Leader peptide or pro-segment mutants of renin are misrouted to mitochondria in autosomal dominant tubulointerstitial kidney disease

Autosomal dominant tubulointerstitial kidney disease (ADTKD), a rare genetic disorder characterised by progressive chronic kidney disease, is caused by mutations in different genes, including REN, encoding renin. Renin is a secreted protease composed of three domains: the leader peptide that allows insertion in the endoplasmic reticulum (ER), a pro-segment regulating its activity, and the mature part of the protein. Mutations in mature renin lead to ER retention of the mutant protein and to late-onset disease, whereas mutations in the leader peptide, associated with defective ER translocation, and mutations in the pro-segment, leading to accumulation in the ER-to-Golgi compartment, lead to a more severe, early-onset disease. In this study, we demonstrate a common, unprecedented effect of mutations in the leader peptide and pro-segment as they lead to full or partial mistargeting of the mutated proteins to mitochondria. The mutated pre-pro-sequence of renin is necessary and sufficient to drive mitochondrial rerouting, mitochondrial import defect and fragmentation. Mitochondrial localisation and fragmentation were also observed for wild-type renin when ER translocation was affected. These results expand the spectrum of cellular phenotypes associated with ADTKD-associated REN mutations, providing new insight into the molecular pathogenesis of the disease.