Sperm derived H2AK119ub1 is required for embryonic development in Xenopus laevis

Area of Science:

• Epigenetics
• Developmental Biology
• Molecular Biology

Background:

• Histone H2A ubiquitylation at lysine 119 (H2AK119ub1) by Polycomb Repressive Complex-1 is vital for facultative heterochromatin in somatic cells.
• The role of sperm-derived H2AK119ub1 in early embryo development remains largely unexplored.

Purpose of the Study:

• To investigate the contribution of sperm-derived H2AK119ub1 to early embryonic development in Xenopus laevis.
• To understand how sperm H2AK119ub1 influences paternal chromatin remodeling and gene expression post-fertilization.

Main Methods:

• Detection of H2AK119ub1 during Xenopus laevis spermiogenesis and early embryogenesis.
• In vitro manipulation of sperm H2AK119ub1 levels using the deubiquitylase USP21 prior to egg injection.
• Analysis of chromatin remodeling, H2AK119ub1 distribution, and gene expression in resulting embryos.

Main Results:

• H2AK119ub1 is maternally transmitted and present in sperm, suggesting a role in epigenetic inheritance.
• Sperm treatment with USP21 disrupted paternal chromatin remodeling, leading to developmental defects and altered gene expression.
• USP21 treatment caused H2AK119ub1 mislocalization from CpG islands to repeat elements, impacting gene regulation.

Conclusions:

• Sperm-derived H2AK119ub1 is essential for instructing egg factor-mediated epigenetic remodeling of paternal chromatin.
• This sperm-borne epigenetic mark is required for successful embryonic development, highlighting its role in transgenerational epigenetic inheritance.