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Human TRPC5 channel activated by a multiplicity of signals in a single cell

Fanning Zeng1, Shang-Zhong Xu, Philippa K Jackson

  • 1School of Biomedical Sciences, University of Leeds, LS2 9JT, UK.

The Journal of Physiology
|July 16, 2004
PubMed

Insights

Human TRPC5 (transient receptor potential cation channel subfamily C member 5) exhibits multiple activation pathways, including receptor stimulation, extracellular ions, and intracellular calcium levels. Store depletion also activates this important ion channel.

Area of Science:

  • Molecular Biology
  • Ion Channel Physiology
  • Cell Signaling

Background:

  • TRPC5 (transient receptor potential cation channel subfamily C member 5) is a human ion channel cloned from a region of the X chromosome linked to mental retardation.
  • Understanding TRPC5 activation mechanisms is crucial for elucidating its physiological roles and potential involvement in neurological disorders.

Purpose of the Study:

  • To investigate the diverse activation mechanisms of human TRPC5.
  • To determine if TRPC5 activation is dependent on a single critical activator or multiple pathways.

Main Methods:

  • Electrophysiological recordings in single cells to assess TRPC5 activity.
  • Stimulation using carbachol (muscarinic receptor agonist), extracellular gadolinium, extracellular calcium, and intracellular calcium manipulation.
  • Utilized a store-depletion/calcium re-entry protocol to mimic endoplasmic reticulum calcium handling changes.

Main Results:

  • Human TRPC5 showed no basal activity but was activated by carbachol (receptor activation), extracellular gadolinium and calcium (external ionic activation), and elevated intracellular calcium (calcium activation).
  • TRPC5 was also activated by store depletion, suggesting a role for endoplasmic reticulum calcium handling.
  • These multiple activation mechanisms were observed in single cells, independent of expression levels or cellular context.

Conclusions:

  • Human TRPC5 is activated by a variety of stimuli, demonstrating a multi-faceted activation profile.
  • This lack of dependence on a single activator distinguishes TRPC5 from many other ion channels.
  • Changes in intracellular calcium handling, particularly by the endoplasmic reticulum, represent a significant activation pathway for TRPC5.

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