Article

Dicentric chromosomes: Unique models to study centromere function and inactivation

Institute for Genome Sciences and Policy, Duke University, Durham, NC 27708, USA.
Chromosome Research (Impact Factor: 2.69). 07/2012; 20(5):595-605. DOI: 10.1007/s10577-012-9302-3
Source: PubMed

ABSTRACT Dicentric chromosomes are products of genome rearrangement that place two centromeres on the same chromosome. Depending on the organism, dicentric stability varies after formation. In humans, dicentrics occur naturally in a substantial portion of the population and usually segregate successfully in mitosis and meiosis. Their stability has been attributed to inactivation of one of the two centromeres, creating a functionally monocentric chromosome that can segregate normally during cell division. The molecular basis for centromere inactivation is not well understood, although studies in model organisms and in humans suggest that genomic and epigenetic mechanisms can be involved. Furthermore, constitutional dicentric chromosomes ascertained in patients presumably represent the most stable chromosomes, so the spectrum of dicentric fates, if it exists, is not entirely clear. Studies of engineered or induced dicentrics in budding yeast and plants have provided significant insight into the fate of dicentric chromosomes. And, more recently, studies have shown that dicentrics in humans can also undergo multiple fates after formation. Here, we discuss current experimental evidence from various organisms that has deepened our understanding of dicentric behavior and the intriguingly complex process of centromere inactivation.

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    • "Indeed, in humans some centromere inactivations were followed by a partial deletion of the centromere-specific a-satellite associated with CENP-A, which are important for the kinetochore assembly (Stimpson et al., 2010). In budding and fission yeast, originally dicentric chromosomes were stabilized by physical deletion of one centromere (Sato et al., 2012; Stimpson et al., 2012). Data on the recombinational loss of centromeric sequences in plants are scarce. "
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    New Phytologist 09/2014; 203(4). DOI:10.1111/nph.12885 · 6.55 Impact Factor
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    • "These heterodicentric chromosomes have two alpha satellite sequences on the same chromosome which leads to a high risk of attachment of the same chromatid to the mitotic spindle from opposite poles and also in the formation of Anaphase Bridge during cell division. But in humans, dicentrics occur naturally in a substantial portion of the population and usually segregate successfully in mitosis and meiosis [8]. Their stability has been attributed to inactivation of one of the two centromeres, creating a functionally monocentric chromosome that can segregate normally during cell division or when the centromeres are very close to each other and form only one heterochromatic block [9]. "
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