α(E)-Catenin induces SRF-dependent transcriptional activity through its C-terminal region and is partly RhoA/ROCK-dependent

The ubiquitous α(E)-catenin is an essential actin cytoskeletal linker. The transcription factor, serum response factor (SRF), induces transcription via binding to the serum response element (SRE) in gene promoters, and in many cases responds to actin dynamics. Here, we report that α(E)-catenin expression in HEK293 cells activates the SRE.L transcriptional reporter, a reporter containing the isolated SRF-binding site, and a stably integrated SRE.L reporter in fibroblasts. α-Catenin-induced reporter activity appears only partly dependent on RhoA GTPase and Rho kinase function. α-Catenin expression has no effect on RhoA activation or localization, and α-catenin-induced SRE.L reporter activation is insensitive to the actin-modulating agent latrunculin B. Ectopic α-catenin expression was not sufficient to induce actin filament assembly as measured by stress fiber formation. SRE.L reporter is activated by the C-terminal ∼300 residue region of α(E)-catenin. These results suggest induction of SRF-mediated transcription by α(E)-catenin either downstream of RhoA or via a parallel pathway.