Cathepsin B Activity Initiates Apoptosis via Digestive Protease Activation in Pancreatic Acinar Cells and Experimental Pancreatitis
Cathepsin B Activity Initiates Apoptosis via Digestive Protease Activation in Pancreatic Acinar Cells and Experimental Pancreatitis
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DOI：
10.1074/jbc.m116.718999
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发表时间：
2016-07-08
影响因子：
4.8
通讯作者：
Lerch, Markus M.
中科院分区：
文献类型：
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作者：
Sendler, Matthias;Maertin, Sandrina;Lerch, Markus M.
胰腺炎与胰腺中消化蛋白酶的过早激活有关。溶酶体水解酶组织蛋白酶B（CTSB）是一种已知的胰蛋白酶原激活剂，其缺失可降低实验性胰腺炎的疾病严重程度。本文研究了CTSB调节蛋白酶活化和细胞损伤的活化机制和亚细胞区室。胆囊收缩素（CCK）增加CTSB，组织蛋白酶L，胰蛋白酶，胰凝乳蛋白酶，和半胱天冬酶3在体内和体外的活性，并诱导CTSB重新分配到一个分泌囊泡丰富的馏分。CTSB蛋白和活性都没有重新分布到胞质溶胶中，其中CTSB抑制剂cystatin-B/C大量存在。CTSB的缺失减少和组织蛋白酶L的缺失增加细胞内胰蛋白酶的激活。CTSB缺失也消除了CCK诱导的caspase 3激活，凋亡诱导因子，以及X-连锁的凋亡抑制蛋白降解，但这些依赖于胰蛋白酶原激活通过CTSB。提高囊泡的pH值，而不是胰蛋白酶抑制，降低CTSB活性。胰蛋白酶抑制不影响肝细胞凋亡。CTSB的缺失影响细胞凋亡，但不影响坏死性腺泡细胞死亡。总之，胰腺炎中的CTSB在分泌、囊泡和酸性隔室中经历激活，在那里它激活胰蛋白酶原。在两种胰腺炎模型中，其缺失或抑制调节腺泡细胞凋亡，但不调节坏死。Caspase 3介导的细胞凋亡依赖于CTSB诱导的囊泡内胰蛋白酶原激活，而不是直接依赖于CTSB活性，并且这种机制是胰腺特异性的。
Pancreatitis is associated with premature activation of digestive proteases in the pancreas. The lysosomal hydrolase cathepsin B (CTSB) is a known activator of trypsinogen, and its deletion reduces disease severity in experimental pancreatitis. Here we studied the activation mechanism and subcellular compartment in which CTSB regulates protease activation and cellular injury. Cholecystokinin (CCK) increased the activity of CTSB, cathepsin L, trypsin, chymotrypsin, and caspase 3 in vivo and in vitro and induced redistribution of CTSB to a secretory vesicle-enriched fraction. Neither CTSB protein nor activity redistributed to the cytosol, where the CTSB inhibitors cystatin-B/C were abundantly present. Deletion of CTSB reduced and deletion of cathepsin L increased intracellular trypsin activation. CTSB deletion also abolished CCK-induced caspase 3 activation, apoptosis-inducing factor, as well as X-linked inhibitor of apoptosis protein degradation, but these depended on trypsinogen activation via CTSB. Raising the vesicular pH, but not trypsin inhibition, reduced CTSB activity. Trypsin inhibition did not affect apoptosis in hepatocytes. Deletion of CTSB affected apoptotic but not necrotic acinar cell death. In summary, CTSB in pancreatitis undergoes activation in a secretory, vesicular, and acidic compartment where it activates trypsinogen. Its deletion or inhibition regulates acinar cell apoptosis but not necrosis in two models of pancreatitis. Caspase 3-mediated apoptosis depends on intravesicular trypsinogen activation induced by CTSB, not CTSB activity directly, and this mechanism is pancreas-specific.