Maternal BCAS2 protects genomic integrity in mouse early embryonic development.

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• Mammalian early embryos require robust genome integrity for proper development, facing challenges from replication, DNA demethylation, and germline mutations.
• The mechanisms safeguarding genome integrity during early mammalian embryogenesis are not fully understood.
• BCAS2 (breast carcinoma amplified sequence 2), a component of the PRP19 complex, is implicated in DNA damage response via the RPA complex, but its physiological role in mammals is unknown.

Purpose of the Study:

• To investigate the physiological role of BCAS2 in maintaining genome integrity and DNA damage response in early mammalian embryos.
• To elucidate the mechanism by which BCAS2 functions in zygotes, particularly its interaction with the RPA complex.

Main Methods:

• Analysis of BCAS2's response to endogenous and exogenous DNA damage in mouse zygotes.
• Investigating the effects of maternal BCAS2 depletion on early embryonic development, DNA damage accumulation, and micronuclei formation.
• Characterizing BCAS2 mutants for RPA1 binding and their impact on DNA repair.
• Examining the localization of phosphorylated RPA2 in zygotes with disrupted maternal BCAS2.

Main Results:

• BCAS2 responds to DNA damage in mouse zygotes.
• Maternal depletion of BCAS2 leads to developmental arrest at the two- to four-cell stage, with increased DNA damage and micronuclei.
• BCAS2 mutants defective in RPA1 binding exhibit impaired zygotic DNA repair.
• Disruption of maternal BCAS2 prevents phosphorylated RPA2 localization to DNA damage sites in zygotes.

Conclusions:

• Maternal BCAS2 plays a critical role in safeguarding genome integrity in early mouse embryos.
• BCAS2 likely functions through the RPA complex to facilitate DNA repair in zygotes.
• BCAS2 is essential for female mouse fertility, highlighting its importance in embryonic development.