Mutational effects of Pannexin 1 R217H depend on the carboxyl-terminus

Area of Science:

• Molecular biology
• Cell physiology
• Ion channel function

Background:

• Pannexin 1 (Panx1) channels are crucial for ATP release, influencing purinergic signaling pathways.
• Extracellular ATP activates P2X and P2Y receptors, mediating various cellular responses.
• A disease-associated mutation, Arg-217-His (R217H), in Panx1 reduces channel function via an unclear mechanism.

Purpose of the Study:

• To investigate the mechanism by which the R217H mutation affects Panx1 channel function.
• To determine if the interaction between residue 217 and the carboxyl terminus (CT) is essential for Panx1 channel activity.

Main Methods:

• Utilized full-length and CT-truncated Panx1 constructs (Panx1-Δ386) with wild-type and R217H mutations.
• Assessed channel currents and cell death in cells expressing different Panx1 variants.
• Investigated the role of the intact carboxyl terminus in mediating the effects of the R217H mutation.

Main Results:

• The R217H mutation reduced currents in full-length Panx1 but not in CT-truncated Panx1-Δ386.
• Cells expressing Panx1-R217H exhibited reduced cell death upon P2X7 receptor activation compared to wild-type.
• Cell death was similar between Panx1-R217H-Δ386 and Panx1-Δ386, indicating the mutation's dependence on an intact CT.

Conclusions:

• The R217H mutation's impact on Panx1 channel function is dependent on an intact carboxyl terminus.
• The R217H mutation likely perturbs the conformational flexibility of the CT, leading to channel dysfunction.
• These findings elucidate a novel mechanism of Panx1 channel regulation and disease association.