| Summary: | 碩士 === 中山醫學大學 === 生化暨生物科技研究所 === 96 === Members of the cyclin-dependent kinase (Cdk) family play important regulatory roles in the control of cell-cycle progression, transcription metabolism, apoptosis, and neuronal function. In this study, we have isolated a novel protein kinase termed cyclin- dependent kinase like 1 in zebrafish (zCDKL1). zCDKL1 which is a Cdc2-related protein kinase, encoded polypeptide that is 350 amino acids with the X-Ser-Pro-X motif, and indicated that this protein belonged to the proline-directed Ser/Thr protein kinase family (KKIALRE). Based on amino acids sequence alignment, we have found that the zebrafish CDKL1 shared 50％ to 77％ homology to orthologs from other species. By reverse transcription-PCR analysis, zCDKL1 mRNA was expressed from fertilization to 48 hours post fertilization of zebrafish. Transcript of zCDKL1 was expressed in all adult tissues and enriched in brain, eyes, testes and ovary. In situ hybridization showed that CDKL1 was expressed in the floor plate, dorsal neuron tube, hypocord at 12 to 48 hours post fertilization whereas expression at pronephric tube was only found in 24 and 36 hour post feterlization. The zCDKL1 was diffusely expressed in nucleus and cytoplasm when overexpressed in HEK293 cells. In vitro kinase assay, the ability of zCDKL1 was toward phosphorylation of myelin basic protein and histone H1. Embryos injected with MOs directed against CDKL1 (cdkl1 MOs) showed developmental defects, including deformed somites, body axis curvature and a shortened trunk by 24hpf. These results suggested that CDKL1 may play a pivotal role in the development of ventral nervous system in zebrafish embryos.
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