Human Coxsackie- and adenovirus receptor is a putative target of neutrophil elastase-mediated shedding

Abstract

Background During viral-induced myocarditis, immune cells migrate towards the site of infection and secrete proteases, which in turn can act as sheddases by cleaving extracellular domains of transmembrane proteins. We were interested in the shedding of the Coxsackie- and adenovirus receptor (CAR) that acts as an entry receptor for both eponymous viruses, which cause myocarditis. CAR shedding by secreted immune proteases could result in a favourable outcome of myocarditis as CAR’s extracellular domain would be removed from the cardiomyocytes’ surface leading to decreased susceptibility to ongoing viral infections. Methods and results In this work, matrix metalloproteinases and serine proteinases were screened for their proteolytic activity towards human CAR. Whereas matrix metalloproteinases, proteinase 3, and cathepsin G did not cleave human recombinant CAR or only within long incubation times, neutrophil elastase showed a distinct cleavage pattern of CAR’s extracellular domain that was time- and dose-dependent. Neutrophil elastase cleaves CAR at its membrane-proximal immunoglobulin domain as we determined by nanoLC-MS/MS. Furthermore, neutrophil elastase treatment of cells reduced CAR surface levels as seen by flow cytometry and immunofluorescence microscopy. Conclusions With this study, we show that CAR might be a target for shedding by neutrophil elastase.

CXADR: From an Essential Structural Component to a Vital Signaling Mediator in Spermatogenesis

“…For example, ectodomain shedding of the extracellular domain of CXADR can result in the production of a soluble fragment that functions as a signaling molecule to disrupt cell junctions and limits the susceptibility to virus infection [ 75 ]. Various serine proteases, such as neutrophil elastase, cathepsin G, and proteinase 3, are able to induce the cleavage of the ectodomain (ECD) of CXADR [ 76 ]. Metalloproteinase like matrix metalloproteinase 3 (MMP-3), but not MMP-1, can trigger CXADR ectodomain shedding in a time- and dose-dependent manner [ 76 ].…”

“…Various serine proteases, such as neutrophil elastase, cathepsin G, and proteinase 3, are able to induce the cleavage of the ectodomain (ECD) of CXADR [ 76 ]. Metalloproteinase like matrix metalloproteinase 3 (MMP-3), but not MMP-1, can trigger CXADR ectodomain shedding in a time- and dose-dependent manner [ 76 ]. For instance, neutrophil elastase cleaves the ECD of CXADR within 5 min, which enables a rapid immune response and inhibits viral entry upon infection [ 76 ].…”

“…Metalloproteinase like matrix metalloproteinase 3 (MMP-3), but not MMP-1, can trigger CXADR ectodomain shedding in a time- and dose-dependent manner [ 76 ]. For instance, neutrophil elastase cleaves the ECD of CXADR within 5 min, which enables a rapid immune response and inhibits viral entry upon infection [ 76 ]. It is also known that ADAM10 can cleave CXADR at M224 to L227 in activated glioma cells or developing neurons [ 74 ].…”