Center for Molecular Physiology Research

National City, DC, United States

Center for Molecular Physiology Research

National City, DC, United States
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Jones J.E.,George Washington University | Jones J.E.,Center for Molecular Physiology Research | Jose P.A.,George Washington University | Jose P.A.,Center for Molecular Physiology Research
Current Hypertension Reports | Year: 2011

The assessment of salt sensitivity of blood pressure is difficult because of the lack of universal consensus on definition. Regardless of the variability in the definition of salt sensitivity, increased salt intake, independent of the actual level of blood pressure, is also a risk factor for cardiovascular morbidity and mortality and kidney disease. A modest reduction in salt intake results in an immediate decrease in blood pressure, with long-term beneficial consequences. However, some have suggested that dietary sodium restriction may not be beneficial to everyone. Thus, there is a need to distinguish salt-sensitive from salt-resistant individuals, but it has been difficult to do so with phenotypic studies. Therefore, there is a need to determine the genes that are involved in salt sensitivity. This review focuses on genes associated with salt sensitivity, with emphasis on the variants associated with salt sensitivity in humans that are not due to monogenic causes. Special emphasis is given to gene variants associated with salt sensitivity whose protein products interfere with cell function and increase blood pressure in transgenic mice. © 2010 Springer Science+Business Media, LLC.

Yang H.,Peking University | Xiong F.X.,Peking University | Lin M.,Peking University | Yang Y.,Center for Molecular Physiology Research | And 2 more authors.
Journal of Cancer Research and Clinical Oncology | Year: 2010

Purpose Lysosomal protein transmembrane 4 beta-35 (LAPTM4B-35) is a tetra-transmembrane glycoprotein that is abundantly localized on membrane-bound organelles including endosomes and lysosomes, and promotes cell proliferation and tumorigenesis through regulation of cell cycle and signaling pathways. The aim of the present study is to determine the potential clinical implications of LAPTM4B-35 expression in hepatocellular carcinoma (HCC). Methods Immunohistochemistry assay was used to determine the expression of LAPTM4B-35 protein in normal and HCC tissues from 71 patients. The correlations of LAPTM4B-35 expression with clinicopathological parameters, including gender, age, background liver, viral status, tumor size, portal vein invasion, histopathological differentiation, serum AFP level, TNM staging and recurrence of HCC were assessed by Chi-squared test. Patient survival and their differences were determined by Kaplan- Meier method and log-rank test. Cox regression (Proportional hazard model) was adopted for multivariate analysis of prognostic factors. Results LAPTM4B-35 immunoreactivity was negative or low in normal liver tissues, but high in HCC tissues (51/71, 71.8%). The overexpression of LAPTM4B-35 was significantly associated with recurrence, TNM staging and portal vein invasion of HCC. Patients with high LAPTM4B-35 expression had significantly poorer overall survival (OS) and disease-free survival (DFS) (both P < 0.001) when compared with patients with the low expression of LAPTM4B-35. On multivariate analysis, LAPTM4B-35 expression was found to be an independent prognostic factor for OS and DFS (P = 0.018 and P = 0.001, respectively). Conclusion LAPTM4B-35 expression showed a strong association with the potencies of recurrence and metastasis and progression of HCC, and that may be applied as a novel marker for the prediction of recurrence and metastasis potency of HCC, and helpful for improving the diagnosis, prognosis and treatment of HCC. © Springer-Verlag 2009.

Yatabe M.S.,Fukushima Medical University | Yatabe J.,Fukushima Medical University | Watanabe T.,Fukushima Medical University | Otsuki M.,Asaka Naika Clinic | And 3 more authors.
American Journal of Clinical Nutrition | Year: 2010

