5mC modification orchestrates choriogenesis and fertilization by preventing prolonged ftz-f1 expression

Area of Science:

• Epigenetics
• Molecular Biology
• Developmental Biology

Background:

• DNA methylation at the fifth position of cytosine (5mC) is a key epigenetic regulator of gene expression.
• The precise role of 5mC in insect reproduction remains largely unexplored.

Purpose of the Study:

• To elucidate the molecular mechanism of DNMT1-mediated 5mC maintenance in regulating female reproduction in the German cockroach (Blattella germanica).

Main Methods:

• Dnmt1 knockdown in Blattella germanica.
• Analysis of 5mC levels in ovarian tissues.
• Gene expression profiling, focusing on choriogenesis-related genes.
• Investigation of promoter methylation status.
• Hormone level quantification (20-hydroxyecdysone).
• Assessment of extracellular matrix remodeling (Mmp1 expression).
• Evaluation of follicle cell fate (anoikis) and chorion protein production.

Main Results:

• Dnmt1 knockdown led to decreased ovarian 5mC levels.
• Upregulation of numerous genes during choriogenesis, notably the transcription factor ftz-f1.
• Hypomethylation of the ftz-f1 promoter resulted in increased and prolonged ftz-f1 expression.
• Elevated 20-hydroxyecdysone levels and excessive Mmp1 upregulation.
• Impaired choriogenesis, follicle cell anoikis, reduced chorion proteins, and malformed sponge-like bodies.

Conclusions:

• DNMT1-mediated DNA methylation is critical for normal female reproduction in insects.
• Disruption of 5mC maintenance impacts key developmental processes like choriogenesis through altered gene expression and hormone signaling.
• This study provides significant insights into the epigenetic regulation of insect reproductive biology.