Nek9, a novel FACT-associated protein, modulates interphase progression.
The heterodimeric Spt16-Pob3/DUF/FACT complex is a class of chromatin structure modulators with important roles in replication and transcription. Although regarded as a transcription elongator for chromatin template, little is known about the mode of action and involvement in other molecular processes of the mammalian FACT. Here we report the identification of a novel interacting and functional partner of FACT, Nek9. Nek9 forms a stable, approximately 600-kDa complex with FACT in the interphase nuclei. Its active form is characterized by phosphorylation-dependent electrophoretic mobility shift and phosphorylation at a conserved residue within the activation loop (Thr(210)). When complexed with FACT, Nek9 exhibits markedly elevated phosphorylation on Thr(210). Cell cycle analysis on the Nek9(dsRNAi) cells directly implicated Nek9 in maintaining proper G(1) and S progression, a role temporally correlated to the formation of a phospho-Nek9-FACT complex. Collectively, these observations provide evidence that Nek9, potentially as an active enzymatic partner of FACT, mediates certain FACT-associated cellular processes, which are ultimately essential for interphase progression.
Tan
Bertrand Chin-Ming
BC
Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
Lee
Sheng-Chung
SC
D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology; D006367:HeLa Cells; D006609:High Mobility Group Proteins / Q000502:physiology; D006801:Humans; D007399:Interphase / Q000502:physiology*; D000072379:NIMA-Related Kinases; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D013997:Time Factors; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors / Q000502:physiology
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; C073537:SSRP1 protein, human; C489489:SUPT16H protein, human; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; C462119:NEK9 protein, human; D000072379:NIMA-Related Kinases; D017346:Protein Serine-Threonine Kinases