Background: The mechanisms by which a derangement of glucose metabolism causes high blood pressure are not fully understood. Objectives: This study aimed to clarify the relation between salt sensitivity of blood pressure and insulin resistance, which are important subcharacteristics of hypertension and impaired glucose metabolism, respectively. Effects on the renin-angiotensin and sympathetic nervous systems were also studied. Design: The state of glucose metabolism was assessed by a hyperinsulinemic euglycemic glucose clamp technique and a 75-g oral-glucose-tolerance test in 24 essential hypertensive patients who were lean and without diabetes or chronic kidney disease. The subjects were classified as salt-sensitive or salt-resistant on the basis of the difference (Δ mean blood pressure ≥5%) between 24-h ambulatory blood pressure monitoring results on the seventh day of low-salt (34 mmol/d) and high-salt (252 mmol/d) diets. Urine and blood samples were collected for analyses. Results: There was a robust inverse relation between the glucose infusion rate (GIR) and the salt sensitivity index. The GIR correlated directly with the change in urinary sodium excretion and was inversely related to the change in hematocrit when the salt diet was changed from low to high, which is indicative of salt and fluid retention in salt-sensitive subjects. The GIR also showed an inverse correlation compared with the changes in urinary norepinephrine excretion, plasma renin activity, and plasma aldosterone concentration. Conclusions: Salt sensitivity of blood pressure is strongly associated with insulin resistance in lean, essential hypertensive patients. Hyperinsulinemia, sympathetic overactivation, and reduced suppression of the renin-angiotensin system may play a role in this relation. © 2010 American Society for Nutrition.

Huang W.-Y.,University of Georgia | Huang W.-Y.,Shanghai JiaoTong University | Huang W.-Y.,Georgetown University | Xie W.,University of Georgia | And 5 more authors.
American Journal of Physiology - Cell Physiology | Year: 2011

Response gene to complement 32 (RGC-32) is activated by transforming growth factor- β (TGF- β) and plays an important role in smooth muscle cell (SMC) differentiation from neural crest Monc-1 cells. The molecular mechanism governing TGF- β activation of RGC-32, however, remains to be determined. The present studies indicate that TGF- β regulates RGC-32 gene transcription. Sequence analysis revealed a Smad binding element (SBE) located in the region from -1344 to -1337 bp upstream of the transcription start site of RGC-32 gene. A polyomavirus enhancer activator (PEA3) binding site is adjacent to the SBE. Mutation at either SBE or PEA3 site significantly inhibited RGC-32 promoter activity. Mutations at both sites completely abolished TGF- β -induced promoter activity. Biochemically, TGF- β stimulated recruitment of Smad2, Smad4, and PEA3 to the RGC-32 promoter, as revealed by gel shift and chromatin immunoprecipitation analyses. Functionally, Smad2, but not Smad3, activated RGC-32 promoter. PEA3 appeared to enhance Smad2 activity. In agreement with their function, Smad2, but not Smad3, physically interacted with PEA3. In TGF- β -induced SMC differentiation of Monc-1 cells, knockdown of Smad2 by short hairpin RNA resulted in downregulation of RGC-32 and SMC marker genes. The downregulation of SMC markers, however, was rescued by exogenously introduced RGC-32. These results demonstrate that Smad2 regulation of RGC-32 transcription is essential for SMC differentiation from neural crest cells. © 2011 the American Physiological Society.

Natarajan A.,Georgetown University | Han G.,Texas A&M University | Chen S.-Y.,University of Georgia | Yu P.,Center for Molecular Physiology Research | And 4 more authors.
Journal of Pharmacology and Experimental Therapeutics | Year: 2010

Large-conductance, calcium- and voltage-activated potassium (BK Ca) channels hyperpolarize coronary artery smooth muscle cells, causing vasorelaxation. Dopamine activates BKCa channels by stimulating D1-like receptor-mediated increases in cAMP in porcine coronary artery myocytes. There are two D1-like receptors (R), D 1R and D5R. We hypothesize that the specific D 1-like receptor involved in BKCa channel activation in human coronary artery smooth muscle cells (HCASMCs) is the D5R and that activation occurs via cAMP cross-activation of cGMP-dependent protein kinase (PKG), rather than cAMP-dependent protein kinase (PKA). The effects of D1-like receptor agonists and antagonists on BKCa channel opening in HCASMCs were examined in the presence and absence of PKG/PKA inhibition by cell-attached patch clamp. In the absence of commercially available ligands specific for D1R or D5R, D1R or D5R protein was down-regulated by transfecting HCASMCs with human D1R or D5R antisense oligonucleotides, respectively: cells transfected with scrambled oligonucleotides and nontransfected HCASMCs served as controls. The predominant ion channel conducting outward currents in nontransfected HCASMCs was identified as the large-conductance, calcium- and voltage-activated potassium (BKCa) channel, which was activated by D1-like receptor agonists despite PKA inhibition with (9R,10S,12S)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9, 12-epoxy-1H-diindolo[1,2,3-fg: 3′,2′,1′-kl]pyrrolo[3,4-i][1,6] benzodiazocine-10-carboxylic acid (KT 5720) (300 nM), but was abolished by inhibitingPKG with 9-methoxy-9-methoxycarbonyl-8-methyl-2, 3,9,10-tetrahydro-8, 11-epoxy-1H,8H,11H-2,7b-11a-triazadibenzo (a,g) cycloocta(cde)-trinden-1-one (KT 5823) (300 nM). D1-like receptor agonists activated BKCa channels in all transfected cells except those transfected with D5R antisense oligonucleotides. Thus, the dopamine (D1-like) receptor mediates activation of BKCa channels in HCASMCs by D5R, not D1R, and via PKG, not PKA. This is the first report of differential D1-like receptor regulation of vascular smooth muscle function in human cells. Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics.

