The Cul3/Klhdc5 E3 ligase regulates p60/katanin and is required for normal mitosis in mammalian cells.
The proper regulation of factors involved in mitosis is crucial to ensure normal cell division. Levels and activities of proteins are regulated in many ways, one of which is ubiquitin-mediated protein degradation. E3 ubiquitin ligases are involved in targeting specific substrates for degradation by facilitating their ubiquitination. In seeking to elucidate additional biological roles for Cul3 we performed a two-hybrid screen and identified Ctb9/KLHDC5 as a Cul3-interacting protein. Overexpression of Ctb9/KLHDC5 resulted in an increase in microtubule density as well as persistent microtubule bridges between post-mitotic cells. Conversely, down-regulation of Ctb9/KLHDC5 showed a pronounced reduction in microtubule density. Based on these observations, we examined the interactions between Cul3, Ctb9/KLHDC5, and the microtubule-severing protein, p60/katanin. Here we show that p60/katanin interacts with a complex consisting of Cul3 and Ctb9/KLHDC5, which results in ubiquitin laddering of p60/katanin. Also, Cul3-deficient cells or Ctb9/KLHDC5-deficient cells show an increase in p60/katanin levels, indicating that Cul3/Ctb9/KLHDC5 is required for efficient p60/katanin removal. We demonstrate a novel regulatory mechanism for p60/katanin that occurs at the level of targeted proteolysis to allow normal mitotic progression in mammalian cells.
Cummings
Cristina M
CM
Department of Molecular Biology, Cell Biology and Biochemistry and the Center for Genomics and Proteomics, Brown University, Providence, Rhode Island 02903, USA.
Bentley
Cornelia A
CA
Perdue
Sarah A
SA
Baas
Peter W
PW
Singer
Jeffrey D
JD
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000502:physiology*; D000595:Amino Acid Sequence; D044842:Cullin Proteins / Q000737:chemistry / Q000502:physiology*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D000074201:Katanin; D008870:Microtubules / Q000378:metabolism*; D008938:Mitosis; D008954:Models, Biological; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*
C503645:CUL3 protein, human; C503646:Cul3 protein, mouse; D044842:Cullin Proteins; D044767:Ubiquitin-Protein Ligases; D000251:Adenosine Triphosphatases; D000074201:Katanin; C541039:KLHL42 protein, human; C541038:Klhl42 protein, mouse