Functional Characterization of CENP-A Post-Translational Modifications in Chromosome Segregation
Technical Report,15 Jun 2014,14 Jun 2015
VIRGINIA UNIV CHARLOTTESVILLE CHARLOTTESVILLE
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Colorectal cancer is the second leading cause of cancer death in the United States. Approximately 85 of colorectal cancers are CIN Chromosomal instability and are associated with poor survival. The molecular mechanisms responsible for the CIN phenotype and hence means to target this pattern of genome instability remains poorly defined. I hypothesize that, posttranslational modifications PTM of the centromeric nucleosome, specifically on the histone variant, CENP-A, will direct centromere activity, and that perturbations of such could lead to aneuploidy and cancer. We proposed to decipher the pathway that leads to CENP-A alpha-amino methylation and to determine the function it plays in ensuring the fidelity of chromosome segregation. We have shown that CENP-A is methylated by NRMT1 both in vitro and in vivo. CENP-A is methylated throughout the cell cycle. We established that CENP-A alpha-amino tri-methylation required for ensuring high fidelity of chromosome segregation, and hence preventing aneuploidy and cancer. Importantly, we found that loss of CENP-A alpha-amino tri-methylation trigger a proliferation advantage and cells form bigger colonies in colony formation assay. We also found that CENP-A methylation contributes to the cell survival and in the absence of it, cells undergoes senescence. This response is dependent on p53 pathway. But in the absence of p53, cells undergo further proliferation, aneuploidy and tumorigenesis. Methylation of CENP-A is required for the assembly of constitutively centromere associated network proteins and that explain the chromosome segregation defect in CENP-A methylation mutant. The results suggests that -amino tri-methylation of CENP-A is an important post-translational modification necessary for maintaining accuracy of chromosome segregation.
- Genetic Engineering and Molecular Biology
- Medicine and Medical Research