Mislocalization of centromeric histone H3 variant CENP-A contributes to chromosomal instability (CIN) in human cells

Abstract

Chromosomal instability (CIN) is a hallmark of many cancers and a major contributor to tumorigenesis. Centromere and kinetochore associated proteins such as the evolutionarily conserved centromeric histone H3 variant CENP-A, associate with centromeric DNA for centromere function and chromosomal stability. Stringent regulation of cellular CENP-A levels prevents its mislocalization in yeast and flies to maintain genome stability. CENP-A overexpression and mislocalization are observed in several cancers and reported to be associated with increased invasiveness and poor prognosis. We examined whether there is a direct relationship between mislocalization of overexpressed CENP-A and CIN using HeLa and chromosomally stable diploid RPE1 cell lines as model systems. Our results show that mislocalization of overexpressed CENP-A to chromosome arms leads to chromosome congression defects, lagging chromosomes, micronuclei formation and a delay in mitotic exit. CENP-A overexpressing cells showed altered localization of centromere and kinetochore associated proteins such as CENP-C, CENP-T and Nuf2 leading to weakened native kinetochores as shown by reduced interkinetochore distance and CIN. Importantly, our results show that mislocalization of CENP-A to chromosome arms is one of the major contributors for CIN as depletion of histone chaperone DAXX prevents CENP-A mislocalization and rescues the reduced interkinetochore distance and CIN phenotype in CENP-A overexpressing cells. In summary, our results establish that CENP-A overexpression and mislocalization result in a CIN phenotype in human cells. This study provides insights into how overexpression of CENP-A may contribute to CIN in cancers and underscore the importance of understanding the pathways that prevent CENP-A mislocalization for genome stability.

The Oncogenic Role of CENPA in Hepatocellular Carcinoma Development: Evidence from Bioinformatic Analysis

“…As a histone H3 variant of centromeric nucleosomes, centromere protein A (CENPA) is required to guarantee kinetochore for proper chromosome segregation assembly [1,2]. Resulting from artificial overexpression, CENPA mislocalization could potentially generate ectopic kinetochores or weaken native kinetochores, leading to aberrant chromosomal segregation and instable genome [3][4][5]. An aberrant expression of CENPA and defects in CENPA function result in disrupted genome integrity, abnormal cell division, and thereby cancer [6][7][8].…”

N-terminal sumoylation of centromeric histone H3 variant Cse4 regulates its proteolysis to prevent mislocalization to non-centromeric chromatin

“…Evolutionarily conserved centromeric histone H3, CENP-A (Cse4 in Saccharomyces cerevisiae, Cnp1 in Schizosaccharomyces pombe, CID in Drosophila, and CENP-A in humans), is essential for faithful chromosome segregation. Overexpression of Cse4, CID, and CENP-A leads to its mislocalization to non-centromeric regions and contributes to aneuploidy in flies, yeast, and human cells, respectively (Heun et al 2006;Moreno-Moreno et al 2006;Collins et al 2004;Au et al 2008;Shrestha et al 2017).…”

DNA replication-mediated error correction of ectopic CENP-A deposition maintains centromere identity

“…Increasing levels of arm-associated CENP-A/CCAN would present a major problem for faithful assembly and function of a single centromere/kinetochore per chromosome, both by acquisition of partial centromere function and by competition with the authentic centromeres for the pool of available CCAN components. Indeed, high levels of CENP-A overexpression 1) leads to recruitment of detectable levels of 3 of 16 CCAN components (CENP-C, CENP-N and Mis18) assembled onto the arms 36, 37, 84 , 2) ongoing chromosome segregation errors 38 , and 3) has been observed in several cancers where it has been associated with increased invasiveness and poor prognosis 39, 85, 86 .…”