PCI Domain Containing Protein 2 (PCID2)

PCID2 expressed in immature and early-stage B lymphocytes and regulates expression of the mitotic checkpoint protein MAD2. Highest expression of Pcid2 in mouse pre-B and immature B cells, as well as in transitional-1 and follicular B cells. Little expression was detected in T2 and marginal zone B cells. Knockdown of PCID2 in HeLa cells by small interfering RNA induced abnormalities in cell cycling, with an increase of apoptotic and hyperploid cells. Knockdown of PCID2 suppressed MAD2 expression, but not expression of other cell cycle checkpoint proteins, such as MAD1 and BUBR1, or cell cycle-associated proteins, such as cyclin A, cyclin B1, and CDK1. In situ hybridization showed that MAD2 expression was markedly decreased in the cytoplasm compared with the nucleus after PCID2 siRNA treatment, suggesting that PCID2 regulates MAD2 mRNA metabolism.