Dissecting individual current components of co-expressed human P2X1 and P2X7 receptors

Area of Science:

• Molecular biology
• Neuroscience
• Pharmacology

Background:

• Purinergic receptors, specifically P2X1 and P2X7 subtypes, are co-expressed in various cell types, including lymphocytes and epithelial cells.
• Understanding the functional interactions and electrophysiological behavior of co-expressed P2X receptor subtypes is crucial for cellular signaling research.
• Development of selective pharmacological tools is essential to differentiate the contributions of individual P2X receptor subtypes in native cellular environments.

Purpose of the Study:

• To investigate potential interactions between co-expressed human P2X1 (hP2X1) and human P2X7 (hP2X7) receptors.
• To evaluate the electrophysiological behavior of hP2X1 and hP2X7 receptors upon co-expression.
• To identify and assess pharmacological compounds for their ability to selectively activate or block individual hP2X receptor subtypes in co-expressing cells.

Main Methods:

• Co-expression of hP2X1 and hP2X7 receptors in Xenopus oocytes.
• Electrophysiological recordings to assess receptor activation, desensitization, deactivation, and recovery.
• Application of various agonists and antagonists, including benzoyl-benzoyl-ATP, ATP with NF449, alphabeta-methylene-ATP, oxidized-ATP, brilliant blue, and KN62, to differentiate receptor currents.

Main Results:

• Co-expression of hP2X1 and hP2X7 receptors did not alter their individual time courses of activation, desensitization, deactivation, or recovery.
• Benzoyl-benzoyl-ATP selectively activated hP2X7 currents without affecting hP2X1 currents.
• ATP in the presence of 1 microM NF449 selectively activated hP2X7 receptors.
• Low ATP concentrations (< 1 microM) or the addition of Mg2+ with higher ATP concentrations allowed for selective activation of hP2X1 currents in co-expressing cells.
• Reported selective agonists and antagonists (alphabeta-methylene-ATP, oxidized-ATP, brilliant blue, KN62) failed to effectively separate hP2X1 and hP2X7 receptor currents.

Conclusions:

• hP2X1 and hP2X7 receptors do not appear to mutually alter their electrophysiological properties when co-expressed.
• Specific pharmacological tools, such as benzoyl-benzoyl-ATP and NF449, can be used to selectively target hP2X7 receptors.
• Selective activation of hP2X1 receptors in co-expressing cells can be achieved using low ATP concentrations or Mg2+ supplementation.