title: Localization of retinoic acid receptors in anterior-human embryo.
abstract: Retinoic acid receptors (RARs) are nuclear transcription factors that are activated by all-trans-retinoic acid or 9-cis-retinoic acid and are found in all tissues but predominantly in developing fetus, dividing tumor cells, and adult skin. Three forms of these receptors, alpha, beta, and gamma, have been described. In this paper we report the presence of RAR alpha and beta determined by hybridization with anti-sense messenger RNA, and histochemical localization of the three forms of RARs using monospecific polyclonal antibodies in various tissues of early human embryos. In a 54-day-old embryo, RAR alpha was expressed primarily in the liver and the brain, with somewhat lesser expression in the intestine. RAR beta was the highest in the brain, followed by a restricted expression in the intestine and the liver. Other organs, i.e., adrenal, kidney, and testis, did not show measurable amounts of RAR beta. The immunohistochemical localization in anterior sections of a 43-day-old embryo indicated that RAR alpha was present in the neuroepithelial cells and in cells lining the primitive pharyngeal sac, dorsal aorta, and pericardium. RAR beta was somewhat less prevalent in same tissues, whereas the expression of RAR gamma was the lowest of the three RARs in any tissues examined. Results indicated that RAR alpha and beta appear at early stages of human embryonic development and their expression is restricted to certain types of tissues.
authors.affiliation: Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
authors.forename: R P
authors.initials: RP
authors.lastname: Sharma
authors.forename: Y W
authors.initials: YW
authors.lastname: Kim
mesh_terms: D015152:Blotting, Northern; D001921:Brain / