title: Molecular biology. Mothers setting boundaries.
abstract: Certain genes are only expressed at one allele, a phenomenon called imprinting. Although it is well established that one allele of certain imprinted genes is silenced through methylation, this does not appear to be the case for all imprinted genes. In a thoughtful Perspective, Thorvaldsen and Bartolomei discuss new findings showing that insertion of insulator elements (boundary regions) between the promoter of a gene and its enhancer (a sequence that boosts gene expression) may be another way in which genes are silenced during imprinting.
authors.affiliation: Howard Hughes Medical Institute and Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. thorvald@mail.med.upenn.edu
authors.forename: J L
authors.initials: JL
authors.lastname: Thorvaldsen
authors.forename: M S
authors.initials: MS
authors.lastname: Bartolomei
mesh_terms: D000483:Alleles; D000818:Animals; D000076246:CCCTC-Binding Factor; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000378:metabolism; D015226:Dinucleoside Phosphates; D004742:Enhancer Elements, Genetic; D005220:Fathers; D005260:Female; D020868:Gene Silencing; D018392:Genomic Imprinting; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics; D008297:Male; D008957:Models, Genetic; D009035:Mothers; D009124:Muscle Proteins / Q000235:genetics; D010063:Ovum / Q000378:metabolism; D011401:Promoter Regions, Genetic; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins; D013094:Spermatozoa / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D016335:Zinc Fingers
chemical_list: D000076246:CCCTC-Binding Factor; D004268:DNA-Binding Proteins; D015226:Dinucleoside Phosphates; D007335:Insulin-Like Growth Factor II; D009124:Muscle Proteins; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D012097:Repressor Proteins; D014157:Transcription Factors; C000619697:CTCF protein, human; C094335:H19 long non-coding RNA; C015772:CpG dinucleotide