94 research outputs found
p63RhoGEF—a key mediator of angiotensin II-dependent signaling and processes in vascular smooth muscle cells
No full textThe purpose of our study was to investigate the role of endogenous p63RhoGEF in G(q/11)-dependent RhoA activation and signaling in rat aortic smooth muscle cells (RASMCs). Therefore, we studied the expression and subcellular localization in freshly isolated RASMCs and performed loss of function experiments to analyze its contribution to RhoGTPase activation and functional responses such as proliferation and contraction. By this, we could show that p63RhoGEF is endogenously expressed in RASMCs and acts there as the dominant mediator of the fast angiotensin II (ANG II)-dependent but not of the sphingosine-1-phosphate (S1P)-dependent RhoA activation. p63RhoGEF is not an activator of the concomitant Rac1 activation and functions independently of caveolae. The knockdown of endogenous p63RhoGEF significantly reduced the mitogenic response of ANG II, abolished ANG II-induced stress fiber formation and cell elongation in 2-D culture, and impaired the ANG II-driven contraction in a collagen-based 3-D model. In conclusion, our data provide for the first time evidence that p63RhoGEF is an important mediator of ANG II-dependent RhoA activation in RASMCs and therewith a leading actor in the subsequently triggered cellular processes, such as proliferation and contraction.-Wuertz, C. M., Lorincz, A., Vettel, C., Thomas, M. A., Wieland, T., Lutz, S. p63RhoGEF-a key mediator of angiotensin II-dependent signaling and processes in vascular smooth muscle cells. FASEB J. 24, 4865-4876 (2010). www.fasebj.orgDeutsche Forschungsgemeinschaft [Lu1486/1-1, SFB TR 23 TP B6
Angiotensin II-induces activation of RhoA via an AT(1)R-, G(q/11)- and p63RhoGEF-dependent pathway in caveolae of neonatal cardiac fibroblasts
No full textAngiotensin II-induces activation of RhoA via an AT(1)R-, G(q/11)- and p63RhoGEF-dependent pathway in caveolae of neonatal cardiac fibroblasts
No full textA novel player in cellular hypertrophy: G(i)beta gamma/PI3K-dependent activation of the RacGEF TIAM-1 is required for alpha(1)-adrenoceptor induced hypertrophy in neonatal rat cardiomyocytes
No full textActivation of alpha(1)-adrenoceptors (alpha(1)-AR) by high catecholamine levels, e.g. in heart failure, is thought to be a driving force of cardiac hypertrophy. In this context several downstream mediators and cascades have been identified to potentially play a role in cardiomyocyte hypertrophy. One of these proteins is the monomeric G protein Rac1. However, until now it is unclear how this essential G protein is activated by alpha(1)-AR agonists and what are the downstream targets inducing cellular growth. By using protein-based as well as pharmacological inhibitors and the shRNA technique, we demonstrate that in neonatal rat cardiomyocytes (NRCM) Rac1 is activated via a cascade involving the alpha(1A)-AR subtype, G(i)beta gamma, the phosphoinositide-3'-kinase and the guanine nucleotide exchange factor Tiam1. We further demonstrate that this signaling induces an increase in protein synthesis, cell size and atrial natriuretic peptide expression. We identified the p21-activated kinase 2 (PAK2) as a downstream effector of Rac1 and were able to link this cascade to the activation of the pro-hypertrophic kinases ERK1/2 and p90RSK. Our data thus reveal a prominent role of the alpha(1A)-AR/G(i)beta gamma/Tiam1-mediated activation of Rac1 and its effector PAK2 in the induction of hypertrophy in NRCM. (C) 2012 Elsevier Ltd. All rights reserved
The activation of RhoC in vascular endothelial cells is required for the S1P receptor type 2-induced inhibition of angiogenesis
No full textSphingosine-1-phosphate (SIP) is a multifunctional phospholipid inducing a variety of cellular responses in endothelial cells (EC). SW responses are mediated by five G protein coupled receptors of which three types (S1P(1)R-S1P(3)R) have been described to be of importance in vascular endothelial cells (EC). Whereas the S1P(1)R regulates endothelial barrier function by coupling to G alpha(i) and the monomeric GTPase Rac1, the signaling pathways involved in the S1P-induced regulation of angiogenesis are ill defined. We therefore studied the sprouting of human umbilical vein EC (HUVEC) in vitro and analyzed the activation of the RhoGTPases RhoA and RhoC. Physiological relevant concentrations of S1P (100-300 nM) induce a moderate activation of RhoA and RhoC. Inhibition or siRNA-mediated depletion of the S1P(2)R preferentially decreased the activation of RhoC Both manipulations caused an increase of sprouting in a spheroid based in vitro sprouting assay. Interestingly, a similar increase in sprouting was detected after effective siRNA-mediated knockdown of RhoC. In contrast, the depletion of RhoA had no influence on sprouting. Furthermore, suppression of the activity of G proteins of the G alpha(12/13) subfamily by adenoviral overexpression of the regulator of G protein signaling domain of LSC as well as siRNA-mediated knockdown of the Rho specific guanine nucleotide exchange factor leukemia associated RhoGEF (LARG) inhibited the S1P-induced activation of RhoC and concomitantly increased sprouting of HUVEC with similar efficacy. We conclude that the angiogenic sprouting of EC is suppressed via the S1P(2)R subtype. Thus, the increase in basal sprouting can be attributed to blocking of the inhibitory action of autocrine SIP stimulating the SiP2R. This inhibitory pathway involves the activation of RhoC via G alpha(12/13) and LARG, while the simultaneously occurring activation of RhoA is apparently dispensable here. (C) 2013 Elsevier Inc. All rights reserved
The expression and secretion of the connective tissue growth factor in cardiac fibroblasts is controlled through the RhoA signaling axis
No full textThe expression and secretion of the connective tissue growth factor in cardiac fibroblasts is controlled through the RhoA signaling axis
No full textPhosphodiesterase 2 activates myofibroblast formation and CTGF synthesis in cardiac fibroblasts and augments stiffness in engineered connective tissue
No full textPhosphodiesterase 2 activates myofibroblast formation and CTGF synthesis in cardiac fibroblasts and augments stiffness in engineered connective tissue
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