Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Physiology and Pharmacology

Supervisor

Drs. Frank Beier

2nd Supervisor

Nathalie Berube

Joint Supervisor

Abstract

Mutations in chromatin organizer CTCF were identified in patients with intellectual disability and skeletal defects. Previous studies demonstrated that depletion of CTCF in murine limb mesenchyme results in apoptosis in the forelimb. The role of CTCF in the hindlimb, however, is unknown. My objective was to investigate effects of CTCF deletion on chondrogenesis and skeletal development in the hindlimb. In vitro wild-type micromass cultures demonstrate that chondrocyte gene expression is delayed in the hindlimb when compared to forelimbs. Embryonic CtcfFl/Fl;Prx1Cre mice were investigated, and qRT-PCR and histology were performed on limb buds and long bones. Results show that E12.5 mutant hindlimb buds have increased apoptosis, but no change in proliferation. Later time points reveal growth plate defects, and delayed cartilage mineralization in mutant tibiae. Furthermore, mutant mice have skull defects, shortened long bones and oligodactyly. Overall, data suggest that CTCF is a key regulator of endochondral/intramembranous ossification and hindlimb development.