ClC-3 regulates the excitability of nociceptive neurons and is involved in inflammatory processes within the spinal sensory pathway

Abstract

ClC-3 Cl–/H+ exchangers are expressed in multiple endosomal compartments and likely modify intra-endosomal pH and [Cl–] via the stoichiometrically coupled exchange of two Cl– ions and one H+. We studied pain perception in Clcn3–/– mice and found that ClC-3 not only modifies the electrical activity of peripheral nociceptors but is also involved in inflammatory processes in the spinal cord. We demonstrate that ClC-3 regulates the number of Nav and Kv ion channels in the plasma membrane of dorsal root ganglion (DRG) neurons and that these changes impair the age-dependent decline in excitability of sensory neurons. To distinguish the role of ClC-3 in Cl–/H+ exchange from its other functions in pain perception, we used mice homozygous for the E281Q ClC-3 point mutation (Clcn3E281Q/E281Q), which completely eliminates transport activity. Since ClC-3 forms heterodimers with ClC-4, we crossed these animals with Clcn4–/– to obtain mice completely lacking in ClC-3-associated endosomal chloride–proton transport. The electrical properties of Clcn3E281Q/E281Q/Clcn4–/– DRG neurons were similar to those of wild-type cells, indicating that the age-dependent adjustment of neuronal excitability is independent of ClC-3 transport activity. Both Clcn3–/– and Clcn3E281Q/E281Q/Clcn4–/– animals exhibited microglial activation in the spinal cord, demonstrating that competent ClC-3 transport is needed to maintain glial cell homeostasis. Our findings illustrate how reduced Cl–/H+ exchange contributes to inflammatory responses and demonstrate a role for ClC-3 in the homeostatic regulation of neuronal excitability beyond its function in endosomal ion balance.

An orally available Cav2.2 calcium channel inhibitor for the treatment of neuropathic pain

“…DRG neurons were cultured according to a previous protocol with minor changes (Sierra‐Marquez et al, 2022). In short, rats were anaesthetised with 5% isoflurane and euthanized by decapitation.…”

Genotype-phenotype correlation in CLCN4-related developmental and epileptic encephalopathy

“…They are found in endosomes owing to ClC-3 tra cking signals that allow them to be deployed in lysosomes, recycling endosomes, and Golgi apparatuses (Gentzsch et al, 2003;Guzman et al, 2015). Recently, experimental data from two independent animal models demonstrated the physiological relevance of this association, showing that the integrity of hippocampal and retinal structures depends on the endosomal presence of these transporters and their associated 2Cl -/H + exchange function (Weinert et al, 2020;Sierra-Marquez et al, 2022).…”