Interactions between retinoids and TGF beta s in mouse morphogenesis.
Using immunocytochemical methods we describe the distribution of different TGF beta isoforms and the effects of excess retinoic acid on their expression during early mouse embryogenesis (8 1/2 - 10 1/2 days of development). In normal embryos at 9 days, intracellular TGF beta 1 is expressed most intensely in neuroepithelium and cardiac myocardium whereas extracellular TGF beta 1 is expressed in mesenchymal cells and in the endocardium of the heart. At later stages, intracellular TGF beta 1 becomes very restricted to the myocardium and to a limited number of head mesenchymal cells; extracellular TGF beta 1 continues to be expressed widely in cells of mesenchymal origin, particularly in head and trunk mesenchyme, and also in endocardium. TGF beta 2 is widely expressed at all stages investigated while TGF beta 3 is not expressed strongly in any tissue at the stages examined. Exposure of early neural plate stage embryos to retinoic acid caused reduced expression of TGF beta 1 and TGF beta 2 proteins but had no effect on TGF beta 3. Intracellular TGF beta 1 expression was reduced in all tissues except in the myocardium, while extracellular TGF beta 1 was specifically reduced in neuroepithelium and cranial neural crest cells at early stages. TGF beta 2 was reduced in all embryonic tissues. The down-regulation of intracellular TGF beta 1 was observed up to 48 hours after initial exposure to retinoic acid while some down-regulation of TGF beta 2 was still seen up to 60 hours after initial exposure.(ABSTRACT TRUNCATED AT 250 WORDS)
Mahmood
R
R
Department of Human Anatomy, Oxford, UK.
Flanders
K C
KC
Morriss-Kay
G M
GM
D000818:Animals; D047108:Embryonic Development; D005314:Embryonic and Fetal Development / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006321:Heart / Q000196:embryology; D007150:Immunohistochemistry; D051379:Mice; D008815:Mice, Inbred Strains; D009024:Morphogenesis / Q000502:physiology; D011247:Pregnancy; D012176:Retinoids / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology
D012176:Retinoids; D016212:Transforming Growth Factor beta; D014212:Tretinoin