AUTHOR=Feng ShangLe , Li XueNan , Wang He , Li WenJuan , Bai ZhiYi 

TITLE=Identification and Functional Analysis of the G1 Phase Cyclin Dependent Kinase Gene Hc-CDK6 in Pearl Mussels (Hyriopsis cumingii)

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.921726

DOI=10.3389/fmars.2022.921726

ISSN=2296-7745

ABSTRACT=<p>Cyclin dependent kinase 6 (CDK6) is a serine/threonine kinase that plays important roles in cell cycle progression and differentiation. In this study, full-length cDNA of <italic>Hc-CDK6</italic> was obtained from freshwater pearl mussels (<italic>Hyriopsis cumingii</italic>, <italic>Hc</italic>) with 3´,5´ rapid-amplification of cDNA ends (RACE). The <italic>Hc-CDK6</italic> expression profiles were analyzed with quantitative real-time PCR and <italic>in situ</italic> hybridization. The function of the <italic>Hc-CDK6</italic> gene was studied with both RNA interference (RNAi) and overexpression in <italic>H. cumingii</italic>. <italic>Hc-CDK6</italic> was found to encode 331 amino acids and to have a CDK4/6-like serine/threonine kinase catalytic structural domain. In terms of the amino acid sequence, the protein Hc-CDK6 was most closely related to its homolog in <italic>Crassostrea gigas</italic>, with a similarity of 75.23%. <italic>Hc-CDK6</italic> was expressed in all examined tissues (adductor, foot, visceral mass, gill, outer mantle, inner mantle and gonads), and the highest expression was observed in the gonads (<italic>P</italic>&lt;0.05). The relative expression of <italic>Hc-CDK6</italic> increased during embryonic development, and was higher in the blastocyst and gastrulation stages, which were characterized by rapid division and differentiation. <italic>Hc-CDK6</italic> showed hybridization signals in all parts of the mantle. After knockdown of <italic>Hc-CDK6</italic> through RNAi, a significant decrease in <italic>CDK6</italic> expression was found, and the percentage of cells in G0/G1 significantly increased. Overexpression of <italic>Hc-CDK6</italic> in mantle cells increased the proliferation of cultured cells (<italic>P</italic>&lt;0.05). <italic>Hc-CDK6</italic> appeared to promote the cell cycle in <italic>H. cumingii</italic>, and overexpression of <italic>Hc-CDK6</italic> promoted mantle cell proliferation. The functional study of this gene may provide new ideas for solving the problem of slow proliferation of shellfish cells in <italic>in vitro</italic> culture.</p>