NHERF2 increases platelet-derived growth factor-induced proliferation through PI-3-kinase/Akt-, ERK-, and Src family kinase-dependent pathway.
Platelet-derived growth factor (PDGF) has multiple functions including inhibition of apoptosis and promotion of cell proliferation. In this study, we show that Na(+)/H(+) exchanger regulatory factor 2 (NHERF2) binds to the carboxyl-terminal PDZ domain-binding motif of the PDGF receptor through a PDZ domain-mediated interaction, and evaluate the consequence on PDGF-induced proliferation. Stable transfection with NHERF2 increased the PDGF-induced phosphorylation of ERK and Akt in Rat1 embryonic fibroblasts. The phosphorylation of Akt was blocked by pretreatment with LY294002, a PI-3-kinase inhibitor, in both Rat1/NHERF2 and Rat1/vector cells. In Rat1/vector cells, PDGF-induced phosphorylation of ERK was completely inhibited by pretreatment with PD98059, a MEK inhibitor. In contrast, the NHERF2-dependent increase of ERK phosphorylation was not affected by pretreatment with PD98059 in Rat1/NHERF2 cells. Thus, the NHERF2-dependent increase of ERK phosphorylation occurs in a MEK-independent fashion. Pretreatment with PP2, a specific inhibitor of Src family tyrosine kinase, completely blocked the NHERF2-dependent increase of the phosphorylation of ERK and Akt, suggesting that NHERF2 up-regulates Erk phosphorylation through a Src family kinase-dependent pathway. Consistent with these results, the PDGF-induced thymidine incorporation was increased in Rat1/NHERF2 cells, and the NHERF2-dependent increase of thymidine incorporation was prevented by treatment with LY294002 and PP2 but not with PD98059. These results suggest that NHERF2 stimulates PDGF-induced proliferation by increasing PI-3-kinase/Akt, MEKindependent ERK, and Src family kinase-mediated signaling pathways.
Jung Kang
Yong
Y
Department of Physiology, College of Medicine, Pusan National University, 1Ga, Ami-Dong, Suh-Gu, Pusan 602-739, South Korea.
Su Jeon
Eun
E
Jin Lee
Hey
H
Oh
Yong-Seok
YS
Suh
Pann-Ghill
PG
Sup Jung
Jin
J
Donowitz
Mark
M
Ho Kim
Jae
J
D020816:Amino Acid Motifs; D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D002867:Chromones / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000378:metabolism / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000378:metabolism; D015151:Immunoblotting; D047468:Immunoprecipitation; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D017923:Sodium-Hydrogen Exchangers; D013936:Thymidine / Q000737:chemistry; D013997:Time Factors; D014162:Transfection; D019061:src-Family Kinases / Q000378:metabolism*
D002867:Chromones; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D009025:Morpholines; D010982:Platelet-Derived Growth Factor; D011993:Recombinant Fusion Proteins; C498832:Slc9a3r2 protein, rat; D017923:Sodium-Hydrogen Exchangers; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D005982:Glutathione Transferase; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D013936:Thymidine