title: A mental retardation gene, motopsin/prss12, modulates cell morphology by interaction with seizure-related gene 6.
abstract: A serine protease, motopsin (prss12), plays a significant role in cognitive function and the development of the brain, since the loss of motopsin function causes severe mental retardation in humans and enhances social behavior in mice. Motopsin is activity-dependently secreted from neuronal cells, is captured around the synaptic cleft, and cleaves a proteoglycan, agrin. The multi-domain structure of motopsin, consisting of a signal peptide, a proline-rich domain, a kringle domain, three scavenger receptor cysteine-rich domains, and a protease domain at the C-terminal, suggests the interaction with other molecules through these domains. To identify a protein interacting with motopsin, we performed yeast two-hybrid screening and found that seizure-related gene 6 (sez-6), a transmembrane protein on the plasma membrane of neuronal cells, bound to the proline-rich/kringle domain of motopsin. Pull-down and immunoprecipitation analyses indicated the interaction between these proteins. Immunocytochemical and immunohistochemical analyses suggested the co-localization of motopsin and sez-6 at neuronal cells in the developmental mouse brain and at motor neurons in the anterior horn of human spinal cords. Transient expression of motopsin in neuro2a cells increased the number and length of neurites as well as the level of neurite branching. Interestingly, co-expression of sez-6 with motopsin restored the effect of motopsin at the basal level, while sez-6 expression alone showed no effects on cell morphology. Our results suggest that the interaction of motopsin and sez-6 modulates the neuronal cell morphology.
authors.affiliation: Department of Rehabilitation Sciences, Gunma University Graduate School of Health Sciences, 3-39-22 Showa, Maebashi 371-8514, Japan. smitsui@gunma-u.ac.jp
authors.forename: Shinichi
authors.initials: S
authors.lastname: Mitsui
authors.forename: Chiharu
authors.initials: C
authors.lastname: Hidaka
authors.forename: Mutsuo
authors.initials: M
authors.lastname: Furihata
authors.forename: Yoji
authors.initials: Y
authors.lastname: Osako
authors.forename: Kazunari
authors.initials: K
authors.lastname: Yuri
mesh_terms: D000818:Animals; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D008607:Intellectual Disability / Q000235:genetics*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000235:genetics* / Q000378:metabolism
chemical_list: D009419:Nerve Tissue Proteins; C093131:Sez6 protein, mouse; D012697:Serine Endopeptidases; C108493:neurotrypsin
keywords: 5-bromo-4-chloro-3-indolyl-α-d-galactopyranoside; ANOVA; Ade; C1r/C1s, urinary EGF, and bone morphogenetic protein; CUB; DIV; Dendrites; EGFP-F; IPTG; Neurotrypsin; P; PBS-T; SCR; SD; SRCR; Serine protease; T-rich; X-α-gal; adenine; analysis of variance; days in vitro; farnesylated enhanced green fluorescent protein; isopropyl β-d-1-thiogalactopyranoside; minimal synthetic dropout medium; phosphate-buffered saline containing 0.3% Triton X-100; postnatal day; scavenger receptor cysteine-rich; sez-6; short consensus repeat; threonine-rich