Gene structure, expression, and DNA methylation characteristics of sea cucumber cyclin B gene during aestivation.
The sea cucumber, Apostichopus japonicus, is a good model for studying environmentally-induced aestivation by a marine invertebrate. One of the central requirements of aestivation is the repression of energy-expensive cellular processes such as cell cycle progression. The present study identified the gene structure of the cell cycle regulator, cyclin B, and detected the expression levels of this gene over three stages of the annual aestivation-arousal cycle. Furthermore, the DNA methylation characteristics of cyclin B were analyzed in non-aestivation and deep-aestivation stages of sea cucumbers. We found that the cyclin B promoter contains a CpG island, three CCAAT-boxes and three cell cycle gene homology regions (CHRs). Application of qRT-PCR analysis showed significant downregulation of cyclin B transcript levels during deep-aestivation in comparison with non-aestivation in both intestine and longitudinal muscle, and these returned to basal levels after arousal from aestivation. Methylation analysis of the cyclin B core promoter revealed that its methylation level showed significant differences between non-aestivation and deep-aestivation stages (p<0.05) and interestingly, a positive correlation between Cyclin B transcripts expression and methylation levels of the core promoter was also observed. Our findings suggest that cell cycle progression may be reversibly arrested during aestivation as indicated by the changes in cyclin B expression levels and we propose that DNA methylation is one of the regulatory mechanisms involved in cyclin B transcriptional variation.
Fisheries College, Ocean University of China, Qingdao, PR China; The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, PR China.
Aijun
A
Zhu
Fisheries College, Ocean University of China, Qingdao, PR China; The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, PR China. Electronic address: chenmuyan@gmail.com.
Muyan
M
Chen
Fisheries College, Ocean University of China, Qingdao, PR China; The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, PR China.
Xiumei
X
Zhang
Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
Kenneth B
KB
Storey
D000818:Animals; D019926:Cyclin B / Q000096:biosynthesis / Q000235:genetics; D019175:DNA Methylation / Q000502:physiology*; D004956:Estivation / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000502:physiology*; D012616:Sea Cucumbers / Q000235:genetics / Q000378:metabolism
D019926:Cyclin B
Aestivation; Cell cycle; DNA methylation; Sea cucumber; cyclin B