Protein-tyrosine phosphatase (PTP) wedge domain peptides: a novel approach for inhibition of PTP function and augmentation of protein-tyrosine kinase function.
Inhibition of protein-tyrosine phosphatases (PTPs) counterbalancing protein-tyrosine kinases (PTKs) offers a strategy for augmenting PTK actions. Conservation of PTP catalytic sites limits development of specific PTP inhibitors. A number of receptor PTPs, including the leukocyte common antigen-related (LAR) receptor and PTPmu, contain a wedge-shaped helix-loop-helix located near the first catalytic domain. Helix-loop-helix domains in other proteins demonstrate homophilic binding and inhibit function; therefore, we tested the hypothesis that LAR wedge domain peptides would exhibit homophilic binding, bind to LAR, and inhibit LAR function. Fluorescent beads coated with LAR or PTPmu wedge peptides demonstrated PTP-specific homophilic binding, and LAR wedge peptide-coated beads precipitated LAR protein. Administration of LAR wedge Tat peptide to PC12 cells resulted in increased proliferation, decreased cell death, increased neurite outgrowth, and augmented Trk PTK-mediated responses to nerve growth factor (NGF), a phenotype matching that found in PC12 cells with reduced LAR levels. PTPmu wedge Tat peptide had no effect on PC12 cells but blocked the PTPmu-dependent phenotype of neurite outgrowth of retinal ganglion neurons on a PTPmu substrate, whereas LAR wedge peptide had no effect. The survival- and neurite-promoting effect of the LAR wedge peptide was blocked by the Trk inhibitor K252a, and reciprocal co-immunoprecipitation demonstrated LAR/TrkA association. The addition of LAR wedge peptide inhibited LAR co-immunoprecipitation with TrkA, augmented NGF-induced activation of TrkA, ERK, and AKT, and in the absence of exogenous NGF, induced activation of TrkA, ERK, and AKT. PTP wedge domain peptides provide a unique PTP inhibition strategy and offer a novel approach for augmenting PTK function.
Xie
Youmei
Y
Department of Neurology, University of North Carolina, Chapel Hill, NC 27599, USA.
Massa
Stephen M
SM
Ensslen-Craig
Sonya E
SE
Major
Denice L
DL
Yang
Tao
T
Tisi
Michelle A
MA
Derevyanny
Vicki D
VD
Runge
William O
WO
Mehta
Brijesh P
BP
Moore
Laura A
LA
Brady-Kalnay
Susann M
SM
Longo
Frank M
FM
D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain; D049109:Cell Proliferation; D005456:Fluorescent Dyes / Q000494:pharmacology; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D016716:PC12 Cells; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D020917:Receptor, trkA / Q000378:metabolism
D005456:Fluorescent Dyes; D009414:Nerve Growth Factors; D020917:Receptor, trkA; D017027:Protein Tyrosine Phosphatases