2000 Fiscal Year Final Research Report Summary
Function of cyclin regulatory factors in cell cycle control.
| Project/Area Number |
11694218
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Cell biology
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
KOBAYASHI Hideki Kyushu University, Graduate School of Medical Science, Associate Professor, 大学院・医学研究院, 助教授 (20150394)
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| Project Period (FY) |
1999 – 2000
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| Keywords | cell cycle / cycline / cyclin-dependent kinase / proteolysis / ubiquitin / proteasome / ubiquitin-related protein |
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| Research Abstract |
The degradation of mitotic cyclins plays an essential role in cell-cycle progression during mitosis. Mitotic cyclins A and B are degraded by ubiquitin-dependent proteolysis and its process requires the N-terminal domain of mitotic cyclins. Using the N-terminus of cyclin A1 in a 2-hybrid screen as a bait, we identified a Xenopus protein, XDRP1, that contains a ubiquitin-like domain in its N-terminus and shows significant homology in its C-terminal 50 residues to S.cerevisiae Dsk2. XDRP1 is a nuclear phosphoprotein in Xenopus cells, and its phosphorylation is mediated by cyclin A dependent kinase. XDRP1 binds to both embryonic and somatic forms of cyclin A (A1 and A2) in Xenopus cells, but not to B-type cyclins. The N-terminal ubiquitin-like domain of XDRP1, but not the C-terminal Dsk2-like domain, is required for interaction with cyclin A.XDRP1 requires residues 130-160 of cyclin A1 for efficient binding, which do not include the destruction box of cyclin A.The addition of bacterially-expressed XDRP1 protein to frog egg extract inhibited the Ca2+-induced degradation of cyclin A, but not that of cyclin B.The injection of XDRP1 protein into fertilized Xenopus eggs blocked embryonic cell division. These results suggest that XDRP1 is a negative regulator of degradation of cyclin A.
XDRP1 contains a ubiquitin-like domain in its N-terminus and shows significant homology to S.cerevisiae Dsk2. Based on above evidence, we investigate the function of XDRP1/Dsk2 on ubiquitin-dependent proteolysis in yeast system. When overexpressed in yeast cells, Dks2 caused to accumulate polyubiquitination. Supprcssors of DSK2 toxicity in yeast were identified as mutations in proteasome subunits ; PRE2 in core subunit, and RPN1 in regulatory subunit, indicating genetic interaction between Dsk2 and proteasome. The results suggest that Dsk2 have a regulatory role in ubiquitin-proteasome degradation pathway.
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Research Products
(10 results)
