title: ADAM28 is elevated in humans with the metabolic syndrome and is a novel sheddase of human tumour necrosis factor-α.
abstract: Metalloproteinases are implicated in cleaving numerous proinflammatory mediators from the cell surface. Interestingly, the elevated levels of tumour necrosis factor-α (TNF-α) have been associated with the metabolic syndrome. We aimed to ascertain whether the human metalloproteinase ADAM28 correlates with parameters of the metabolic syndrome and whether ADAM28 is a novel sheddase of human TNF-α. To identify novel metalloproteinases associated with the metabolic syndrome, we conducted microarray studies on peripheral blood mononuclear cells from a well characterised human cohort. Human ADAM28 and TNF-α were overexpressed and ADAM28 expression or activity was reduced with small-interfering RNA (siRNA) or pharmacological inhibition. TNF-α levels were measured in cell supernatant by enzyme-linked immunosorbent assay. We also conducted ADAM28 inhibition studies in human THP-1 macrophages. Human ADAM28 expression levels were positively correlated with parameters of the metabolic syndrome. When human ADAM28 and TNF-α were overexpressed in HEK293 cells, both proteins co-localised, co-immunoprecipitated and promoted TNF-α shedding. The shedding was significantly reduced when ADAM28 activity was inhibited or ADAM28 expression was downregulated. In human THP-1 macrophages, endogenous ADAM28 and TNF-α were co-expressed and TNF-α shedding was significantly reduced when ADAM28 was inhibited by pharmacological inhibition or siRNA knockdown. Our data suggest a novel mechanistic role for the metalloproteinase ADAM28 in inflammation, obesity and type 2 diabetes.
authors.affiliation: Genomics and Systems Biology, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia.
authors.forename: Jeremy B M
authors.initials: JB
authors.lastname: Jowett
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Okada
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Leedman
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Curran
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Johnson
authors.forename: Eric K
authors.initials: EK
authors.lastname: Moses
authors.forename: Harald H H
authors.initials: HH
authors.lastname: Goring
authors.forename: Satsuki
authors.initials: S
authors.lastname: Mochizuki
authors.forename: John
authors.initials: J
authors.lastname: Blangero
authors.forename: Leah
authors.initials: L
authors.lastname: Stone
authors.forename: Holly
authors.initials: H
authors.lastname: Allen
authors.forename: Chris
authors.initials: C
authors.lastname: Mitchell
authors.forename: Vance B
authors.initials: VB
authors.lastname: Matthews
mesh_terms: D051722:ADAM Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism*; D015992:Body Mass Index; D055106:Genome-Wide Association Study; D057809:HEK293 Cells; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism* / Q000473:pathology; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D024821:Metabolic Syndrome / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism*; D046228:Microarray Analysis; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000235:genetics; D019076:Transgenes / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D051722:ADAM Proteins; C410224:ADAM28 protein, human