Piao Yu Ji, Seo Yong Hak, Hong Feng, Kim Jin Hwan, Kim Young-Joo, Kang Myung Ho, Kim Bum Shik, Jo Sangmee Ahn, Jo Inho, Jue Dae-Myung, Kang Insug, Ha Joohun, Kim Sung Soo
Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, #1, Hoegi-dong, Dongdaemoon-gu, Seoul 130-701, Korea.
Free Radic Biol Med. 2005 Apr 15;38(8):989-1001. doi: 10.1016/j.freeradbiomed.2004.11.011.
The NF-kappaB/iNOS pathway stimulates muscle differentiation downstream of the PI 3-kinase/p38 MAPK pathway and diverse antioxidants block muscle differentiation. Therefore, we here investigated whether Nox 2 links those two myogenic pathways in H9c2 and C2C12 myoblasts. Compared with the proliferation stage, ROS generation was enhanced from the early stage of differentiation and gradually increased as differentiation progressed. Antioxidants suppressed the activated NF-kappaB/iNOS pathway during muscle differentiation. Nox 2 activity was also increased during muscle differentiation. Treatment with DPI and apocynin, two inhibitors of NADPH oxidase, and suppression of Nox 2 expression using siRNA, but not Nox 1, inhibited NADPH oxidase activity, muscle differentiation, and the NF-kappaB/iNOS pathway. Inhibition of PI 3-kinase and p38 MAPK suppressed the Nox 2/NF-kappaB/iNOS pathway. Nitric oxide restored muscle differentiation blocked by treatment with antioxidants or suppression of the Nox 2/NF-kappaB/iNOS pathway. In conclusion, Nox 2 stimulates muscle differentiation downstream of the PI 3-kinase/p38 MAPK pathway by activating the NF-kappaB/iNOS pathway via ROS generation.
NF-κB/iNOS信号通路在PI 3-激酶/p38丝裂原活化蛋白激酶（MAPK）信号通路的下游刺激肌肉分化，多种抗氧化剂可阻断肌肉分化。因此，我们在此研究了Nox 2是否在H9c2和C2C12成肌细胞中连接这两条生肌信号通路。与增殖阶段相比，从分化早期开始活性氧（ROS）生成增强，并随着分化进程逐渐增加。抗氧化剂在肌肉分化过程中抑制活化的NF-κB/iNOS信号通路。Nox 2活性在肌肉分化过程中也增加。用二苯基碘鎓（DPI）和夹竹桃麻素这两种烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶抑制剂处理，以及使用小干扰RNA（siRNA）抑制Nox 2表达，而非Nox 1，可抑制NADPH氧化酶活性、肌肉分化以及NF-κB/iNOS信号通路。抑制PI 3-激酶和p38 MAPK可抑制Nox 2/NF-κB/iNOS信号通路。一氧化氮可恢复因抗氧化剂处理或Nox 2/NF-κB/iNOS信号通路抑制而受阻的肌肉分化。总之，Nox 2通过经由ROS生成激活NF-κB/iNOS信号通路，在PI 3-激酶/p38 MAPK信号通路的下游刺激肌肉分化。
