| Genomic microarray analysis reveals distinct locations for the CENP-A binding domains in three human chromosome 13q32 neocentromeres (2003) | |||||||||||||
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| Human neocentromeres are fully functional centromeres that provide mitotic stability to rearranged chromosomes that have separated from endogenous centromeres. A disproportionate number of neocentromeres have been observed in certain regions such as chromosome 3q (n=6), 15q (n=9) and 13q32 (n=7), suggesting that these regions contain DNA sequences with a high propensity for neocentromere formation. Therefore, we have addressed the role of primary DNA sequence in neocentromere formation by asking whether multiple independent neocentromeres that were cytologically localized to chromosome 13q32 are in fact localized to the same underlying genomic DNA. Analysis of four independent 13q32 neocentromeres using simultaneous FISH with ordered YAC probes and immunofluorescence with antibodies to CENP-C have localized three neocentromeres to a distal ∼7 Mbp domain in chromosome 13q32, and one to an overlapping proximal domain of ∼7 Mbp. DNA was obtained from three of these neocentromeres by CENP-A chromatin immunoprecipitation (ChIP) and used to screen ordered BACs using both a slot-blotted BAC pool approach and a genomic microarray that contiguously spans 13q31.3 to 13q33.1. The CENP-A binding domains from each of these neocentromeres was identified to distinct genomic locations of ∼ 130 kb, 275 kb, 215 kb within an ∼6.5 Mbp region. Thus, the lack of coincidence of these neocentromeres to the same underlying DNA sequence refutes the idea of a DNA sequence based neocentromere "hotspot" in 13q32 and further supports the sequence-independent epigenetic formation of human neocentromeres. The screening of genomic microarrays with ChIP DNA provides a powerful method to identify mammalian DNA sequences associated with particular functional chromatin states. | |||||||||||||
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