Functional epialleles at an endogenous human centromere.
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Human centromeres are defined by megabases of homogenous alpha-satellite DNA arrays that are packaged into specialized chromatin marked by the centromeric histone variant, centromeric protein A (CENP-A). Although most human chromosomes have a single higher-order repeat (HOR) array of alpha satellites, several chromosomes have more than one HOR array. Homo sapiens chromosome 17 (HSA17) has two juxtaposed HOR arrays, D17Z1 and D17Z1-B. Only D17Z1 has been linked to CENP-A chromatin assembly. Here, we use human artificial chromosome assembly assays to show that both D17Z1 and D17Z1-B can support de novo centromere assembly independently. We extend these in vitro studies and demonstrate, using immunostaining and chromatin analyses, that in human cells the centromere can be assembled at D17Z1 or D17Z1-B. Intriguingly, some humans are functional heterozygotes, meaning that CENP-A is located at a different HOR array on the two HSA17 homologs. The site of CENP-A assembly on HSA17 is stable and is transmitted through meiosis, as evidenced by inheritance of CENP-A location through multigenerational families. Differences in histone modifications are not linked clearly with active and inactive D17Z1 and D17Z1-B arrays; however, we detect a correlation between the presence of variant repeat units of D17Z1 and CENP-A assembly at the opposite array, D17Z1-B. Our studies reveal the presence of centromeric epialleles on an endogenous human chromosome and suggest genomic complexities underlying the mechanisms that determine centromere identity in humans.
Centromere Protein B
Chromatin Assembly and Disassembly
Chromosomal Proteins, Non-Histone
Published Version (Please cite this version)10.1073/pnas.1203126109
Publication InfoMaloney, Kristin A; Sullivan, Lori L; Matheny, Justyne E; Strome, Erin D; Merrett, Stephanie L; Ferris, Alyssa; & Sullivan, Beth A (2012). Functional epialleles at an endogenous human centromere. Proc Natl Acad Sci U S A, 109(34). pp. 13704-13709. 10.1073/pnas.1203126109. Retrieved from https://hdl.handle.net/10161/12802.
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Professor of Molecular Genetics and Microbiology
Research in the Sullivan Lab is focused on chromosome organization, with a specific emphasis on the genomics and epigenetics of the chromosomal locus called the centromere and the formation and fate of chromosome abnormalities that are associated with birth defects, reproductive abnormalities, and cancer. The centromere is a specialized chromosomal site involved in chromosome architecture and movement, kinetochore function, heterochromatin assembly, and sister chromatid cohesion.Our