Regulation of interleukin 1 and its receptor in human keratinocytes.
Keratinocytes in culture synthesize and respond to interleukin 1 (IL-1). We have measured surface IL-1 receptor (IL-1R) on keratinocytes in culture using radiolabeled IL-1 binding assays. Surface IL-1R levels are less than 2000 receptors per cell in postconfluent cultures but increase 9- to 20-fold 24 hr after treatment with phorbol 12-myristate 13-acetate (PMA) at 10 ng/ml or after raising the extracellular Ca2+ concentration to 2 mM. This induction of surface IL-1R can be blocked by the addition of retinoic acid and parallels induction of squamous differentiation markers. These results imply that IL-1R levels may be related to the degree of differentiation of these cells. In parallel studies IL-1 protein levels were determined by bioassay and by Western blotting (immunoblots). All detectable IL-1 protein and essentially all IL-1 activity was cell-associated. Although constitutive levels of IL-1 biological activity and protein are significant in these cultures, IL-1 levels increase when either PMA or retinoic acid alone are added to cultures. IL-1 does not increase when PMA and retinoic acid are added simultaneously to cultures; nor is it induced when extracellular Ca2+ concentrations are raised to 2 mM. Thus, cell-associated IL-1 levels do not necessarily parallel surface IL-1R levels in these cultures. Taken together, these results demonstrate that IL-1 and surface IL-1R levels are differentially and complexly regulated in keratinocyte cultures. Possible implications of these results in terms of normal and abnormal regulation of proliferation and differentiation are discussed.
Blanton
R A
RA
Fred Hutchinson Cancer Research Center, Seattle, WA 98104.
Kupper
T S
TS
McDougall
J K
JK
Dower
S
S
D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007375:Interleukin-1 / Q000096:biosynthesis / Q000378:metabolism*; D007633:Keratins / Q000378:metabolism; D007700:Kinetics; D008297:Male; D011971:Receptors, Immunologic / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins / Q000378:metabolism; D012867:Skin / Q000166:cytology; D012879:Skin Physiological Phenomena; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology
D007375:Interleukin-1; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D014212:Tretinoin; D007633:Keratins; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium