title: Protein tyrosine phosphatase receptor type Z is involved in hippocampus-dependent memory formation through dephosphorylation at Y1105 on p190 RhoGAP.
abstract: Ptprz is a receptor-type protein tyrosine phosphatase predominantly expressed in the brain as a chondroitin sulfate proteoglycan. Ptprz-deficient mice exhibit an age (maturation)-dependent impairment of spatial learning in the Morris water maze test and enhancement of long-term potentiation (LTP) in the CA1 region in hippocampal slices. The enhanced LTP is canceled out by pharmacological inhibition of Rho-associated kinase (ROCK), suggesting that the lack of Ptprz causes learning impairment due to aberrant activation of ROCK. Here, we report that Ptprz-deficient mice exhibit impairments in hippocampus-dependent contextual fear memory because of abnormal tyrosine phosphorylation of p190 RhoGAP, a GTPase-activating protein (GAP) for Rho GTPase. We found that phosphorylation at Y1105, a major tyrosine phosphorylation site on p190 RhoGAP, is decreased 1h after the conditioning in the hippocampus of wild-type mice, but not of Ptprz-deficient mice. Pleiotrophin, a ligand for Ptprz, increased tyrosine phosphorylation of p190 RhoGAP in B103 neuroblastoma cells. Furthermore, Ptprz selectively dephosphorylated pY1105 of p190 RhoGAP in vitro, and the tyrosine phosphorylation at Y1105 controls p190 RhoGAP activity in vivo. These results suggest that Ptprz plays a critical role in memory formation by modulating Rho GTPase activity through dephosphorylation at Y1105 on p190 RhoGAP.
authors.affiliation: Division of Molecular Neurobiology, National Institute for Basic Biology, 5-1 Higashiyama, Okazaki 444-8787, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tamura
authors.forename: Masahide
authors.initials: M
authors.lastname: Fukada
authors.forename: Akihiro
authors.initials: A
authors.lastname: Fujikawa
authors.forename: Masaharu
authors.initials: M
authors.lastname: Noda
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D002460:Cell Line; D002522:Chlorocebus aethiops; D011508:Chondroitin Sulfate Proteoglycans / Q000502:physiology*; D003213:Conditioning, Psychological; D016207:Cytokines / Q000494:pharmacology; D004268:DNA-Binding Proteins; D004558:Electric Stimulation; D005239:Fear; D020690:GTPase-Activating Proteins; D006624:Hippocampus / Q000502:physiology*; D008024:Ligands; D018782:Maze Learning; D008568:Memory / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D017354:Point Mutation; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5; D012097:Repressor Proteins; D014443:Tyrosine / Q000378:metabolism*
chemical_list: C513041:Arhgap35 protein, mouse; C513042:Arhgap5 protein, mouse; D002352:Carrier Proteins; D011508:Chondroitin Sulfate Proteoglycans; D016207:Cytokines; D004268:DNA-Binding Proteins; D020690:GTPase-Activating Proteins; D008024:Ligands; D012097:Repressor Proteins; C066845:pleiotrophin; D014443:Tyrosine; D017027:Protein Tyrosine Phosphatases; C516896:Ptprz1 protein, mouse; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5