Cellular cholesterol depletion triggers shedding of the human interleukin-6 receptor by ADAM10 and ADAM17 (TACE).
Interleukin-6 (IL-6) activates cells by binding to the membrane-bound IL-6 receptor (IL-6R) and subsequent formation of a glycoprotein 130 homodimer. Cells that express glycoprotein 130, but not the IL-6R, can be activated by IL-6 and the soluble IL-6R which is generated by shedding from the cell surface or by alternative splicing. Here we show that cholesterol depletion of cells with methyl-beta-cyclodextrin increases IL-6R shedding independent of protein kinase C activation and thus differs from phorbol ester-induced shedding. Contrary to cholesterol depletion, cholesterol enrichment did not increase IL-6R shedding. Shedding of the IL-6R because of cholesterol depletion is highly dependent on the metalloproteinase ADAM17 (tumor necrosis factor-alpha-converting enzyme), and the related ADAM10, which is identified here for the first time as an enzyme involved in constitutive and induced shedding of the human IL-6R. When combined with protein kinase C inhibition by staurosporine or rottlerin, breakdown of plasma membrane sphingomyelin or enrichment of the plasma membrane with ceramide also increased IL-6R shedding. The effect of cholesterol depletion was confirmed in human THP-1 and Hep3B cells and in primary human peripheral blood monocytes, which naturally express the IL-6R. For decades, high cholesterol levels have been considered harmful. This study indicates that low cholesterol levels may play a role in shedding of the membrane-bound IL-6R and thereby in the immunopathogenesis of human diseases.
Matthews
Vance
V
Biochemisches Institut, Christian Albrechts Universität zu Kiel, Germany.
Schuster
Björn
B
Schütze
Stefan
S
Bussmeyer
Ingo
I
Ludwig
Andreas
A
Hundhausen
Christian
C
Sadowski
Thorsten
T
Saftig
Paul
P
Hartmann
Dieter
D
Kallen
Karl-Josef
KJ
Rose-John
Stefan
S
D051722:ADAM Proteins; D000072197:ADAM10 Protein; D000072198:ADAM17 Protein; D000098:Acetophenones / Q000494:pharmacology; D017398:Alternative Splicing; D053829:Amyloid Precursor Protein Secretases; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D003505:Cyclodextrins / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D050356:Lipid Metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009000:Monocytes / Q000378:metabolism; D011233:Precipitin Tests; D011493:Protein Kinase C / Q000378:metabolism; D017434:Protein Structure, Tertiary; D019947:Receptors, Interleukin-6 / Q000378:metabolism*; D013109:Sphingomyelins / Q000378:metabolism; D019311:Staurosporine / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D047392:beta-Cyclodextrins
D000098:Acetophenones; D001578:Benzopyrans; D002518:Ceramides; D003505:Cyclodextrins; D004791:Enzyme Inhibitors; D015850:Interleukin-6; D008565:Membrane Proteins; D019947:Receptors, Interleukin-6; D013109:Sphingomyelins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol; C085746:rottlerin; D011493:Protein Kinase C; D053829:Amyloid Precursor Protein Secretases; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000072197:ADAM10 Protein; C491236:ADAM10 protein, human; C491234:Adam10 protein, mouse; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human; C000606463:Adam17 protein, mouse; D019311:Staurosporine