Fish MicroRNA Responses to Thermal Stress: Insights and Implications for Aquaculture and Conservation Amid Global Warming

Abstract

Under the backdrop of global warming, heat tolerance emerges as an important physiological trait governing the distribution and survival of fish species worldwide. While knowledge on fish heat tolerance and stress has progressed from behavioral studies to transcriptomic analyses, our understanding at the transcriptomic level remains limited. Recently, the highly conserved nature of microRNAs (miRNAs) has introduced new ways of explaining molecular mechanisms of heat stress in fish. Here, we systematically review current research across three main reference databases to explain the universal responses and mechanisms of fish miRNAs to heat stress. An initial screen of 569 articles yielded 13 target papers for comprehensive analysis. Among these, at least 214 differentially expressed genes (DEGs) were identified, with 15 DEGs recurring in at least two studies (12 upregulated, 13 downregulated). The 15 recurrent DEGs were subjected to DIANA mirPath v.3 utilizing the microT-CDS v5.0 database to identify potential target genes. The results indicate that multiple miRNAs target genes, forming a complex network to regulate glucose and energy balance metabolism, maintain homeostasis, and modulate inflammation and immune disorders. Notably, miR-1, miR-122, let-7a, and miR-30b are identified as potential biomarkers of heat stress in fish. Due to their high conservation across species, these miRNAs could be used to monitor the health of wild fish populations, improve selective breeding programs in aquaculture, and guide conservation strategies for species that are vulnerable to climate change. This review provides a framework for further investigation into the molecular mechanisms of fish heat tolerance.