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Functional Characterization of CENP-A Post-Translational Modifications in Chromosome Segregation

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Technical Report,15 Jun 2013,14 Jun 2016

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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 hypothesized 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-amino methylation and to determine the function it plays in ensuring the fidelity of chromosome segregation. We have shown here that CENP-A is methylated by NRMT1 both in vitro and in vivo. CENP-A is methylated before it is deposited into the centromere and that methylation persists throughout the cell cycle. We also found that CENP-Amethylation required for cell survival. We established that CENP-A -amino tri-methylation required for ensuring high fidelity of chromosome segregation by recruiting CENP-T and CENP-I into centromere. In the absence of methylation, the centromere localization of these proteins decreases which reduce the localization of the NDC80. NDC80 connects the kinetochore to the spindle pole. We found that tumor suppressor p53 plays a role in monitoring the accuracy of the chromosome segregation and formation of bipolar spindle. In the absence of p53, loss of CENP-A methylation leads to multipolar spindle formation. This triggers chromosomal instability and evolution of aggressive tumors. Importantly, we found that loss of CENP-A -amino trimethylation trigger a proliferation advantage and cells form bigger colonies in colony formation assay. Suggesting the evolution of aggressive clones.

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  • Genetic Engineering and Molecular Biology
  • Medicine and Medical Research

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