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Olfactory CNG channel desensitization by Ca2+/CaM via the B1b subunit affects response termination but not

Yijun Song1, Katherine D Cygnar, Botir Sagdullaev

  • 1Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.

Neuron
|May 10, 2008
PubMed

Insights

Calcium/calmodulin desensitization of olfactory cyclic nucleotide-gated (CNG) channels is crucial for terminating sensory neuron responses, not adaptation to repeated stimuli. This finding impacts our understanding of olfactory signal processing.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Sensory Physiology

Background:

  • Calcium (Ca2+)/calmodulin-mediated negative feedback regulates Ca2+-permeable ion channels.
  • This mechanism is believed to be key for olfactory sensory neuron (OSN) adaptation.
  • The cyclic nucleotide-gated (CNG) channel in OSNs is a primary target of this regulation.

Purpose of the Study:

  • To investigate the role of Ca2+/calmodulin desensitization in olfactory CNG channel function.
  • To determine the specific contribution of fast desensitization to OSN adaptation and response termination.

Main Methods:

  • Generated a mouse model with a mutation in the CNGB1b subunit of the CNG channel, conferring resistance to Ca2+/calmodulin desensitization.
  • Recorded OSN responses to olfactory stimuli in both wild-type and mutant mice.

Main Results:

  • Mutant OSNs exhibited normal adaptation to repeated odorant stimulation.
  • However, mutant OSNs displayed slower response termination and reduced olfactory information transmission to the olfactory bulb.
  • A reduced decline in response during sustained odorant exposure was also observed in mutant OSNs.

Conclusions:

  • Fast Ca2+/calmodulin desensitization of olfactory CNG channels plays a minor role in adaptation to recurring stimuli.
  • This desensitization mechanism is primarily important for the timely termination of OSN responses.
  • The findings necessitate a re-evaluation of the role of CNG channel desensitization in olfactory signal processing.

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