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 induced by the Gq/11 protein-coupled Angiotensin II (Ang II) type1 receptor (AT1-R). First, we studied the effect of general Ca2+ chelation by BAPTA-AM on Ang II-dependent CTGF regulation in isolated neonatal rat CF and found that this treatment reduced significantly the effect of Ang II on CTGF expression and secretion while the basal levels were unchanged. In the next step we used xestospongin-C (XeC), a substance which selectively blocks the IP3 receptors on the endoplasmic reticulum (ER), and consequently inhibits Ca2+ release from the ER. In contrast to general Ca2+ chelation, XeC application significantly reduced the basal as well as the Ang II-induced level of CTGF secretion but had no impact on CTGF expression. In addition, we investigated the contribution of actin filaments and microtubules to the basal and Ang II-dependent regulation of CTGF by using latrunculin A (LAT-A) and colchicine as specific filament disrupting toxins, respectively. Colchicine strongly increased the basal levels of CTGF expression and secretion and by additional application of Ang II no further augmentation could be detected. In contrast, LAT-A treatment inhibited selectively the Ang II-dependent effect on CTGF expression and secretion. As shown by immunofluorescence analyses the likeliest explanation for this difference relies in 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 had no obvious effect. In summary, our data suggest that CTGF is complexly regulated involving Ca2+, microtubles and actin filaments as key players.
Multiple Signaling Pathways Regulate Connective Tissue Growth Factor Expression and Secretion in Cardiac Fibroblasts. Available from: https://www.researchgate.net/publication/269706621_Multiple_Signaling_Pathways_Regulate_Connective_Tissue_Growth_Factor_Expression_and_Secretion_in_Cardiac_Fibroblasts [accessed Apr 29, 2015].