SIN3A Regulates Porcine Early Embryonic Development by Modulating CCNB1 Expression.

Area of Science:

• Developmental Biology
• Epigenetics
• Mammalian Embryogenesis

Background:

• SIN3A is a key scaffold protein in the SIN3/histone deacetylase (HDAC) transcriptional repressor complex.
• SIN3A influences mouse preimplantation development by modulating HDAC1 expression.
• The conserved function of SIN3A in other mammals remains largely unexplored.

Purpose of the Study:

• To investigate the role and conserved function of SIN3A in early embryonic development across different mammalian species.
• To elucidate the molecular mechanisms underlying SIN3A's function in porcine and bovine early embryogenesis.
• To identify downstream targets of SIN3A involved in embryonic development.

Main Methods:

• RNA sequencing (RNA-seq) to analyze SIN3A and CCNB1 mRNA levels in oocytes and early embryos.
• Immunofluorescence to determine SIN3A protein localization and abundance.
• SIN3A and HDAC1 depletion experiments using RNA interference (RNAi) in porcine and bovine embryos.
• CCNB1 knockdown and rescue experiments via mRNA injection.

Main Results:

• SIN3A mRNA shows maternal origin in pigs, cattle, mice, and humans, with protein levels peaking at the four-cell stage in pigs and morula stage in cattle.
• SIN3A depletion caused a two-cell developmental arrest in pigs but not in cattle.
• SIN3A depletion had minimal impact on HDAC1 expression in pigs and cattle, unlike in mice.
• HDAC1 knockdown reduced blastocyst rates but did not cause a two-cell block.
• RNA-seq identified Cyclin B1 (CCNB1) as a key downstream target, with its depletion mimicking SIN3A depletion.
• Exogenous CCNB1 mRNA partially rescued SIN3A-depleted porcine embryos.

Conclusions:

• SIN3A plays an essential, species-specific role in porcine early embryonic development, likely through regulating CCNB1 expression.
• The functional significance of SIN3A in early embryogenesis is not conserved across all mammals, with pigs showing a critical dependence.
• CCNB1 is a crucial downstream effector of SIN3A in porcine early development, mediating the prevention of the two-cell block.