- Email: [email protected]
Transferrin responsiveness and embryonic induction
400
401
TRANSFERRIN RESPONSIVENESS AND EMBRYONIC INDUCTION. P. Ekblom, W. Landschulz, I. Thesle ff Dept Pathol,Univ Helsinki, Finland and Friedrich-Miescher Lab. ,Max-Planck-Gesell schaft, Spemannstr. 37,7400, West-Germany The development of the metanephric mesenchyme to epithelial kidney tubules requires the presence of an inductor tissue. During induction, the mesenchyme changes its matrix type, starts to proliferate, and becomes responsive to transferrin(tf). We now studied the tf-receptor mediated route of Fe uptake. The tfreceptor was shown with monoclonal antibodies. Induced cells seem to contain more receptors than uninduced cells. The receptor antibody inhibits growth, but this effect can be overcome by adding Pcchelators that by-pass the receptor-mediated route. Indeed, growth stimulation is correlated with the amount of Fe delivered intracellularly, as judged by uptake of 59-Fe. These studies suggest that induction stimulates the expression of tfreceptors, which are required in vivo for the uptake of Fe, a crucial event in the proliferation and differentiation of the induced cells. We cannot stimulate the induced cells with other growth factors (EGF, FGF, PDGF, SGF,MSA, insulin).
DIHYDROTESTOSTERONE(DHT) UNCOUPLES CELL INTERACTIONS IN DEVELOPING LUNG.J.Torday. Dept. Pediatrics,Harvard Medical School, Boston MA 02115. Animal studies indicate that the delay in male lung maturation is due to androgen. In organotypic culture 10-8M DHT blocks cortisol(F)stimulation of surfactant. Since F stimulates this process via fibroblast-pneumonocyte factor (FPF), the effect of DHT on FPF production and action were assessed. DHT blocked both FPF production and stimulation of surfactant synthesis by epithelial type II (TII) cells. Study of sex-specific fibroblasts revealed that male FPF production is lower than female and is less sensitive to F. These findings are consistent wJth the effects of DHT on this process. Sex-specific TII cells showed no difference in activity. TII cells proliferating in DHT showed a dose-dependent decrease in doubling time and surfactant synthesis at i0 _8 to 10-6M. The daughter cells were unable to respond to FPF, even in the ab~ sence of DHT. Conclusion: (1)male lung fibroblasts are immature relative to female lung fibroblasts, likely due to androgens in male circulation; (2)DHT alters TII cells by blocking their response to FPF and by causing "de-differentiation".
402
403
DIFFERENTIAL R E S P O N S E OF E N D O D E R M A L T I S S U E S TO THE I N D U C T I V E INFLUENCE OF D I G E S T I V E TRACT MESENCNYME IN THE A V I A N E M 8 R Y O S . S. Yasugi, K. Takiguchi and T. Mizuno. Soul. Inst., Fac. of Sci., Univ. Tokyo, Hongo, Tokyo, ll3 Japan. Primary hypoblast (destined to differentiate i n t o y 0 1 k sac e n d 0 derm), allantoic, or g i z z a r d endoderm were associated with proventricular mesenchyme (PVM) and r e c o m b i n a n t s were cultured on CAM or in e m b r y o n i c coelom. Primary hypoblast and g i z z a r d endoderm could differentiate morphologically and f u n c t i o n a l l y into proventricular epithelium and p r o d u c e p e p s i n o g e n s , while allantoic endoderm formed welldeveloped g l a n d s but n e v e r p r o duced pepsinogens. These results s h o w t h a t P V M can i n d u c e g l a n d u l a r morphogenesis and f u n c t i o n a l cytodifferentiation in v a r i o u s endodermal tissues, but the e n d o derms respond differentially to the i n f l u e n c e of P V M as to the pepsinogen expression.
BETA-KERATIN SYNTHESIS IN NEUTRAL CHICK EPITHELIA RECOMBINED WITH CHICK PLANTAR DERMIS. D. Dhouailly and R.H. Sawyer, Universit@ de Grenoble i, B.P. 68, F-38402 St Martin d'Heres and Department of Biology, University of South Carolina, Columbia, S.C. 29208, USA. In birds, the reticulate scales which cover the plantar face of the foot elaborate only alpha-keratins, while the other avian scales, as well as the feathers are made up of alpha- and beta-keratins. Previous studies having shown that the dermis controls the epidermal keratinizatio~ the question arises whether the plantar dermis as the interappendage dermis is only able to support the synthesis of alph~ keratin. Recombinants of 10-day chick embryo plantar dermis and 10-day amnion epithelium or 10-day midventral apteric epidermis have been analysed with s p e c i ~ c alpha and beta-keratins antibodies. In both cases, abnormal structures involving beta-keratins formed. Furthermore, most of the explants of plantar dermis and apterie epidermis differentiated short feathers. These results emphasize the role of dermal-epidermal interactions in the acquisition of dermal properties.
