BACKGROUND Intramuscular fat (IMF) content is an important factor in porcine meat quality. Previously, we showed that miR-34a was less abundant in liver tissue from pigs with higher backfat thickness, compared to pigs with lower backfat thickness. The purpose of this present study was to explore the role of miR-34a in adipogenesis. RESULT Bioinformatics analysis identified Acyl-CoA synthetase long chain family member 4 (ACSL4) as a putative target of miR-34a. Using a luciferase reporter assay, we verified that miR-34a binds the ACSL4 mRNA at the 3'UTR. To examine the role of the miR-34a-ACSL4 interaction in IMF deposition in the pig, mRNA and protein expression of the ACSL4 gene was measured in primary intramuscular preadipocytes transfected with miR-34a mimic and inhibitor. Our results showed that ACSL4 is expressed throughout the entire differentiation process in pig preadipocytes, similar to the lipogenesis-associated genes PPARγ and aP2. Transfection with miR-34a mimic reduced lipid droplet formation during adipogenesis, while miR-34a inhibitor increased lipid droplet accumulation. Transfection with miR-34a mimic also reduced the mRNA and protein expression of ACSL4 and lipogenesis genes, including PPARγ, aP2, and SREBP-1C, but increased the expression of steatolysis genes such as ATGL and Sirt1. In contrast, the miR-34a inhibitor had the opposite effect on gene expression. Further, knockdown of ACSL4 decreased lipid droplet accumulation. CONCLUSIONS Our results support the hypothesis that miR-34a regulates intramuscular fat deposition in porcine adipocytes by targeting ACSL4.

中文翻译：

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miR-34a 通过靶向 ACSL4 调节猪肌内脂肪细胞的脂肪生成。

背景技术肌内脂肪(IMF)含量是影响猪肉品质的重要因素。此前，我们发现，与背膘厚度较低的猪相比，背膘厚度较高的猪的肝组织中 miR-34a 的含量较低。本研究的目的是探讨 miR-34a 在脂肪生成中的作用。结果 生物信息学分析确定酰基辅酶 A 合成酶长链家族成员 4 (ACSL4) 是 miR-34a 的推定靶标。使用荧光素酶报告基因测定，我们验证了 miR-34a 在 3'UTR 处结合 ACSL4 mRNA。为了研究 miR-34a-ACSL4 相互作用在猪 IMF 沉积中的作用，在用 miR-34a 模拟物和抑制剂转染的原代肌内前脂肪细胞中测量了 ACSL4 基因的 mRNA 和蛋白表达。我们的结果表明，ACSL4 在猪前脂肪细胞的整个分化过程中表达，类似于脂肪生成相关基因 PPARγ 和 aP2。转染 miR-34a 模拟物可减少脂肪生成过程中的脂滴形成，而 miR-34a 抑制剂则增加脂滴积累。转染 miR-34a 模拟物还降低了 ACSL4 和脂肪生成基因（包括 PPARγ、aP2 和 SREBP-1C）的 mRNA 和蛋白表达，但增加了脂肪分解基因（如 ATGL 和 Sirt1）的表达。相反，miR-34a抑制剂对基因表达具有相反的作用。此外，ACSL4 的敲除减少了脂滴的积累。结论我们的结果支持以下假设：miR-34a 通过靶向 ACSL4 调节猪脂肪细胞的肌内脂肪沉积。