors.
Kidney International | Year: 2013

Albuminuria and a reduced glomerular filtration rate are conventional predictors of a future decline in kidney function in patients with type 2 diabetes mellitus. Using a nested case-control study we assessed whether circulating transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-7 (BMP-7) levels more accurately predict renal end points than the conventional markers. Cases were defined as those who developed a renal end point (doubling of serum creatinine to at least 200 μmol/l, the need for renal replacement therapy, or death due to renal disease) during the study. Using propensity scoring, two controls were selected for each of 281 cases. Participants who developed renal end points had significantly higher total TGF-β1, lower BMP-7 levels, and a higher total TGF-β1 to BMP-7 ratio at baseline. A graded increase in risk was found in individuals with lower BMP-7 levels (odds ratio 24.07, for the lowest to the highest tertile), or significantly higher TGF-β1 levels (odds ratio for the highest to the lowest tertile, 8.43). The area under the receiver operating characteristic curve (c-statistic) for the conventional predictors was 0.73. Using BMP-7 and total and active TGF-β1, the c-statistic was 0.94 (significantly higher to conventional predictors). Thus, our results suggest these novel kidney markers are better predictors of renal progression than the conventional predictors in patients with type 2 diabetes mellitus. © 2012 International Society of Nephrology.


PubMed | Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus, Charles University, Academy of Sciences of the Czech Republic and Institute for Clinical and Experimental Medicine
Type: Journal Article | Journal: PloS one | Year: 2014

The plasma profile of major lipoprotein classes and its subdivision into particular fractions plays a crucial role in the pathogenesis of atherosclerosis and is a major predictor of coronary artery disease. Our aim was to identify genomic determinants of triglyceride and cholesterol distribution into lipoprotein fractions and lipoprotein particle sizes in the recombinant inbred rat set PXO, in which alleles of two rat models of the metabolic syndrome (SHR and PD inbred strains) segregate together with those from Brown Norway rat strain. Adult male rats of 15 PXO strains (n=8-13/strain) and two progenitor strains SHR-Lx (n=13) and BXH2/Cub (n=18) were subjected to one-week of high-sucrose diet feeding. We performed association analyses of triglyceride (TG) and cholesterol (C) concentrations in 20 lipoprotein fractions and the size of major classes of lipoprotein particles utilizing 704 polymorphic microsatellite markers, the genome-wide significance was validated by 2,000 permutations per trait. Subsequent in silico focusing of the identified quantitative trait loci was completed using a map of over 20,000 single nucleotide polymorphisms. In most of the phenotypes we identified substantial gradient among the strains (e.g. VLDL-TG from 5.6 to 66.7 mg/dl). We have identified 14 loci (encompassing 1 to 65 genes) on rat chromosomes 3, 4, 7, 8, 11 and 12 showing suggestive or significant association to one or more of the studied traits. PXO strains carrying the SHR allele displayed significantly higher values of the linked traits except for LDL-TG and adiposity index. Cholesterol concentrations in large, medium and very small LDL particles were significantly associated to a haplotype block spanning part of a single gene, low density lipoprotein receptor-related protein 1B (Lrp1b). Using genome-wide association we have identified new genetic determinants of triglyceride and cholesterol distribution into lipoprotein fractions in the recombinant inbred panel of rat model strains.


Bouallegue A.,Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus | Bouallegue A.,University of Montréal | Simo Cheyou E.R.,Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus | Simo Cheyou E.R.,University of Montréal | And 3 more authors.
Cell Calcium | Year: 2013

