Elgaabari Alaa, Imatomi Nana, Kido Hirochika, Seki Miyumi, Tanaka Sakiho, Matsuyoshi Yuji, Nakashima Takashi, Sawano Shoko, Mizunoya Wataru, Suzuki Takahiro, Nakamura Mako, Anderson Judy E, Tatsumi Ryuichi
Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Fukuoka 819-0395, Japan.
Department of Physiology, Faculty of Veterinary Medicine, Kafrelsheikh University, El-Geish Street, Kafrelsheikh 33516, Egypt.
Biochem Biophys Rep. 2022 Jun 11;31:101295. doi: 10.1016/j.bbrep.2022.101295. eCollection 2022 Sep.
Protein tyrosine residue (Y) nitration, a post-translational chemical-modification mode, has been associated with changes in protein activity and function; hence the accumulation of specific nitrated proteins in tissues may be used to monitor the onset and progression of pathological disorders. To verify the possible impact of nitration on postnatal muscle growth and regeneration, a pilot study was designed to examine the nitration/dysfunction of hepatocyte growth factor (HGF), a key ligand that is released from the extracellular tethering and activates myogenic stem satellite cells to enter the cell cycle upon muscle stretch and injury. Exposure of recombinant HGF (a hetero-dimer of α- and β-chains) to peroxynitrite induces Y nitration in HGF α-chain under physiological conditions. Physiological significance of this finding was emphasized by Western blotting that showed the NK1 segment of HGF (including a K1 domain critical for signaling-receptor c-met binding) undergoes nitration with a primary target of Y198. Peroxynitrite treatment abolished HGF-agonistic activity of the NK1 segment, as revealed by c-met binding and bromodeoxyuridine-incorporation assays. Importantly, direct-immunofluorescence microscopy of rat lower hind-limb muscles from two aged-groups (2-month-old "young" and 12-month-old "retired/adult") provided evidence for age-related nitration of extracellular HGF (Y198). Overall, findings provide the insight that HGF/NK1 nitration/dysfunction perturbs myogenic stem cell dynamics and homeostasis; hence NK1 nitration may stimulate progression of muscular disorders and diseases including sarcopenia.
蛋白质酪氨酸残基（Y）硝化是一种翻译后化学修饰模式，与蛋白质活性和功能的变化有关；因此，组织中特定硝化蛋白质的积累可用于监测病理疾病的发生和进展。为了验证硝化对出生后肌肉生长和再生的可能影响，设计了一项初步研究来检查肝细胞生长因子（HGF）的硝化/功能障碍，HGF是一种关键配体，从细胞外束缚中释放出来，在肌肉拉伸和损伤时激活成肌干细胞卫星细胞进入细胞周期。在生理条件下，重组HGF（α链和β链的异二聚体）暴露于过氧亚硝酸盐会诱导HGFα链中的Y硝化。蛋白质印迹法强调了这一发现的生理意义，该方法显示HGF的NK1片段（包括对信号受体c-met结合至关重要的K1结构域）发生硝化，主要靶点为Y198。如c-met结合和溴脱氧尿苷掺入试验所示，过氧亚硝酸盐处理消除了NK1片段的HGF激动活性。重要的是，对两个年龄组（2个月大的“年轻”组和12个月大的“退休/成年”组）大鼠后肢下部肌肉的直接免疫荧光显微镜检查提供了细胞外HGF（Y198）与年龄相关硝化的证据。总体而言，研究结果表明HGF/NK1硝化/功能障碍扰乱了成肌干细胞动力学和体内平衡；因此，NK1硝化可能会促进包括肌肉减少症在内的肌肉疾病的进展。
