Role of paternal germline TET1 function in embryonic viability and reproduction

Infertility is a common and world-wide health issue that can be devastating to affected couples. The rate of infertility is between 5% to 15% in both developed and under-developed nations. People in every socioeconomic status, both males and females, and every race and ethnicity are affected. There are several factors that play a role in reproductive success. One of the most important factors is epigenetic regulation of the genome in the germline, initially through a major reprogramming event where DNA methylation and histone modification erasure sets the baseline for subsequent sex-specific epigenetic mark establishment. While most of the genome undergoes passive demethylation via replication-coupled passive dilution, there are certain regions of the genome that require active demethylation via Ten-Eleven Translocation enzymes (TETs). In particular, research from our lab and others has shown that TET1 is responsible for active demethylation of a subset of imprinting control regions (ICRs) as well as at meiosis specific promoters, among other germline- specific differentially methylated regions. DNA methylation erasure at these loci is critical for proper development. Abnormal methylation patterning at these loci results in imprinting gene disorders such as Prader-Willi, Angelman, Beckwith-Wiedemann, and Silver Russell syndromes. In addition, hypermethylation at meiotic promoters can result in delayed meiotic entry, further compromising gamete integrity. While our lab and others have explored the effect of loss of TET1 function on PGCs, little is known about the effects this has on offspring. My preliminary data in combination with previously reported data from our lab and others show that when Tet1 mutant mice are bred with wildtype females, there is a subfertility phenotype occurring at ~E10.5- E12.5, we observed ~50% survival to adulthood. At the same developmental timepoints, mutant offspring from this cross have hypermethylated ICRs. Nevertheless, the mechanism underlying the fetal demise has not yet been elucidated. Additionally, our lab has developed Tet1 catalytic mutants, which have a subset of hypermethylation perturbations relative to Tet1 null mice, but which also have mid-gestation partial lethality. The goals and training plan outlined in this proposal will address this question, in Aim 1 I will determine the effects of loss of TET1 in the germline on early embryonic development in paternal Tet1 mutant offspring. I will examine DNA methylation and RNA expression at various timepoints after fertilization to determine (1) when and if DNA methylation profiles are corrected and (2) the gene expression changes that could be responsible for fetal demise. Aim 2 will characterize the heritable effects of loss of TET1 in the paternal germline on offspring’s germline and future reproductive success. Together these experiments will determine the consequences of abnormal DNA methylation reprogramming in the paternal germline. Project Number: 1F32HD120017-01 | Fiscal Year: 2025 | NIH Institute/Center: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) | Principal Investigator: Christine Rourke | Institution: UNIVERSITY OF PENNSYLVANIA, PHILADELPHIA, PA | Award Amount: $75,052 | Activity Code: F32 | Study Section: Special Emphasis Panel[ZRG1 F06-F (20)] View on NIH RePORTER: https://reporter.nih.gov/project-details/1F32HD12001701