Jin-Liang Zhao

miR-206 regulates the growth of the teleost tilapia (Oreochromis niloticus) through the modulation of IGF-1 gene expression

SUMMARY MicroRNAs (miRNAs) are ~22-nucleotide noncoding RNAs that play a crucial role in regulating muscle development. Our previous study shows that miR-206 is specifically expressed in tilapia skeletal muscle, and exhibits a dynamic expression pattern at different developmental stages. Here, we reveal that miR-206 emerges as a crucial regulator of tilapia growth. miR-206 loss of function leads to the acceleration of tilapia growth. IGF-1 is identified as the target gene of miR-206. miR-206 directly changes IGF-1 expression by targeting its 3′ UTR, and inhibition of miR-206 substantially increases the IGF-1 mRNA level in vivo. Thus, miR-206 could be developed as a molecular marker to assist fish breeding.

miR-203b: a novel regulator of MyoD expression in tilapia skeletal muscle

SUMMARY MyoD is one of the helix-loop-helix proteins regulating muscle-specific gene expression in tilapia. Tight regulation of the MyoD protein level is necessary for the precise regulation of skeletal muscle development. MicroRNAs (miRNAs) are a class of regulatory RNAs that post-transcriptionally regulate gene expression. An increasing amount of evidence has suggested that miRNAs play an important role in regulating skeletal muscle development. We reasoned that MyoD expression may be regulated by miRNAs. Predictions from bioinformatics have identified a putative miR-203b target site in the 3′-UTR of the MyoD gene. Interestingly, miR-203b expression is negatively correlated with MyoD expression, whereas miR-203b suppression leads to a significant increase in MyoD expression, thereby activating MyoD downstream genes. A 3′-UTR luciferase reporter assay further verifies the direct interaction between miR-203b and MyoD. Taken together, our results reveal a novel molecular mechanism in which miRNA participates in transcriptional circuits that regulate gene expression in tilapia skeletal muscle.

MicroRNA repertoire for functional genome research in tilapia identified by deep sequencing.

Abstract The Nile tilapia (Oreochromis niloticus; Cichlidae) is an economically important species in aquaculture and occupies a prominent position in the aquaculture industry. MicroRNAs (miRNAs) are a class of noncoding RNAs that post-transcriptionally regulate gene expression involved in diverse biological and metabolic processes. To increase the repertoire of miRNAs characterized in tilapia, we used the Illumina/Solexa sequencing technology to sequence a small RNA library using pooled RNA sample isolated from the different developmental stages of tilapia. Bioinformatic analyses suggest that 197 conserved and 27 novel miRNAs are expressed in tilapia. Sequence alignments indicate that all tested miRNAs and miRNAs* are highly conserved across many species. In addition, we characterized the tissue expression patterns of five miRNAs using real-time quantitative PCR. We found that miR-1/206, miR-7/9, and miR-122 is abundantly expressed in muscle, brain, and liver, respectively, implying a potential role in the regulation of tissue differentiation or the maintenance of tissue identity. Overall, our results expand the number of tilapia miRNAs, and the discovery of miRNAs in tilapia genome contributes to a better understanding the role of miRNAs in regulating diverse biological processes.