Complementary Roles of DNA Methylation and miRNA in Regulating Gene Expression Under Environmental Stress in...

Area of Science:

• Molecular Biology
• Ecology
• Genetics

Background:

• Biological invasions pose a significant threat to global biodiversity and ecosystem stability.
• Understanding the epigenetic mechanisms, particularly DNA methylation and microRNAs (miRNAs), underlying adaptation to environmental stressors is crucial for predicting invasion success.
• The interplay between different epigenetic layers in response to stress is poorly understood.

Purpose of the Study:

• To investigate the epigenetic regulatory mechanisms, specifically DNA methylation and miRNAs, involved in the response of the invasive species *Ciona robusta* to repeated salinity stress.
• To elucidate the distinct and complementary roles of DNA methylation and miRNAs in regulating stress-responsive gene expression.
• To explore the potential for a multilayered gene regulation model involving these epigenetic mechanisms.

Main Methods:

• Employed an integrative multi-omics approach on *Ciona robusta* specimens subjected to repeated salinity stress.
• Focused on canonical osmotic regulation pathways to analyze gene expression, DNA methylation patterns, and miRNA activity.
• Utilized permutation tests to assess the non-randomness of dual epigenetic regulation.

Main Results:

• Revealed dynamic and coordinated regulation of stress-responsive genes, with miRNAs and DNA methylation playing distinct yet complementary roles.
• MiRNAs were identified as dominant regulators through widespread gene targeting, while DNA methylation offered more selective regulation.
• Observed co-regulation of specific genes by both mechanisms in distinct genomic regions, supporting a multilayered regulatory model, and found reduced methylation in miRNA-targeted genes.

Conclusions:

• The complex interplay between DNA methylation and miRNAs is critical for enabling rapid phenotypic plasticity in invasive species.
• These epigenetic mechanisms provide complementary regulation across multiple functional pathways, contributing to invasion success under environmental stress.
• Findings offer novel insights into the molecular basis of adaptation and invasion dynamics in changing environments.