Volume 17, No 2, Feb 2007
ISSN: 1001-0602
EISSN: 1748-7838 2018
impact factor 17.848*
(Clarivate Analytics, 2019)
Volume 17 Issue 2, February 2007: 163-173
ORIGINAL ARTICLES
Developmental expression of Cyclin H and Cdk7 in zebrafish: the essential role of Cyclin H during early embryo development
Qing Yun Liu1, Zhi Li Wu1, Wen Jian Lv1, Yuan Chang Yan1,2, Yi Ping Li1
1Lab of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Science, Chinese
Academy of Sciences, Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China; 2Model
Organism Division, E-institutes of Shanghai University, Shanghai 200025, China
Correspondence: Yiping Li(yipingli@sibs.ac.cn)
Cyclin-dependent kinase 7 (Cdk7) is the catalytic subunit of the metazoan Cdk-activating kinase (CAK). Activation of Cdk7 requires its association with a regulatory subunit, Cyclin H. Although the Cdk7/Cyclin H complex has been implicated in the regulation of RNA polymerase in several species, the precise function of their orthologs in zebrafish has not been fully elucidated. In this study, we isolated from zebrafish blastula embryos two cDNAs encoding the orthologs of human Cyclin H and Cdk7, and examined the role of Cdk7/Cyclin H in zebrafish embryogenesis. Sequence analysis showed that the zebrafish Cyclin H and Cdk7 cDNAs encode proteins with 65% and 86% identity to the respective human orthologs. RT-PCR and whole-mount in situ hybridization analyses of their expression in unfertilized eggs, embryos and organs of adult fish suggested that Cyclin H and Cdk7 messages are maternally loaded. Our data also showed that their transcripts were detected throughout development. Distribution of Cyclin H transcripts was found to be ubiquitous during early stages of development and become restricted to the anterior neural tube, brain, eyes, procreate tissues, liver and heart by 5 days post-fertilization. Expression of a dominant-negative form of Cyclin H delayed the onset of zygotic transcription in the early embryo, resulting in apoptosis at 5 hours post-fertilization and leading to sever defects in tissues normally exhibiting high levels of Cyclin H expression. These results implicate Cyclin H in the regulation of the transcriptional machinery during midblastula transition and suggest that it is an essential gene in early zebrafish larval development.
Cell Research (2007) 17:163-173. doi: 10.1038/sj.cr.7310144; published online 6 February 2007
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