Dual Effect of CTCF Loss on Neuroprogenitor Differentiation and Survival

• DOI: 10.1523/jneurosci.3769-13.2014
• Publication Date: 2014-02-19T17:41:24Z
• Authors: L. Ashley Watson; Xu Wang; Adrienne Elbert; Kristin D. Kernohan; Niels Galjart; Nathalie G. Bérubé
• Keywords: 570; CCCTC-Binding Factor; Chromatin Immunoprecipitation; Antimetabolites; Cell Survival; Neurogenesis; 610; Fluorescent Antibody Technique; Apoptosis; Mouse model; Nestin; Mice; 03 medical and health sciences; Neural Stem Cells; Image Processing, Computer-Assisted; Animals; Mice, Knockout; 0303 health sciences; Cell Death; EMC MGC-02-13-02; Brain; Cell Differentiation; Exons; CTCF; Genes, p53; Bromodeoxyuridine; Differentiation; Female; Puma; Apoptosis Regulatory Proteins

An increasing number of proteins involved in genome organization have been implicated in neurodevelopmental disorders, highlighting the importance of chromatin architecture in the developing CNS. The CCCTC-binding factor (CTCF) is a zinc finger DNA binding protein involved in higher-order chromatin organization, and mutations in the humanCTCFgene cause an intellectual disability syndrome associated with microcephaly. However, information on CTCF functionin vivoin the developing brain is lacking. To address this gap, we conditionally inactivated theCtcfgene at early stages of mouse brain development. Cre-mediatedCtcfdeletion in the telencephalon and anterior retina at embryonic day 8.5 triggered upregulation of the p53 effector PUMA (p53 upregulated modulator of apoptosis), resulting in massive apoptosis and profound ablation of telencephalic structures. Inactivation ofCtcfseveral days later at E11 also resulted in PUMA upregulation and increased apoptotic cell death, and theCtcf-null forebrain was hypocellular and disorganized at birth. Although deletion of bothCtcfandPumain the embryonic brain efficiently rescuedCtcf-null progenitor cell apoptosis, it failed to improve neonatal hypocellularity due to decreased proliferative capacity of rescued apical and outer radial glia progenitor cells. This was exacerbated by an independent effect of CTCF loss that resulted in depletion of the progenitor pool due to premature neurogenesis earlier in development. Our findings demonstrate that CTCF activities are required for two distinct events in early cortex formation: first, to correctly regulate the balance between neuroprogenitor cell proliferation and differentiation, and second, for the survival of neuroprogenitor cells, providing new clues regarding the contributions of CTCF in microcephaly/intellectual disability syndrome pathologies.