A 210-kb segment of tandem repeats and retroelements located between imprinted subdomains of mouse distal chromosome 7.
Mammalian genes subject to genomic imprinting often form clusters and are regulated by long-range mechanisms. The distal imprinted domain of mouse chromosome 7 is orthologous to the Beckwith-Wiedemann syndrome domain in human chromosome 11p15.5 and contains at least 13 imprinted genes. This domain consists of two subdomains, which are respectively regulated by an imprinting center. We here report the finished-quality sequence of a 0.6-Mb region encompassing the more centromeric subdomain. The sequence contains four imprinted genes (Ascl2/Mash2, Ins2, Igf2 and H19) and reveals previously unidentified CpG islands and tandem repeats, which may be features of imprinted genes. Most interestingly, a unique 210-kb segment consisting almost exclusively of tandem repeats and retroelements is identified. This segment, located between Th and Ins2, has features of heterochromatin-forming DNA and is highly methylated at CpG sites. The segment exhibits asynchronous replication on the parental chromosomes, a feature of the imprinted domains. We propose that this repeat segment could serve either as a boundary between the two subdomains or as a target for epigenetic chromatin modifications that regulate imprinting.
Shirohzu
Hisao
H
Division of Human Genetics, Department of Integrated Genetics, National Institute of Genetics, Research Organization of Information and Systems, 1111 Yata, Mishima 411-8540, Japan.
Yokomine
Takaaki
T
Sato
Chiyoko
C
Kato
Reiko
R
Toyoda
Atsushi
A
Purbowasito
Wahyu
W
Suda
Chikako
C
Mukai
Tsunehiro
T
Hattori
Masahira
M
Okumura
Katsuzumi
K
Sakaki
Yoshiyuki
Y
Sasaki
Hiroyuki
H
D000818:Animals; D001483:Base Sequence; D002843:Chromatin; D033481:Chromosomes, Mammalian / Q000235:genetics*; D019175:DNA Methylation; D042522:DNA Replication Timing; D018392:Genomic Imprinting; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D008969:Molecular Sequence Data; D018626:Retroelements; D020080:Tandem Repeat Sequences
D002843:Chromatin; D018626:Retroelements