Photopharmacology reveals high-specificity linkage of Ca entry at TRPC6 nanodomains to NFAT activation in mast cells.

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 transients in response to photoisomerization of the TRPC6 actuator OptoBI-1. These Ca signals originated exclusively from Ca entry across the plasma membrane. Transient TRPC6 activation in response to UV pulses of 1s duration (3 mW/cm) just exceeded the detection threshold for monitoring of Ca 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 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.