Intramuscular fat refers to the adipose tissue distributed in the muscle. It is an important indicator that affects the quality of goat meat, and can directly affect the tenderness and flavor of goat meat. Our previous study revealed the mRNA that may be crucial for intramuscular fat deposition during goat growth; however, how the microRNAs (miRNAs) are involved in the process is largely unclear. In the present study, a total of 401 known miRNAs and 120 goat novel miRNAs, including 110 differentially expressed (DE) miRNAs, were identified among longissimus dorsi from three growth stages (2, 9, and 24 months) by miRNA sequencing. Combining analysis of the DE mRNAs and DE miRNAs was then performed by miRDB and miRwalk, and miR-145-5p and FOXO1, miR-487b-3p, and PPARG coactivator 1 α (PPARGC1A), miR-345-3p, and solute carrier family 2 member 4 (SLC2A4), etc. were shown to closely associate with lipid metabolism, which was then validated by a correlation analysis. The final DE mRNAs were significantly enriched in fatty acid transmembrane transport, fatty acid homeostasis, apelin signaling pathway, glucagon signaling pathway, insulin signaling pathway, and AMPK signaling pathway by gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis. Besides, miR-145-5p showed a certain effect on goat intramuscular fat metabolism by acting on the possible target gene Forkhead Box O1 (FOXO1). These data provide some theoretical support for improving the quality of goat meat.

中文翻译：

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对出生后不同阶段不同表达的 microRNA 和 mRNA 的综合分析揭示了山羊 (Capra hircus) 的肌内脂肪沉积调节

肌内脂肪是指分布在肌肉中的脂肪组织。它是影响山羊肉品质的重要指标，能直接影响山羊肉的嫩度和风味。我们之前的研究揭示了可能对山羊生长过程中肌内脂肪沉积至关重要的 mRNA；然而，microRNA (miRNA) 如何参与这一过程尚不清楚。在本研究中，通过miRNA测序，在三个生长阶段（2、9和24个月）的背最长肌中总共鉴定了401个已知的miRNA和120个山羊新的miRNA，其中包括110个差异表达（DE）miRNA。然后通过 miRDB 和 miRwalk、miR-145-5p 和FOXO1、miR-487b-3p 和 PPARG 共激活因子 1 α ( PPARGC1A )、miR-345-3p 和溶质载体对 DE mRNA 和 DE miRNA 进行组合分析家族2成员4（SLC2A4）等被证明与脂质代谢密切相关，并通过相关性分析得到验证。通过基因本体论和京都基因与基因组百科全书分析，最终的DE mRNA在脂肪酸跨膜转运、脂肪酸稳态、apelin信号通路、胰高血糖素信号通路、胰岛素信号通路和AMPK信号通路上显着富集。此外，miR-145-5p通过作用于可能的靶基因Forkhead Box O1（ FOXO1），对山羊肌内脂肪代谢表现出一定的影响。这些数据为提高山羊肉品质提供了一定的理论支持。