Department of Gastroenterology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Shanghai Key Laboratory of Pancreatic Disease, Institute of Pancreatic Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Am J Physiol Gastrointest Liver Physiol. 2020 Jun 1;318(6):G1000-G1012. doi: 10.1152/ajpgi.00354.2019. Epub 2020 Apr 20.
Trypsinogen activation is the hallmark of acute pancreatitis (AP) independent of intra-acinar NF-κB activation and inflammation. We previously found that dopamine (DA) receptor 2 (DRD2) activation controls inflammation during AP via PP2A-dependent NF-κB activation. In this study, we sought to examine whether DRD2 signaling mediates trypsinogen activation and the underlying mechanisms. Pancreatic acinar cells were stimulated with cholecystokinin-8 in vitro. AP was induced by intraperitoneal injections of caerulein and LPS or l-arginine. Pancreatitis severity was assessed biochemically and histologically. We found that activation of DRD2 by quinpirole, a potent DRD2 agonist, resulted in the reduction of trypsinogen activation and the upregulation of HSP70 in vitro and in vivo. Mechanistically, we found that quinpirole induced dephosphorylation of heat shock factor 1 (HSF1), a master transcription factor of HSP70, leading to increased nuclear translocation of HSF1 in a PP2A-dependent pathway. Furthermore, DRD2 activation restored lysosomal pH and, therefore, maintained lysosomal cathepsin B activity in a HSP70-dependent manner. VER155008, a potent HSP70 antagonist, abolished the protective effects observed with DRD2 activation in vitro and in two experimental models of AP. Our data showed that besides controlling NF-κB activation, DRD2 activation prevented trypsinogen activation during acute pancreatitis via PP2A-dependent upregulation of HSP70 and further support that DRD2 agonist could be a promising therapeutic strategy for treating AP. The current study demonstrated that activation of DRD2 by quinpirole protects against trypsinogen activation in the in vitro and in vivo setting of acute pancreatitis by upregulating HSP70 and restoring lysosomal degradation via a PP2A-dependent manner, therefore leading to reduced pancreatic injury. These findings provide a new mechanistic insight on the protective effect of DRD2 activation in acute pancreatitis.
胰酶原激活是急性胰腺炎 (AP) 的标志，与腺泡内 NF-κB 激活和炎症无关。我们之前发现，多巴胺 (DA) 受体 2 (DRD2) 的激活通过 PP2A 依赖性 NF-κB 激活控制 AP 中的炎症。在这项研究中，我们试图研究 DRD2 信号是否介导胰酶原激活及其潜在机制。在体外用胆囊收缩素-8 刺激胰腺腺泡细胞。通过腹腔内注射亮抑蛋白酶原和 LPS 或 l-精氨酸诱导 AP。通过生化和组织学评估胰腺炎严重程度。我们发现，DRD2 激动剂喹吡罗尔激活 DRD2 可减少胰酶原激活，并在体外和体内上调 HSP70。从机制上讲，我们发现喹吡罗尔诱导 HSP70 的主要转录因子热休克因子 1 (HSF1) 的去磷酸化，导致 HSP70 依赖性的 HSF1 核易位增加。此外，DRD2 的激活以 HSP70 依赖的方式恢复溶酶体 pH 值，从而维持溶酶体组织蛋白酶 B 的活性。强效 HSP70 拮抗剂 VER155008 消除了 DRD2 激活在体外和两种 AP 实验模型中观察到的保护作用。我们的数据表明，除了控制 NF-κB 激活外，DRD2 激活还通过 PP2A 依赖性 HSP70 上调防止急性胰腺炎期间的胰酶原激活，并进一步支持 DRD2 激动剂可能是治疗 AP 的一种有前途的治疗策略。本研究表明，喹吡罗尔激活 DRD2 通过上调 HSP70 并通过 PP2A 依赖性方式恢复溶酶体降解，从而减少胰腺损伤，在急性胰腺炎的体外和体内环境中保护胰酶原免于激活。这些发现为 DRD2 激活在急性胰腺炎中的保护作用提供了新的机制见解。
