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Updated: Jun 1, 2026
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Preparation of Pancreatic Acinar Cells for the Purpose of Calcium Imaging, Cell Injury Measurements, and Adenoviral Infection
Published on: July 5, 2013
Expression, localization, and functional role for synaptotagmins in pancreatic acinar cells
Michelle A Falkowski1, Diana D H Thomas, Scott W Messenger
1Department of Nutritional Sciences, University of Wisconsin-Madison, USA.
Summary
Pancreatic acinar cells use synaptotagmin 1 to regulate secretion. This protein is inserted into the apical membrane during zymogen granule fusion, indicating its crucial role in exocytosis.
Area of Science:
- Cell biology
- Gastroenterology
- Molecular biology
Background:
- Intracellular calcium (Ca2+) changes are crucial for pancreatic acinar secretion.
- Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes regulate zymogen granule (ZG) exocytosis.
- Synaptotagmins, a family of SNARE-associated proteins, regulate Ca2+-stimulated exocytosis in nerve and endocrine cells.
Purpose of the Study:
- To investigate the potential role of synaptotagmins in pancreatic acinar secretion.
- To determine which synaptotagmin isoforms are expressed in pancreatic acini.
- To elucidate the specific functions of synaptotagmin 1 and 3 in acinar cells.
Main Methods:
- Reverse transcription polymerase chain reaction (RT-PCR) to detect synaptotagmin mRNA expression.
- Immunoblotting and immunofluorescence to localize synaptotagmin proteins.
- Functional assays using synaptotagmin C2AB domain peptides in permeabilized acini.
- Antibody-based detection of externalized synaptotagmin 1 on intact acini.
Main Results:
- Synaptotagmin isoforms 1, 3, 6, and 7 were detected in isolated pancreatic acini.
- Synaptotagmin 1 was localized in the apical cytoplasm and ZG fractions, colocalizing with vesicle-associated membrane protein 2.
- Synaptotagmin 3 was found in membrane fractions and colocalized with an endolysosomal marker.
- Introduction of the synaptotagmin 1 C2AB domain inhibited Ca2+-dependent exocytosis by 35%, while synaptotagmin 3 constructs had no effect.
- Externalized synaptotagmin 1 was detected on the apical membrane and its immunoreactivity increased fourfold after CCK-8 stimulation.
Conclusions:
- Pancreatic acini express synaptotagmin 1, which plays a functional role in regulating ZG exocytosis.
- Synaptotagmin 1 is inserted into the apical membrane during ZG fusion, confirming its involvement in secretion.
- Synaptotagmin 3 appears to be involved in endolysosomal membrane trafficking rather than exocytosis.
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