Abstract
INTRODUCTION: Photopharmacology has recently emerged as a strategy for high-precision modulation of immune functions. Here we explored efficiency and specificity of interventions based on light-induced TRPC6 activation in the RBL-2H3 mast cell model. RESULTS: Expression of TRPC6 fusion constructs in RBL-2H3 allowed for generation of temporally well-defined, cytosolic Ca(2+) transients in response to photoisomerization of the TRPC6 actuator OptoBI-1. These Ca(2+) signals originated exclusively from Ca(2+) entry across the plasma membrane. Transient TRPC6 activation in response to UV pulses of 1s duration (3 mW/cm(2)) just exceeded the detection threshold for monitoring of Ca(2+) signals within the TRPC6-jRGECO1a nano/microdomain. Activation of TRPC6-jRGECO1a by single, 1s UV light pulses was sufficient to trigger maximal cytosolic to nuclear translocation of NFATc1 (NFAT2) equivalent to the level generated by ionomycin (1 µM)-induced Ca(2+) entry. TRPC6 photopharmacology enabled control over NFATc1 nuclear translocation devoid of any detectable degranulation responses. CONCLUSION: We report here the exceptionally efficient and specific modulation of mast cell activity by TRPC6 photopharmacology.