Endothelin-1 (ET-1), a potent vasoactive peptide with a pathogenic role in vascular diseases, has been shown to induce the activation of ERK1/2, PKB and the expression of a transcriptional regulator, the early growth response 1 (Egr-1), key mediators of hypertrophic and proliferative responses in vascular smooth muscle cells (VSMC). We have demonstrated earlier that ET-1 requires H2O2 generation to activate these signaling pathways and Ca2+, calmodulin (CaM) and Ca2+/CaM-dependent protein kinase II (CaMKII), play a critical role to trigger H2O2-induced effects in VSMC. However, an involvement of CaMKII in mediating ET-1-induced responses in VSMC remains unknown. Therefore, by utilizing pharmacological inhibitors of CaM, CaMKII, a CaMKII inhibitor peptide and CaMKII knockdown techniques, we have investigated the contribution of CaM and CaMKII in ET-1-induced ERK1/2 and PKB signaling, Egr-1 expression and hypertrophic and proliferative responses in VSMC. W-7 and calmidazolium, antagonists of CaM, as well as KN-93, an inhibitor of CaMKII activity, attenuated ET-1-induced ERK1/2 and PKB phosphorylation. In addition, transfection of VSMC with a CaMKII inhibitory peptide suppressed ET-1-evoked ERK1/2 and PKB phosphorylation. Similarly, siRNA-mediated CaMKII silencing reduced ET-1-produced ERK1/2 and PKB phosphorylation. CaM and CaMKII blockade also significantly lowered the ET-1-induced protein and DNA synthesis as well as Egr-1 expression. These findings demonstrate that CaMKII plays a critical role in ET-1-induced growth promoting signaling pathways as well as hypertrophic and proliferative responses in VSMC. © 2013 Elsevier Ltd.


Platonova A.,Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus | Platonova A.,Moscow State University | Koltsova S.,Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus | Koltsova S.,Russian Academy of Medical Sciences | And 4 more authors.
Journal of Membrane Biology | Year: 2011

This study examined the role of cell volume modulation in plasma membrane rupture and death documented in ouabain-treated renal epithelial cells. Long-term exposure to ouabain caused massive death of C11-MDCK (Madin-Darby canine kidney) epithelial cells, documented by their detachment, chromatin cleavage and complete loss of lactate dehydrogenase (LDH), but did not affect the survival of vascular smooth muscle cells (VSMCs) from the rat aorta. Unlike the distinct impact on cell survival, 2-h exposure to ouabain led to sharp elevation of the [Na+]i/[K+]i ratio in both cell types. A similar increment of Na i + content was evoked by sustained inhibition of Na+,K+-ATPase in K+-free medium. However, in contrast to ouabain, C11-MDCK cells survived perfectly during 24-h exposure to K+-free medium. At 3 h, the volume of ouabain-treated C11-MDCK cells and VSMCs, measured by the recently developed dual-image surface reconstruction technique, was increased by 16 and 12%, respectively, whereas 5-10 min before the detachment of ouabain-treated C11-MDCK cells, their volume was augmented by ∼30-40%. To examine the role of modest swelling in the plasma membrane rupture of ouabain-treated cells, we compared actions of hypotonic medium on volume and LDH release. We observed that LDH release from hyposmotically swollen C11-MDCK cells was triggered when their volume was increased by approximately fivefold. Thus, our results showed that the rupture of plasma membranes in ouabain-treated C11-MDCK cells was not directly caused by cell volume modulation evoked by Na+,K +-ATPase inhibition and inversion of the [Na+] i/[K+]i ratio. © 2011 Springer Science+Business Media, LLC.


Koltsova S.V.,Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus
PloS one | Year: 2012

