title: Effects of p35 Mutations Associated with Mental Retardation on the Cellular Function of p35-CDK5.
abstract: p35 is an activation subunit of the cyclin-dependent kinase 5 (CDK5), which is a Ser/Thr kinase that is expressed predominantly in neurons. Disruption of the CDK5 or p35 (CDK5R1) genes induces abnormal neuronal layering in various regions of the mouse brain via impaired neuronal migration, which may be relevant for mental retardation in humans. Accordingly, mutations in the p35 gene were reported in patients with nonsyndromic mental retardation; however, their effect on the biochemical function of p35 has not been examined. Here, we studied the biochemical effect of mutant p35 on its known properties, i.e., stability, CDK5 activation, and cellular localization, using heterologous expression in cultured cells. We also examined the effect of the mutations on axon elongation in cultured primary neurons and migration of newborn neurons in embryonic brains. However, we did not detect any significant differences in the effects of the mutant forms of p35 compared with wild-type p35. Therefore, we conclude that these p35 mutations are unlikely to cause mental retardation.
authors.affiliation: Laboratory of Molecular Neuroscience, Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Takada
authors.affiliation: Centre for Cellular Basis of Behavior, Institute of Psychiatry, King's College London, 125 Coldharbour Lane, London, United Kingdom.
authors.forename: Keiko
authors.initials: K
authors.lastname: Mizuno
authors.affiliation: Laboratory of Molecular Neuroscience, Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Saito
authors.affiliation: Laboratory of Molecular Neuroscience, Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Asada
authors.affiliation: Centre for Cellular Basis of Behavior, Institute of Psychiatry, King's College London, 125 Coldharbour Lane, London, United Kingdom.
authors.forename: Karl Peter
authors.initials: KP
authors.lastname: Giese
authors.affiliation: Laboratory of Molecular Neuroscience, Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo, Japan.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Hisanaga
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000502:physiology; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004622:Embryo, Mammalian; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D051379:Mice; D008813:Mice, Inbred ICR; D009154:Mutation / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000502:physiology*
chemical_list: D009419:Nerve Tissue Proteins; C089495:neuronal Cdk5 activator (p25-p35)