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Mol. Cell. Biol., 02 1997, 707-712, Vol 17, No. 2
J Kuromitsu, H Yamashita, H Kataoka, T Takahara, M Muramatsu, T Sekine, N Okamoto, Y Furuichi and Y Hayashizaki
To understand the effect of trisomic chromosome 21 on the cause of Down
syndrome (DS), DNA methylation in the CpG island, which regulates the
expression of adjacent genes, was investigated with the DNAs of chromosome
21 isolated from DS patients and their parents. A methylation-sensitive
enzyme, BssHII, was used to digest DNAs of chromosome 21, and the resulting
DNA fragments were subjected to RLGS (restriction landmark genomic
scanning). Surprisingly, the CpG island of the h2-calponin gene was shown
to be specifically methylated by comparative studies with RLGS and Southern
blot analysis. In association with this methylation, h2-calponin gene
expression was attenuated to the normal level, although other genes in the
DS region of chromosome 21 were expressed dose dependently at 1.5 times the
normal level. These results and the high miscarriage rate associated with
trisomy 21 embryos imply that the altered in vivo methylation that
attenuates downstream gene expression, which is otherwise lethal, permits
the generation of DS neonates. The h2-calponin gene detected by the RLGS
procedure may be one such gene that is attenuated.
Copyright © 1997, American Society for Microbiology
A unique downregulation of h2-calponin gene expression in Down syndrome: a possible attenuation mechanism for fetal survival by methylation at the CpG island in the trisomic chromosome 21
Genome Science Laboratory, RIKEN Tsukuba Life Science Center, The Institute of Physical and Chemical Research (RIKEN), Tsukuba, Ibaraki, Japan.
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