164S
401
TRANSFERRIN RESPONSIVENESS AND EMBRYONIC INDUCTION. P. Ekblom, W. Landschulz, I. Thesle ff Dept Pathol,Univ Helsinki, Finland and Friedrich-Miescher Lab. ,Max-Planck-Gesell schaft, Spemannstr. 37,7400, West-Germany The development of the metanephric mesenchyme to epithelial kidney tubules requires the presence of an inductor tissue. During induction, the mesenchyme changes its matrix type, starts to proliferate, and becomes responsive to transferrin(tf). We now studied the tf-receptor mediated route of Fe uptake. The tfreceptor was shown with monoclonal antibodies. Induced cells seem to contain more receptors than uninduced cells. The receptor antibody inhibits growth, but this effect can be overcome by adding Pcchelators that by-pass the receptor-mediated route. Indeed, growth stimulation is correlated with the amount of Fe delivered intracellularly, as judged by uptake of 59-Fe. These studies suggest that induction stimulates the expression of tfreceptors, which are required in vivo for the uptake of Fe, a crucial event in the proliferation and differentiation of the induced cells. We cannot stimulate the induced cells with other growth factors (EGF, FGF, PDGF, SGF,MSA, insulin).
DIHYDROTESTOSTERONE(DHT) UNCOUPLES CELL INTERACTIONS IN DEVELOPING LUNG.J.Torday. Dept. Pediatrics,Harvard Medical School, Boston MA 02115. Animal studies indicate that the delay in male lung maturation is due to androgen. In organotypic culture 10-8M DHT blocks cortisol(F)stimulation of surfactant. Since F stimulates this process via fibroblast-pneumonocyte factor (FPF), the effect of DHT on FPF production and action were assessed. DHT blocked both FPF production and stimulation of surfactant synthesis by epithelial type II (TII) cells. Study of sex-specific fibroblasts revealed that male FPF production is lower than female and is less sensitive to F. These findings are consistent wJth the effects of DHT on this process. Sex-specific TII cells showed no difference in activity. TII cells proliferating in DHT showed a dose-dependent decrease in doubling time and surfactant synthesis at i0 _8 to 10-6M. The daughter cells were unable to respond to FPF, even in the ab~ sence of DHT. Conclusion: (1)male lung fibroblasts are immature relative to female lung fibroblasts, likely due to androgens in male circulation; (2)DHT alters TII cells by blocking their response to FPF and by causing "de-differentiation".
402
403
DIFFERENTIAL R E S P O N S E OF E N D O D E R M A L T I S S U E S TO THE I N D U C T I V E INFLUENCE OF D I G E S T I V E TRACT MESENCNYME IN THE A V I A N E M 8 R Y O S . S. Yasugi, K. Takiguchi and T. Mizuno. Soul. Inst., Fac. of Sci., Univ. Tokyo, Hongo, Tokyo, ll3 Japan. Primary hypoblast (destined to differentiate i n t o y 0 1 k sac e n d 0 derm), allantoic, or g i z z a r d endoderm were associated with proventricular mesenchyme (PVM) and r e c o m b i n a n t s were cultured on CAM or in e m b r y o n i c coelom. Primary hypoblast and g i z z a r d endoderm could differentiate morphologically and f u n c t i o n a l l y into proventricular epithelium and p r o d u c e p e p s i n o g e n s , while allantoic endoderm formed welldeveloped g l a n d s but n e v e r p r o duced pepsinogens. These results s h o w t h a t P V M can i n d u c e g l a n d u l a r morphogenesis and f u n c t i o n a l cytodifferentiation in v a r i o u s endodermal tissues, but the e n d o derms respond differentially to the i n f l u e n c e of P V M as to the pepsinogen expression.
BETA-KERATIN SYNTHESIS IN NEUTRAL CHICK EPITHELIA RECOMBINED WITH CHICK PLANTAR DERMIS. D. Dhouailly and R.H. Sawyer, Universit@ de Grenoble i, B.P. 68, F-38402 St Martin d'Heres and Department of Biology, University of South Carolina, Columbia, S.C. 29208, USA. In birds, the reticulate scales which cover the plantar face of the foot elaborate only alpha-keratins, while the other avian scales, as well as the feathers are made up of alpha- and beta-keratins. Previous studies having shown that the dermis controls the epidermal keratinizatio~ the question arises whether the plantar dermis as the interappendage dermis is only able to support the synthesis of alph~ keratin. Recombinants of 10-day chick embryo plantar dermis and 10-day amnion epithelium or 10-day midventral apteric epidermis have been analysed with s p e c i ~ c alpha and beta-keratins antibodies. In both cases, abnormal structures involving beta-keratins formed. Furthermore, most of the explants of plantar dermis and apterie epidermis differentiated short feathers. These results emphasize the role of dermal-epidermal interactions in the acquisition of dermal properties.
164S