Renalase stimulates aldosterone production via PMCA4b/cAMP in NCI-H295R cells

We recently observed a significantly higher level of renalase (RNLS) in aldosterone-producing adenomas (APAs) than in the APA-adjacent adrenal glands (AAGs). RNLS is a flavin adenine dinucleotide-dependent monoamine oxidase. In this study, we investi-gated the effect of RNLS on adrenocortical aldosterone production. RNLS upregulated aldosterone production in adrenocortical cells without interfering with cell proliferation. RNLS (4 μg/ml) increased the mRNA expression of HSD3B2 (<i>p</i> = 0.0128) and CYP21A2 (<i>p</i> = 0.0013) and markedly stimulated that of CYP11B2 (<i>p</i> < 0.0001). Regarding the mechanism, we excluded classical calcium signalling stimulation and found that RNLS activated cAMP/PKA signalling and then upregulated the transcription factor NR4A2 and the phosphorylation of ATF/CREB family members. Immunofluorescence and immuno-precipitation results revealed that RNLS bound to the receptor PMCA4b on the cell membrane, with siPMCA4b preventing RNLS from exerting pro-aldosterone production (<i>p</i> = 0.0157, RNLS+siPMCA4b vs RNLS+siNC). RNLS facilitates aldosterone secretion and may emerge as a hazardous molecule for promoting aldosterone-mediated pathological conditions.