Unscheduled epigenetic modifications cause genome instability and sterility through aberrant R-loops following...

Area of Science:

• Genetics
• Epigenetics
• Molecular Biology

Background:

• Organisms alter gene expression and metabolism during starvation to manage energy stress.
• AMP-activated protein kinase (AMPK) is crucial for cellular energy homeostasis.
• Previous work linked AMPK deficiency to transgenerational reproductive defects in C. elegans post-starvation.

Purpose of the Study:

• To investigate the molecular mechanisms underlying transgenerational reproductive defects in starved AMPK-mutant C. elegans.
• To determine the role of histone modifications and R-loop formation in these defects.
• To elucidate the function of AMPK in maintaining genome stability during starvation recovery.

Main Methods:

• DNA-RNA immunoprecipitation followed by high-throughput sequencing (DRIP-seq) to detect R-loops.
• Chromatin immunoprecipitation (ChIP) to assess histone modifications (H3K4me3).
• Microscopy to visualize RAD-51 foci as indicators of DNA damage and repair.

Main Results:

• AMPK mutants exhibit increased H3K4me3 marks at gene promoters, driving aberrant transcription and R-loop accumulation.
• R-loops are widespread in the genome, particularly at H3K4me3-modified promoter regions.
• R-loops and H3K4me3 marks are heritable, correlating with transgenerational reproductive defects.
• Increased RAD-51 foci at R-loop sites suggest compromised DNA repair and genome stability in AMPK mutants.

Conclusions:

• AMPK plays a critical role in maintaining genome stability following starvation by preventing aberrant R-loop formation.
• Heritable R-loops contribute to transgenerational reproductive defects and may link to epigenetic alterations in human diseases like cancer.
• The study highlights a novel link between AMPK, R-loops, DNA damage, and epigenetic inheritance.