Loss of acinar cell IKKα triggers spontaneous pancreatitis in mice
Ning Li, … , Jörg Kleeff, Michael Karin
Ning Li, … , Jörg Kleeff, Michael Karin
Published April 8, 2013
Citation Information: J Clin Invest. 2013;123(5):2231-2243. https://doi.org/10.1172/JCI64498.
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Research Article Gastroenterology

Loss of acinar cell IKKα triggers spontaneous pancreatitis in mice

Abstract

Chronic pancreatitis is an inflammatory disease that causes progressive destruction of pancreatic acinar cells and, ultimately, loss of pancreatic function. We investigated the role of IκB kinase α (IKKα) in pancreatic homeostasis. Pancreas-specific ablation of IKKα (IkkαΔpan) caused spontaneous and progressive acinar cell vacuolization and death, interstitial fibrosis, inflammation, and circulatory release of pancreatic enzymes, clinical signs resembling those of human chronic pancreatitis. Loss of pancreatic IKKα causes defective autophagic protein degradation, leading to accumulation of p62-mediated protein aggregates and enhanced oxidative and ER stress in acinar cells, but none of these effects is related to NF-κB. Pancreas-specific p62 ablation prevented ER and oxidative stresses and attenuated pancreatitis in IkkαΔpan mice, suggesting that cellular stress induced by p62 aggregates promotes development of pancreatitis. Importantly, downregulation of IKKα and accumulation of p62 aggregates were also observed in chronic human pancreatitis. Our studies demonstrate that IKKα, which may control autophagic protein degradation through its interaction with ATG16L2, plays a critical role in maintaining pancreatic acinar cell homeostasis, whose dysregulation promotes pancreatitis through p62 aggregate accumulation.

Authors

Ning Li, Xuefeng Wu, Ryan G. Holzer, Jun-Hee Lee, Jelena Todoric, Eek-Joong Park, Hisanobu Ogata, Anna S. Gukovskaya, Ilya Gukovsky, Donald P. Pizzo, Scott VandenBerg, David Tarin, Çiǧdem Atay, Melek C. Arkan, Thomas J. Deerinck, Jorge Moscat, Maria Diaz-Meco, David Dawson, Mert Erkan, Jörg Kleeff, Michael Karin

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Figure 5

IKKα interacts with ATG16L2.

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IKKα interacts with ATG16L2. (A) IKKα interacts with ATG16L2 in mammalia...
(A) IKKα interacts with ATG16L2 in mammalian cells. HEK293 cells were transfected with HA-IKKα and Flag-ATG16L2 constructs as indicated. After 36 hours, the cells were lysed and immunoprecipitated with Flag antibody. The disrupted immunoprecipitates and original lysates were subjected to IB analysis with the indicated antibodies. (B) Endogenous IKKα interacts with ATG16L2 in pancreatic acinar cells. Lysates of IkkαF/F and IkkαΔpan acinar cells were immunoprecipitated with the indicated antibodies. The disrupted immunocomplexes and original lysates were IB with the indicated antibodies. (C) Mouse acinar cells were treated with 0.5 μM thapsigargin (Tg) or 10 μg/ml tunicamycin (Tm) for 4 hours. Cells were then collected and lysed, and the interaction between IKKα and ATG16L2 was analyzed as above. (D) Freshly isolated WT mouse pancreatic acinar cells were transfected with control or Atg16l2 siRNA. After 60 hours, cell lysates were collected and expression of the indicated proteins was analyzed by IB. (E) ATG16L2 knockdown increases susceptibility to ER stress–induced cell death. Freshly isolated mouse acinar cells were transfected with control or Atg16l2 siRNA. After 2 days, cells were incubated with or without tunicamycin (10 μg/ml) for 24 hours. An MTT assay was performed to analyze cell viability. (F) ER stress–induced (10 μg/ml tunicamycin for 4 hours) autophagic flux in control and Atg16l2 siRNA–transfected acinar cells in the absence or presence of the autophagy inhibitor 3MA (10 mM). Results are shown as mean ± SEM. *P < 0.05; ***P < 0.001.