Keratinocyte growth factor and embryonic rat lung morphogenesis.
Masanori ShiratoriEiki OshikaLing P UngGurmukh SinghHisashi ShinozukaDavid WarburtonGeorge K. MichalopoulosS. L. Katyal
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We examined possible roles of keratinocyte growth factor (KGF) and hepatocyte growth factor (HGF) in lung morphogenesis. By polymerase chain reaction, transcripts for both KGF and its receptor were detected early (rat gestational days 16 and 14, respectively) and their abundance increased during lung morphogenesis. To evaluate possible role of KGF in lung morphogenesis, day 14 lung explants were cultured in Dulbecco's modified Eagle medium + 10% fetal calf serum for 1 to 4 days in the presence (5-50 ng/ml) or absence of KGF (control). KGF (at 25 and 50 ng/ml) induced a marked reduction in the number of terminal branches and destination of the distal epithelium into cyst-like structures. These effects of exogenous KGF were progressively diminished by increasing concentrations of anti-KGF (2-16 micrograms/ml). Electron microscopic examination revealed that the epithelial cells of the cystic structures contained lamellar bodies, and were therefore type II cells and/or their progenitors. Northern blot analysis showed higher expression of surfactant protein C (SP-C) mRNA (a marker for alveolar epithelial type II cells) in KGF-treated fetal lungs. In situ hybridization of the KGF-treated lungs revealed that the SP-C mRNA-expressing cells were arranged distally in the form of linear arrays, a pattern distinctly different from that in control lungs. Acidic fibroblast growth factor, which also binds KGF receptors, in the presence of heparin mimicked the effect of KGF on branching. Transforming growth factor-beta(1) (TGF-beta 1) inhibited branching of fetal lungs in culture, and this effect dominated over that induced by KGF. Blocking of endogenous HGF with antibodies or addition of HGF to cultures of fetal lung explants had no significant effect on branching or growth. In conclusion, KGF markedly influences branching, and epithelial growth, differentiation, and patterning during lung morphogenesis.Keywords:
Keratinocyte growth factor
Lamellar granule
We have shown that pulmonary epithelial growth and differentiation can occur if pulmonary mesenchyme is replaced with a mixture of growth factors [total growth medium (TGM)] that consists of adult rat bronchoalveolar lavage fluid, insulin, epidermal growth factor (EGF), cholera toxin (CT), acidic fibroblast growth factor (aFGF), and fetal bovine serum. In the present study, we have defined the importance of specific components of TGM. Day 14 fetal rat distal lung epithelium, devoid of mesenchyme, was enrobed in growth factor-depleted Matrigel and cultured for 5 days in various soluble factors. We found that deleting aFGF or CT from TGM significantly reduced DNA synthesis. Epithelial proliferation was not significantly different when keratinocyte growth factor (KGF) replaced aFGF in TGM. KGF, however, required the presence of a basal medium containing CT, insulin, and serum for optimal proliferation. We then added specific growth factors to the basal medium and showed that aFGF and KGF were more potent mitogens than EGF, transforming growth factor-alpha, and hepatocyte growth factor. Additionally, basal medium + KGF also allowed progression to a distal alveolar phenotype. We conclude that aFGF and KGF may be important mediators in epithelial-mesenchymal interactions.
Keratinocyte growth factor
Mesenchyme
Matrigel
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We examined possible roles of keratinocyte growth factor (KGF) and hepatocyte growth factor (HGF) in lung morphogenesis. By polymerase chain reaction, transcripts for both KGF and its receptor were detected early (rat gestational days 16 and 14, respectively) and their abundance increased during lung morphogenesis. To evaluate possible role of KGF in lung morphogenesis, day 14 lung explants were cultured in Dulbecco's modified Eagle medium + 10% fetal calf serum for 1 to 4 days in the presence (5-50 ng/ml) or absence of KGF (control). KGF (at 25 and 50 ng/ml) induced a marked reduction in the number of terminal branches and destination of the distal epithelium into cyst-like structures. These effects of exogenous KGF were progressively diminished by increasing concentrations of anti-KGF (2-16 micrograms/ml). Electron microscopic examination revealed that the epithelial cells of the cystic structures contained lamellar bodies, and were therefore type II cells and/or their progenitors. Northern blot analysis showed higher expression of surfactant protein C (SP-C) mRNA (a marker for alveolar epithelial type II cells) in KGF-treated fetal lungs. In situ hybridization of the KGF-treated lungs revealed that the SP-C mRNA-expressing cells were arranged distally in the form of linear arrays, a pattern distinctly different from that in control lungs. Acidic fibroblast growth factor, which also binds KGF receptors, in the presence of heparin mimicked the effect of KGF on branching. Transforming growth factor-beta(1) (TGF-beta 1) inhibited branching of fetal lungs in culture, and this effect dominated over that induced by KGF. Blocking of endogenous HGF with antibodies or addition of HGF to cultures of fetal lung explants had no significant effect on branching or growth. In conclusion, KGF markedly influences branching, and epithelial growth, differentiation, and patterning during lung morphogenesis.
