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Drug-induced Sensitization of Adenylyl Cyclase: Assay Streamlining and Miniaturization for Small Molecule and siRNA Screening Applications
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Protein kinase C inhibits adenylyl cyclase type VI activity during desensitization of the A2a-adenosine

H L Lai1, T H Yang, R O Messing

  • 1Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.

The Journal of Biological Chemistry
|February 21, 1997
PubMed

Insights

Protein kinase C (PKC) inhibits adenylyl cyclase type VI (AC6) activity during A2a adenosine receptor desensitization. This calcium-independent PKC regulation fine-tunes cAMP synthesis in PC12 cells.

Area of Science:

  • Cellular signaling
  • Molecular pharmacology
  • Neuroscience

Background:

  • Adenylyl cyclase type VI (AC6) activity is suppressed during A2a adenosine receptor desensitization in PC12 cells.
  • Previous studies suggested phosphorylation mediates this suppression.

Purpose of the Study:

  • To identify the kinase responsible for AC6 phosphorylation and inhibition during A2a desensitization.
  • To elucidate the role of protein kinase C (PKC) in regulating AC6 activity.

Main Methods:

  • Inhibition of PKC using multiple methods.
  • Direct phosphorylation and inhibition assays using purified PKC and recombinant AC6.
  • Overexpression of PKC isoforms (PKCdelta, PKCepsilon) in PC12 cells.
  • Measurement of Ca2+-independent PKC activity.

Main Results:

  • PKC inhibition blocked AC6 suppression during A2a desensitization.
  • Purified PKC directly phosphorylated and inhibited AC6.
  • Overexpression of PKC isoforms reduced AC6 activity.
  • A2a receptor stimulation increased Ca2+-independent PKC activity.

Conclusions:

  • A calcium-independent PKC isoform is responsible for inhibiting AC6 activity during A2a desensitization in PC12 cells.
  • This pathway represents a novel mechanism for regulating cAMP synthesis.
  • Independent regulation by PKC and Ca2+ allows fine-tuning of signaling pathways.

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