Fig. 5
From: SRF: a seriously responsible factor in cardiac development and disease
Impact of SRF transcriptional activation on the cytoarchitecture and cell–cell contact of cardiomyocytes- Under physiological conditions, SRF is activated upon RhoA-mediated activation, which is dependent on actin treadmilling. Striated muscle activators of Rho signaling (STARS) also facilitates this activation upon ABLIM stimulation. However, as seen in the right panel, when cell contact is disrupted, actin polymerization is inhibited, affecting actin treadmilling. In this case, G-actin-bound MRTF is retained in the cytoplasm, inhibiting SRF transcriptional activation and leading to structural destabilization because of sarcomere disruption. Furthermore, stress activates MEF2 expression, which inhibits MRTF-SRF activity via STARS. Thus, Rho plays a pivotal role in SRF activation. RhoA Ras homology family member A; ABLIM Actin binding LIM; STARS striated muscle activators of Rho signaling; MRTF myocardin related transcription factor; SRF Serum response factor; MEF2 Myocyte enhancer factor 2A