The Drosophila homolog of the mammalian imprint regulator, CTCF, maintains the maternal genomic imprint in Drosophila melanogaster.
BACKGROUND
CTCF is a versatile zinc finger DNA-binding protein that functions as a highly conserved epigenetic transcriptional regulator. CTCF is known to act as a chromosomal insulator, bind promoter regions, and facilitate long-range chromatin interactions. In mammals, CTCF is active in the regulatory regions of some genes that exhibit genomic imprinting, acting as insulator on only one parental allele to facilitate parent-specific expression. In Drosophila, CTCF acts as a chromatin insulator and is thought to be actively involved in the global organization of the genome.


RESULTS
To determine whether CTCF regulates imprinting in Drosophila, we generated CTCF mutant alleles and assayed gene expression from the imprinted Dp(1;f)LJ9 mini-X chromosome in the presence of reduced CTCF expression. We observed disruption of the maternal imprint when CTCF levels were reduced, but no effect was observed on the paternal imprint. The effect was restricted to maintenance of the imprint and was specific for the Dp(1;f)LJ9 mini-X chromosome.


CONCLUSIONS
CTCF in Drosophila functions in maintaining parent-specific expression from an imprinted domain as it does in mammals. We propose that Drosophila CTCF maintains an insulator boundary on the maternal X chromosome, shielding genes from the imprint-induced silencing that occurs on the paternally inherited X chromosome. See commentary: http://www.biomedcentral.com/1741-7007/8/104.
MacDonald
William A
WA
Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada. wamacd@dal.ca
Menon
Debashish
D
Bartlett
Nicholas J
NJ
Sperry
G Elizabeth
GE
Rasheva
Vanya
V
Meller
Victoria
V
Lloyd
Vett K
VK
D000483:Alleles; D000818:Animals; D000076246:CCCTC-Binding Factor; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D005786:Gene Expression Regulation; D018392:Genomic Imprinting; D012097:Repressor Proteins / Q000235:genetics*; D014960:X Chromosome
D000076246:CCCTC-Binding Factor; C524946:CTCF protein, Drosophila; D029721:Drosophila Proteins; D012097:Repressor Proteins