Primordial germ cell DNA demethylation and development require DNA translesion synthesis

Area of Science:

• Reproductive Biology
• Molecular Biology
• Genetics

Background:

• DNA damage response (DDR) mutations are linked to human infertility.
• DNA translesion synthesis (TLS) is a DDR pathway essential for bypassing replication impediments.
• Germ cell development and meiosis require DDR mechanisms.

Purpose of the Study:

• To investigate the role of TLS in mammalian germ cell development and fertility.
• To determine if TLS is essential for early embryonic germ cell progression.
• To understand the impact of TLS deficiency on germline epigenetic reprogramming.

Main Methods:

• Analysis of REV1-deficient human PGC-like cells (hPGCLCs).
• Generation and analysis of TLS-deficient mouse models (Rev1-/- , Pcna^K164R/K164R, Rev7-/-).
• Assessment of primordial germ cell (PGC) numbers, fertility, somatic tissue homeostasis, transcriptional program activation, and DNA demethylation.

Main Results:

• Loss of TLS factors significantly inhibits hPGCLC induction.
• TLS-deficient mice exhibit a >150-fold reduction in PGCs and are sterile.
• TLS absence does not affect somatic tissue growth, function, or homeostasis.
• Germ cell transcriptional program activation and DNA demethylation fail in TLS-deficient embryos.

Conclusions:

• TLS is essential for pre-meiotic germ cell development in mammals.
• TLS is required for primordial germ cell formation and epigenetic reprogramming, not just meiotic recombination.
• Deficiencies in TLS lead to infertility due to failures in early germ cell development stages.