A Disintegrin and Metalloenzyme

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. 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. Our data show for the first time that [beta]1 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.