Original Article

Cell Biochemistry and Biophysics

, Volume 39, Issue 2, pp 119-131

Distinct domains of human CDC5 direct its nuclear import and association with the spliceosome

  • Liansen LiuAffiliated withCardiovascular Research Institute, University of California San Francisco
  • , Remo GräubAffiliated withCardiovascular Research Institute, University of California San Francisco
  • , Myint HlaingAffiliated withCardiovascular Research Institute, University of California San Francisco
  • , Conrad L. EptingAffiliated withCardiovascular Research Institute, University of California San FranciscoDepartment of Pediatrics, University of California San Francisco
  • , Christoph W. TurckAffiliated withHoward Hughes Medical Institute, University of California San Francisco
  • , Xiao-Qin XuAffiliated withDepartment of Pediatrics, University of California San Francisco
  • , Leanne ZhangAffiliated withCardiovascular Research Institute, University of California San Francisco
  • , Harold S. BernsteinAffiliated withCardiovascular Research Institute, University of California San FranciscoCancer Center, University of California San FranciscoDepartment of Pediatrics, University of California San Francisco Email author 

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Abstract

Genetic studies have shown that CDC5 proteins are essential for G2 progression and mitotic entry. CDC5 homologs in yeast and mammals are essential for pre-messenger ribonucleic acid (mRNA) processing. Other gene products also have been shown to play roles in both pre-mRNA splicing and cell cycle regulation, prompting the description of several models to explain the mechanism(s) linking these two processes. In this study, we demonstrate that the amino-terminus of human CDC5 directs nuclear import independent of consensus nuclear localization signals or phosphorylation, and that the carboxyl-terminus of human CDC5 preferentially associates with spliceosomal complexes in proximity of RNA transcription during interphase. hCDC5 colocalizes with Sm proteins in a cell cycle- and domain-dependent manner, and several proteins in the human CDC5-associated complex are identified that suggest potential roles for the complex in coupling pre-mRNA splicing to transcriptional activation and protein translation. These results indicate that human CDC5 may function in pre-mRNA processing and cell cycle progression through more than one mechanism.

Index Entries

Cell cycle nuclear speckle nuclear import phosphorylation pre-mRNA splicing spliceosome