There is a high morbidity and mortality rate in mechanical trauma (MT)-induced hepatic injury. Currently, the molecular mechanisms underlying liver MT are largely unclear. Exploring the underlying mechanisms and developing safe and effective medicines to alleviate MT-induced hepatic injury is an urgent requirement. The aim of this study was to reveal the role of mitochondria-associated ER membranes (MAMs) in post-traumatic liver injury, and ascertain whether melatonin protects against MT-induced hepatic injury by regulating MAMs. Hepatic mechanical injury was established in Sprague–Dawley rats and primary hepatocytes. A variety of experimental methods were employed to assess the effects of melatonin on hepatic injury, apoptosis, MAMs formation, mitochondrial function and signaling pathways. Significant increase of IP3R1 expression and MAMs formation were observed in MT-induced hepatic injury. Melatonin treatment at the dose of 30 mg/kg inhibited IP3R1-mediated MAMs and attenuated MT-induced liver injury in vivo. In vitro, primary hepatocytes cultured in 20% trauma serum (TS) for 12 h showed upregulated IP3R1 expression, increased MAMs formation and cell injury, which were suppressed by melatonin (100 μmol/L) treatment. Consequently, melatonin suppressed mitochondrial calcium overload, increased mitochondrial membrane potential and improved mitochondrial function under traumatic condition. Melatonin’s inhibitory effects on MAMs formation and mitochondrial calcium overload were blunted when IP3R1 was overexpressed. Mechanistically, melatonin bound to its receptor (MR) and increased the expression of phosphorylated ERK1/2, which interacted with FoxO1 and inhibited the activation of FoxO1 that bound to the IP3R1 promoter to inhibit MAMs formation. Melatonin prevents the formation of MAMs via the MR-ERK1/2-FoxO1-IP3R1 pathway, thereby alleviating the development of MT-induced liver injury. Melatonin-modulated MAMs may be a promising therapeutic therapy for traumatic hepatic injury.

中文翻译：

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IP3R1介导的MAMs形成有助于机械创伤引起的肝损伤以及褪黑激素的保护作用

机械创伤（MT）引起的肝损伤具有很高的发病率和死亡率。目前，肝脏 MT 的分子机制尚不清楚。探索潜在机制并开发安全有效的药物来减轻MT引起的肝损伤是当务之急。本研究的目的是揭示线粒体相关内质网膜 (MAM) 在创伤后肝损伤中的作用，并确定褪黑激素是否通过调节 MAM 来预防 MT 诱导的肝损伤。在 Sprague-Dawley 大鼠和原代肝细胞中建立了肝脏机械损伤。采用多种实验方法评估褪黑激素对肝损伤、细胞凋亡、MAMs 形成、线粒体功能和信号通路的影响。在 MT 诱导的肝损伤中观察到 IP3R1 表达和 MAM 形成显着增加。 30 mg/kg 剂量的褪黑激素治疗可抑制 IP3R1 介导的 MAM 并减轻 MT 诱导的体内肝损伤。体外，原代肝细胞在 20% 创伤血清 (TS) 中培养 12 小时，结果显示 IP3R1 表达上调、MAM 形成增加和细胞损伤增加，而褪黑素 (100 μmol/L) 处理可抑制这些现象。因此，褪黑激素抑制线粒体钙超载，增加线粒体膜电位并改善创伤条件下的线粒体功能。当 IP3R1 过度表达时，褪黑素对 MAM 形成和线粒体钙超载的抑制作用会减弱。从机制上讲，褪黑素与其受体（MR）结合并增加磷酸化ERK1/2的表达，该磷酸化ERK1/2与FoxO1相互作用并抑制与IP​​3R1启动子结合的Fo​​xO1的激活，从而抑制MAMs的形成。褪黑激素通过 MR-ERK1/2-FoxO1-IP3R1 途径阻止 MAM 的形成，从而减轻 MT 引起的肝损伤的发展。褪黑激素调节的 MAM 可能是治疗创伤性肝损伤的一种有前途的治疗方法。