The cohesin complex holds sister chromatids together and is essential for 
chromosome segregation. Recently, cohesins have been implicated in 
transcriptional regulation and insulation through genome-wide colocalization 
with the insulator protein CTCF, including involvement at the imprinted H19/Igf2 
locus. CTCF binds to multiple imprinted loci and is required for proper 
imprinted expression at the H19/Igf2 locus. Here we report that cohesins 
colocalize with CTCF at two additional imprinted loci, the Dlk1-Dio3 and the 
Kcnq1/Kcnq1ot1 loci. Similar to the H19/Igf2 locus, CTCF and cohesins 
preferentially bind to the Gtl2 differentially methylated region (DMR) on the 
unmethylated maternal allele. To determine the functional importance of the 
binding of CTCF and cohesins at the three imprinted loci, CTCF and cohesins were 
depleted in mouse embryonic fibroblast cells. The monoallelic expression of 
imprinted genes at these three loci was maintained. However, mRNA levels for 
these genes were typically increased; for H19 and Igf2 the increased level of 
expression was independent of the CTCF-binding sites in the imprinting control 
region. Results of these experiments demonstrate an unappreciated role for CTCF 
and cohesins in the repression of imprinted genes in somatic cells.