Role of the SNARE protein SNAP‐23 on cAMP‐stimulated Renin release from mouse Juxtaglomerular (JG) cells

Abstract

Exocytosis of renin containing granules is likely involved in renin release from juxtaglomerular (JG) cells; a process stimulated by cAMP. In non‐neuronal endocrine cells granule exocytosis is mediated by SNAP‐23, a protein of the soluble N‐ethylmaleimide‐sensitive factor attachment protein receptor (SNARE) family. We hypothesized that cAMP‐stimulated renin release from JG cells is in part mediated by SNAP‐23. We measured: 1) the expression of SNAP‐23 by Western blot and immunofluorescence confocal microscopy; and 2) the effect of adenoviral delivery of a dominant‐negative SNAP‐23 and botulinum toxin E on cAMP‐stimulated renin release in mouse JG cell primary cultures. cAMP was increased with Forkolin plus IBMX (F/I). SNAP‐23 was detected by Western blot in JG cell lysates and co‐localized with renin granules in JG cells. In control JG cells transduced with a scramble sequence, increasing cAMP stimulated renin release from 1.3±0.3 to 5.3±1.2 % of renin content. In cells transduced with dominant‐negative SNAP‐23, F/I increased renin from 1.0±0.1 to 3±0.6 % of renin content, a 50% blockade (p<0.02). Botulinum toxin E, which cleaves and inactivates SNAP‐23, reduced cAMP‐stimulated renin release from 5.0±0.7 to 2.45±0.5 % of renin content, a 50% blockade (p< 0.05). We concluded that the SNARE protein SNAP‐23 partially mediates cAMP‐stimulated renin release. These data show for the first time that renin release is mediated by SNAREs.