Cannabidiol inhibits Na_v channels through two distinct binding sites

Area of Science:

• Neuroscience
• Pharmacology
• Structural Biology

Background:

• Cannabidiol (CBD) is a non-psychoactive cannabis compound used for epilepsy and pain.
• The precise molecular targets of CBD's clinical effects remain largely unknown.
• CBD interacts with numerous proteins at high concentrations, necessitating target identification.

Purpose of the Study:

• To investigate the interaction between Cannabidiol (CBD) and sodium channel Na_v1.7.
• To determine the binding affinity and mechanism of CBD interaction with Na_v1.7.
• To elucidate the structural basis of CBD binding to Na_v1.7.

Main Methods:

• Electrophysiological experiments to assess CBD's effect on Na_v1.7 channel function.
• Cryo-electron microscopy (cryo-EM) to determine the structure of CBD bound to Na_v1.7.
• Site-directed mutagenesis to validate the identified CBD binding sites.

Main Results:

• CBD binds to Na_v1.7 channels in a state-dependent manner at sub-micromolar concentrations.
• CBD exhibits high affinity (approx. 50 nM dissociation constant) for the inactivated state of Na_v1.7.
• Cryo-EM revealed two distinct CBD binding sites on Na_v1.7, one near the pore and another stabilizing the inactivation gate.

Conclusions:

• CBD directly stabilizes the inactivated state of the Na_v1.7 channel.
• The identified binding sites are crucial for CBD's state-dependent interaction with Na_v1.7.
• Understanding these interactions may facilitate the development of novel therapeutics targeting Na_v1.7 for pain and epilepsy.