State Key Laboratory of Livestock and Poultry Breeding, Guangdong Public Laboratory of Animal Breeding and Nutrition, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China, China.
State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510006, China.
Acta Biochim Biophys Sin (Shanghai). 2022 Aug 25;54(8):1122-1132. doi: 10.3724/abbs.2022095.
Delving into porcine embryonic myogenesis is the key to elucidate the complex regulation of breed-specific differences in growth performance and meat production. Increasing evidence proves that pigs with less meat production show earlier embryonic myogenesis, but little is known about the underlying mechanisms. In this study, we examine the longissimus dorsi muscle (LDM) by immunohistochemistry and confirm that the differentiation of myogenic progenitors is increased ( <0.05) in Lantang (LT, fatty) pigs compared with that in Landrace (LR, lean) pigs, which results in more ( <0.001) differentiated myoblasts (Pax7 /MyoD ) and less ( <0.001) myogenic progenitors (Pax7 /MyoD ) in LT pigs at 35 days post-conception (35dpc). Additionally, embryonic myogenic progenitors isolated from LT pigs show greater ( <0.001) differentiation capacity with earlier expression of MyoD compared with those from LR pigs. Moreover, Notch signaling is more active ( <0.05) in LR pig myogenic progenitors than in LT pig myogenic progenitors. Inhibition of Notch signaling in LR myogenic progenitors suppresses Pax7 expression and increases MyoD expression, thus promoting myogenic differentiation. Consistently, the process of myogenic progenitors differentiating into myoblasts in embryo limbs is accelerated when Notch signaling is inhibited. These results indicate that Notch signaling facilitates the maintenance of myogenic progenitors and antagonizes myogenic differentiation by promoting Pax7 expression and preventing MyoD expression in LR pigs.
深入研究猪胚胎成肌发生是阐明生长性能和肉质生产中品种特异性差异的复杂调控机制的关键。越来越多的证据证明，产肉量较少的猪表现出更早的胚胎成肌发生，但对于其潜在机制知之甚少。在本研究中，我们通过免疫组织化学检查了背最长肌（LDM），并证实与长白猪（LR，瘦肉型）相比，蓝塘猪（LT，脂肪型）的肌源性祖细胞分化增加（ <0.05），这导致更多的（ <0.001）分化的成肌细胞（Pax7 / MyoD）和更少的（ <0.001）肌源性祖细胞（Pax7 / MyoD）在受孕后 35 天（35dpc）的 LT 猪中。此外，从 LT 猪中分离出的胚胎成肌祖细胞表现出更高的（ <0.001）分化能力，并且与 LR 猪相比，MyoD 的表达更早。此外，与 LT 猪的成肌祖细胞相比，LR 猪的成肌祖细胞中的 Notch 信号更为活跃（ <0.05）。抑制 LR 成肌祖细胞中的 Notch 信号会抑制 Pax7 的表达并增加 MyoD 的表达，从而促进成肌分化。一致地，当 Notch 信号被抑制时，胚胎肢部的成肌祖细胞向成肌细胞分化的过程被加速。这些结果表明，Notch 信号通过促进 Pax7 的表达和阻止 MyoD 的表达来促进 LR 猪中肌源性祖细胞的维持和拮抗成肌分化。
