An interaction between Gβγ and RNA polymerase II regulates transcription in cardiac fibroblasts

Gβγ subunits are involved in many different signalling processes in various compartments of the cell, including the nucleus. To gain insight into the functions of nuclear Gβγ, we investigated the functional role of Gβγ signalling in regulation of GPCR-mediated gene expression in primary rat neonatal cardiac fibroblasts. Following activation of the angiotensin II type I receptor in these cells, Gβγ dimers interact with RNA polymerase II (RNAPII). Our findings suggest that Gβ1 recruitment to RNAPII negatively regulates the fibrotic transcriptional response, which can be overcome by strong fibrotic stimuli. The interaction between Gβγ subunits and RNAPII expands the role for Gβγ signalling in cardiac fibrosis. The Gβγ-RNAPII interaction was regulated by signaling pathways in HEK 293 cells that diverged from those operating in cardiac fibroblasts. Thus, the interaction may be a conserved feature of transcriptional regulation although such regulation may be cell-specific.