Title: G-protein coupled receptor kinase 5 mediates lipopolysaccharide-induced NFκB activation in primary macrophages and modulates inflammation in vivo in mice.

Authors: Patial, Sonika; Shahi, Shipra; Saini, Yogesh; Lee, Taehyung; Packiriswamy, Nandakumar; Appledorn, Daniel M; Lapres, John J; Amalfitano, Andrea; Parameswaran, Narayanan

Published In J Cell Physiol, (2011 May)

Abstract: G-protein coupled receptor kinase-5 (GRK5) is a serine/threonine kinase discovered for its role in the regulation of G-protein coupled receptor signaling. Recent studies have shown that GRK5 is also an important regulator of signaling pathways stimulated by non-GPCRs. This study was undertaken to determine the physiological role of GRK5 in Toll-like receptor-4-induced inflammatory signaling pathways in vivo and in vitro. Using mice genetically deficient in GRK5 (GRK5(-/-) ) we demonstrate here that GRK5 is an important positive regulator of lipopolysaccharide (LPS, a TLR4 agonist)-induced inflammatory cytokine and chemokine production in vivo. Consistent with this role, LPS-induced neutrophil infiltration in the lungs (assessed by myeloperoxidase activity) was markedly attenuated in the GRK5(-/-) mice compared to the GRK5(+/+) mice. Similar to the in vivo studies, primary macrophages from GRK5(-/-) mice showed attenuated cytokine production in response to LPS. Our results also identify TLR4-induced NFκB pathway in macrophages to be selectively regulated by GRK5. LPS-induced IκBα phosphorylation, NFκB p65 nuclear translocation, and NFκB binding were markedly attenuated in GRK5(-/-) macrophages. Together, our findings demonstrate that GRK5 is a positive regulator of TLR4-induced IκBα-NFκB pathway as well as a key modulator of LPS-induced inflammatory response.

PubMed ID: 20945396

MeSH Terms: No MeSH terms associated with this publication