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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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Dopamine D(2) Receptor-Mediated Heterologous Sensitization of AC5 Requires Signalosome Assembly

Karin F K Ejendal1, Carmen W Dessauer, Terence E Hébert

  • 1Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907-2051, USA.

Journal of Signal Transduction
|April 24, 2012
PubMed

Insights

Persistent activation of D2 dopamine receptors leads to enhanced adenylyl cyclase activity, a process known as heterologous sensitization. This study reveals Gα(s) interactions with adenylyl cyclase 5 (AC5) are crucial for this sensitization.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Biochemistry

Background:

  • Chronic activation of dopamine receptors affects central nervous system disorders.
  • D2 dopamine receptors, coupled to Gα(i), typically inhibit adenylyl cyclase acutely.
  • Persistent activation results in heterologous sensitization, enhancing adenylyl cyclase activity.

Purpose of the Study:

  • To elucidate the mechanism of Gα(s) dependency in D(2)-induced heterologous sensitization of adenylyl cyclase 5 (AC5).
  • To investigate the roles of Gα(s) palmitoylation and Gβγ interactions in this sensitization process.

Main Methods:

  • Expression of Gα(s) mutants in Gα(s)-deficient cells (Gnas(E2-/E2-)).
  • Assessment of adenylyl cyclase 5 (AC5) sensitization.
  • Coexpression of βARKct-CD8 or Sar1(H79G) to block sensitization pathways.

Main Results:

  • Gα(s)-palmitoylation and direct Gα(s)-Gβγ interactions were not required for AC5 sensitization.
  • Coexpression of βARKct-CD8 or Sar1(H79G) inhibited heterologous sensitization.
  • Findings suggest a direct role for Gα(s)-AC5 interactions in sensitization.

Conclusions:

  • Gα(s) interactions with AC5 are critical for heterologous sensitization.
  • Gβγ may play an indirect role, potentially in signalosome assembly, for AC5 sensitization.
  • Understanding these pathways is vital for addressing CNS disorders involving dopamine signaling.

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