title: Diaphanous formin mDia2 regulates CENP-A levels at centromeres.
abstract: Centromeres of higher eukaryotes are epigenetically defined by centromere protein A (CENP-A), a centromere-specific histone H3 variant. The incorporation of new CENP-A into centromeres to maintain the epigenetic marker after genome replication in S phase occurs in G1 phase; however, how new CENP-A is loaded and stabilized remains poorly understood. Here, we identify the formin mDia2 as essential for stable replenishment of new CENP-A at centromeres. Quantitative imaging, pulse-chase analysis, and high-resolution ratiometric live-cell studies demonstrate that mDia2 and its nuclear localization are required to maintain CENP-A levels at centromeres. Depletion of mDia2 results in a prolonged centromere association of holiday junction recognition protein (HJURP), the chaperone required for CENP-A loading. A constitutively active form of mDia2 rescues the defect in new CENP-A loading caused by depletion of male germ cell Rac GTPase-activating protein (MgcRacGAP), a component of the small GTPase pathway essential for CENP-A maintenance. Thus, the formin mDia2 functions downstream of the MgcRacGAP-dependent pathway in regulating assembly of new CENP-A containing nucleosomes at centromeres.
authors.affiliation: Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032.
authors.forename: Chenshu
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032 ym2183@cumc.columbia.edu.
authors.forename: Yinghui
authors.initials: Y
authors.lastname: Mao
mesh_terms: D001324:Autoantigens / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D045744:Cell Line, Tumor; D002503:Centromere / Q000378:metabolism*; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D004261:DNA Replication / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D044127:Epigenesis, Genetic / Q000502:physiology; D016193:G1 Phase / Q000502:physiology; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009707:Nucleosomes / Q000378:metabolism; D016196:S Phase / Q000502:physiology
chemical_list: D001324:Autoantigens; D015415:Biomarkers; C000619700:CENPA protein, human; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D020690:GTPase-Activating Proteins; D006657:Histones; D008869:Microtubule-Associated Proteins; D009707:Nucleosomes