Competing endogenous RNA (ceRNA) in a non-model animal: Non-coding RNAs respond to heat stress in rainbow trout (Oncorhynchus mykiss) through ceRNA-regulated mechanisms.

Background: Rainbow trout (Oncorhynchus mykiss) is a typical cold-water fish. With global warming and extreme heat, high summer temperatures are the biggest threat to rainbow trout farming. Rainbow trout initiate stress defense mechanisms in response to thermal stimuli, and competing endogenous RNA (ceRNA) regulation of target genes (mRNAs) mediated by non-coding RNAs (microRNAs [miRNAs], long non-coding RNAs) may be the main strategy for responding to thermal stimuli and enhancing adaptation.

Results: We screened the LOC110485411-novel-m0007-5p-hsp90ab1 ceRNA relationship pairs for affect heat stress in rainbow trout and validated their targeting relationships and functions based on preliminary high-throughput sequencing analysis results. The transfection of exogenous novel-m0007-5p mimics and inhibitors into primary rainbow trout hepatocytes effectively bound and inhibited the target genes hsp90ab1 and LOC110485411 without significant effects on hepatocyte viability, proliferation, and apoptosis. The inhibitory effect of novel-m0007-5p overexpression on hsp90ab1 and LOC110485411 under heat stress was time-efficient. Similarly, small interfering RNAs (siRNAs) affected hsp90ab1 mRNA expression by silencing LOC110485411 expression time-efficiently.

Conclusions: In conclusion, we found that in rainbow trout, LOC110485411 and hsp90ab1 can bind competitively to novel-m0007-5p via 'sponge adsorption' and that interference with LOC110485411 affects hsp90ab1 expression. These results provide potential for anti-stress drug screening in rainbow trout.