Stimulus-dependent elevation of intracellular Ca(2+) ([Ca(2+)](i)) affects the expression of numerous genes--a phenomenon known as excitation-transcription coupling. Recently, we found that increases in [Na(+)](i) trigger c-Fos expression via a novel Ca(2+) (i)-independent pathway. In the present study, we identified ubiquitous and tissue-specific [Na(+)](i)/[K(+)](i)-sensitive transcriptomes by comparative analysis of differentially expressed genes in vascular smooth muscle cells from rat aorta (RVSMC), the human adenocarcinoma cell line HeLa, and human umbilical vein endothelial cells (HUVEC). To augment [Na(+)](i) and reduce [K(+)](i), cells were treated for 3 hrs with the Na(+),K(+)-ATPase inhibitor ouabain or placed for the same time in the K(+)-free medium. Employing Affymetrix-based technology, we detected changes in expression levels of 684, 737 and 1839 transcripts in HeLa, HUVEC and RVSMC, respectively, that were highly correlated between two treatments (p<0.0001; R(2)>0.62). Among these Na(+) (i)/K(+) (i)-sensitive genes, 80 transcripts were common for all three types of cells. To establish if changes in gene expression are dependent on increases in [Ca(2+)](i), we performed identical experiments in Ca(2+)-free media supplemented with extracellular and intracellular Ca(2+) chelators. Surprisingly, this procedure elevated rather than decreased the number of ubiquitous and cell-type specific Na(+) (i)/K(+) (i)-sensitive genes. Among the ubiquitous Na(+) (i)/K(+) (i)-sensitive genes whose expression was regulated independently of the presence of Ca(2+) chelators by more than 3-fold, we discovered several transcription factors (Fos, Jun, Hes1, Nfkbia), interleukin-6, protein phosphatase 1 regulatory subunit, dual specificity phosphatase (Dusp8), prostaglandin-endoperoxide synthase 2, cyclin L1, whereas expression of metallopeptidase Adamts1, adrenomedulin, Dups1, Dusp10 and Dusp16 was detected exclusively in Ca(2+)-depleted cells. Overall, our findings indicate that Ca(2+) (i)-independent mechanisms of excitation-transcription coupling are involved in transcriptomic alterations triggered by elevation of the [Na(+)](i)/[K(+)](i) ratio. There results likely have profound implications for normal and pathological regulation of mammalian cells, including sustained excitation of neuronal cells, intensive exercise and ischemia-triggered disorders.


Koltsova S.V.,Moscow State University | Tremblay J.,Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus | Hamet P.,Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus | Orlov S.N.,Moscow State University | Orlov S.N.,Tomsk National Research University
Cell Calcium | Year: 2015

Previously, we reported that Ca2+ depletion increased permeability of the plasma membrane for Na+. This study examined the relative impact of [Na+]i/[K+]i-mediated signaling on transcriptomic changes in cultured vascular smooth muscle cells from rat aorta (VSMC) subjected to Ca2+-depletion by extra-(EGTA) and intracellular (BAPTA-AM) Ca2+ chelators. Na+,K+-ATPase inhibition in K+-free medium during 3h led to elevation of [Na+]i and attenuation of [K+]i by ~7- and 10-fold, whereas Ca2+-depletion resulted in alteration of these parameters by ~3- and 2-fold, respectively. Augmented VSMC permeability for Na+ and elevation of the [Na+]i/[K+]i ratio was triggered by addition to Ca2+-free medium 50μM EGTA and was not affected by 10μM BAPTA-AM. Na+,K+-ATPase inhibition and Ca2+-depletion changed expression of 3677 and 4610 mRNA transcripts, respectively. We found highly significant (p<10-12) positive (R2>0.51) correlation between levels of expression of 2071 transcripts whose expression was affected by both stimuli. Among genes whose expression in Ca2+-depleted cells was augmented by more than 7-fold we noted cyclic AMP-dependent transcription factor Atf3, early growth response protein Egr1 and nuclear receptor subfamily 4, group A member Nr4a1. Dissipation of transmembrane gradients of monovalent cations in high-K+, low-Na+-medium abolished the increments of the [Na+]i/[K+]i ratio as well as the augmented expression of these genes triggered by incubation of VSMC in EGTA containing medium. Thus, our results demonstrate, for the first time, that robust transcriptomic changes triggered by Ca2+-depletion in the presence of extracellular Ca2+-chelators are at least partially mediated by elevation of the [Na+]i/[K+]i ratio and activation of Ca2+i-independent, [Na+]i/[K+]i-mediated mechanism of excitation-transcription coupling. These results shad a new light on analysis of data obtained in cells subjected to long-term exposure to Ca2+ chelators. © 2015 Elsevier Ltd.


