Platelet-derived growth factor receptor association with Na(+)/H(+) exchanger regulatory factor potentiates receptor activity.
Platelet-derived growth factor (PDGF) is a potent mitogen for many cell types. The PDGF receptor (PDGFR) is a receptor tyrosine kinase that mediates the mitogenic effects of PDGF by binding to and/or phosphorylating a variety of intracellular signaling proteins upon PDGF-induced receptor dimerization. We show here that the Na(+)/H(+) exchanger regulatory factor (NHERF; also known as EBP50), a protein not previously known to interact with the PDGFR, binds to the PDGFR carboxyl terminus (PDGFR-CT) with high affinity via a PDZ (PSD-95/Dlg/Z0-1 homology) domain-mediated interaction and potentiates PDGFR autophosphorylation and extracellular signal-regulated kinase (ERK) activation in cells. A point-mutated version of the PDGFR, with the terminal leucine changed to alanine (L1106A), cannot bind NHERF in vitro and is markedly impaired relative to the wild-type receptor with regard to PDGF-induced autophosphorylation and activation of ERK in cells. NHERF potentiation of PDGFR signaling depends on the capacity of NHERF to oligomerize. NHERF oligomerizes in vitro when bound with PDGFR-CT, and a truncated version of the first NHERF PDZ domain that can bind PDGFR-CT but which does not oligomerize reduces PDGFR tyrosine kinase activity when transiently overexpressed in cells. PDGFR activity in cells can also be regulated in a NHERF-dependent fashion by stimulation of the beta(2)-adrenergic receptor, a known cellular binding partner for NHERF. These findings reveal that NHERF can directly bind to the PDGFR and potentiate PDGFR activity, thus elucidating both a novel mechanism by which PDGFR activity can be regulated and a new cellular role for the PDZ domain-containing adapter protein NHERF.
Maudsley
S
S
Howard Hughes Medical Institute, Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
Zamah
A M
AM
Rahman
N
N
Blitzer
J T
JT
Luttrell
L M
LM
Lefkowitz
R J
RJ
Hall
R A
RA
D020816:Amino Acid Motifs; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D005799:Genes, Dominant; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism / Q000494:pharmacology; D017354:Point Mutation; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers
D010750:Phosphoproteins; D010982:Platelet-Derived Growth Factor; D018343:Receptors, Adrenergic, beta-2; D011993:Recombinant Fusion Proteins; D017923:Sodium-Hydrogen Exchangers; C093376:sodium-hydrogen exchanger regulatory factor; D017479:Receptors, Platelet-Derived Growth Factor; D020928:Mitogen-Activated Protein Kinases