Phase of the Cell Cycle 2 and Acts in G The cdc 2 - related Kinase , PISSLRE , Is Essential for Cell Growth

Mammalian cell cycle progression is regulated by several protein kinases that are activated by cyclically expressed proteins called cyclins. These cyclin-dependent kinases, the prototype of which is the cdc2 mitosispromoting kinase, are known to phosphorylate substrates the modified status of which is critical for the cell to progress into sequential phases of the cycle. Recently, a new cdcl-related protein kinase has been discovered, PISSLRK, named with respect to its homolog} to the cdc2 PSTA1RE amino acid domain. Here we report that by using both antisense and dominant-negative mutant constructs of PISSLRE when overexpressed in U2OS cells, a growth suppression is found. Furthermore, the dominant negative forms of PISSLRE halt cell cycle progression in G2-M. There fore, PISSLRE is essential for cellular proliferation, and its effect is exerted in (, ,-M. This describes the first evidence since cdc2 of a cdc2related kinase acting through (. .-M.