title: Protein-tyrosine phosphatase (PTP) wedge domain peptides: a novel approach for inhibition of PTP function and augmentation of protein-tyrosine kinase function.
abstract: 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.
authors.affiliation: Department of Neurology, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Youmei
authors.initials: Y
authors.lastname: Xie
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Massa
authors.forename: Sonya E
authors.initials: SE
authors.lastname: Ensslen-Craig
authors.forename: Denice L
authors.initials: DL
authors.lastname: Major
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Tisi
authors.forename: Vicki D
authors.initials: VD
authors.lastname: Derevyanny
authors.forename: William O
authors.initials: WO
authors.lastname: Runge
authors.forename: Brijesh P
authors.initials: BP
authors.lastname: Mehta
authors.forename: Laura A
authors.initials: LA
authors.lastname: Moore
authors.forename: Susann M
authors.initials: SM
authors.lastname: Brady-Kalnay
authors.forename: Frank M
authors.initials: FM
authors.lastname: Longo
mesh_terms: 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
chemical_list: D005456:Fluorescent Dyes; D009414:Nerve Growth Factors; D020917:Receptor, trkA; D017027:Protein Tyrosine Phosphatases