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Sanada S, Maekawa M, Tate S, Nakaoka H, Fujisawa Y, Sayama K, Higashiyama S. SPOP is essential for DNA replication licensing through maintaining translation of CDT1 and CDC6 in HaCaT cells. Biochem Biophys Res Commun 2023; 651:30-38. [PMID: 36791496 DOI: 10.1016/j.bbrc.2023.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 02/03/2023] [Indexed: 02/05/2023]
Abstract
Speckle-type pox virus and zinc finger (POZ) protein (SPOP), a substrate recognition receptor for the cullin-3/RING ubiquitin E3 complex, leads to the ubiquitination of >40 of its target substrates. Since a variety of point mutations in the substrate-binding domain of SPOP have been identified in cancers, including prostate and endometrial cancers, the pathological roles of those cancer-associated SPOP mutants have been extensively elucidated. In this study, we evaluated the cellular functions of wild-type SPOP in non-cancerous human keratinocyte-derived HaCaT cells expressing wild-type SPOP gene. SPOP knockdown using siRNA in HaCaT cells dramatically reduced cell growth and arrested their cell cycles at G1/S phase. The expression of DNA replication licensing factors CDT1 and CDC6 in HaCaT cells drastically decreased on SPOP knockdown as their translation was inhibited. CDT1 and CDC6 downregulation induced p21 expression without p53 activation. Our results suggest that SPOP is essential for DNA replication licensing in non-cancerous keratinocyte HaCaT cells.
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Affiliation(s)
- Sayoko Sanada
- Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0295, Japan; Department of Biochemistry and Molecular Genetics, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0295, Japan
| | - Masashi Maekawa
- Department of Biochemistry and Molecular Genetics, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0295, Japan; Division of Cell Growth and Tumor Regulation, Proteo-Science Center, Ehime University, Toon, Ehime, 791-0295, Japan.
| | - Sota Tate
- Department of Biochemistry and Molecular Genetics, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0295, Japan; Division of Cell Growth and Tumor Regulation, Proteo-Science Center, Ehime University, Toon, Ehime, 791-0295, Japan
| | - Hiroki Nakaoka
- Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0295, Japan
| | - Yasuhiro Fujisawa
- Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0295, Japan
| | - Koji Sayama
- Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0295, Japan
| | - Shigeki Higashiyama
- Department of Biochemistry and Molecular Genetics, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0295, Japan; Division of Cell Growth and Tumor Regulation, Proteo-Science Center, Ehime University, Toon, Ehime, 791-0295, Japan; Department of Oncogenesis and Tumor Regulation, Osaka International Cancer Institute, Chuo-ku, Osaka, 541-8567, Japan.
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