title: Structural basis for inflammation-driven shedding of CD163 ectodomain and tumor necrosis factor-α in macrophages.
abstract: The haptoglobin-hemoglobin receptor CD163 and proTNF-α are transmembrane macrophage proteins subjected to cleavage by the inflammation-responsive protease ADAM17. This leads to release of soluble CD163 (sCD163) and bioactive TNF-α. Sequence comparison of the juxtamembrane region identified similar palindromic sequences in human CD163 ((1044)Arg-Ser-Ser-Arg) and proTNF-α ((78)Arg-Ser-Ser-Ser-Arg). In proTNF-α the Arg-Ser-Ser-Ser-Arg sequence is situated next to the previously established ADAM17 cleavage site. Site-directed mutagenesis revealed that the sequences harbor essential information for efficient cleavage of the two proteins upon ADAM17 stimulation. This was further evidenced by analysis of mouse CD163 that, like CD163 in other non-primates, does not contain the palindromic CD163 sequence in the juxtamembrane region. Mouse CD163 resisted endotoxin- and phorbol ester-induced shedding, and ex vivo analysis of knock-in of the Arg-Ser-Ser-Arg sequence in mouse CD163 revealed a receptor shedding comparable with that of human CD163. In conclusion, we have identified an essential substrate motif for ADAM17-mediated CD163 and proTNF-α cleavage in macrophages. In addition, the present data indicate that CD163, by incorporation of this motif in late evolution, underwent a modification that allows for an instant down-regulation of surface CD163 expression and inhibition of hemoglobin uptake. This regulatory modality seems to have coincided with the evolution of an enhanced hemoglobin-protecting role of the haptoglobin-CD163 system in primates.
authors.affiliation: From the Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Etzerodt
authors.forename: Mie Rostved
authors.initials: MR
authors.lastname: Rasmussen
authors.forename: Pia
authors.initials: P
authors.lastname: Svendsen
authors.forename: Athena
authors.initials: A
authors.lastname: Chalaris
authors.forename: Jeanette
authors.initials: J
authors.lastname: Schwarz
authors.forename: Ian
authors.initials: I
authors.lastname: Galea
authors.forename: Holger Jon
authors.initials: HJ
authors.lastname: Møller
authors.forename: Søren Kragh
authors.initials: SK
authors.lastname: Moestrup
mesh_terms: D051722:ADAM Proteins / Q000235:genetics / Q000378:metabolism; D000072198:ADAM17 Protein; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D015214:Antigens, Differentiation, Myelomonocytic / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D002478:Cells, Cultured; D019446:Endotoxemia / Q000235:genetics / Q000378:metabolism; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D015151:Immunoblotting; D007249:Inflammation / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009154:Mutation; D059748:Proteolysis / Q000187:drug effects; D034622:RNA Interference; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*; D000098902:CD163 Antigen
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D000098902:CD163 Antigen; D004792:Enzyme Precursors; D008070:Lipopolysaccharides; D011956:Receptors, Cell Surface; D014409:Tumor Necrosis Factor-alpha; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human; C000606463:Adam17 protein, mouse; D013755:Tetradecanoylphorbol Acetate
keywords: ADAM ADAMTS; Hemoglobin; Macrophages; Membrane proteins; Scavenger receptor; Shedding