期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 290, 期 34, 页码 20893-20903出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M114.633727
关键词
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资金
- Department of Biotechnology Grant (DBT) [BT/PR11415/BRB/10/656/2008]
- Department of Science and Technology Grant, Government of India [SR/SO/HS-51/2008]
- Center for Advanced Studies in Biochemistry (University Potential for Excellence) (University Grants Commission)
- Center for Modern Biology (University Potential for Excellence) (University Grants Commission)
- Calcutta University (CU)-DBT-Interdisciplinary Program in Life Sciences (IPLS)
- Council of Scientific and Industrial Research, Government of India
- Biomolecular Assembly, Recognition and Dynamics Project Grant from the Department of Atomic Energy, Government of India [12-RD-SIN-5.040103]
- Department of Biotechnology, Government of India
Phosphoinositide signaling has been implicated in the regulation of numerous cellular processes including cytoskeletal dynamics, cellular motility, vesicle trafficking, and gene transcription. Studies have also shown that nuclear phosphoinositide(s) regulates processes such as mRNA export, cell cycle progression, gene transcription, and DNA repair. We have shown previously that the nuclear form of phosphatidylinositol-4-phosphate 5-kinase 1 alpha (PIP5K), the enzyme responsible for phosphatidylinositol 4,5-bisphosphate synthesis, is modified by small ubiquitin-like modifier (SUMO)-1. In this study, we have shown that due to the site-specific Lys to Ala mutations of PIP5K at Lys-244 and Lys-490, it is unable to localize in the nucleus and nucleolus, respectively. Furthermore, by using chromatin immunoprecipitation assays, we have observed that PIP5K associates with the chromatin silencing complex constituted of H3K9me3 and heterochromatin protein 1 alpha at multiple ribosomal DNA (rDNA) loci. These interactions followed a definite cyclical pattern of occupancy (mostly G(1)) and release from the rDNA loci (G(1)/S) throughout the cell cycle. Moreover, the immunoprecipitation results clearly demonstrate that PIP5K SUMOylated at Lys-490 interacts with components of the chromatin silencing machinery, H3K9me3 and heterochromatin protein 1 alpha. However, PIP5K does not interact with the gene activation signature protein H3K4me3. This study, for the first time, demonstrates that PIP5K, an enzyme actively associated with lipid modification pathway, has additional roles in rDNA silencing.
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