Identification, genome mapping, and CTCF binding of potential insulators within the FXYD5-COX7A1 locus of human chromosome 19q13.12.
Identification of insulators is one of the most difficult problems in functional mapping of genomes. For this reason, up to now only a few insulators have been described. In this article we suggest an approach that allows direct isolation of insulators by a simple positive-negative selection based on blocking enhancer effects by insulators. The approach allows selection of fragments capable of blocking enhancers from mixtures of genomic fragments prepared from up to 1-Mb genomic regions. Using this approach, a 1-Mb human genome locus was analyzed and eight potential insulators were selected. Five of the eight sequences were positioned in intergenic regions and two were within introns. The genes of the alpha-polypeptide H+/K+ exchanging ATPase (ATP4A) and amyloid beta (A4) precursor-like protein 1 (APLP1) within the locus studied were found to be flanked by insulators on both sides. Both genes are characterized by distinct tissue-specific expression that differs from the tissue specificity of the surrounding genes. The data obtained are consistent with the conception that insulators subdivide genomic DNA into loop domains that comprise genes characterized by similar expression profiles. Using chromatin immunoprecipitation assay, we demonstrated also that at least six of the putative insulators revealed in this work could bind the CTCF transcription factor in vivo. We believe that the proposed approach could be a useful instrument for functional analysis of genomes.
Akopov
Sergey B
SB
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117977, Moscow, Russia.
Ruda
Vera M
VM
Batrak
Vera V
VV
Vetchinova
Anna S
AS
Chernov
Igor P
IP
Nikolaev
Lev G
LG
Bode
Jürgen
J
Sverdlov
Eugene D
ED
D000818:Animals; D000076246:CCCTC-Binding Factor; D016466:CHO Cells; D002874:Chromosome Mapping / Q000379:methods*; D002888:Chromosomes, Human, Pair 19; D003001:Cloning, Molecular; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000235:genetics*; D015698:Genomic Library; D006367:HeLa Cells; D006801:Humans; D038101:Insulator Elements; D007473:Ion Channels; D008562:Membrane Glycoproteins / Q000235:genetics*; D008840:Microfilament Proteins; D009363:Neoplasm Proteins / Q000235:genetics*; D012097:Repressor Proteins / Q000378:metabolism*
D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; D004268:DNA-Binding Proteins; C451410:FXYD5 protein, human; D007473:Ion Channels; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D009363:Neoplasm Proteins; D012097:Repressor Proteins; C513901:COX7A1 protein, human; D003576:Electron Transport Complex IV