Gelsolin inhibits autophagy by regulating actin depolymerization in pancreatic ductal epithelial cells in acute pancreatitis

Abstract

Gelsolin (GSN) can sever actin filaments associated with autophagy. This study investigated how GSN-regulated actin filaments control autophagy in pancreatic ductal epithelial cells (PDECs) in acute pancreatitis (AP). AP was produced in a rat model and PDECs using caerulein (CAE). Rat pancreatic duct tissue and HPDE6-C7 cells were extracted at 6, 12, 24, and 48 h after CAE treatment. HPDE6-C7 cells in the presence of CAE were treated with cytochalasin B (CB) or silenced for GSN for 24 h. Pancreatic histopathology and serum amylase levels were analyzed. Cellular ultrastructure and autophagy in PDECs were observed by transmission electron microscopy after 24 h of CAE treatment. The expression of GSN and autophagy markers LC3, P62, and LAMP2 was evaluated in PDECs by immunohistochemistry and western blotting. Actin filaments were observed microscopically. Amylase levels were highest at 6 h of AP, and pancreatic tissue damage increased over time. Mitochondrial vacuolization and autophagy were observed in PDECs. CAE increased GSN expression in these cells over time, increased the LC3-II/LC3-I ratio and LAMP2 expression at 24 and 6 h of treatment, respectively, and decreased P62 expression at all time points. CB treatment for 24 h decreased the LC3-II/LC3-I ratio and LAMP2 expression, increased P62 levels, but had no impact on GSN expression in CAE-treated PDECs. CAE induced actin depolymerization, and CB potentiated this effect. GSN silencing increased the LC3-II/LC3-I ratio and LAMP2 expression and reduced actin depolymerization in CAE-treated PDECs. GSN may inhibit autophagosome biogenesis and autophagosome-lysosome fusion by increasing actin depolymerization in PDECs in AP.

Mitochondrial calcium uniporter promotes mitophagy by regulating the PINK1/Parkin pathway in caerulein‑treated pancreatic ductal epithelial cells in vitro

“…Caerulein (CAE), an analog of cholecystokinin, has been widely used in vitro and in vivo to establish models of AP (22). Our previous studies found that the change in protein expression of autophagy marker, the apoptosis and pyroptosis protein expression of NLPR3, cleaved caspase-1 and cleaved caspase-3, the tight junction protein expression of ZO-1 and occludin in HPDE6-C7 cells treated with CAE in vitro were consistent with the rat model of AP (8,9,23,24). In the present study, it was hypothesized that MCU-associated mitochondrial Ca 2+ overload promotes mitophagy by regulating the PINK1/Parkin pathway in AP.…”

“…A reduction in the expression of TOMM20, which is a translocase of the outer mitochondrial membrane 20, indicates that impaired mitochondria may be removed by mitophagy. Our previous study found that CAE induced autophagy activation in the early stage of AP ( 8 ). RR mainly inhibits mitochondrial Ca 2+ and is recognized as a potent inhibitor of MCU.…”

“…PDECs play a key role in maintaining pancreatic homeostasis and avoiding substantial pancreatic inflammation (4)(5)(6). Studies have shown that transient high pressure, intracellular Ca 2+ overload, and cytoskeletal changes of PDECs can aggravate AP (7)(8)(9). In addition, PDECs are an important component of the pancreatic ductal mucosal barrier (PDMB) and play an important role in preventing abnormal activation of trypsinogen and the reflux of digestive enzymes to the pancreas (5,10).…”