Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
Department of Biochemistry and Chemistry of Nutrition, Faculty of Veterinary Medicine, Menoufia University, Menoufia, Egypt.
Cell Biochem Funct. 2021 Jan;39(1):116-125. doi: 10.1002/cbf.3592. Epub 2020 Oct 2.
Uncoupling protein 1 (UCP1) is responsible for non-shivering thermogenesis, with restricted expression in brown/beige adipocytes in humans and rodents. We have previously shown an unexpected expression of UCP1 in bovine skeletal muscles. This study evaluated factors affecting Ucp1 gene expression in cultured bovine myogenic cells. Myosatellite cells, which were isolated from the bovine musculus longissimus cervicis, were induced to differentiate into myotubes in the presence of 2% horse serum. Previous studies using murine brown/beige adipocytes revealed that Ucp1 expression levels are directly increased by forskolin and all-trans retinoic acid (RA). The transforming growth factor-β (TGF-β)/activin pathway negatively regulated Ucp1 expression, whereas activation of the bone morphogenetic protein (BMP) pathway indirectly increases Ucp1 expression through the stimulation of brown/beige adipogenesis. Neither forskolin nor RA significantly affected Ucp1 mRNA levels in bovine myogenic cells. A-83-01, an inhibitor of the TGF-β/activin pathway, stimulated myogenesis in these cells. A-83-01 significantly increased the expression of some brown fat signature genes such as Pgc-1α, Cox7a1, and Dio2, with a quantitative but not significant increase in the expression of Ucp1. Treatment with LDN-193189, an inhibitor of the BMP pathway, did not affect the differentiation of bovine myosatellite cells. Rather, LDN-193189 increased Ucp1 mRNA levels without modulating the levels of other brown/beige adipocyte-related genes. The current results indicate that the regulation of Ucp1 expression in bovine myogenic cells is distinct from that in murine brown/beige adipocytes, which has been more intensely characterized. SIGNIFICANCE OF THE STUDY: We previously reported unexpected expression of Ucp1 in bovine muscle tissues; Ucp1 expression has been known to be detected predominantly in brown/beige adipocytes. This study examined regulatory expression of bovine Ucp1 in myogenic cells. Consistent with the changes in expression levels of brown/beige adipocyte-selective genes, Ucp1 expression tended to be increased by inhibition of endogenous TGF-β activity. In contrast, inhibition of endogenous BMP significantly increased Ucp1 expression without affecting brown/beige adipocyte-selective gene expression. The current results indicate that regulatory expression of Ucp1 in bovine myogenic cells is distinct from that in murine brown/beige adipocytes that is more intensely characterized.
解偶联蛋白 1（UCP1）负责非颤抖性产热，在人类和啮齿动物的棕色/米色脂肪细胞中表达受限。我们之前已经证明了 UCP1 在牛骨骼肌中的意外表达。本研究评估了在培养的牛肌原细胞中影响 Ucp1 基因表达的因素。肌卫星细胞从牛颈最长肌中分离出来，在 2%马血清的存在下诱导分化为肌管。以前使用鼠类棕色/米色脂肪细胞的研究表明，Ucp1 的表达水平直接受到 forskolin 和全反式视黄酸（RA）的增加。转化生长因子-β（TGF-β）/激活素途径负调控 Ucp1 的表达，而骨形态发生蛋白（BMP）途径的激活通过刺激棕色/米色脂肪生成间接增加 Ucp1 的表达。福司可林和 RA 都没有显著影响牛肌原细胞中 Ucp1 mRNA 的水平。TGF-β/激活素途径的抑制剂 A-83-01 刺激这些细胞的肌生成。A-83-01 显著增加了一些棕色脂肪特征基因的表达，如 Pgc-1α、Cox7a1 和 Dio2，Ucp1 的表达也有一定程度的增加，但没有显著性。BMP 途径的抑制剂 LDN-193189 处理并不影响牛肌卫星细胞的分化。相反，LDN-193189 增加了 Ucp1 mRNA 的水平，而不调节其他棕色/米色脂肪细胞相关基因的水平。目前的结果表明，牛肌原细胞中 Ucp1 表达的调节与已被更深入研究的鼠类棕色/米色脂肪细胞的调节不同。研究的意义：我们之前报道了 Ucp1 在牛肌肉组织中的意外表达；Ucp1 的表达主要在棕色/米色脂肪细胞中检测到。本研究检查了牛肌原细胞中 Ucp1 的调节表达。与棕色/米色脂肪细胞选择性基因表达水平的变化一致，内源性 TGF-β 活性的抑制使 Ucp1 的表达趋于增加。相反，内源性 BMP 的抑制显著增加 Ucp1 的表达，而不影响棕色/米色脂肪细胞选择性基因的表达。目前的结果表明，牛肌原细胞中 Ucp1 的调节表达与已被更深入研究的鼠类棕色/米色脂肪细胞的调节不同。
