Premium
Amphiregulin‐dependent proliferation of cultured human keratinocytes: Autocrine growth, the effects of exogenous recombinant cytokine, and apparent requirement for heparin‐like glycosaminoglycans
Author(s) -
Piepkorn Michael,
Lo Christine,
Plowman Greg
Publication year - 1994
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041590115
Subject(s) - amphiregulin , autocrine signalling , epidermal growth factor , growth factor , glycosaminoglycan , biology , iduronic acid , epidermal growth factor receptor , chemistry , microbiology and biotechnology , heparan sulfate , biochemistry , receptor
Amphiregulin, a member of the epidermal growth factor family with heparin binding affinity, functions as a natural regulator of keratinocyte growth. Autocrine signaling by amphiregulin and the effects of exogenous recombinant cytokine were studied in serum‐free cultures of human neonatal keratinocytes. A metabolic inhibitor of proteoglycan sulfation was used to assess the role of cellular heparin‐like glycosaminoglycans in amphiregulin‐dependent growth. Keratinocytes plated at >10 3 cells/cm 2 grew in an autocrine manner in the absence of exogenous epidermal growth factor or amphiregulin. Incubation of keratinocytes with an amphiregulin‐blocking antibody indicated that ∼70% of autocrine growth is mediated by endogenous amphiregulin. Proliferation potential in the presence of recombinant human amphiregulin was dose dependent and saturable and above ∼1 ng/ml was comparable to that achieved with similar concentrations of epidermal growth factor. Sodium chlorate, which blocks glycosaminoglycan sulfation, reversibly inhibited epidermal growth factor‐dependent proliferation by 42%, exogenous amphiregulin‐dependent proliferation by 75%, and autocrine growth by 95%; concurrent incubation with 1‐100 μg/ml heparin partially reversed this inhibition. Exogenous heparin in the absence of chlorate, however, nearly completely inhibited growth under autocrine conditions and in the presence of recombinant amphiregulin. Structure‐function studies indicate that the polymerization level, high sulfate group density, and possibly iduronic acid content of heparin‐like moieties correlate with their inhibitory activity. Collectively, these observations indicate that amphiregulin is the major autocrine factor for keratinocytes and demonstrate that exogenous amphiregulin is an effective growth promoting factor with molar potency similar to that of epidermal growth factor. Autocrine and paracrine signaling by amphiregulin may require cellular heparin‐like glycosaminoglycans, presumably as matrix or membrane proteoglycans, whereas soluble glycosaminoglycans inhibit signaling, possibly by competing for cytokine binding. © 1994 wiley‐Liss, Inc.