Keratinocyte growth factor
Lamellar granule
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Keratinocyte growth factor
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The specific binding of [125I]epidermal growth factor ([126I]EGF) to hepatic microsomal membranes was about 2-fold higher in adult male than in adult female rats. Scatchard analysis of the binding data showed that the sex difference in EGF binding was due to the difference in EGF receptor concentration rather than to a change in receptor affinity. From the developmental study, an apparent sex difference in EGF binding was observed from the pubertal period (4 weeks of age). Castration of adult male rats slightly, but significantly, decreased the EGF receptor level; and moreover, treatment of adult females with testosterone increased it only slightly. On the other hand, castration of neonatal male rats decreased the EGF receptor content almost to the female level. The decreased level of the receptor was completely restored by the combination of neonatal and pubertal treatments with testosterone. Neonatal or pubertal treatment alone of castrated animals had no significant effect on the decreased level of EGF receptors. These effects of testosterone were similarly observed when normal female rats were treated with the steroid. Moreover, hypophysectomy of the rats resulted in the marked decrease in EGF receptors only in the male animals. Treatment of hypophysectomized rats with either testosterone or T3 had no apparent effect on the EGF receptors. The membrane protein, cross-linked with [125I]EGF, had a mol wt of 170,000, and this protein (EGF receptor) was phosphorylated basally or by the addition of EGF. The rate of affinity labeling, or phosphorylation of EGF receptors, was in good agreement with the results of the EGF binding study. These results strongly suggest that the EGF receptor level in rat liver plasma membranes is in part regulated by the hypothalamopituitary unit and that neonatal androgens are essential for this regulation, probably through their effects on the hypothalamus. (Endocrinology122: 1707–1714, 1988)
Hypophysectomy
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Keratinocyte growth factor
Gene transfer
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Introduction: Growth factors have been shown to affect the complex cascade of wound healing; however, interaction between different growth factors during dermal and epidermal regeneration are still not entirely defined. In the present study we determined the interaction between keratinocyte growth factor (KGF), an epidermal growth factor, administered as liposomal cDNA, with other dermal and epidermal growth factors and collagen types I, III, and IV synthesis in an acute wound. Method: Adult male Sprague-Dawley rats received 30% total body surface area scalds under general anesthesia. They were then divided into two groups to receive weekly subcutaneous injections of liposomes plus the Lac Z gene (0.2 μg, vehicle), or liposomes plus the KGF cDNA (2.2 μg) and Lac Z gene (0.2 μg), for 4 weeks. Immunological assays, histological, and immunohistochemical techniques were used to determine growth factor concentrations and different types of collagen (I, III, and IV), rate of reepithelialization and dermal morphology, after KGF cDNA gene transfer. Results: KGF cDNA transfer significantly increased IGF-I (Insulin-like Growth Factor-I), IGFBP-3 (Insulin-like Growth Factor Binding Protein-3), and FGF (Fibroblast Growth Factor) and decreased TGF-β(Transforming Growth Factor–beta) levels (p < 0.05). KGF had no effect on PDGF (Platelet-Derived Growth Factor). KGF cDNA significantly increased collagen type IV (p < 0.02) at the wound edge as well as the wound bed, while it had no effect on collagen type I and III. KGF cDNA significantly increased reepithelialization compared to the control group. Conclusion: Exogenous KGF cDNA increases IGF-I, IGF-BP3, FGF expression and decreases TGF-β concentration in an acute wound. It accelerates re-epithelialization, improves dermal morphology and increases basement membrane formation, without a concomitant increase in inflammation or scarring. Acknowledgments: Clayton Foundation for Research
Keratinocyte growth factor
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We have developed a model of human squamous epithelial cell invasion in human skin organ culture. Epidermal invasion of the dermis occurs in this model when the tissue is exposed to an exogenous source of epithelial cell growth factor. In the present study we sought to determine to what extent growth factor-induced invasion correlates with the ability of the growth factor to induce epithelial cell motility. Histological examination of tissue treated with epidermal growth factor (EGF), hepatocyte growth factor (HGF), insulin-like growth factor-1 (IGF-1) or keratinocyte growth factor (KGF) showed that only HGF and EGF were inducers of invasion while KGF- and IGF-1-treated tissues were histologically similar to untreated controls. In parallel studies, HGF and EGF were found to be potent stimulators of epidermal keratinocyte motility while IGF-1 was less effective and KGF was even less so. None of the growth factors stimulated dermal fibroblast motility while HGF and to a lesser extent IGF-1 (but not EGF or KGF) stimulated motility of dermal vascular endothelial cells. Thus, there is a strong correlation between growth factor capacity to induce epidermal keratinocytes to invade the underlying dermal tissue and to induce motility in the invasive population of cells.
Keratinocyte growth factor
Epidermis (zoology)
Organ culture
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Keratinocyte growth factor
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