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Expression and processing of prohormones in nonendocrine cells
C J Dickinson1, T Takeuchi, Y J Guo
1Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109.
The American Journal of Physiology
|March 1, 1993
Summary
Posttranslational processing of pancreatic polypeptide (PP) and gastrin requires storage in secretory granules. Nonendocrine cells lack these granules and cannot fully process these peptide hormones.
Area of Science:
- Molecular Biology
- Cell Biology
- Endocrinology
Background:
- Pancreatic polypeptide (PP) and gastrin are synthesized as precursors requiring posttranslational processing.
- This processing involves cleavage and amidation, typically occurring in secretory granules of endocrine cells.
Purpose of the Study:
- To investigate if nonendocrine cells possess mechanisms for prohormone processing.
- To determine if posttranslational processing of PP and gastrin occurs in nonendocrine cell lines.
Main Methods:
- Retroviral vector-mediated expression of human PP and gastrin cDNAs in fibroblast (psi-2, BHK), hepatocyte (Hepa), and exocrine pancreatic (AR42J) cell lines.
- Analysis of precursor processing and secretion in transfected cell lines.
Main Results:
- Fibroblast and hepatocyte cell lines secreted PP precursor constitutively with minimal intracellular storage and processing.
- Exocrine pancreatic AR42J cells successfully expressed, stored, and processed PP and gastrin, including C-terminal amidation.
- Nonendocrine cells showed limited posttranslational processing of the PP precursor.
Conclusions:
- Posttranslational processing of peptide hormone precursors like PP and gastrin is dependent on storage within secretory granules.
- Sorting mechanisms for endocrine and exocrine cells appear similar, highlighting the role of cellular compartmentalization in peptide processing.