ACE as a Mechanosensor to Shear Stress Influences the Control of Its Own Regulation via Phosphorylation of Cytoplasmic Ser1270

Objectives: We tested whether angiotensin converting enzyme (ACE) and phosphorylation of Ser(1270) are involved in shear-stress (SS)-induced downregulation of the enzyme. Methods and Results: Western blotting analysis showed that SS (18 h, 15 dyn/cm(2)) decreases ACE expression and phosphorylation as well as p-JNK inhibition in human primary endothelial cells (EC). CHO cells expressing wild-type ACE (wt-ACE) also displayed SS-induced decrease in ACE and p-JNK. Moreover, SS decreased ACE promoter activity in wt-ACE, but had no effect in wild type CHO or CHO expressing ACE without either the extra-or the intracellular domains, and decreased less in CHO expressing a mutated ACE at Ser(1270) compared to wt-ACE (13 vs. 40%, respectively). The JNK inhibitor (SP600125, 18 h), in absence of SS, also decreased ACE promoter activity in wt-ACE. Finally, SS-induced inhibition of ACE expression and phosphorylation in EC was counteracted by simultaneous exposure to an ACE inhibitor. Conclusions: ACE displays a key role on its own downregulation in response to SS. This response requires both the extra- and the intracellular domains and ACE Ser(1270), consistent with the idea that the extracellular domain behaves as a mechanosensor while the cytoplasmic domain elicits the downstream intracellular signaling by phosphorylation on Ser(1270).Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[01/00009-0]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[03/14115-2]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[06/52053-7]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[480120/2007-2

Circulating Dipeptidyl Peptidase IV Activity Correlates With Cardiac Dysfunction in Human and Experimental Heart Failure

Background the present study addresses the hypothesis that the activity of dipeptidyl peptidase IV (DPPIV), an enzyme that inactivates peptides that possess cardioprotective actions, correlates with adverse outcomes in heart failure (HF). the therapeutic potential of DPPIV inhibition in preventing cardiac dysfunction is also investigated.Methods and Results Measurements of DPPIV activity in blood samples obtained from 190 patients with HF and 42 controls demonstrated that patients with HF exhibited an increase of approximate to 130% in circulating DPPIV activity compared with healthy subjects. Furthermore, an inverse correlation was observed between serum DPPIV activity and left ventricular (LV) ejection fraction in patients with HF. Similarly, radiofrequency LV ablation-induced HF rats displayed higher DPPIV activity in the plasma (approximate to 50%) and heart tissue (approximate to 3.5-fold) compared with sham-operated rats. Moreover, positive correlations were observed between the plasma DPPIV activity and LV end-diastolic pressure and lung congestion. Two days after surgery, 1 group of LV ablation-induced HF rats was treated with the DPPIV inhibitor sitagliptin (40 mg/kg BID) for 6 weeks, whereas the remaining rats were administered water. Hemodynamic measurements demonstrated that radiofrequency LV-ablated rats treated with sitagliptin exhibited a significant attenuation of HF-related cardiac dysfunction, including LV end-diastolic pressure, systolic performance, and chamber stiffness. Sitagliptin treatment also attenuated cardiac remodeling and cardiomyocyte apoptosis and minimized pulmonary congestion.Conclusions Collectively, the results presented herein associate circulating DPPIV activity with poorer cardiovascular outcomes in human and experimental HF. Moreover, the results demonstrate that long-term DPPIV inhibition mitigates the development and progression of HF in rats

Thioredoxin interacting protein genetic variation is associated with diabetes and hypertension in the Brazilian general population

Objective: To investigate the relationship between TXNIP polymorphisms, diabetes and hypertension phenotypes in the Brazilian general population. Methods: Five hundred seventy-six individuals randomly selected from the general urban population according to the MONICA-WHO project guidelines were phenotyped for cardiovascular risk factors. A second, independent, sample composed of 487 family-trios from a different site was also selected. Nine TXNIP polymorphisms were studied. The potential association between TXNIP variability and glucose-phenotypes in children was also explored. TXNIP expression was quantified by real-time PCR in 53 samples from human smooth muscle cells primary culture. Results: TXNIP rs7211 and rs7212 polymorphisms were significantly associated with glucose and blood pressure related phenotypes. In multivariate logistic regression models the studied markers remained associated with diabetes even after adjustment for covariates. TXNIP rs7211 T/rs7212 G haplotype (present in approximately 17% of individuals) was significantly associated to diabetes in both samples. In children, the TXNIP rs7211 T/rs7212 G haplotype was associated with fasting insulin concentrations. Finally, cells harboring TXNIP rs7212 G allele presented higher TXNIP expression levels compared with carriers of TXNIP rs7212 CC genotype (p = 0.02). Conclusion: Carriers of TXNIP genetic variants presented higher TXNIP expression, early signs of glucose homeostasis derangement and increased susceptibility to chronic metabolic conditions such as diabetes and hypertension. Our data suggest that genetic variation in the TXNIP gene may act as a "common ground" modulator of both traits: diabetes and hypertension. (C) 2011 Elsevier Ireland Ltd. All rights reserved.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [01-00009-0]Prefeitura de Vitoria/FacitecPrefeitura de Vitoria/Facite