Regulating neuronal excitability: The role of -palmitoylation in Na1.7 activity and voltage sensitivity.

-palmitoylation, a reversible lipid post-translational modification, regulates the functions of numerous proteins. Voltage-gated sodium channels (Nas), pivotal in action potential generation and propagation within cardiac cells and sensory neurons, can be directly or indirectly modulated by -palmitoylation, impacting channel trafficking and function. However, the role of -palmitoylation in modulating Na1.7, a significant contributor to pain pathophysiology, has remained unexplored. Here, we addressed this knowledge gap by investigating if -palmitoylation influences Na1.7 channel function. Acyl-biotin exchange assays demonstrated that heterologously expressed Na1.7 channels are modified by -palmitoylation. Blocking -palmitoylation with 2-bromopalmitate resulted in reduced Na1.7 current density and hyperpolarized steady-state inactivation. We identified two -palmitoylation sites within Na1.7, both located in the second intracellular loop, which regulated different properties of the channel. Specifically, -palmitoylation of cysteine 1126 enhanced Na1.7 current density, while -palmitoylation of cysteine 1152 modulated voltage-dependent inactivation. Blocking -palmitoylation altered excitability of rat dorsal root ganglion neurons. Lastly, in human sensory neurons, Na1.7 undergoes -palmitoylation, and the attenuation of this post-translational modification results in alterations in the voltage-dependence of activation, leading to decreased neuronal excitability. Our data show, for the first time, that -palmitoylation affects Na1.7 channels, exerting regulatory control over their activity and, consequently, impacting rodent and human sensory neuron excitability. These findings provide a foundation for future pharmacological studies, potentially uncovering novel therapeutic avenues in the modulation of -palmitoylation for Na1.7 channels.