RbAp46/48(LIN-53) Is Required for Holocentromere Assembly in Caenorhabditis elegans

• Published in: Cell reports (Cambridge) 2016-03, Vol.14 (8), p.1819-1828
• Main Authors: Lee, Bernard Chi Hang, Lin, Zhongyang, Yuen, Karen Wing Yee
• Format: Article
• Language: English
• Subjects: Anaphase; Animals; Autoantigens - genetics; Autoantigens - metabolism; Caenorhabditis elegans - embryology; Caenorhabditis elegans - genetics; Caenorhabditis elegans - metabolism; Caenorhabditis elegans - ultrastructure; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Carrier Proteins - genetics; Carrier Proteins - metabolism; Centromere - metabolism; Centromere - ultrastructure; Centromere Protein A; Chromatin - metabolism; Chromatin - ultrastructure; Chromosomal Proteins, Non-Histone - genetics; Chromosomal Proteins, Non-Histone - metabolism; Chromosome Segregation; DNA Replication; Embryo, Nonmammalian; Epigenesis, Genetic; Histones - genetics; Histones - metabolism; Kinetochores - metabolism; Kinetochores - ultrastructure; Metaphase; Protein Transport; Repressor Proteins - genetics; Repressor Proteins - metabolism; Signal Transduction
• ISSN: 2211-1247
• DOI: 10.1016/j.celrep.2016.01.065

Centromeres, the specialized chromosomal regions for recruiting kinetochores and directing chromosome segregation, are epigenetically marked by a centromeric histone H3 variant, CENP-A. To maintain centromere identity through cell cycles, CENP-A diluted during DNA replication is replenished. The licensing factor M18BP1(KNL-2) is known to recruit CENP-A to holocentromeres. Here, we show that RbAp46/48(LIN-53), a conserved histone chaperone, is required for CENP-A(HCP-3) localization in holocentric Caenorhabditis elegans. Indeed, RbAp46/48(LIN-53) and CENP-A(HCP-3) localizations are interdependent. RbAp46/48(LIN-53) localizes to the centromere during metaphase in a CENP-A(HCP-3)- and M18BP1(KNL-2)-dependent manner, suggesting CENP-A(HCP-3) loading may occur before anaphase. RbAp46/48(LIN-53) does not function at the centromere through histone acetylation, H3K27 trimethylation, or its known chromatin-modifying complexes. RbAp46/48(LIN-53) may function independently to escort CENP-A(HCP-3) for holocentromere assembly but is dispensable for other kinetochore protein recruitment. Nonetheless, depletion of RbAp46/48(LIN-53) leads to anaphase bridges and chromosome missegregation. This study unravels the holocentromere assembly hierarchy and its conservation with monocentromeres.