Abstract
SummaryKallistatin, an endogenous protein, protects against vascular injury by inhibiting oxidative stress and inflammation in hypertensive rats and enhancing the mobility and function of endothelial progenitor cells (EPCs). We aimed to determine the role and mechanism of kallistatin in vascular senescence and aging using cultured EPCs, streptozotocin (STZ)‐induced diabetic mice, and Caenorhabditis elegans (C. elegans). Human kallistatin significantly decreased TNF‐α‐induced cellular senescence in EPCs, as indicated by reduced senescence‐associated β‐galactosidase activity and plasminogen activator inhibitor‐1 expression, and elevated telomerase activity. Kallistatin blocked TNF‐α‐induced superoxide levels, NADPH oxidase activity, and microRNA‐21 (miR‐21) and p16INK 4a synthesis. Kallistatin prevented TNF‐α‐mediated inhibition of SIRT1, eNOS, and catalase, and directly stimulated the expression of these antioxidant enzymes. Moreover, kallistatin inhibited miR‐34a synthesis, whereas miR‐34a overexpression abolished kallistatin‐induced antioxidant gene expression and antisenescence activity. Kallistatin via its active site inhibited miR‐34a, and stimulated SIRT1 and eNOS synthesis in EPCs, which was abolished by genistein, indicating an event mediated by tyrosine kinase. Moreover, kallistatin administration attenuated STZ‐induced aortic senescence, oxidative stress, and miR‐34a and miR‐21 synthesis, and increased SIRT1, eNOS, and catalase levels in diabetic mice. Furthermore, kallistatin treatment reduced superoxide formation and prolonged wild‐type C. elegans lifespan under oxidative or heat stress, although kallistatin's protective effect was abolished in miR‐34 or sir‐2.1 (SIRT1 homolog) mutant C. elegans. Kallistatin inhibited miR‐34, but stimulated sir‐2.1 and sod‐3 synthesis in C. elegans. These in vitro and in vivo studies provide significant insights into the role and mechanism of kallistatin in vascular senescence and aging by regulating miR‐34a‐SIRT1 pathway.
Highlights
Endothelial progenitor cells (EPCs) are a major contributor to vascular repair, and can be derived from bone marrow, circulating mononuclear cells, and cord blood (Lin et al, 2000; Reyes et al, 2002)
To identify the effect of kallistatin on cellular senescence in cultured EPCs, we evaluated senescence markers, including SA-b-gal activity, plasminogen activator inhibitor-1 (PAI-1) synthesis, and telomerase activity
Exposure of EPCs to TNF-a for 6 days markedly increased SA-b-galpositive cell numbers compared with the control group, whereas preincubation with purified human kallistatin significantly reduced TNF-ainduced SA-b-gal-positive cells
Summary
Endothelial progenitor cells (EPCs) are a major contributor to vascular repair, and can be derived from bone marrow, circulating mononuclear cells, and cord blood (Lin et al, 2000; Reyes et al, 2002). Circulating EPCs are the most important cell population for the replenishment of damaged or senescent endothelial cells. Senescent or impaired EPCs contribute to endothelial dysfunction, which is a predictor of cardiovascular diseases (Heiss et al, 2005). Type 1 diabetes is one of cardiovascular-associated diseases characterized by reduced EPC numbers and vascular repair (Loomans et al, 2004). The nematode Caenorhabditis elegans (C. elegans) has a number of distinct advantages that are useful for understanding the molecular basis of organismal dysfunction underlying age-related diseases. EPCs, streptozotocin (STZ)-induced diabetic mice, and C. elegans are valuable models for examining the mechanisms of vascular senescence and aging
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