Advancing the health and well-being of animals and people


Principal Investigator:Joanna Kim Holloway 

Department of Biomedical Sciences
Contact Information:  Email:  jkh44@cornell.edu, Phone:  607-253-4273
Sponsor:  NIH- National Institute of Child Health and Human Development (NICHD)
Grant Number:  4 R00 HD065870-03
Title:  Functional Analysis of the Dual Specificity Kinase NEK1 in Mammalian Meiosis
Annual Direct Cost:  $249,000
Project Period:  07/01/2012-06/30/2015

DESCRIPTION (provided by applicant):  During meiosis, homologous chromosomes seek each other out and are then tethered together by the synaptonemal complex (SC) and sister chromatid cohesion, without which homologous recombination and meiotic division cannot occur.  Mice with mutations in any of the SC component or cohesion genes show meiotic pairing defects, and in most cases are completely sterile.  The SC protein, FKBP6, which is essential for completion of male meiosis in mice, interacts with a novel meiotic kinase, NEK1 (NIMA-related kinase 1).  NEK1 is a dual activity serine/threonine ad tyrosine kinase, which is highly expressed in germ cells, particularly the narrow window encompassing the entry into, and progression through, Prophase I.  Nek1 mutant mice show severe developmental defects, not only in their fertility, but also show growth defects, cranial-facial abnormalities and polycystic kidney disease.  The central hypothesis of this proposal is that NEK1 is critical to meiotic progression in mice, as a result of persistent cohesion proteins in NEK1-feficient cells, and that NEK1 affects phosphorylation of these proteins, either directly or indirectly. The fertility issue during the K99 portion of funding has been addressed and will now concentrate on the relationship between NEK1 and the meiotic cohesion proteins during prophase I.  The in vivo analysis will make use of a line of Nek1kat2J mice harboring a single nucleotide insertion and a subsequent premature stop, resulting in truncation of the protein product and a mull phenotype. An in-depth study will be performed of the relationship between NEK1 and various proteins by determining if NEK1 acts as a kinase directly on the chosen cohesins, using a classical kinase assay. A study the interactions of these proteins both in vivo and in vitro, using cell culture experiments is proposed. The serine/threonine and tyrosine kinase activities of both the wild type and mutant forms of NEK1 directly in mouse germ cells will be assessed.  These experiments will provide novel and exciting data on the role of NEK1 in meiotic progression, as well as on the mechanisms of cohesion removal at the end of prophase I, a subject on which there is very little reported data.