NCBI Summary:
The protein encoded by this gene is a member of the highly conserved polo-like kinase family of serine/threonine kinases. Members of this family are characterized by an amino-terminal kinase domain and a carboxy-terminal bipartite polo box domain that functions as a substrate-binding motif and a cellular localization signal. Polo-like kinases are important regulators of cell cycle progression. This gene has also been implicated in stress responses and double-strand break repair. In human cell lines, this protein is reported to associate with centrosomes in a microtubule-dependent manner, and during mitosis, the protein becomes localized to the mitotic apparatus. Expression of a kinase-defective mutant results in abnormal cell morphology caused by changes in microtubule dynamics and mitotic arrest followed by apoptosis. [provided by RefSeq, Sep 2015]
General function
Enzyme
Comment
Cellular localization
Cytoplasmic
Comment
Ovarian function
Luteinization
Comment
Hormonal induction of polo-like kinases (plks) and impact of plk2 on cell cycle progression in the rat ovary. Li F et al. The highly conserved polo-like kinases (Plks) are potent regulators of multiple functions in the cell cycle before and during mitotic cell division. We investigated the expression pattern of Plk genes and their potential role(s) in the rat ovary during the periovulatory period. Plk2 and Plk3 were highly induced both in intact ovaries and granulosa cells in vivo after treatment with the luteinizing hormone (LH) agonist, human chorionic gonadotropin (hCG). In vitro, hCG stimulated the expression of Plk2 in granulosa cells, but not Plk3. This induction of Plk2 expression was mimicked by both forskolin and phorbol 12 myristate 13-acetate (PMA). Moreover, Plk2 expression was reduced by inhibitors of prostaglandin synthesis or the EGF pathway, but not by progesterone receptor antagonist (RU486) treatment. At the promoter level, mutation of the Sp1 binding sequence abolished the transcriptional activity of the Plk2 gene. ChIP assays also revealed the interaction of endogenous Sp1 protein in the Plk2 promoter region. Functionally, the over-expression of Plk2 and Plk3 arrested granulosa cells at the G0/G1 phase of the cell cycle. In contrast, the knockdown of Plk2 expression in granulosa cells decreased the number of cells in the G0/G1 stage of the cell cycle, but increased granulosa cell viability. In summary, hCG induced Plk2 and Plk3 expression in the rat ovary. Prostaglandins and the EGF signaling pathway are involved in regulating Plk2 expression. The transcription factor Sp1 is important for Plk2 transcriptional up-regulation. Our findings suggest that the increase in Plk2 and Plk3 expression contributes to the cell cycle arrest of granulosa cells which is important for the luteinization of granulosa cells during the periovulatory period.