Wang D.,Georgetown University | Luo Z.,Georgetown University | Wang X.,Georgetown University | Wang X.,Center for Molecular Physiology Research | And 7 more authors.
Hypertension | Year: 2010

Angiotensin (Ang) II causes endothelial dysfunction, which is associated with cardiovascular risk. We investigated the hypothesis that Ang II increases microvascular reactive oxygen species and asymmetrical dimethylarginine and switches endothelial function from vasodilator to vasoconstrictor pathways. Acetylcholine-induced endothelium-dependent responses of mesenteric resistance arterioles were assessed in a myograph and vascular NO and reactive oxygen species by fluorescent probes in groups (n=6) of male rats infused for 14 days with Ang II (200 ng/kg per minute) or given a sham infusion. Additional groups of Ang or sham-infused rats were given oral Tempol (2 mmol • L). Ang II infusion increased mean blood pressure (119±5 versus 89±7 mm Hg; P<0.005) and plasma malondialdehyde (0.57±0.02 versus 0.37±0.05 μmol • L; P<0.035) and decreased maximal endothelium-dependent relaxation (18±5% versus 54±6%; P<0.005) and hyperpolarizing (19±3% versus 29±3%; P<0.05) responses and NO activity (0.9±0.1 versus 1.6±0.2 U; P<0.01) yet enhanced endothelium-dependent contraction responses (23±5% versus 5±5%; P<0.05) and reactive oxygen species production (0.82±0.05 versus 0.15±0.03 U; P<0.01). Ang II decreased the expression of dimethylarginine dimethylaminohydrolase 2 and increased asymmetrical dimethylarginine in vessels (450±50 versus 260±35 pmol/mg of protein; P<0.01) but not plasma. Tempol prevented any significant changes with Ang II. In conclusion, Ang redirected endothelial responses from relaxation to contraction, reduced vascular NO, and increased asymmetrical dimethylarginine. These effects were dependent on reactive oxygen species and could, therefore, be targeted with effective antioxidant therapy. © 2010 American Heart Association, Inc.

Hai B.,Huazhong University of Science and Technology | Yang Y.,Center for Molecular Physiology Research | Xiao Y.,Huazhong University of Science and Technology | Li B.,Huazhong University of Science and Technology | Chen C.,Huazhong University of Science and Technology
Journal of the Canadian Urological Association | Year: 2012

Objectives: The objective of this study is to evaluate the diagnosis and prognosis of malignant mesothelioma of the tunica vaginalis testis through an additional 6 patients with urogenital mesothe-lioma. Methods: Six patients with urogenital mesothelioma who under-went adequate surgical procedures and histopathologic analysis from 1990 to 2009 were identified and retrospectively reviewed. Results: Six patients between the ages of 26 and 78 years with urogenital mesothelioma, 5 of which originated in the scrotum and 1 in the spermatic cord. Histopathologic analysis showed that CK5/6 and calretinin were positive in all cases, 5 cases were positive for vimentin, and 1 case showed focal weak positive reaction with MOC3, but none of the cases stained for CEA or CD15. The overall recurrence rate of urogenital mesothelioma after surgery was 5/6, including local recurrences and fatalities due to tumour. Conclusions: In cases of mesothelioma of the tunica vaginalis testis, the histopathologic markers we chose helped confirm the histo-pathological diagnosis; adequate surgical procedures are typically not curative, and this tumour is often fatal. © 2012 Canadian Urological Association.

