Loss of Maternal CTCF Is Associated with Peri-Implantation Lethality of Ctcf Null Embryos

Abstract

CTCF is a highly conserved, multifunctional zinc finger protein involved in critical aspects of gene regulation including transcription regulation, chromatin insulation, genomic imprinting, X-chromosome inactivation, and higher order chromatin organization. Such multifunctional properties of CTCF suggest an essential role in development. Indeed, a previous report on maternal depletion of CTCF suggested that CTCF is essential for pre-implantation development. To distinguish between the effects of maternal and zygotic expression of CTCF, we studied pre-implantation development in mice harboring a complete loss of function Ctcf knockout allele. Although we demonstrated that homozygous deletion of Ctcf is early embryonically lethal, in contrast to previous observations, we showed that the Ctcf nullizygous embryos developed up to the blastocyst stage (E3.5) followed by peri-implantation lethality (E4.5–E5.5). Moreover, one-cell stage Ctcf nullizygous embryos cultured ex vivo developed to the 16–32 cell stage with no obvious abnormalities. Using a single embryo assay that allowed both genotype and mRNA expression analyses of the same embryo, we demonstrated that pre-implantation development of the Ctcf nullizygous embryos was associated with the retention of the maternal wild type Ctcf mRNA. Loss of this stable maternal transcript was temporally associated with loss of CTCF protein expression, apoptosis of the developing embryo, and failure to further develop an inner cell mass and trophoectoderm ex vivo. This indicates that CTCF expression is critical to early embryogenesis and loss of its expression rapidly leads to apoptosis at a very early developmental stage. This is the first study documenting the presence of the stable maternal Ctcf transcript in the blastocyst stage embryos. Furthermore, in the presence of maternal CTCF, zygotic CTCF expression does not seem to be required for pre-implantation development.

Reciprocal Regulation of the Cardiac Epigenome by Chromatin Structural Proteins Hmgb and Ctcf

“…This observation is in agreement with data from COS-1 cells, in which Hmgb2 knockdown suppresses cell division (46). Furthermore, the cell type-specific lethality of Ctcf levels is also in agreement with data showing that Ctcf knockout is embryonic lethal in mice (47,48). Ctcf depletion in isolated cells often affects cell division or cell death processes, but in a cell type-dependent manner, potentially due to the cell type-specific localization of Ctcf and arrangement of a higher order structure coordinated by the protein (49).…”

The chromatin insulator CTCF and the emergence of metazoan diversity

“…These findings, however, refer to the mouse developing limb and do not rule out a role of CTCF during early embryogenesis when the proposed kernel is active. In line with this idea, a recent report demonstrated that CTCF knockout mice die after the blastocyst stage (33). Fourth, animals that display Hox gene clustering should possess CTCF, and vice versa.…”

The Role of CCCTC-Binding Factor (CTCF) in Genomic Imprinting, Development, and Reproduction1

“…CTCF may activate or derepress transcription in oocytes, and its depletion can induce mitotic defects and apoptosis [24]. Moreover, in the presence of maternal CTCF, zygotic CTCF expression does not CTCF ROLE IN EPIGENETICS, REPRODUCTION AND ARTS seem to be required for preimplantation mouse embryo development, and the loss of maternal transcripts is associated with apoptosis in the developing embryo and peri-implantation lethality [79]. During mouse ESC differentiation, unmethylated CpG islands showed reduced nucleosome occupancy and enrichment in CTCF-binding sites [80].…”