The role of Ca² influx in endocytic vacuole formation in pancreatic acinar cells.

Voronina, Svetlana; Collier, David; Chvanov, Michael; Middlehurst, Ben; Beckett, Alison J.; Prior, Ian A.; Criddle, David N.; Begg, Malcolm; Katsuhiko Mikoshiba; Sutton, Robert; Tepikin, Alexei V.

The inducers of acute pancreatitis trigger a prolonged increase in the cytosolic Ca2 concentration ([Ca2 ]c), which is responsible for the damage to and eventual death of pancreatic acinar cells. Vacuolization is an important indicator of pancreatic acinar cell damage. Furthermore, activation of trypsinogen occurs in the endocytic vacuoles; therefore the vacuoles can be considered as 'initiating' organelles in the development of the cell injury. In the present study, we investigated the relationship between the formation of endocytic vacuoles and Ca2 influx developed in response to the inducers of acute pancreatitis [bile acid taurolithocholic acid 3-sulfate (TLC-S) and supramaximal concentration of cholecystokinin-8 (CCK)]. We found that the inhibitor of STIM (stromal interaction molecule)/Orai channels, GSK-7975A, effectively suppressed both the Ca2 influx (stimulated by inducers of pancreatitis) and the formation of endocytic vacuoles. Cell death induced by TLCS or CCK was also inhibited by GSK-7975A.We documented the formation of endocytic vacuoles in response to store-operated Ca2 entry (SOCE) induced by thapsigargin [TG; inhibitor of sarcoplasmic/endoplasmic reticulum (ER) Ca2 pumps] and observed strong inhibition of TG-induced vacuole formation by GSK-7975A. Finally, we found that structurally-unrelated inhibitors of calpain suppress formation of endocytic vacuoles, suggesting that this Ca2 -dependent protease is a mediator between Ca2 elevation and endocytic vacuole formation.

PANCREATIC acinar cells; CALCIUM ions; TRYPSINOGEN; ENDOCYTOSIS; CELL death; ORGANELLES; THAPSIGARGIN; ENDOPLASMIC reticulum

Biochemical Journal, 2015, Vol 465, Issue 3, p405

0264-6021

Academic Journal

10.1042/BJ20140398