MicroRNAs regulate survival in oxygen-deprived environments.

Area of Science:

• * Molecular Biology
• * Environmental Physiology
• * Crustacean Biology

Background:

• * Many aquatic animals face periodic oxygen deprivation (hypoxia and anoxia).
• * Northern crayfish (Orconectes virilis) are a model organism for studying anoxia tolerance due to their resilience in varied aquatic conditions.
• * MicroRNAs (miRNAs) are key regulators of gene expression involved in cellular adaptation to environmental stresses.

Purpose of the Study:

• * To investigate the role of microRNAs in the molecular mechanisms underlying anoxia resistance in northern crayfish.
• * To identify anoxia-responsive miRNAs and their target pathways in different tissues (hepatopancreas and muscle).

Main Methods:

• * Surveyed expression profiles of 76 conserved microRNAs in crayfish hepatopancreas and tail muscle.
• * Exposed crayfish to normoxic, acute (2h), and chronic (20h) anoxia conditions.
• * Utilized bioinformatic analysis for microRNA target enrichment and identification of key regulatory pathways.

Main Results:

• * Identified 22 anoxia-responsive miRNAs in the hepatopancreas and 4 in the muscle, indicating tissue-specific responses.
• * Anoxia-downregulated miRNAs in the hepatopancreas targeted Hippo signaling, suggesting regulation of cell proliferation and apoptosis.
• * Specific miRNAs (miR-125-5p, miR-33-5p, miR-190-5p) targeting HIF1 were downregulated, coinciding with increased HIF1α transcript levels.

Conclusions:

• * MicroRNAs play a significant role in mediating anoxia tolerance in crayfish by reprioritizing resources and regulating cellular processes.
• * The regulation of Hippo signaling and the hypoxia-inducible factor 1 (HIF1) pathway by miRNAs is crucial for surviving oxygen deprivation.
• * Further research into miRNA-mediated cytoprotective mechanisms is essential for understanding stress responses in aquatic invertebrates.