Dermal fibroblast-derived growth factors restore the ability of beta(1) integrin-deficient embryonal stem cells to differentiate into keratinocytes.
Embryonal stem (ES) cells that are homozygous null for the beta(1) integrin subunit fail to differentiate into keratinocytes in vitro but do differentiate in teratomas and wild-type/beta(1)-null chimeric mice. The failure of beta(1)-null ES cells to differentiate in culture might be the result of defective extracellular matrix assembly or reduced sensitivity to soluble inducing factors. By culturing embryoid bodies on dead, deepidermized human dermis (DED) we showed that epidermal basement membrane did not induce beta(1)-null ES cells to undergo keratinocyte differentiation and did not stimulate the differentiation of wild-type ES cells. Coculture with epidermal keratinocytes also had no effect. However, when human dermal fibroblasts were incorporated into DED, the number of epidermal cysts formed by wild-type ES cells increased dramatically, and small groups of keratin 14-positive cells differentiated from beta(1)-null ES cells. Fibroblast-conditioned medium stimulated differentiation of K14-positive cells in wild-type and beta(1)-null embryoid bodies. Of a range of growth factors tested, KGF, FGF10, and TGFalpha all stimulated differentiation of keratin 14-positive beta(1)-null cells, and KGF and FGF10 were shown to be produced by the fibroblasts used in coculture experiments. The effects of the growth factors on wild-type ES cells were much less pronounced, suggesting that the concentrations of inducing factors already present in the medium were not limiting for wild-type cells. We conclude that the lack of beta(1) integrins decreases the sensitivity of ES cells to soluble factors that induce keratinocyte differentiation.
Keratinocyte Laboratory, Imperial Cancer Research Fund, 44 Lincoln's Inn Fields, London, WC2A 3PX, United Kingdom.
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Bagutti
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Hutter
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Chiquet-Ehrismann
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R
Fässler
F M
FM
Watt
D016475:3T3 Cells; D000818:Animals; D001485:Basement Membrane / Q000378:metabolism; D002448:Cell Adhesion; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000378:metabolism; D020405:Dermis / Q000166:cytology* / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology*; D004817:Epidermis / Q000378:metabolism; D051526:Fibroblast Growth Factor 10; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006133:Growth Substances / Q000502:physiology*; D006801:Humans; D019012:Integrin beta1 / Q000235:genetics* / Q000502:physiology; D053547:Keratin-14; D015603:Keratinocytes / Q000166:cytology* / Q000502:physiology; D007633:Keratins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D011994:Recombinant Proteins / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology; D016211:Transforming Growth Factor alpha / Q000378:metabolism*
D017077:Culture Media, Conditioned; C496463:FGF10 protein, human; C496453:FGF7 protein, human; C496464:Fgf10 protein, mouse; C496454:Fgf7 protein, mouse; D051526:Fibroblast Growth Factor 10; D006133:Growth Substances; D019012:Integrin beta1; C507540:KRT14 protein, human; D053547:Keratin-14; C507446:Krt14 protein, mouse; D011994:Recombinant Proteins; D016211:Transforming Growth Factor alpha; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D007633:Keratins