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Targeted protein kinase A and PP-2B regulate insulin secretion through reversible phosphorylation
L B Lester1, M C Faux, J B Nauert
1Division of Endocrinology , Oregon Health Sciences University, Portland, Oregon 97201, USA. lesterl@ohsu.edu
Endocrinology
|February 22, 2001
Summary
The study reveals that cAMP-dependent protein kinase (PKA) and PP-2B phosphatase activities are coordinated to regulate insulin secretion. AKAP proteins may anchor these enzymes, influencing insulin release.
Area of Science:
- Cellular signaling
- Molecular biology
- Endocrinology
Background:
- Protein kinases and phosphatases are crucial in signal integration for insulin secretion.
- The interplay between cAMP-dependent protein kinase (PKA) and PP-2B phosphatase in regulating insulin release is not fully understood.
Purpose of the Study:
- To investigate the coordinated regulation of insulin secretion by PKA and PP-2B.
- To explore the role of AKAP proteins in mediating the interaction between PKA and PP-2B.
Main Methods:
- Utilized rat islets and RINm5F cells to study insulin secretion.
- Employed FK506 to transiently inhibit PP-2B activity.
- Investigated protein dephosphorylation and enzyme activity following forskolin treatment.
- Examined the effects of AKAP79 expression on insulin secretion and PP-2B activity.
Main Results:
- Transient PP-2B inhibition with FK506 enhanced forskolin-stimulated insulin secretion.
- Forskolin treatment led to synapsin 1 dephosphorylation and increased PP-2B activity.
- Expression of AKAP79 in RINm5F cells reduced insulin secretion and PP-2B activity, causing FK506 insensitivity.
Conclusions:
- PKA and PP-2B activities are coordinated to regulate insulin secretion.
- AKAP proteins may anchor PKA and PP-2B, forming a signal transduction complex.
- This complex likely controls reversible phosphorylation events critical for insulin secretion regulation.