The Function Of Polo-like Kinase 5 On The Cell Cycle Regulation

Polo-like kinase(PLK) family is a class of serine / threonine protein kinases, playing crucial roles in cell cycle regulation.Up to now,four mammalian PLKs have been identified.They are PLK1,PLK2/SNK,PLK3/FNK/PRK and PLK4/SAK.PLK family is associated with tumorigenesis,which are promising anti-cancer targets. Scientists focus on studying the functions of known PLKs as well as the discovery of novel PLK members and their potential functions in cell cycle.By bioinformatics analysis and biological technology,we have cloned a gene predicted to encode a novel serine/threonine protein kinase-mPLK5(mammalian PLK5).The deduced mPLK5 amino acid sequence has 34%,39%,41%and 26% overall identity to known mouse PLK1,PLK2,PLK3,PLK4,respectively.The similarity(54%) and identity(34%) between PLK5 and PLK1 is higher than the similarity(32%) and identity(16%) between PLK4 and PLK1.Therefore,we preliminary defined it as a novel member of PLKs and named it as mPLK5 (mammalian PLK5 or mouse PLK5).Western blot analysis revealed that mPLK5 is mainly expressed in cerebrum,cerebellum and spinal cord.The epitopic expression of mPLK5 shows that mPLK5 was mainly located in the nucleus.The mutation of conserved amino acid of mPLK5(W417F) did not change the subcellular localization of mPLK5.Compared with control cells,overexprssion of mPLK5 may inhibite the proliferation of HeLa cells and interfere with the entry into mitosis.Hence,mPLK5, similar to other members of PLKs,may involve in the regulation of cell progression.