Rossetti Alberto, Togliatto Gabriele, Rolo Anabela P, Teodoro João S, Granata Riccarda, Ghigo Ezio, Columbano Amedeo, Palmeira Carlos M, Brizzi Maria Felice
Department of Medical Sciences, University of Turin, Turin, Italy.
Department of Life Sciences and Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal.
Cell Death Discov. 2017 Dec 4;3:17077. doi: 10.1038/cddiscovery.2017.77. eCollection 2017.
Ischemia/reperfusion (I/R) injury is a common cause of liver dysfunction during hepatectomy, liver transplantation procedures and in generalized shock. Although effort has been dedicated to rescuing tissue damage in these clinical settings, there is still an urgent need for an effective treatment to protect the liver from the burden of I/R injury. In this study, we have investigated the potential clinical impact of unacylated-ghrelin (UnAG) in a liver I/R rat model. Particular attention has been paid to mitochondria. We demonstrate that UnAG was able to reduce the lag-phase time in response to ADP administration and increase oxygen consumption in experiments using liver mitochondria recovered from rats subjected to I/R. Moreover, we found that UnAG rescued the expression of a key regulator of mitochondrial morphology and electron transport chain function; the optic atrophy 1 (Opa1) protein. Cytochrome oxidase (COX), ATP synthase (complex V) activity and mitochondrial permeability transition pore (mPTP) opening were also affected by UnAG administration . An , hepatic I/R model was used to validate these data. We demonstrate that UnAG upregulates the expression of Cox subunit IV (CoxIV) and increases cellular ATP content. This results in Bcl-2 upregulation and protection against apoptosis. Opa1 silencing shows that Opa1 is crucial for a UnAG-induced increase in cellular ATP content, apoptosis resistance, Bcl-2 and CoxIV expression. Finally, we show that UnAG improves Opa1's interaction with MIC60 in the I/R setting, hinting at its role in cristae shape regulation. Our results demonstrate that UnAG administration rescues the intrinsic mitochondrial pathway triggered by I/R damage. Opa1's contribution in mediating this effect is also reported. This suggests that UnAG can interfere with mitochondrial dysfunction, via Opa1, in a preclinical liver I/R model. We therefore provide the rationale for exploiting UnAG as an alternative means to rescuing mitochondrial damage and organ dysfunction.
缺血/再灌注（I/R）损伤是肝切除术、肝移植手术及全身休克期间肝功能障碍的常见原因。尽管人们致力于在这些临床情况下挽救组织损伤，但仍迫切需要一种有效的治疗方法来保护肝脏免受I/R损伤的负担。在本研究中，我们在肝I/R大鼠模型中研究了去酰基胃饥饿素（UnAG）的潜在临床影响。我们特别关注了线粒体。我们证明，在使用从I/R大鼠中回收的肝线粒体进行的实验中，UnAG能够缩短对ADP给药的延迟期时间并增加氧气消耗。此外，我们发现UnAG挽救了线粒体形态和电子传递链功能的关键调节因子——视神经萎缩蛋白1（Opa1）的表达。细胞色素氧化酶（COX）、ATP合酶（复合体V）活性以及线粒体通透性转换孔（mPTP）开放也受到UnAG给药的影响。此外，使用肝I/R模型来验证这些数据。我们证明UnAG上调Cox亚基IV（CoxIV）的表达并增加细胞ATP含量。这导致Bcl-2上调并防止细胞凋亡。Opa1沉默表明Opa1对于UnAG诱导的细胞ATP含量增加、抗凋亡、Bcl-2和CoxIV表达至关重要。最后，我们表明UnAG在I/R环境中改善了Opa1与MIC60的相互作用，暗示了其在嵴形态调节中的作用。我们的结果表明，给予UnAG可挽救由I/R损伤触发的内源性线粒体途径。还报道了Opa1在介导这种效应中的作用。这表明在临床前肝I/R模型中，UnAG可通过Opa1干扰线粒体功能障碍。因此，我们为利用UnAG作为挽救线粒体损伤和器官功能障碍的替代手段提供了理论依据。
