The microRNA expression profiles changes associated with constant heat stress in porcine skeletal muscle as measured by deep sequencing. Sus scrofa

To characterize the changes of miRNAs in skeletal muscle responding to heat stress, the miRNA expression profiles of longissimus dorsi muscles of pigs raised under constant heat stress (30°C, n=8) or control temperature (22 C, n=8) for 21 days were analyzed by Illumina deep sequencing. 58 differentially expressed miRNAs were identified with 30 down-regulated and 28 up-regulated and 63 differentially expressed target genes were predicted by miRNA-mRNA joint analysis. GO and KEGG analyses showed that the genes regulated by differentially expressed miRNAs were enriched in glucose metabolism, cytoskeletal structure and function, and stress response. Real-time PCR showed that the mRNA levels of PDK4, HSP90 and DES were significantly increased whereas those of SCD and LDH-A significantly decreased by heat exposure. The protein levels of CALM, DES and HIF1α were also significantly increased by constant heat. These results demonstrated that the change of miRNA expression in porcine longissimus dorsi muscle underlie the changes of muscle structure and metabolism in porcine skeletal muscle affected by constant heat stress. Overall design: Characterize and compare expression profiling of the miRNA transcriptome in 2 groups of porcine skeletal muscle.

为阐明骨骼肌微小RNA（miRNAs）对热应激的响应变化，本研究采用Illumina高通量测序技术，对持续暴露于30℃恒定热应激环境（样本量n=8）与22℃对照温度（样本量n=8）条件下21天的猪背最长肌组织的miRNA表达谱进行了分析。共鉴定出58个差异表达miRNAs，其中30个表达下调、28个表达上调；通过miRNA-mRNA联合分析预测得到63个差异表达靶基因。基因本体（Gene Ontology，GO）与京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes，KEGG）富集分析显示，差异表达miRNAs调控的基因显著富集于葡萄糖代谢、细胞骨架结构与功能以及应激响应通路。实时荧光定量聚合酶链式反应（Real-time PCR）结果表明，热暴露后PDK4、HSP90与DES的mRNA水平显著上调，而SCD与LDH-A的mRNA水平显著下调；此外，CALM、DES与HIF1α的蛋白水平在持续热应激后也显著升高。上述结果证实，持续热应激条件下猪背最长肌组织中miRNA表达的变化，是热应激影响猪骨骼肌结构与代谢变化的分子基础。整体实验设计：对两组猪骨骼肌组织的miRNA转录组表达谱进行表征与比较分析。