This is a Shannon Award providing partial support for the research projects that fall short of the assigned institute's funding range but are in the margin of excellence. The Shannon Award is intended to provide support to test the feasibility of the approach; develop further tests and refine research techniques; perform secondary analysis of available data sets; or conduct discrete projects that can demonstrate the PI's research capabilities or lend additional weight to an already meritorious application. The abstract below is taken from the original document submitted by the principal investigator. nimA was first identified as an essential mitotic regulator in Aspergillus nidulans. nimA encodes a protein kinase only very distantly related to other known cell cycle regulators. Aspergillus strains expressing temperature-sensitive alleles of nimA arrest in late G2-phase at the restrictive temperature. Recent studies suggest that NimA is a key downstream effector of Cdc2 A key question is whether NimA is a universal regulator of M-phase, like Cdc2, or whether its role in M-phase control is unique to Aspergillus. Recently a NimA homolog has been identified in a second filamentous fungus, Neurospora crassa. We designed PCR primers based on sequences conserved between the Aspergillus and Neurospora NimA proteins, and began a search for a homolog in Xenopus laevis oocytes. Xenopus oocytes and eggs offer a number of powerful approaches to studies of cell cycle regulators. We have identified three NimA-related proteins, Xnek1, Xnek3, and Xnek4, and have chosen to focus on Xnek1. Xnek1 is a close relative of the mouse Nek1 protein kinase, which was discovered in the course of studies aimed at identifying novel protein tyrosine kinases. The kinase domain of Xnek1 is 42% identical to that of NimA, and Xnek1 and NimA both possess long, basic C-terminal tails that contain nuclear localization sequences, PEST sequences, and multiple potential Cdc2 phosphorylation sites. Xnek1 mRNA is expressed at particularly high levels in oocytes, raising the possibility that it may play a role in meiosis. We propose to examine the regulation and function of the Xnek1 protein during meiotic and mitotic cell cycles. We should address the following specific questions: (1) Where and when is Xnek1 expressed? (2) Is Xnek1 activity regulated during meiosis and mitosis? (3) How is Xnek1 regulated, if it is regulated? (4) What biochemical and cell biological events depend upon Xnek1 function? Our overall aim is to understand what role this protein plays in cell cycle regulation.
