An-Najah Staff

ABSTRACT Cardiac fibroblasts (CF) play a major role in fibrogenesis associated with heart failure as they are responsible for the production of ECM components as well as the secretion of several important fibrosis-associated mediators, such as connective tissue growth factor (CTGF). Here we investigate the role of Ca2+-dependent and cytoskeleton-dependent pathways in the regulation of CTGF expression and secretion, which is induced by Angiotensin II (Ang II) type1 receptor (AT1-R) in neonatal rat CF. Live cell Ca2+ imaging demonstrated that AT1-R stimulation by Ang II causes phospholipase-C-beta -dependent Ca2+ transient, which is mainly generated from intracellular Ca2+ stores. The contribution of extracellular Ca2+ is minor and seems to tune the release of the intracellular Ca2+. Moreover, biochemical analysis for CF treated separately with BAPTA-AM (intracellular Ca2+ chelator), pyrazole-3 (TRPC3 Ca2+ channel blocker) and cyclosporine-A (calcineurin inhibitor) followed by Ang II treatment, showed that Ca2+ transient is essential for the regulation of CTGF expression and secretion. On the other hand, to investigate the contribution of actin filaments and microtubules to the basal and Ang II-dependent regulation of CTGF, latrunculin-A (LAT-A) and colchicine were used respectively. Colchicine treatment depolymerized microtubules and strongly increased the basal levels of CTGF expression and secretion and upon Ang II treatment no further augmentation could be detected. In contrast, the disruption of actin filaments by LAT-A inhibited selectively the Ang II-dependent effect on CTGF expression and secretion. Based on the immunofluorescence analyses, the likeliest explanation for this difference relies on the impact of both toxins on the main CTGF storage compartment, the Golgi apparatus. Colchicine treatment led to a complete dispersion of the Golgi, whereas LAT-A caused Golgi stacks to condense. In summary, our data suggest that CTGF is complexly regulated; involving Ca2+, microtubles and actin filaments as key players.

Ang II-Induced Calcium Signaling Complexly Regulates CTGF in Cardiac Fibroblasts. Available from: https://www.researchgate.net/publication/269706597_Ang_II-Induced_Calcium_Signaling_Complexly_Regulates_CTGF_in_Cardiac_Fibroblasts [accessed Apr 29, 2015].