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Published on: June 15, 2013
Cholecystokinin-induced changes in polysome structure regulate protein synthesis in pancreas
1Department of Medicine, Veterans Administration Medical Center, San Diego, California.
Biochimica Et Biophysica Acta
|September 9, 1992
Summary
Cholecystokinin-octapeptide (CCK-OP) temporarily reduces digestive enzyme production by decreasing active ribosomes on the endoplasmic reticulum. This translational regulation is reversible, with synthesis returning to normal levels post-stimulation.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Physiology
Background:
- Digestive enzyme synthesis is crucial for nutrient absorption.
- Short-term hormonal regulation of enzyme production is not fully understood.
- Cholecystokinin-octapeptide (CCK-OP) is a key regulator of pancreatic function.
Purpose of the Study:
- To investigate the translational regulation of digestive enzyme synthesis by CCK-OP.
- To determine the mechanism by which CCK-OP affects protein synthesis in the pancreas.
- To examine the role of polysome size and mRNA levels in CCK-OP-mediated regulation.
Main Methods:
- Minced rabbit pancreas was used to study protein synthesis.
- [3H]leucine incorporation measured protein synthesis rates.
- Rough endoplasmic reticulum (RER)-bound polysome size was analyzed.
- Northern blot analysis assessed amylase and elastase mRNA levels.
Main Results:
- CCK-OP significantly decreased protein synthesis by approximately 50% at maximal concentrations.
- CCK-OP reversibly inhibited the synthesis of major digestive enzymes.
- No changes in amylase or elastase mRNA levels were observed.
- CCK-OP reduced the size of RER-bound polysomes, indicating decreased translational activity.
Conclusions:
- CCK-OP regulates digestive enzyme synthesis at the translational level.
- The inhibition is mediated by a reduction in actively translating ribosomes on the RER.
- This translational control mechanism is reversible and does not involve changes in mRNA abundance.
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