Characterization of ryanodine receptor type 1 single channel activity using "on-nucleus" patch clamp

Area of Science:

• Cellular physiology
• Ion channel biophysics
• Molecular pharmacology

Background:

• Ryanodine receptor type 1 (RyR1) plays a crucial role in calcium signaling and muscle contraction.
• Understanding RyR1 biophysical and pharmacological properties is essential for disease research.
• Existing methods for studying RyR1 in native membranes have limitations.

Purpose of the Study:

• To describe the biophysical and pharmacological properties of RyR1 expressed in a native membrane.
• To establish and validate an experimental platform for monitoring RyR channel single-channel properties.
• To investigate the direct modulation of RyR1 by specific pharmacological agents.

Main Methods:

• Established a stable HEK-RyR1 cell line expressing rabbit RyR1 using the FLP-in 293 cell system.
• Utilized the on-nucleus patch clamp technique to record RyR1 channel activity in isolated nuclei.
• Confirmed RyR1 expression via immunoblotting and immunocytochemistry.

Main Results:

• RyR1 agonists (4-CMC, caffeine) activated Ca(2+) release, inhibited by ryanodine.
• Patch clamp revealed a large conductance cation channel consistent with RyR1.
• Caffeine enhanced channel activity, while ryanodine induced a subconductance state.
• cADPr, NAADP, and dantrolene did not directly modulate RyR1 activity.

Conclusions:

• The study successfully describes the properties of RyR1 in a native membrane environment.
• The developed experimental platform enables monitoring of single RyR channel properties.
• This system holds potential for characterizing RyR mutations and modulation mechanisms.