College of Animal Science and Technology, Nanjing Agricultural University, No. 1, Weigang, Nanjing, 210095, China.
Lipids. 2021 May;56(3):279-287. doi: 10.1002/lipd.12294. Epub 2020 Dec 10.
Intramuscular fat (IMF) and subcutaneous fat (SCF) are important traits affecting the economics of the pork industry, in which less SCF and more IMF content is desirable. However, the mechanisms that regulate IMF and SCF content are not clear yet. In this study, we demonstrate that KLF3 (Krüppel-like factor 3) was negatively correlated with IMF content in the longissimus dorsi muscle of Erhualian pigs. In addition, the expression level of KLF3 was significantly higher in IMF than SCF. Overexpression and knockdown experiments revealed that KLF3 could suppress adipocyte differentiation in vitro by downregulating adipogenic markers, including PPARG, C/EBPA, and FABP4. Luciferase activity analysis proved that miR-32-5p was able to suppress KLF3. Notably, miR-32-5p level was negatively correlated to KLF3 mRNA level in both IMF and SCF tissues. The same relationship was proved in samples with different IMF content. Further studies showed that miR-32-5p could promote adipocyte differentiation via inhibiting KLF3. Our results suggest that the miR-32-5p-KLF3 pathway is involved in the regulation of differential fat deposition of IMF and SCF tissues.
肌内脂肪（IMF）和皮下脂肪（SCF）是影响猪肉产业经济效益的重要特征，人们希望猪肉中的 SCF 含量更低，IMF 含量更高。然而，调节 IMF 和 SCF 含量的机制尚不清楚。在本研究中，我们证明了 Krüppel 样因子 3（KLF3）与二花脸猪背最长肌中的 IMF 含量呈负相关。此外，KLF3 的表达水平在 IMF 中明显高于 SCF。过表达和敲低实验表明，KLF3 可以通过下调脂肪生成标志物（包括 PPARG、C/EBPA 和 FABP4）来抑制体外脂肪细胞分化。荧光素酶活性分析证明 miR-32-5p 能够抑制 KLF3。值得注意的是，miR-32-5p 的水平与 IMF 和 SCF 组织中的 KLF3 mRNA 水平呈负相关。在 IMF 含量不同的样本中也证明了这种关系。进一步的研究表明，miR-32-5p 可以通过抑制 KLF3 来促进脂肪细胞分化。我们的研究结果表明，miR-32-5p-KLF3 通路参与了 IMF 和 SCF 组织中脂肪沉积差异的调节。
