Jen joined the Trowbridge lab in August 2018. She is interested in the role of genetics and epigenetics in the blood compartment during normal development, aging, and cancer. Jen received her BA from Colby College. She worked for three years at Children’s Hospital Boston in the laboratory of Dr. Louis Kunkel studying muscular dystrophies before joining Dr. Marisa Bartolomei’s lab at the University of Pennsylvania for her graduate training. Jen’s thesis research focused on the epigenetic regulator, Tet1, and its role in development epigenetic reprogramming, specifically in the context of genomic imprinting.
Parent-of-origin-specific expression at imprinted genes is regulated by allele-specific DNA methylation at imprinting control regions (ICRs). This mechanism of gene regulation, where one element controls allelic expression of multiple genes, is not fully understood. Furthermore, the mechanism of gene dysregulation through ICR epimutations, such as loss or gain of DNA methylation, remains a mystery. We have used genetic mouse models to dissect ICR-mediated genetic and epigenetic regulation of imprinted gene expression. The H19/insulin-like growth factor 2 (Igf2) ICR has a multifunctional role including insulation, activation and repression. Microdeletions at the human H19/IGF2 ICR (IC1) are proposed to be responsible for IC1 epimutations associated with imprinting disorders such as Beckwith-Wiedemann syndrome (BWS). Here, we have generated and characterized a mouse model that mimics BWS microdeletions to define the role of the deleted sequence in establishing and maintaining epigenetic marks and imprinted expression at the H19/IGF2 locus. These mice carry a 1.3 kb deletion at the H19/Igf2 ICR [Δ2,3] removing two of four CCCTC-binding factor (CTCF) sites and the intervening sequence, ∼75% of the ICR. Surprisingly, the Δ2,3 deletion does not perturb DNA methylation at the ICR; however, it does disrupt imprinted expression. While repressive functions of the ICR are compromised by the deletion regardless of tissue type, insulator function is only disrupted in tissues of mesodermal origin where a significant amount of CTCF is poly(ADP-ribosyl)ated. These findings suggest that insulator activity of the H19/Igf2 ICR varies by cell type and may depend on cell-specific enhancers as well as posttranslational modifications of the insulator protein CTCF.