The PI3K/Akt/mTOR pathway regulates the replicative senescence of human VSMCs.

Replicative senescence of vascular smooth muscle cells (VSMCs) contributes to aging as well as age-related cardiovascular diseases. Rapamycin can delay the onset of aging-related diseases via inhibition of the mammalian target of rapamycin (mTOR), but its role in vascular aging remains elusive. This study investigated the involvement of mTOR signaling in replicative senescence of VSMCs. Replicative senescence was induced by the extended passages of human VSMCs. Aging-related cell morphology was observed. The aging-related proteins and enzyme activity, and oxidative stress were measured. Significant increase in SA-ß-gal activity and protein expression, p53 and p16 protein expression, proliferation index (PI), malondialdehyde (MDA) concentration, superoxide dismutase (SOD) and glutathione peroxidase (GPX) activity, and significant decrease in telomerase activity was observed in aging VSMCs compared to young cells. Significant activation of PI3K/Akt/mTOR signaling was observed in aging cells but not young cells. Pretreatment of VSMCs with PI3K inhibitor blocked while PI3K activator increased the changes of the above replicative senescence-related parameters in VSMCs. Rapamycin and silencing of mTOR expression inhibited replicative senescence in VSMCs through decreasing the level of p-mTOR Ser2448, p-mTOR Thr2446, and S6K1 phosphorylation. This study for the first time demonstrated that the PI3K/Akt/mTOR/S6K1 signal pathway plays an important role in regulating replicative senescence of human VSMCs.

AMPK/TSC2/mTOR pathway regulates replicative senescence of human vascular smooth muscle cells.

Age-associated diseases, including vascular diseases, are on the rise with the increase in the aging population. However, the mechanisms of aging and age-associated vascular dysfunction remain to be fully elucidated. Replicative senescence of vascular smooth muscle cells (VSMCs) contributes to aging as well as age-associated vascular diseases. Rapamycin may delay aging-associated diseases via inhibition of the mammalian target of rapamycin (mTOR), but its role in VSMC aging has remained elusive. The present study investigated the involvement of mTOR signaling in replicative senescence of VSMCs. Replicative senescence was induced in human VSMCs by extended passages and identified by assessing the cell morphology, senescence-associated ß-galactosidase activity, and p53 and p21 protein expression. Protein expression and phosphorylation were determined by western blot analysis. Significant senescence of VSMCs was observed in cells subjected to extended passaging (until passage 15). Significant decreases in adenosine monophosphate-activated protein kinase (AMPK)/tuberous sclerosis complex 2 (TSC2) phosphorylation, but significant increases in mTOR/ribosomal protein S6 kinase 1 (S6K1) phosphorylation, were observed in cells with replicative senescence compared with those in young cells. Pre-treatment of VSMCs with AMPK activator and mTOR inhibitor delayed replicative senescence and reversed changes in AMPKα, TSC2, mTOR and S6K1 phosphorylation in senescent VSMCs. The AMPK/TSC2/mTOR/S6K1 signaling axis was found to have an important role in regulating replicative senescence of human VSMCs.

Function, Role, and Clinical Application of MicroRNAs in Vascular Aging.

Vascular aging, a specific type of organic aging, is related to age-dependent changes in the vasculature, including atherosclerotic plaques, arterial stiffness, fibrosis, and increased intimal thickening. Vascular aging could influence the threshold, process, and severity of various cardiovascular diseases, thus making it one of the most important risk factors in the high mortality of cardiovascular diseases. As endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are the main cell biological basis of these pathology changes of the vasculature, the structure and function of ECs and VSMCs play a key role in vascular aging. MicroRNAs (miRNAs), small noncoding RNAs, have been shown to regulate the expression of multiple messenger RNAs (mRNAs) posttranscriptionally, contributing to many crucial aspects of cell biology. Recently, miRNAs with functions associated with aging or aging-related diseases have been studied. In this review, we will summarize the reported role of miRNAs in the process of vascular aging with special emphasis on EC and VSMC functions. In addition, the potential application of miRNAs to clinical practice for the diagnosis and treatment of cardiovascular diseases will also be discussed.

Sarco-Osteoporosis: Prevalence and Association with Frailty in Chinese Community-Dwelling Older Adults.

The aim was to apply AWGS criteria to estimate the prevalence of sarco-osteoporosis and investigate its relationship with frailty, in a sample of 316 community-dwelling Chinese older people. Regression analysis was performed using frailty as the dependent variable. The results showed that the prevalence rate of sarco-osteoporosis was 10.4% in older men and 15.1% in older women. ≧80 years old (OR 4.8; 95% CI, 3.05-10.76; P = 0.027), women (OR 2.6; 95% CI, 1.18-2.76; P = 0.036), and higher level of comorbidity (OR 3.71; 95% CI, 1.61-10.43; P = 0.021) were independently associated with the likelihood of being sarco-osteoporosis. In the frail group, sarco-osteoporosis occurred in 26.3% of men, in 38.5% of women, and in lower proportion in the prefrail (13.6% of men; 16.2% of women) and nonfrail group (1.6% of men; 1.9% of women) (P < 0.05, resp.). Furthermore, the likelihood of being frail/prefrail was substantially higher in the presence of sarco-osteoporosis (OR 4.16; 95% CI, 2.17-17.65; P = 0.019 in men; and OR 4.67; 95% CI, 2.42-18.86; P = 0.007 in women). The results indicate that patients with sarco-osteoporosis are more likely to be ≧80 yrs with higher burden of comorbidities and to have frailty/prefrailty, especially for women.

Artery calcification, osteoporosis, and plasma adiponectin levels in Chinese elderly.

OBJECTIVES: The purpose of this study is to investigate the plasma adiponectin level and thoracic aortic calcification (TAC) in Chinese elderly. BACKGROUND: The association of serum adiponectin levels and thoracic aortic calcification has not been reported. METHODS: Total plasma adiponectin level was measured by ELISA. TAC was evaluated by posterior-anterior chest radiographs. Osteoporosis was diagnosed using dual energy X-ray absorptiometry. RESULTS: The mean plasma adiponectin level was 6.3 ± 3.7 µg/ml, TAC was detected in 58% of subjects, and comorbidities of TAC and osteoporosis were observed in 33.6% subjects. The percentages of TAC or comorbidities of TAC and osteoporosis were higher in subjects with low adiponectin tertile level than that in patients with intermediate or high adiponectin tertile level. Multivariable logistic regression analysis showed that adiponectin level was negatively associated with TAC prevalence. CONCLUSIONS: Plasma adiponectin level is associated with TAC and lower plasma adiponectin level may be a useful indicator of artery calcification in the elderly.