Renin and Prorenin Activate Pathways Implicated in Organ Damage in Human Mesangial Cells Independent of Angiotensin II Production

BACKGROUND: The mechanism by which an activated renin-angiotensin system (RAS) leads to the development of renal diseases, such as fibrosis, is only partially explained by the downstream effects of angiotensin II. The discovery of a receptor that binds renin and prorenin, and the consequent production of profibrotic molecules, revealed a novel axis within the RAS pathway that may contribute to the pathogenesis of organ damage in patients with elevated renin and/or prorenin levels. METHODS: To better understand the genes and networks underlying the receptor-mediated effects of renin and prorenin, a gene expression profiling study was performed on human mesangial cells in the presence of angiotensin-II-blocking agents. RESULTS: Renin and prorenin induce highly overlapping gene expression signatures that are dependent, only in part, on the presence of the (pro)renin receptor. We found that 2 distinct pathways were activated by renin and prorenin: a TGFbeta-dependent pathway and a TGFbeta-independent pathway. Bioinformatic analysis was used to show that both pathways are highly enriched with genes implicated in fibrosis, hypertrophy and atherosclerosis. CONCLUSIONS: This study suggests that both renin and inactive prorenin are capable of inducing genetic programs that could contribute to end-organ damage and atherogenesis, through receptor-mediated angiotensin-independent mechanisms.