STIM1 functionally couples to transient receptor potential ankyrin 1 contributing to nociception

Abstract – STIM1 is a calcium sensor that can sense calcium level changes in the endoplasmic reticulum (ER) and respond to extracellular stimuli. We have reported that STIM1 is expressed in nociceptors. However, its functional significance remains unclear. Here, we show that STIM1 plays an important role in sensing cold, chemical, and noxious mechanical stimuli in both male and female mice. We found that activation of transient receptor potential ankyrin 1 (TRPA1) triggers ER Ca2+ release, STIM1 translocation, and store-operated Ca2+ entry (SOCE). Immunostaining and western blot results reveal that TRPA1 is expressed in the ER. In addition, STIM1 deficiency in the primary sensory neurons reduces cold-, allyl isothiocyanate (TRPA1 agonist)-, and bradykinin-induced Ca2+ entry and nociception. Moreover, intraplantar injection of thapsigargin, an ER Ca2+–ATPase inhibitor, evokes nociception and increases pain hypersensitivity, which is significantly attenuated in STIM1 conditional knockout or L3/L4 dorsal root ganglia STIM1 knockdown mice. Mechanistic studies demonstrate that STIM1-mediated SOCE increases neuronal excitability and decreases potassium channel Kv4-mediated outward currents in small to medium-sized dorsal root ganglion neurons, which is abolished by inhibiting the mitogen-activated protein kinase/extracellular receptor kinase pathway. Our findings demonstrate that STIM1 acts as a transducer of nociception and uncover a novel link between STIM1 and TRPA1_ER. Our study also provides new insights into TRPA1-mediated nociception.