CtcfHaploinsufficiency Mediates Intron Retention in A Tissue-specific Manner

CTCF is a master regulator of gene transcription and chromatin organization with occupancy at thousands of DNA target sites. CTCF is essential for embryonic development and somatic cell viability and has been characterized as a haploinsufficient tumor suppressor. Increasing evidence demonstrates CTCF as a key player in several alternative splicing (AS) regulatory mechanisms, including transcription elongation, regulation of splicing factors, and epigenetic regulation. However, the genome-wide impact of Ctcf dosage on AS has not been investigated. We examined the effect of Ctcf haploinsufficiency on gene expression and AS in multiple tissues from Ctcf hemizygous ( Ctcf +/- ) mice. Distinct tissue-specific differences in gene expression and AS were observed in Ctcf +/- mice compared to wildtype mice. We observed a surprisingly large number of increased intron retention (IR) events in Ctcf +/- liver and kidney, specifically in genes associated with cytoskeletal organization, splicing and metabolism. This study provides further evidence for Ctcf dose-dependent and tissue-specific regulation of gene expression and AS. Our data provide a strong foundation for elucidating the mechanistic role of CTCF in AS regulation and its biological consequences.