Vanasco Virginia, Ropolo Alejandro, Grasso Daniel, Ojeda Diego S, García María Noé, Vico Tamara A, Orquera Tamara, Quarleri Jorge, Alvarez Silvia, Vaccaro María I
Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Bioquímica y Medicina Molecular (IBIMOL), Facultad de Farmacia y Bioquímica, Buenos Aires, Argentina.
Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Buenos Aires, Argentina.
Front Cell Dev Biol. 2021 Mar 18;9:640094. doi: 10.3389/fcell.2021.640094. eCollection 2021.
Mitophagy and zymophagy are selective autophagy pathways early induced in acute pancreatitis that may explain the mild, auto limited, and more frequent clinical presentation of this disease. Adequate mitochondrial bioenergetics is necessary for cellular restoration mechanisms that are triggered during the mild disease. However, mitochondria and zymogen contents are direct targets of damage in acute pancreatitis. Cellular survival depends on the recovering possibility of mitochondrial function and efficient clearance of damaged mitochondria. This work aimed to analyze mitochondrial dynamics and function during selective autophagy in pancreatic acinar cells during mild experimental pancreatitis in rats. Also, using a cell model under the hyperstimulation of the G-coupled receptor for CCK (CCK-R), we aimed to investigate the mechanisms involved in these processes in the context of zymophagy. We found that during acute pancreatitis, mitochondrial O consumption and ATP production significantly decreased early after induction of acute pancreatitis, with a consequent decrease in the ATP/O ratio. Mitochondrial dysfunction was accompanied by changes in mitochondrial dynamics evidenced by optic atrophy 1 (OPA-1) and dynamin-related protein 1 (DRP-1) differential expression and ultrastructural features of mitochondrial fission, mitochondrial elongation, and mitophagy during the acute phase of experimental mild pancreatitis in rats. Mitophagy was also evaluated by confocal assay after transfection with the pMITO-RFP-GFP plasmid that specifically labels autophagic degradation of mitochondria and the expression and redistribution of the ubiquitin ligase Parkin1. Moreover, we report for the first time that vacuole membrane protein-1 (VMP1) is involved and required in the mitophagy process during acute pancreatitis, observable not only by repositioning around specific mitochondrial populations, but also by detection of mitochondria in autophagosomes specifically isolated with anti-VMP1 antibodies as well. Also, VMP1 downregulation avoided mitochondrial degradation confirming that VMP1 expression is required for mitophagy during acute pancreatitis. In conclusion, we identified a novel DRP1-Parkin1-VMP1 selective autophagy pathway, which mediates the selective degradation of damaged mitochondria by mitophagy in acute pancreatitis. The understanding of the molecular mechanisms involved to restore mitochondrial function, such as mitochondrial dynamics and mitophagy, could be relevant in the development of novel therapeutic strategies in acute pancreatitis.
线粒体自噬和酶原自噬是急性胰腺炎早期诱导的选择性自噬途径，这可能解释了该疾病较轻、自限性且更常见的临床表现。在轻症疾病期间触发的细胞修复机制需要足够的线粒体生物能量学。然而，线粒体和酶原含量是急性胰腺炎中损伤的直接靶点。细胞存活取决于线粒体功能的恢复可能性以及受损线粒体的有效清除。这项工作旨在分析大鼠轻症实验性胰腺炎期间胰腺腺泡细胞选择性自噬过程中的线粒体动力学和功能。此外，使用一种在胆囊收缩素G偶联受体（CCK-R）过度刺激下的细胞模型，我们旨在研究酶原自噬背景下这些过程所涉及的机制。我们发现，在急性胰腺炎期间，急性胰腺炎诱导后早期线粒体氧消耗和ATP生成显著降低，ATP/O比值随之下降。线粒体功能障碍伴随着线粒体动力学的变化，这在大鼠轻症实验性胰腺炎急性期通过视神经萎缩蛋白1（OPA-1）和动力相关蛋白1（DRP-1）的差异表达以及线粒体分裂、线粒体延长和线粒体自噬的超微结构特征得以证明。在用特异性标记线粒体自噬降解的pMITO-RFP-GFP质粒转染后，通过共聚焦分析评估线粒体自噬以及泛素连接酶Parkin1的表达和重新分布。此外，我们首次报道液泡膜蛋白-1（VMP1）在急性胰腺炎期间的线粒体自噬过程中发挥作用且是必需的，这不仅可通过其在特定线粒体群体周围的重新定位观察到，还可通过用抗VMP1抗体特异性分离的自噬体中线粒体的检测观察到。而且，VMP1下调可避免线粒体降解，证实VMP1表达是急性胰腺炎期间线粒体自噬所必需的。总之，我们鉴定出一条新的DRP1-Parkin1-VMP1选择性自噬途径，其在急性胰腺炎中通过线粒体自噬介导受损线粒体的选择性降解。对恢复线粒体功能所涉及的分子机制（如线粒体动力学和线粒体自噬）的理解可能与急性胰腺炎新治疗策略的开发相关。
