Abstract P119: S100A6 Regulates Endothelial Cell Physiology
Endothelial cell dysfunction is central to the development of cardiovascular pathologies. While Calcium cycling is of recognized importance to myocyte physiology and cardiac perfomance, the role of Ca2+ signaling in endothelial cell (EC) physiology remains relatively unexplored. In this study we investigated the role of S100A6 (calcyclin), an EF-hand type Ca2+ -binding protein that modulates target protein function dependent upon intracellular Ca2+ signaling. S100A6 displays cytoplasmic distribution in quiescent, confluent HUVEC, but translocates to the nucleus upon serum stimulation. Oxidative stress, induced by incubation of HUVEC with H¬2O2 (150 uM) leads to redistribution of nuclear S100A6 to the cytosol and cell cycle arrest. Knockdown of S100A6 by siRNA transfection reduced S100A6 levels by over 70% and diminished DNA synthesis by more than 75% (±12%, n=9, p<0.01), as well as expression of the proliferation markers PCNA and KI-67 (by more than 70% (±15%, n=9, p<0.01). Reduced S100A6 levels in HUVEC lead to an increase in cellular senescence, as measured by the expression of senescence associated β-galactosidase expression (by more than 6-fold, n=4, p<0.01) and a reduction of EC tube formation on matrigel matrix (by more than 90%, n=3, p<0.01). Reduction of S100A6 increased the expression of the cell cycle control and DNA repair-associated gene BRCA2, but did not change in the expression of BRCA1, cyclins or p53 (by RT-PCR array). We conclude that Ca2+ regulation by S100A6 is essential for multiple aspects of EC physiology.
- © 2011 by American Heart Association, Inc.