Plasma membrane-endoplasmic reticulum coupling probed with genetically encoded voltage sensors.

Area of Science:

• Cell Biology
• Neuroscience
• Biophysics

Background:

• The endoplasmic reticulum (ER) is a vital organelle with a complex membrane potential.
• Studying ER membrane potential is experimentally challenging, limiting understanding of its functions.
• Voltage gradients across the ER membrane influence ion flux and cellular processes.

Purpose of the Study:

• To develop novel optical probes for measuring ER membrane potential.
• To investigate the electrical coupling between the plasma membrane and the ER.
• To provide tools for assessing the impact of ER voltage on cellular function.

Main Methods:

• Genetically encoded voltage sensors (hybrid voltage sensor family) were engineered.
• Probes were targeted to the ER using specific protein motifs (Sec61β, cytochrome P450, cytochrome b5 type A).
• Patch-clamp fluorometry was used to record ER membrane potential changes.

Main Results:

• New optical probes successfully visualized ER membrane potential.
• Plasma membrane voltage changes were shown to elicit voltage changes at the ER membrane.
• Evidence suggests direct electrical coupling between the plasma membrane and ER via membrane contacts.

Conclusions:

• The developed probes offer a powerful method for imaging ER voltage.
• Rapid electrical coupling between plasma membrane and ER regulates ER function, especially in excitable cells.
• These findings advance our understanding of ER's role in cellular electrophysiology.