title: Cathepsin S generates soluble CX3CL1 (fractalkine) in vascular smooth muscle cells.
abstract: CX3CL1 chemokine (fractalkine) is highly expressed by vascular smooth muscle cells (VSMCs) in atherosclerotic lesions. Its membrane-bound form promotes cell-cell interactions, whereas the soluble form induces chemotaxis of CX3CR1- expressing leukocytes. We show that the cysteine protease cathepsin S, expressed by VSMCs, is able to cleave membrane-anchored CX3CL1, releasing a 55-kDa fragment to the medium, thus regulating the adhesion of VSMCs and the capture of monocytes to the sites of atherogenesis. Moreover, strong co-localization of cathepsin S and CX3CL1 with a recycling endosome marker Rab11a suggests a processing of CX3CL1 in recycling endosomes during its redistribution to the plasma membrane.
authors.forename: Urša Pečar
authors.initials: UP
authors.lastname: Fonović
authors.forename: Zala
authors.initials: Z
authors.lastname: Jevnikar
authors.forename: Janko
authors.initials: J
authors.lastname: Kos
mesh_terms: D002403:Cathepsins / Q000378:metabolism*; D002448:Cell Adhesion; D054428:Chemokine CX3CL1 / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000201:enzymology / Q000378:metabolism*; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism
chemical_list: D054428:Chemokine CX3CL1; D010446:Peptide Fragments; D002403:Cathepsins; C028217:cathepsin S