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Mareninova OA, Jia W, Gretler SR, Holthaus CL, Thomas DDH, Pimienta M, Dillon DL, Gukovskaya AS, Gukovsky I, Groblewski GE. Transgenic expression of GFP-LC3 perturbs autophagy in exocrine pancreas and acute pancreatitis responses in mice. Autophagy 2020; 16:2084-2097. [PMID: 31942816 PMCID: PMC7595606 DOI: 10.1080/15548627.2020.1715047] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 12/25/2019] [Accepted: 01/08/2020] [Indexed: 12/20/2022] Open
Abstract
Pancreatitis is a common, sometimes fatal, disease of exocrine pancreas, initiated by damaged acinar cells. Recent studies implicate disordered macroautophagy/autophagy in pancreatitis pathogenesis. ATG8/LC3 protein is critical for autophagosome formation and a widely used marker of autophagic vacuoles. Transgenic GFP-LC3 mice are a valuable tool to investigate autophagy ; however, comparison of homeostatic and disease responses between GFP-LC3 and wild-type (WT) mice has not been done. We examined the effects of GFP-LC3 expression on autophagy, acinar cell function, and experimental pancreatitis. Unexpectedly, GFP-LC3 expression markedly increased endogenous LC3-II level in pancreas, caused by downregulation of ATG4B, the protease that deconjugates/delipidates LC3-II. By contrast, GFP-LC3 expression had lesser or no effect on autophagy in liver, lung and spleen. Autophagic flux analysis showed that autophagosome formation in GFP-LC3 acinar cells increased 3-fold but was not fully counterbalanced by increased autophagic degradation. Acinar cell (ex vivo) pancreatitis inhibited autophagic flux in WT and essentially blocked it in GFP-LC3 cells. In vivo pancreatitis caused autophagy impairment in WT mice, manifest by upregulation of LC3-II and SQSTM1/p62, increased number and size of autophagic vacuoles, and decreased level of TFEB, all of which were exacerbated in GFP-LC3 mice. GFP-LC3 expression affected key pancreatitis responses; most dramatically, it worsened increases in serum AMY (amylase), a diagnostic marker of acute pancreatitis, in several mouse models. The results emphasize physiological importance of autophagy for acinar cell function, demonstrate organ-specific effects of GFP-LC3 expression, and indicate that application of GFP-LC3 mice in disease models should be done with caution.Abbreviations: AP: acute pancreatitis; Arg-AP: L-arginine-induced acute pancreatitis; ATG: autophagy-related (protein); AVs: autophagic vacuoles; CCK: cholecystokinin-8; CDE: choline-deficient, D,L-ethionine supplemented diet; CER: caerulein (ortholog of CCK); CTSB: cathepsin B; CTSD: cathepsin D; CTSL: cathepsin L; ER: endoplasmic reticulum; LAMP: lysosomal-associated membrane protein; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; TEM: transmission electron microscopy; TFEB: transcription factor EB; ZG: zymogen granule(s).
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Affiliation(s)
- Olga A. Mareninova
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Pancreatic Research Group, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Wenzhuo Jia
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Department of General Surgery, Beijing Hospital, National Centre of Gerontology, Beijing, China
| | - Sophie R. Gretler
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Pancreatic Research Group, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Conner L. Holthaus
- Department of Nutritional Sciences, University of Wisconsin, Madison, WI, USA
| | - Diana D. H. Thomas
- Department of Nutritional Sciences, University of Wisconsin, Madison, WI, USA
| | - Michael Pimienta
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Dustin L. Dillon
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Pancreatic Research Group, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Anna S. Gukovskaya
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Pancreatic Research Group, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Ilya Gukovsky
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Pancreatic Research Group, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Guy E. Groblewski
- Department of Nutritional Sciences, University of Wisconsin, Madison, WI, USA
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Messenger SW, Jones EK, Holthaus CL, Thomas DDH, Cooley MM, Byrne JA, Mareninova OA, Gukovskaya AS, Groblewski GE. Acute acinar pancreatitis blocks vesicle-associated membrane protein 8 (VAMP8)-dependent secretion, resulting in intracellular trypsin accumulation. J Biol Chem 2017; 292:7828-7839. [PMID: 28242757 DOI: 10.1074/jbc.m117.781815] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Indexed: 11/06/2022] Open
Abstract
Zymogen secretory granules in pancreatic acinar cells express two vesicle-associated membrane proteins (VAMP), VAMP2 and -8, each controlling 50% of stimulated secretion. Analysis of secretion kinetics identified a first phase (0-2 min) mediated by VAMP2 and second (2-10 min) and third phases (10-30 min) mediated by VAMP8. Induction of acinar pancreatitis by supramaximal cholecystokinin (CCK-8) stimulation inhibits VAMP8-mediated mid- and late-phase but not VAMP2-mediated early-phase secretion. Elevation of cAMP during supramaximal CCK-8 mitigates third-phase secretory inhibition and acinar damage caused by the accumulation of prematurely activated trypsin. VAMP8-/- acini are resistant to secretory inhibition by supramaximal CCK-8, and despite a 4.5-fold increase in total cellular trypsinogen levels, are fully protected from intracellular trypsin accumulation and acinar damage. VAMP8-mediated secretion is dependent on expression of the early endosomal proteins Rab5, D52, and EEA1. Supramaximal CCK-8 (60 min) caused a 60% reduction in the expression of D52 followed by Rab5 and EEA1 in isolated acini and in in vivo The loss of D52 occurred as a consequence of its entry into autophagic vacuoles and was blocked by lysosomal cathepsin B and L inhibition. Accordingly, adenoviral overexpression of Rab5 or D52 enhanced secretion in response to supramaximal CCK-8 and prevented accumulation of activated trypsin. These data support that acute inhibition of VAMP8-mediated secretion during pancreatitis triggers intracellular trypsin accumulation and loss of the early endosomal compartment. Maintaining anterograde endosomal trafficking during pancreatitis maintains VAMP8-dependent secretion, thereby preventing accumulation of activated trypsin.
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Affiliation(s)
- Scott W Messenger
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Elaina K Jones
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Conner L Holthaus
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Diana D H Thomas
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Michelle M Cooley
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Jennifer A Byrne
- Molecular Oncology Laboratory, Children's Cancer Research Unit, The Children's Hospital at Westmead, New South Wales 2145, Australia, and
| | - Olga A Mareninova
- Department of Veterans Affairs Greater Los Angeles Healthcare System and UCLA, Los Angeles, California 90073
| | - Anna S Gukovskaya
- Department of Veterans Affairs Greater Los Angeles Healthcare System and UCLA, Los Angeles, California 90073
| | - Guy E Groblewski
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706,
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