Simao S.,University of Porto | Gomes P.,University of Porto | Jose P.A.,Center for Molecular Physiology Research | Soares-da-Silva P.,University of Porto
Biochemical Pharmacology | Year: 2010

We have previously demonstrated that exogenous H2O2 stimulates Cl-/HCO3- exchanger activity in immortalized renal proximal tubular epithelial (PTE) cells from both the Wistar-Kyoto (WKY) rat and the spontaneously hypertensive rat (SHR), this effect being more pronounced in SHR cells. The aim of the present study was to examine the mechanism of H2O2-induced stimulation of Cl-/HCO3- exchanger activity in WKY and SHR cells. It is now reported that the SHR PTE cells were endowed with an enhanced capacity to produce H2O2, comparatively with WKY cells and this was accompanied by a decreased expression of SOD2, SOD3, and catalase in SHR PTE cells. The stimulatory effect of H2O2 on the exchanger activity was blocked by SP600125 (JNK inhibitor), but not by U0126 (MEK1/2 inhibitor) or SB203580 (p38 inhibitor) in both cell lines. Basal JNK1 and JNK2 protein expression was higher in SHR PTE cells than in WKY PTE cells. H2O2 had no effect on p-JNK1/2 in WKY PTE cells over time. By contrast, H2O2 treatment resulted in a rapid and sustained increase in JNK1/2 phosphorylation in SHR PTE cells, which was completely abolished by apocynin. Treatment of SHR PTE cells with apocynin significantly decreased the H2O2-induced stimulation of Cl-/HCO3- exchanger activity. It is concluded that H2O2-induced stimulation of Cl-/HCO3- exchanger activity is regulated by JNK1/2, particularly by JNK2, in SHR PTE cells. The imbalance between oxidant and antioxidant mechanisms in SHR PTE cells enhances the response of JNK1/2 to H2O2, which contributes to their increased sensitivity to H2O2. © 2010 Elsevier Inc.

Guo X.,University of Georgia | Jose P.A.,Center for Molecular Physiology Research | Chen S.-Y.,University of Georgia
American Journal of Physiology - Cell Physiology | Year: 2011

Previous studies demonstrate that response gene to complement 32 (RGC-32) mediates transforming growth factor-β1-induced epithelial-mesenchymal transition (EMT) of human renal proximal tubular cells. However, the mechanisms underlying RGC-32 function remain largely unknown. In the present study, we found that RGC-32 function in EMT is associated with Smad3. Coexpression of RGC-32 and Smad3, but not Smad2, induces a higher mesenchymal marker α-smooth muscle actin (α-SMA) protein expression as compared with RGC-32 or Smad3 alone, while knockdown of Smad3 using short hairpin interfering RNA blocks RGC-32-induced α-SMA expression. These data suggest that RGC-32 interacts with Smad3, but not Smad2, in the regulation of EMT. In addition to α-SMA, RGC-32 and Smad3 also synergistically activate the expression of extracellular matrix protein fibronectin and downregulate the epithelial marker E-cadherin. RGC-32 colocalizes with Smad3 in the nuclei of renal proximal tubular cells. Coimmunoprecipitation assays showed that Smad3, but not Smad2, physically interacts with RGC-32 in renal proximal tubular cells. Mechanistically, RGC-32 and Smad3 coordinate the induction of EMT by regulating the EMT regulators Slug and Snail. Taken together, our data demonstrate for the first time that RGC-32 interacts with Smad3 to mediate the EMT of human renal proximal tubular cells. © 2011 the American Physiological Society.

Guo Y.,Center for Molecular Physiology Research | Jose P.A.,Center for Molecular Physiology Research
PLoS ONE | Year: 2011

The dopamine D 1 receptor (D 1R), a G protein-coupled receptor, plays a critical role in regulating blood pressure through its actions on renal hemodynamics and epithelial ion transport, which are highly linked to its intracellular trafficking. In this study, we generated a series of C-terminal mutants of D 1R that were tagged with or without enhanced yellow fluorescent protein, and analyzed the consequences of these mutants on the plasma membrane trafficking of D 1R and cyclic AMP response to D 1R stimulation. D 1R with mutations within the endocytic recycling signal (amino acid residues 360-382) continued to be functional, albeit decreased relative to wild-type D 1R. Mutation of the palmitoylation site (347C>S) of D 1R did not impair its trafficking to the plasma membrane, but abolished its ability to increase cyclic AMP accumulation. In contrast, replacement of di-leucines (344-345L>A) by alanines resulted in the retention of D 1R in the early endosome, decreased its glycosylation, and prevented its targeting to the plasma membrane. Our studies suggest that di-L motif at the C-terminus of D 1R is critical for the glycosylation and cell surface targeting of D 1R. © 2011 Guo, Jose.

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