Abstract

Gα12 and Gα13 belong to the G12/13 subfamily of heterotrimeric guanine nucleotide-binding proteins. Much work has been done to identify downstream effectors and regulators of Gα12/13 due to their implication in many human cancers. p114RhoGEF is a downstream effector of Gα12 but not Gα13 that regulates the activity of the monomeric GTPase RhoA. Despite the existing evidence of p114RhoGEF interacting with Gα12 and RhoA, the mechanism of these interactions and the cellular functions they facilitate remain unknown. To understand the significance of the Gα12-p114RhoGEF-RhoA signaling cascade, we examined the ability of overexpressed wildtype-p114RhoGEF to drive signaling through four pathways implicated in growth and tumorigenic signaling (SRE, TEAD, NFκB, and AP1) in transcription-based firefly luciferase assays. We used the RhoA inhibitor, Clostridium botulinum C3 toxin, to determine which of these processes are RhoA-dependent. p114RhoGEF drove signaling through all pathways except AP1 and required functional RhoA to do so. The most dramatic effect was seen in SRE-luciferase assays, with luminometric readings over twice as high as in NFκB assays. p114RhoGEF also caused a small but reproducible increase in TEAD pathway stimulation as. These results demonstrate a role of p114RhoGEF and RhoA in stimulating three distinct transcriptional responses implicated in oncogenesis. Future work will include resolving the structural determinants of p114RhoGEF that mediate its interaction with Gα12 and RhoA, and examining whether Gα12 increases p114RhoGEF’s ability to drive these pathways. Unraveling the mechanism of action in the Gα12- p114RhoGEF-RhoA signaling cascade, as well as its underlying physical structure, could lead to the development of novel cancer therapeutic strategies.

How to Cite