A mutant in the NimA-like kinase, cnk10, has flagellar and cell-cycle defects
Huawen Lin, Alan L. Kwan, and Susan K. Dutcher
Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
An insertional mutant in the CNK10 locus was isolated in a screen for Taxol-sensitive strains. In addition, the mutant displays flagellar coordination defects that prevent effective swimming. The wild-type CNK10 gene encodes a Chlamydomonas NIMA-related protein kinase (NEK) and localizes to the basal body region. NEKs are known to be involved in diverse biological processes including cell cycle regulation, centrosome stability, and ciliogenesis. CNK10 is most similar to NEK1 in mice. The nek1 mutant mice show cystic renal defects, hydrocephalus, testicular hypoplasia, and bile duct proliferation. The cnk10-1 insertional event results in a truncated Cnk10 protein, which localizes to the nucleus. Basal body mutant strains (bld2, bld10, vfl3) show Taxol sensitivity and fail to localize katanin p80 to the basal bodies (Esparza, O'Toole, Li, and Dutcher, in preparation). Immunofluorescence shows that katanin p60 is localized to the basal body region in wild-type but not in cnk10-1 mutant cells. Therefore, the Taxol-sensitive phenotype of cnk10 may be caused by a failure to recruit katanin to the basal bodies. Massively parallel mRNA sequencing (RNAseq) of vegetativley grown wild-type and cnk10 cells was performed to investigate genome-wide transcriptome changes caused by the mutation. Many of the proteins involved in basal body function have reduced transcript levels in cnk10. Additionally, proteins involved in DNA replication are universally knocked down in cnk10 cells, which suggests that Cnk10 may be involved in cell cycle regulation. Studies on transcriptional regulation of these genes by CNK10 in synchronous cells are currently in progress.
e-mail address of presenting author: huawen.lin@wustl.edu