More than 80% of patients with type 2 diabetes mellitus develop hypertension, and approx. 20% of patients with hypertension develop diabetes. This combination of cardiovascular risk factors will account for a large proportion of cardiovascular morbidity and mortality. Lowering elevated blood pressure in diabetic hypertensive individuals decreases cardiovascular events. In patients with hypertension and diabetes, the pathophysiology of cardiovascular disease is multifactorial, but recent evidence points toward the presence of an important component dependent on a low-grade inflammatory process. Angiotensin II may be to a large degree responsible for triggering vascular inflammation by inducing oxidative stress, resulting in up-regulation of pro-inflammatory transcription factors such as NF-kappaB (nuclear factor kappaB). These, in turn, regulate the generation of inflammatory mediators that lead to endothelial dysfunction and vascular injury. Inflammatory markers (e.g. C-reactive protein, chemokines and adhesion molecules) are increased in patients with hypertension and metabolic disorders, and predict the development of cardiovascular disease. Lifestyle modification and pharmacological approaches (such as drugs that target the renin-angiotensin system) may reduce blood pressure and inflammation in patients with hypertension and metabolic disorders, which will reduce cardiovascular risk, development of diabetes and cardiovascular morbidity and mortality.

Background-Enhanced production of reactive oxygen species (ROS) has been recognized as the major determinant of age-related endothelial dysfunction. The p66 shc protein controls cellular responses to oxidative stress. Mice lacking p66 shc (p66 shcϪ/Ϫ ) have increased resistance to ROS and a 30% prolonged life span. The present study investigates age-dependent changes of endothelial function in this model. Methods and Results-Aortic rings from young and old p66shcϪ/Ϫ or wild-type (WT) mice were suspended for isometric tension recording. Nitric oxide (NO) release was measured by a porphyrinic microsensor. Expression of endothelial NO synthase (eNOS), inducible NOS (iNOS), superoxide dismutase, and nitrotyrosine-containing proteins was assessed by Western blotting. Nitrotyrosine residues were also identified by immunohistochemistry. Superoxide (O 2 Ϫ ) production was determined by coelenterazine-enhanced chemiluminescence. Endothelium-dependent relaxation in response to acetylcholine was age-dependently impaired in WT mice but not in p66shcϪ/Ϫ mice. Accordingly, an age-related decline of NO release was found in WT but not in p66shcϪ/Ϫ mice. The expression of eNOS and manganese superoxide dismutase was not affected by aging either in WT or in p66shcϪ/Ϫ mice, whereas iNOS was upregulated only in old WT mice. It is interesting that old WT mice displayed a significant increase of O 2 Ϫ production as well as of nitrotyrosine expression compared with young animals. Such age-dependent changes were not found in p66shcϪ/Ϫ mice. Conclusions-We report that inactivation of the p66shc gene protects against age-dependent, ROS-mediated endothelial dysfunction. These findings suggest that the p66 shc is part of a signal transduction pathway also relevant to endothelial integrity and may represent a novel target to prevent vascular aging. Key Words: aging Ⅲ endothelium Ⅲ free radicals Ⅲ nitric oxide Ⅲ genes S hc proteins are adaptor proteins that exist in 3 different isoforms with relative molecular masses of 46, 52, and 66 kDa. P52shc /p46 shc is involved in the transmission of mitogenic signals from tyrosine kinases to Ras. 1 p66 shc has the same modular structure of p52 shc /p46 shc (SH2-CH1-PTB) and contains a unique N-terminal region (CH2); however, it is not involved in Ras regulation but rather functions in the intracellular pathway that converts oxidative signals into apoptosis. Indeed, embryo fibroblasts from mice carrying a targeted mutation of p66 shc (p66 shcϪ/Ϫ ) are more resistant to oxidative stress-induced apoptosis. 2 p66 shcϪ/Ϫ mice have an approximately 30% increase in life span and reduced early atherogenesis after long-term consumption of a high-fat diet, 3 suggesting that p66shc is implicated in aging and in the pathogenesis of aging-associated diseases in mammals. The biochemical function of p66 shc remains, however, largely unknown. Recent reports demonstrated that p66 shc acts as a downstream target of the tumor suppressor p53 and is indispensable to the ability of activated p53 to induce elevation of intra...

Abstract-Magnesium modulates vascular smooth muscle cell (VSMC) function. However, molecular mechanisms regulating VSMC Mg 2ϩ remain unknown. Using biochemical, pharmacological, and genetic tools, the role of transient receptor potential membrane melastatin 7 (TRPM7) cation channel in VSMC Mg 2ϩ homeostasis was evaluated. Rat, mouse, and human VSMCs were studied. Reverse transcriptase polymerase chain reaction and immunoblotting demonstrated TRPM7 presence in VSMCs (membrane and cytosol). Angiotensin II (Ang II) and aldosterone increased TRPM7 expression. Gene silencing using small interfering RNA (siRNA) against TRPM7, downregulated TRPM7 (mRNA and protein). Basal [1][2][3][4] Mg 2ϩ also influences growth processes associated with remodeling and fibrosis, characteristic features of vascular damage in hypertension, atherosclerosis, and diabetes. 5,6 At the subcellular level, these effects occur, at least in part, through Mg 2ϩ -dependent regulation of mitogen-activated protein (MAP) kinases, tyrosine kinases, and reactive oxygen species, important signaling molecules involved in VSMC proliferation, fibrosis, and inflammation. [7][8][9] Microarray studies demonstrated that changes in [Mg 2ϩ ] i have potent modulatory actions on expression of various growth signaling molecules. 10 polypeptides with dual-function ion channel/ protein kinases, characterized by six transmembrane spanning domains with an adjacent coiled coil region, a long, highly conserved cytoplasmic N-terminal region, and a cytoplasmic C terminus, which has enzymatic activity. 22-24 TRPM6 and TRPM7, which have an overall amino acid sequence homology of 52%, harbor serine/threonine kinase domains in their C termini. 21,25,26 TRPM6 is preferentially expressed in small intestine, colon, and kidney, participating in gastrointestinal and renal Mg 2ϩ absorption. 21,27,28 Mutations in TRPM6 cause hypomagnesemia with secondary hypocalcemia. 27,29,30 Expression of TRPM7 is widespread with transcripts in brain, spleen, lung, kidney, heart, and liver. 22,[31][32][33] It is also expressed in lymphoid-derived cell lines, hematopoietic cells, granulocytes, leukemia cells, and microglia. 20,25 In various cell lines, TRPM7 is regulated by intracellular levels of Mg-ATP and is strongly activated when Mg-ATP falls below 1 mmol/L. 32,34 Studies in microglial and HEK293-transfected cells demonstrated that TRPM7 activity is also modulated through its endogenous kinase in a cAMP-, PKA-, and Src-dependent manner 25,35 and is inactivated by PIP2 hydrolysis in cardiac fibroblasts. 36 To our knowledge nothing is known about the status of TRPM7 in the vasculature. It is unclear whether this cation channel influences Mg 2ϩ transport in vascular cells and whether vasoactive agents regulate TRPM7. To gain insights into the putative role of TRPM7 in vascular Mg 2ϩ homeostasis, we used a combination of biochemical, pharmacological, molecular and genetic approaches to investigate the presence and functional significance of TRPM7 in VSMCs. Our data demonstrate that VSMCs poss...