Koltsova S.V.,Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus | Koltsova S.V.,Russian Academy of Medical Sciences | Trushina Y.,Moscow State University | Haloui M.,Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus | And 7 more authors.
PLoS ONE | Year: 2012

Stimulus-dependent elevation of intracellular Ca2+ ([Ca2+]i) affects the expression of numerous genes - a phenomenon known as excitation-transcription coupling. Recently, we found that increases in [Na+]i trigger c-Fos expression via a novel Ca2+ i-independent pathway. In the present study, we identified ubiquitous and tissue-specific [Na+]i/[K+]i-sensitive transcriptomes by comparative analysis of differentially expressed genes in vascular smooth muscle cells from rat aorta (RVSMC), the human adenocarcinoma cell line HeLa, and human umbilical vein endothelial cells (HUVEC). To augment [Na+]i and reduce [K+]i, cells were treated for 3 hrs with the Na+,K+-ATPase inhibitor ouabain or placed for the same time in the K+-free medium. Employing Affymetrix-based technology, we detected changes in expression levels of 684, 737 and 1839 transcripts in HeLa, HUVEC and RVSMC, respectively, that were highly correlated between two treatments (p<0.0001; R2>0.62). Among these Na+ i/K+ i-sensitive genes, 80 transcripts were common for all three types of cells. To establish if changes in gene expression are dependent on increases in [Ca2+]i, we performed identical experiments in Ca2+-free media supplemented with extracellular and intracellular Ca2+ chelators. Surprisingly, this procedure elevated rather than decreased the number of ubiquitous and cell-type specific Na+ i/K+ i-sensitive genes. Among the ubiquitous Na+ i/K+ i-sensitive genes whose expression was regulated independently of the presence of Ca2+ chelators by more than 3-fold, we discovered several transcription factors (Fos, Jun, Hes1, Nfkbia), interleukin-6, protein phosphatase 1 regulatory subunit, dual specificity phosphatase (Dusp8), prostaglandin-endoperoxide synthase 2, cyclin L1, whereas expression of metallopeptidase Adamts1, adrenomedulin, Dups1, Dusp10 and Dusp16 was detected exclusively in Ca2+-depleted cells. Overall, our findings indicate that Ca2+ i-independent mechanisms of excitation-transcription coupling are involved in transcriptomic alterations triggered by elevation of the [Na+]i/[K+]i ratio. There results likely have profound implications for normal and pathological regulation of mammalian cells, including sustained excitation of neuronal cells, intensive exercise and ischemia-triggered disorders. © 2012 Koltsova et al.


PubMed | Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus
Type: Journal Article | Journal: PloS one | Year: 2012

Stimulus-dependent elevation of intracellular Ca(2+) ([Ca(2+)](i)) affects the expression of numerous genes--a phenomenon known as excitation-transcription coupling. Recently, we found that increases in [Na(+)](i) trigger c-Fos expression via a novel Ca(2+) (i)-independent pathway. In the present study, we identified ubiquitous and tissue-specific [Na(+)](i)/[K(+)](i)-sensitive transcriptomes by comparative analysis of differentially expressed genes in vascular smooth muscle cells from rat aorta (RVSMC), the human adenocarcinoma cell line HeLa, and human umbilical vein endothelial cells (HUVEC). To augment [Na(+)](i) and reduce [K(+)](i), cells were treated for 3 hrs with the Na(+),K(+)-ATPase inhibitor ouabain or placed for the same time in the K(+)-free medium. Employing Affymetrix-based technology, we detected changes in expression levels of 684, 737 and 1839 transcripts in HeLa, HUVEC and RVSMC, respectively, that were highly correlated between two treatments (p<0.0001; R(2)>0.62). Among these Na(+) (i)/K(+) (i)-sensitive genes, 80 transcripts were common for all three types of cells. To establish if changes in gene expression are dependent on increases in [Ca(2+)](i), we performed identical experiments in Ca(2+)-free media supplemented with extracellular and intracellular Ca(2+) chelators. Surprisingly, this procedure elevated rather than decreased the number of ubiquitous and cell-type specific Na(+) (i)/K(+) (i)-sensitive genes. Among the ubiquitous Na(+) (i)/K(+) (i)-sensitive genes whose expression was regulated independently of the presence of Ca(2+) chelators by more than 3-fold, we discovered several transcription factors (Fos, Jun, Hes1, Nfkbia), interleukin-6, protein phosphatase 1 regulatory subunit, dual specificity phosphatase (Dusp8), prostaglandin-endoperoxide synthase 2, cyclin L1, whereas expression of metallopeptidase Adamts1, adrenomedulin, Dups1, Dusp10 and Dusp16 was detected exclusively in Ca(2+)-depleted cells. Overall, our findings indicate that Ca(2+) (i)-independent mechanisms of excitation-transcription coupling are involved in transcriptomic alterations triggered by elevation of the [Na(+)](i)/[K(+)](i) ratio. There results likely have profound implications for normal and pathological regulation of mammalian cells, including sustained excitation of neuronal cells, intensive exercise and ischemia-triggered disorders.


