To activate NAD(P)H oxidase with a brief pulse of photodynamic action

UVA is known to elicit calcium oscillations in rodent mast cells, due to activation of NOX2. Different from multi-subunit NOX2, NOX5 is a single subunit NOX, therefore is chosen here to study. Human NOX5 is expressed in rodent cell line CHO-K1 and effect of UVA irradiation is examined by Fura-2 fluorescent calcium imaging. UVA (380 nm) is found to induce repetitive calcium spikes in NOX5-CHO-K1 cells, which are inhibited by NOX inhibitor DPI and blocked by 1O2 quencher Trolox-C. A brief pulse of photodynamic action with SALPC (675 nm) in NOX5-CHO-K1, or with miniSOG (450 nm) in miniSOG-NOX5-CHO-K1 cells, both induce persistent calcium oscillations, which are blocked by DPI and Trolox-C. These data together suggest that NOX5 can be activated permanently with a brief pulse of photodynamic action (UVA irradiation, blue or red light with exogenous photosensitizer miniSOG or SALPC); photodynamic activation might be similarly applied to other NOX enzymes.