Journal of Biological Chemistry

Gβγ subunits mediate many different signaling processes in various compartments of the cell, including the nucleus. To gain insight into the functions of nuclear Gβγ signaling, we investigated the functional role of Gβγ signaling in the regulation of GPCR-mediated gene expression in primary rat neonatal cardiac fibroblasts. We identified a novel, negative, regulatory role for the Gβ1γ dimer in the fibrotic response. Depletion of Gβ1 led to derepression of the fibrotic response at the mRNA and protein levels under basal conditions and an enhanced fibrotic response after sustained stimulation of the angiotensin II type I receptor. Our genome-wide chromatin immunoprecipitation experiments revealed that Gβ1 colocalized and interacted with RNA polymerase II on fibrotic genes in an angiotensin II-dependent manner. Additionally, blocking transcription with inhibitors of Cdk9 prevented association of Gβγ with transcription complexes. Together, our findings suggest that Gβ1γ is a novel transcriptional regulator of the fibrotic response that may act to restrict fibrosis to conditions of sustained fibrotic signaling. Our work expands the role for Gβγ signaling in cardiac fibrosis and may have broad implications for the role of nuclear Gβγ signaling in other cell types.

GPCRs

G proteins

cardiac fibrosis

transcription

cellular signalling

angiotensin II type I receptor

angiotensin II type II receptor

Dulbecco's modified Eagle's medium

G protein-coupled receptor

Hank’s Balanced salt solution

human embryonic kidney

label-free quantification

penicillin/streptomycin

rat neonatal cardiac fibroblast

transforming growth factor

© 2023 THE AUTHORS. Published by Elsevier Inc on behalf of American Society for Biochemistry and Molecular Biology.