Engineering Research Center of North-East Cold Region Beef Cattle Science & Technology Innovation, Ministry of Education, Yanbian University, Yanji, 133002, China.
Jilin Provincial Key Laboratory of Transgenic Animal and Embryo Engineering, Yanbian University, Yanji, 133002, Jilin, China.
Transgenic Res. 2022 Oct;31(4-5):553-565. doi: 10.1007/s11248-022-00322-w. Epub 2022 Aug 17.
Myostatin (MSTN), a member of the TGF-β superfamily, negatively regulates muscle growth. MSTN inhibition has been known to cause a double-muscled phenotype in skeletal muscle and fibrosis reduction in the heart. However, the role of MSTN in the cardiac extracellular matrix (ECM) needs more studies in various species of animal models to draw more objective conclusions. The main objective of the present study was to investigate whether loss of MSTN affects the cardiac extracellular matrix in pigs. Three MSTN knockouts (MSTN-/-) and three wild type (WT) male pigs were generated by crossing MSTN ± heterozygous gilts and boars. Cardiac ECM and underlying mechanisms were determined post-mortem. The role of MSTN on collagen expression was investigated by treating cardiac fibroblasts with active MSTN protein in vitro. MSTN protein was detected in WT hearts, while no expression was detected in MSTN-/- hearts. The heart-to-body weight ratio was significantly decreased in MSTN-/- pigs. The morphometric analyses, including picrosirius red staining, immunofluorescent staining, and ultra-structural thickness examination of the endomysium, revealed a significant reduction of connective tissue content in MSTN-/- hearts compared to WT. Hydroxyproline, type I collagen (Col1A), and p-Smad3/Smad3 levels were significantly lower in MSTN-/- hearts in vivo. On the contrary, cardiac fibroblasts treated with exogenous MSTN protein overexpressed Col1A and activated Smad and AKT signaling pathways in vitro. The present study suggests that inhibition of MSTN decreases cardiac extracellular matrix.
肌肉生长抑制素（MSTN）是 TGF-β 超家族的成员，负向调节肌肉生长。已知 MSTN 抑制会导致骨骼肌出现双肌表型和心脏纤维化减少。然而，MSTN 在心脏细胞外基质（ECM）中的作用需要在各种动物模型中进行更多研究，以得出更客观的结论。本研究的主要目的是研究 MSTN 缺失是否会影响猪的心脏细胞外基质。通过杂交 MSTN±杂合母猪和公猪，产生了 3 只 MSTN 敲除（MSTN-/-）和 3 只野生型（WT）雄性猪。死后确定心脏 ECM 和潜在机制。通过在体外用活性 MSTN 蛋白处理心脏成纤维细胞，研究 MSTN 对胶原蛋白表达的作用。在 WT 心脏中检测到 MSTN 蛋白，而在 MSTN-/-心脏中未检测到。MSTN-/-猪的心脏/体重比显著降低。形态计量学分析，包括苦味酸天狼星红染色、免疫荧光染色和内膜超微结构厚度检查，显示 MSTN-/-心脏中的结缔组织含量明显低于 WT。体内 MSTN-/-心脏中的羟脯氨酸、I 型胶原蛋白（Col1A）和 p-Smad3/Smad3 水平明显降低。相反，体外用外源性 MSTN 蛋白处理的心脏成纤维细胞过度表达了 Col1A，并激活了 Smad 和 AKT 信号通路。本研究表明，MSTN 抑制会减少心脏细胞外基质。
