ナカムラ　フミオ   Fumio Nakamura   中村　史雄    所属   医学部 医学科    職種   教授・基幹分野長
言語種別	英語
発表タイトル	Hyperphosphorylation of SIRP alpha in PTP delta knockout mouse brains
会議名	The 42nd Annual Meeting of the Japan Neuroscience Society
学会区分	全国規模の学会
発表形式	ポスター掲示
講演区分	一般
発表者・共同発表者	Miyu Wakatsuki, Fumio Nakamura
発表年月日	2019/07/25
開催地 （都市, 国名）	Niihgata, Japan
概要	Protein tyrosine phosphatase delta (PTP delta) is one of vertebrate Leukocyte common antigen-related (LAR) class PTPs. We previously reported that PTP delta is involved in the development of cortical pyramidal neurons through the activation of Fyn tyrosine kinase. However, in vivo substrates of PTP delta are largely unknown. As we observed hyperphosphorylated proteins in PTP delta knockout mouse brains by immunoblotting with anti-phosphotyrosine (pY) antibody, we carried out phospho-proteomics analysis of the knockout and wild-type brains (postnatal day 25). Among the identified proteins, Signal Regulatory Protein alpha (SIRP alpha) gave the strongest phosphorylated ratio of knockout to wild-type. We then examined the phosphorylation of SIRP alpha in mouse brains (postnatal day 22) using antibodies against phosphotyrosine (pY), SIRP alpha, and phosphorylated Tyr501 in SIRP alpha (pY501). Combination of SIRP alpha-immunoprecipitation and pY-blotting as well as anti-pY501 immunoblotting revealed the hyperphosphorylation of SIRP alpha in the knockouts. We next examined immunohistochemistry. Almost entire CNS regions were immunostained with anti-pY antibody in both genotypes, however, the signal was stronger in the knockout sections than in wild-type. Cortical layers from Ⅱ to V, reticular thalamic nucleus, and subthalamic nuclei were hyperphosphorylated in the knockouts. Phospho-Y501 SIRP alpha immunostaining revealed that in the knockout sections, olfactory bundle, cortical II and III layers, striate body, fimbria, corpus callosum, reticular thalamic nucleus, ethmoid thalamic nucleus, and pyramidal tract were hyperphosphorylated. In addition, rostral migratory stream (RMS) was strongly immunostained with pY501 SIRP alpha in both genotypes. SIRP alpha-hyperphosphorylated regions in the knockouts partially correlated with the regions expressing PTP delta in wild-type including neocortex and thalamic reticular nucleus. This suggests that SIRP alpha may be one of the endogenous substrates of PTP delta.