The 10q25 neocentromere and its inactive progenitor have identical primary nucleotide sequence: further evidence for epigenetic modification.
We have previously localized the core centromere protein-binding domain of a 10q25.2-derived neocentromere to an 80-kb genomic region. Detailed analysis has indicated that the 80-kb neocentromere (NC) DNA has a similar overall organization to the corresponding region on a normal chromosome 10 (HC) DNA, derived from a genetically unrelated CEPH individual. Here we report sequencing of the HC DNA and its comparison to the NC sequence. Single-base differences were observed at a maximum rate of 4.6 per kb; however, no deletions, insertions, or other structural rearrangements were detected. To investigate whether the observed changes, or subsets of these, might be de novo mutations involved in neocentromerization (i.e., in committing a region of a chromosome to neocentromere formation), the progenitor DNA (PnC) from which the NC DNA descended, was cloned and sequenced. Direct comparison of the PnC and NC sequences revealed 100% identity, suggesting that the differences between NC and HC DNA are single nucleotide polymorphisms (SNPs) and that formation of the 10q25.2 NC did not involve a change in DNA sequence in the core centromere protein-binding NC region. This is the first study in which a cloned NC DNA has been compared directly with its inactive progenitor DNA at the primary sequence level. The results form the basis for future sequence comparison outside the core protein-binding domain, and provide direct support for the involvement of an epigenetic mechanism in neocentromerization.
Barry
A E
AE
The Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville 3052, Australia.
Bateman
M
M
Howman
E V
EV
Cancilla
M R
MR
Tainton
K M
KM
Irvine
D V
DV
Saffery
R
R
Choo
K H
KH
D000483:Alleles; D001483:Base Sequence / Q000235:genetics*; D002460:Cell Line; D002503:Centromere / Q000235:genetics*; D002879:Chromosomes, Human, Pair 10 / Q000737:chemistry / Q000235:genetics*; D003001:Cloning, Molecular; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D018386:Kinetochores; D008297:Male; D008969:Molecular Sequence Data; D015203:Reproducibility of Results; D017422:Sequence Analysis, DNA