Department of Internal Medicine, Section of Digestive Diseases, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
Am J Physiol Gastrointest Liver Physiol. 2012 Sep 15;303(6):G723-32. doi: 10.1152/ajpgi.00082.2012. Epub 2012 Jul 19.
The premature activation of digestive enzyme zymogens in the pancreatic acinar cell is an important initiating event in acute pancreatitis. We have previously demonstrated that vacuolar ATPase (vATPase) activity is required for zymogen activation. Adenosine monophosphate-activated protein kinase (AMPK) regulates vATPase function in kidney and epididymal clear cells. To determine whether AMPK could affect pancreatitis responses, its effects were first examined in a cellular model of pancreatitis, cerulein-hyperstimulated (100 nM) pancreatic acini. This treatment caused a prominent increase in trypsin and chymotrypsin activities. Pretreatment with AICAR or metformin (AMPK activators) or compound C (an AMPK inhibitor) reduced or increased cerulein-induced zymogen activation, respectively. The association of the vATPase E subunit with membranes, a marker of its activation, tended to be inversely related to AMPK activity (assessed by AICAR and compound C treatments). Cerulein treatment did not change AMPK (α and β) levels but did lead to an increase in its activation (phosphorylation of Thr172) and induced the time-dependent translocation of the enzyme to a Triton-insoluble compartment. Basal in vivo studies showed that AMPK was widely distributed between membrane and soluble fractions generated by differential centrifugation. After cerulein hyperstimulation, AMPK levels selectively decreased in fractions containing the highest levels of active zymogens. These studies suggest that AMPK activity has a protective role in the pancreatic acinar cell that inhibits zymogen activation in the basal state, and this AMPK effect is reduced during pancreatitis. Therapies that prevent the selective reduction of AMPK in compartments that support zymogen activation could reduce injury during pancreatitis.
消化酶酶原在胰腺腺泡细胞中的过早激活是急性胰腺炎的一个重要起始事件。我们之前已经证明，液泡型 ATP 酶（vATPase）的活性是酶原激活所必需的。腺苷单磷酸激活蛋白激酶（AMPK）调节肾脏和附睾透明细胞中的 vATPase 功能。为了确定 AMPK 是否能影响胰腺炎反应，首先在胰腺腺泡细胞的细胞模型中研究了其作用，用促胰液素（100 nM）刺激细胞。这种处理导致胰蛋白酶和糜蛋白酶活性明显增加。用 AICAR 或二甲双胍（AMPK 激活剂）或化合物 C（AMPK 抑制剂）预处理分别减少或增加了促胰液素诱导的酶原激活。vATPase E 亚基与膜的结合，是其激活的标志，与 AMPK 活性（通过 AICAR 和化合物 C 处理评估）呈负相关。促胰液素处理并不改变 AMPK（α和β）水平，但会导致其激活（Thr172 磷酸化）增加，并诱导酶向 Triton 不溶性隔室的时间依赖性易位。基础体内研究表明，AMPK 广泛分布在差速离心产生的膜和可溶部分之间。在促胰液素过度刺激后，AMPK 水平在含有最高水平活性酶原的部分中选择性降低。这些研究表明，AMPK 活性在胰腺腺泡细胞中具有保护作用，在基础状态下抑制酶原激活，而在胰腺炎期间这种 AMPK 作用会降低。防止在支持酶原激活的隔室中 AMPK 选择性减少的疗法可能会减少胰腺炎期间的损伤。
