Stress resets ancestral heritable small RNA responses.

Area of Science:

• Epigenetics and Heredity
• Molecular Biology
• Stress Response Mechanisms

Background:

• Small RNAs are inherited across generations in Caenorhabditis elegans, forming a memory of ancestral environments.
• Aberrant heritable small RNA responses can be maladaptive, potentially leading to sterility.
• Understanding the regulation of transgenerational small RNA inheritance is crucial for heredity.

Purpose of the Study:

• To investigate whether environmental stress can reset ancestral small RNA responses.
• To identify the molecular pathways involved in stress-induced resetting of small RNA inheritance.
• To determine the adaptive significance of stress-dependent termination of small RNA inheritance.

Main Methods:

• Induction of stress (starvation, heat, high osmolarity) in C. elegans.
• Analysis of heritable small RNA levels and inheritance dynamics.
• Genetic analysis of mutants in stress response pathways, including the p38 MAPK pathway and SKN-1/Nrf2.

Main Results:

• Various environmental stresses induce genome-wide reduction in heritable small RNA levels, resetting ancestral responses.
• Mutants defective in stress pathways show irregular RNAi inheritance even without stress.
• Resetting of ancestral RNAi responses is specifically mediated by the p38 MAPK pathway and SKN-1/Nrf2.

Conclusions:

• Stress-dependent termination of small RNA inheritance acts as a protective mechanism.
• This resetting prevents the perpetuation of environment-irrelevant heritable gene regulation.
• The p38 MAPK pathway and SKN-1/Nrf2 are key regulators of this adaptive process.