Genetic Ablation of KLHL1 Alters CaV3.2 Expression in DRG Neurons and Mechanical Pain Transmission

Pain signaling is initiated by the detection of noxious stimuli through specialized primary nociceptors located in peripheral endings in dorsal root ganglion (DRG) neurons. Low voltage activated CaV3.2 T-type calcium channels play a major role in sensory perception in these neurons; silencing their activity with antisense RNA or genetic ablation results in anti-nociceptive, anti-hyperalgesic and anti-allodynic effects1-3. These channels are regulated by a plethora of proteins, including KLHL1, a neuronal actin binding protein that stabilizes channel activity by increasing its recycling back to the plasma membrane via recycling endosome activity. We explored the role of KLHL1 and its effects on CaV3.2 and mechanical peripheral pain transmission using the KLHL1 KO mouse model. Total T-type calcium current amplitude was smaller in KO DRG neurons (12 ± 2.03 pA/pF, n=18) compared to controls (18 ± 1.89 pA/pF, n=13; p<0.05), without significant changes in voltage dependence as expected in the absence of its modulator. Western blot analysis confirmed CaV3.2 but not CaV3.1 or CaV3.3 protein was significantly decreased. Interestingly, von Frey hair tests show paw withdrawal threshold in KO mice was increased. Our data establishes KLHL1 is a calcium channel regulator in DRG neurons, providing a novel target to control peripheral pain sensation. Downregulation of CaV3.2 activity by as little as ∼30% was sufficient to alter pain perception in the KO model.