title: BIT/SHPS-1 enhances brain-derived neurotrophic factor-promoted neuronal survival in cultured cerebral cortical neurons.
abstract: Brain-derived neurotrophic factor (BDNF) activates a variety of signaling molecules to exert various functions in the nervous system, including neuronal differentiation, survival, and regulation of synaptic plasticity. Previously, we have suggested that BIT/SHPS-1 (brain immunoglobulin-like molecule with tyrosine-based activation motifs/SHP substrate 1) is a substrate of Shp-2 and is involved in BDNF signaling in cultured cerebral cortical neurons. To elucidate the biological function of BIT/SHPS-1 in cultured cerebral cortical neurons in connection with its role in BDNF signaling, we generated recombinant adenovirus vectors expressing the wild type of rat BIT/SHPS-1 and its 4F mutant in which all tyrosine residues in the cytoplasmic domain of BIT/SHPS-1 were replaced with phenylalanine. Overexpression of wild-type BIT/SHPS-1, but not the 4F mutant, in cultured cerebral cortical neurons induced tyrosine phosphorylation of BIT/SHPS-1 itself and an association of Shp-2 with BIT/SHPS-1 even without addition of BDNF. We found that BDNF-promoted survival of cultured cerebral cortical neurons was enhanced by expression of the wild type and also 4F mutant, indicating that this enhancement by BIT/SHPS-1 does not depend on its tyrosine phosphorylation. BDNF-induced activation of mitogen-activated protein kinase was not altered by the expression of these proteins. In contrast, BDNF-induced activation of Akt was enhanced in neurons expressing wild-type or 4F mutant BIT/SHPS-1. In addition, LY294002, a specific inhibitor of phosphatidylinositol 3-kinase, blocked the enhancement of BDNF-promoted neuronal survival in both neurons expressing wild-type and 4F mutant BIT/SHPS-1. These results indicate that BIT/SHPS-1 contributes to BDNF-promoted survival of cultured cerebral cortical neurons, and that its effect depends on the phosphatidylinositol 3-kinase-Akt pathway. Our results suggest that a novel action of BIT/SHPS-1 does not occur through tyrosine phosphorylation of BIT/SHPS-1 in cultured cerebral cortical neurons.
authors.affiliation: Division of Protein Biosynthesis, Institute for Protein Research, Osaka University, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Araki
authors.forename: M
authors.initials: M
authors.lastname: Yamada
authors.forename: H
authors.initials: H
authors.lastname: Ohnishi
authors.forename: S I
authors.initials: SI
authors.lastname: Sano
authors.forename: H
authors.initials: H
authors.lastname: Hatanaka
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D000943:Antigens, Differentiation; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017208:Rats, Wistar; D011971:Receptors, Immunologic; D014162:Transfection
chemical_list: D000943:Antigens, Differentiation; D019208:Brain-Derived Neurotrophic Factor; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D011971:Receptors, Immunologic; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516727:Ptpn11 protein, rat; C509250:Ptpn6 protein, rat