PubMed | Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus
Type: Journal Article | Journal: American journal of hypertension | Year: 2010

Recent studies demonstrated a key role of ubiquitous isoform of Na+,K+,2Cl- co-transport (NKCC1) in regulation of myogenic tone and peripheral resistance. We examined the impact of race, gender, and plasma lipid on NKCC1 activity in French Canadians and African Americans with hypertension and dyslipidemia.NKCC and passive erythrocyte membrane permeability to K+, measured as ouabain-resistant, bumetanide-sensitive, and (ouabain+bumetanide)-resistant 86Rb influx, respectively, were compared in 111 French-Canadian men, 107 French-Canadian women, 26 African-American men, and 45 African-American women with essential hypertension and dyslipidemia.The African-American men and women were 7 years younger and presented twofold decreased plasma triglycerides compared to their French-Canadian counterparts (P < 0.01) whereas body mass index (BMI), total cholesterol, low-density lipoprotein, and high-density lipoprotein (HDL) were not different. NKCC was respectively 50 and 38% lower in the African-American men and women than in the French Canadians (P < 0.005) without any differences in passive erythrocyte membrane permeability for K+. We did not observe any impact of age on NKCC in all groups under investigation, whereas plasma triglycerides correlated positively with the activity of this carrier in the French-Canadian men only.NKCC1 activity is lower in erythrocytes of African Americans with essential hypertension and dyslipidemia than in Caucasian counterparts. We suggest that decreased NKCC1 may contribute to the feature of the pathogenesis of salt-sensitive hypertension seen in African Americans.


PubMed | Center Hospitalier Of Luniversite Of Montreal Crchum Technopole Angus
Type: Journal Article | Journal: Canadian journal of physiology and pharmacology | Year: 2012

Na(+),K(+)-ATPase is a heterodimer consisting of catalytic 1-4 and regulatory 1-3 subunits. Recently, we reported that transfection with ouabain-resistant 1R-Na(+),K(+)-ATPase rescues renal epithelial C7-MDCK cells exclusively expressing the ouabain-sensitive 1S-isoform from the cytotoxic action of ouabain. To explore the role of 2 subunit in ion transport and cytotoxic action of ouabain, we compared the effect of ouabain on K(+) ((86)Rb) influx and the survival of ouabain-treated C7-MDCK cells stably transfected with 1R- and 2R-Na(+),K(+)-ATPase. 2R mRNA in transfected cells was 8-fold more abundant than 1R mRNA, whereas immunoreactive 2R protein content was 5-fold lower than endogenous 1S protein. A concentration of 10mol/L ouabain led to complete inhibition of (86)Rb influx both in mock- and 2R-transfected cells, whereas maximal inhibition of (86)Rb influx in 1R-transfectd cells was observed at 1000mol/L ouabain. In contrast to the massive death of mock- and 2R-transfected cells exposed to 3mol/L ouabain , 1R-cells survived after 24h incubation with 1000mol/L ouabain. Thus, our results show that unlike 1R, the presence of 2R-Na(+),K(+)-ATPase subunit mRNA and immunoreactive protein does not contribute to Na(+)/K(+) pump activity, and does not rescue C7-MDCK cells from the cytotoxic action of ouabain. Our results also suggest that the lack of impact of transfected 2-Na(+),K(+)-ATPase on Na(+)/K(+) pump activity and cell survival can be attributed to the low efficiency of its translation and (or) delivery to the plasma membrane of renal epithelial cells.

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