A Disintegrin and Metalloenzyme (ADAM) 17 Activation Is Regulated by α5β1 Integrin in Kidney Mesangial Cells

Background: The disintegrin and metalloenzyme ADAM17 participates in numerous inflammatory and proliferative diseases, and its pathophysiological role was implicated in kidney fibrosis, polycystic kidney disease and other chronic kidney diseases. At present, we have little understanding how the enzyme activity is regulated. In this study we wanted to characterize the role of alpha 5 beta 1 integrin in ADAM17 activity regulation during G protein-coupled receptor (GPCR) stimulation. Methodology/Principal Findings: We showed previously that the profibrotic GPCR agonist serotonin (5-HT) induced kidney mesangial cell proliferation through ADAM17 activation and heparin-binding epidermal growth factor (HB-EGF) shedding. In the present studies we observed that in unstimulated mesangial cell lysates alpha 5 beta 1 integrin co-precipitated with ADAM17 and that 5-HT treatment of the cells induced dissociation of alpha 5 beta 1 integrin from ADAM17. Using fluorescence immunostaining and in situ proximity ligation assay, we identified the perinuclear region as the localization of the ADAM17/alpha 5 beta 1 integrin interaction. In cell-free assays, we showed that purified alpha 5 beta 1 integrin and beta 1 integrin dose-dependently bound to and inhibited activity of recombinant ADAM17. We provided evidence that the conformation of the integrin determines its ADAM17-binding ability. To study the effect of beta 1 integrin on ADAM17 sheddase activity, we employed alkaline phosphatase-tagged HB-EGF. Overexpression of beta 1 integrin lead to complete inhibition of 5-HT-induced HB-EGF shedding and silencing beta 1 integrin by siRNA significantly increased mesangial cells ADAM17 responsiveness to 5-HT. Conclusions/Significance: Our data show for the first time that b1 integrin has an important physiological role in ADAM17 activity regulation. We suggest that regulating alpha 5 beta 1 integrin binding to ADAM17 could be an attractive therapeutic target in chronic kidney diseases.