Mechanical Stretch Redefines Membrane Gαq-Calcium Signaling Complexes

Area of Science:

• Cell Biology
• Biophysics
• Physiology

Background:

• Muscle cells experience mechanical stretch.
• The effect of stretch on membrane domain organization and GPCR-Gαq signaling is not well understood.
• GPCR-Gαq signaling increases intracellular calcium, particularly when localized in caveolae.

Purpose of the Study:

• To investigate how mechanical stretch affects GPCR-Gαq protein signaling in muscle cells.
• To determine the role of caveolae in mediating stretch-induced calcium signaling.
• To explore the impact of different stretch types (static vs. oscillating) on cellular calcium levels.

Main Methods:

• Utilized rat aortic smooth muscle A10 cells.
• Applied static and oscillating mechanical stretch.
• Employed silencing RNA technology to reduce caveolae levels.
• Assessed cellular calcium using a calcium indicator.
• Examined caveolae configuration changes using monoclonal caveolin antibodies.

Main Results:

• Static stretch (1-5%) did not perturb basal cellular calcium but altered bradykinin type 2 receptor (B2R)/Gαq pathway signaling, causing calcium loss.
• Oscillating stretch enhanced calcium levels.
• Stretch altered caveolae configuration, as indicated by antibody binding changes.
• Reduced caveolae levels impaired cell survival under stretch cycles.
• Stretch-induced calcium signal modulation is dependent on stretch type and caveolae abundance.

Conclusions:

• Mechanical stretch significantly influences GPCR-Gαq signaling in muscle cells.
• Caveolae organization and abundance are critical for mediating the cellular response to mechanical stretch.
• The type of mechanical stimulus dictates the direction of calcium signal modulation.