title: Cyclin-dependent kinase 5 influences Rohon-Beard neuron survival in zebrafish.
abstract: Cyclin-dependent kinase 5 (cdk5), a member of the cyclin-dependent kinase family, is expressed predominantly in post-mitotic cell populations. Unlike the other cdks, cdk5 is abundant and most active in differentiated neurons. Here, we describe the function of a cdk5 ortholog in zebrafish. Cdk5 catalytic activity is meager but present in early stages of development. However, at 24 h post-fertilization (hpf), the activity is remarkably higher and continues to be high through 48 and 72 hpf. Knocking down cdk5 by micro-injection of a specific siRNA resulted in decreased cdk5 protein level accompanied by reduced kinase activity. In the cdk5 siRNA-injected embryos, the number of primary sensory Rohon-Beard (RB) neurons was significantly reduced and there were more apoptotic cells in the brain. These phenotypes were rescued by co-injection of cdk5 mRNA. Within the first two days of development, RB neurons undergo apoptosis in zebrafish. To examine whether cdk5 has a role in RB neuron survival, cdk5 mRNA was injected into the one- to two-cell embryos. In these embryos, RB neuron apoptosis was inhibited compared with the uninjected control embryos. These results suggest that in zebrafish, cdk5 influences RB neuron survival and potentially regulates early neuronal development.
authors.affiliation: Laboratory of Neurochemistry, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Jyotshnabala
authors.initials: J
authors.lastname: Kanungo
authors.forename: Bing-Sheng
authors.initials: BS
authors.lastname: Li
authors.forename: Yali
authors.initials: Y
authors.lastname: Zheng
authors.forename: Harish C
authors.initials: HC
authors.lastname: Pant
mesh_terms: D000818:Animals; D016923:Cell Death; D002470:Cell Survival; D051360:Cyclin-Dependent Kinase 5 / Q000235:genetics* / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000166:cytology; D047108:Embryonic Development; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D009474:Neurons / Q000166:cytology* / Q000201:enzymology*; D034741:RNA, Small Interfering / Q000235:genetics; D015027:Zebrafish / Q000196:embryology; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; D029961:Zebrafish Proteins; D051360:Cyclin-Dependent Kinase 5