Potentiation of platelet-derived growth factor receptor-? signaling mediated by integrin-associated MFG-E8.

ABSTRACT: OBJECTIVE:Pericytes/pericyte precursors produce milk fat globule-associated protein with epidermal growth factor and factor VIII-like domains (MFG-E8) in vivo, and this ?(v) integrin ligand enhances angiogenesis in tumors and in oxygen-induced retinopathy in mice. Inhibition of MFG-E8 production or function attenuates platelet-derived growth factor-BB (PDGF-BB)-induced migration of pericyte/pericyte precursor-like 10T1/2 cells in vitro. Herein, we describe mechanisms by which MFG-E8 modulates PDGF-BB:PDGF receptor ? (PDGFR?) signaling in 10T1/2 cells. METHODS AND RESULTS:Small interfering RNA depletion of MFG-E8 from 10T1/2 cells or antibody inhibition of MFG-E8 action enhanced PDGF-BB-dependent degradation of PDGFR? and attenuated signaling. Coimmunoprecipitation revealed transient association of MFG-E8 with PDGFR? in PDGF-BB-treated 10T1/2 cells and reduced PDGFR?-focal adhesion kinase association in MFG-E8-depleted cells. Confocal microscopy demonstrated that MFG-E8 binding to 10T1/2 cells was RGD motif and ?(v) dependent but PDGF-BB treatment independent, whereas colocalization of MFG-E8 with PDGFR? was enhanced by PDGF-BB. Ubiquitination of PDGFR? was also increased in MFG-E8 small interfering RNA-transfected cells. CONCLUSION:Integrin ?(v)-bound MFG-E8 associates with PDGFR? and focal adhesion kinase after PDGF-BB treatment, results in cell surface retention of PDGFR?, delays receptor degradation, potentiates downstream signaling, and enhances migration of 10T1/2 cells. MFG-E8 may promote angiogenesis, in part, via cell autonomous actions on pericytes or pericyte precursors that result in enhanced PDGF-BB:PDGFR? signaling mediated via integrin-growth factor receptor cross-talk.

SUBMITTER: Motegi S 

PROVIDER: S-EPMC6999705 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature