Identification and functional study of CDK gene family in cell proliferation in the Chinese mitten crab (Eriocheir sinensis)

CDK genes play crucial roles in key biological processes such as cell cycle progression and transcriptional regulation. However, the specific number of CDK gene family members in the Chinese mitten crab (Eriocheir sinensis) remained unclear. In this study, we identified 19 CDK genes in E. sinensis through genome-wide analysis. Phylogenetic analysis classified them into 13 major subfamilies, all containing a relatively conserved S_TKc domain. The majority of these 19 genes showed high expression levels in epidermal and muscle tissues. Furthermore, six of them were significantly upregulated upon bacterial challenge. Since bacterial stimulation promotes cell proliferation, we knocked down the highly expressed CDK genes and found that depletion of CDK2-L1 or CDK4 abolished the pro-proliferative phenotype, indicating their essential role in regulating cell proliferation. Additionally, we demonstrated that CDK2-L1 interacts with CyclinE and Cyclin A, and CDK4 binds to Cyclin D—both cyclins being key regulators of cell proliferation. Thus, this study reveals that CDK2-L1 and CDK4 regulate cell proliferation by forming functional complexes with their respective cyclin partners.