G-protein-coupled receptor kinase-2 is a critical regulator of TNF? signaling in colon epithelial cells.

ABSTRACT: G-protein-coupled receptor kinase-2 (GRK2) belongs to the GRK family of serine/threonine protein kinases critical in the regulation of G-protein-coupled receptors. Apart from this canonical role, GRK2 is also involved in several signaling pathways via distinct intracellular interactomes. In the present study, we examined the role of GRK2 in TNF? signaling in colon epithelial cell-biological processes including wound healing, proliferation, apoptosis, and gene expression. Knockdown of GRK2 in the SW480 human colonic cells significantly enhanced TNF?-induced epithelial cell wound healing without any effect on apoptosis/proliferation. Consistent with wound-healing effects, GRK2 knockdown augmented TNF?-induced matrix metalloproteinases (MMPs) 7 and 9, as well as urokinase plasminogen activator (uPA; factors involved in cell migration and wound healing). To assess the mechanism by which GRK2 affects these physiological processes, we examined the role of GRK2 in TNF?-induced MAPK and NF-?B pathways. Our results demonstrate that while GRK2 knockdown inhibited TNF?-induced I?B? phosphorylation, activation of ERK was significantly enhanced in GRK2 knockdown cells. Our results further demonstrate that GRK2 inhibits TNF?-induced ERK activation by inhibiting generation of reactive oxygen species (ROS). Together, these data suggest that GRK2 plays a critical role in TNF?-induced wound healing by modulating MMP7 and 9 and uPA levels via the ROS-ERK pathway. Consistent with in vitro findings, GRK2 heterozygous mice exhibited enhanced intestinal wound healing. Together, our results identify a novel role for GRK2 in TNF? signaling in intestinal epithelial cells.

SUBMITTER: Steury MD 

PROVIDER: S-EPMC5561658 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature