Abstract 3480: Shedding of (Pro)renin Receptor is Essential for Intracellular Signaling
Background: (Pro)renin receptor [(P)RR] plays a pivotal effect of the activation of the renin-angiotensin system through non-proteolytic activation of prorenin. (P)RR also evokes its own intracellular signaling, the activation of MAP kinases. We already reported that (pro)renin receptor was cleaved in its ectodomain. It still remains, however, controversial about the relevance between shedding and its own signaling. To uncover this aspect, we performed following experiments.
Results: Stable cell lines, which express human (P)RR tagged with green fluorescent protein, were established using CHO cells ((P)RR-GFP-CHO). (P)RR-GFP-CHO cells showed ERK1/2 phosphorylation evoked by prorenin and constitutively ectodomain shedding of (P)RR. The culture medium of these cells was collected and concentrated using Amicon Ultra-4 (Millipore, Billerica, MA). Using concentrated sample from the culture medium, shed (P)RR was detected with anti-(pro)renin receptor antibody. These results suggest that an extracellular domain of (P)RR may be secreted in the conditioned medium after shedding. Using mutant (P)RR-GFP, which is deleted its exon 4, stable cell lines were also established (Delta4-GFP-CHO) and same experiments were performed. Mutant (P)RR was not cleaved in its ectodomain and ERK1/2 was not activated upon prorenin stimulation in Delta4-GFP-CHO cells.
Conclusion: We found a novel mechanism of machinery of prorenin (P)RR activation. (P)RR may activate the renin-angiotensin system through non-proteolytic activation of prorenin independent of its own shedding. However, intracellular signaling of (P)RR may require its own shedding.