RhoA prevents apoptosis during zebrafish embryogenesis through activation of Mek/Erk pathway

Abstract

RhoA small GTPase, as a key regulator for actin cytoskeletal rearrangement, plays pivotal roles during morphogenesis, cytokinesis, phagocytosis and cell migration, but little is known about its signaling mechanism that controls cell survival in vivo. Using zebrafish as a model, we show that non-overlapping antisense morpholinos that block either translation or splicing of rhoA lead to extensive apoptosis during embryogenesis, resulting in overall reduction of body size and body length. These defects are associated with reduced activation of growth-promoting Erk and decreased expression of anti-apoptotic bcl-2. Moreover, ectopic expression of rhoA, Mek or BCL-2 mRNA rescues such phenotypes. Consistently, combined suppression of RhoA and Mek/Erk or Bcl-2 pathways by sub-optimal dose of rhoA morpholino and pharmacological inhibitors for either Mek (U0126) or Bcl-2 (HA 14-1) can induce developmental abnormalities and enhanced apoptosis, similar to those caused by effective RhoA knockdown. Furthermore, U0126 abrogates the rescue by RhoA and MEK but not BCL-2. In contrast, HA 14-1 effectively abolishes all functional rescues by RhoA, MEK or BCL-2, supporting that RhoA prevents apoptosis by activation of Mek/Erk pathway and requiring Bcl-2. These findings reveal an important genetic and functional relationship between RhoA with Mek/Erk and Bcl-2 for cell survival control during embryogenesis.

Spatiotemporal 16p11.2 Protein Network Implicates Cortical Late Mid-Fetal Brain Development and KCTD13-Cul3-RhoA Pathway in Psychiatric Diseases

“…For example, KCTD13 or CUL3 knockdowns in the cell culture systems lead to RhoA/RhoA-GTP accumulation and actin stress fibers formation (Chen et al, 2009b). The decrease of the RhoA level has been previously linked to extensive apoptosis during embryogenesis, resulting in dramatic reduction of head and body size in zebrafish model (Zhu et al, 2008). Alternatively, the upregulation of RhoA through its constitutive expression has been linked to suppression of dendritic spine morphogenesis and to dramatic loss of spines (Govek et al, 2011; Zhang and Macara, 2008).…”

Pseudomonas aeruginosa ExoT Induces Mitochondrial Apoptosis in Target Host Cells in a Manner That Depends on Its GTPase-activating Protein (GAP) Domain Activity

“…RhoA has been shown to up-regulate anti-apoptotic Bcl2 expression in T cells (48). RhoA has also been shown to activate ERK survival pathway in glomerular epithelial cells (49) and to enhance the expression of Erk/Bcl2 survival pathway in zebra fish (50).…”

PHR Regulates Growth Cone Pausing at Intermediate Targets through Microtubule Disassembly

“…Stock solutions of SP600125 (Tocris) and SB203580 (Merck), were prepared at a concentration of 100 and 50 mM respectively, in cell culture grade DMSO (Sigma). Both compounds have previously been used on zebrafish (Fujii et al, 2000;Zhu et al, 2008).…”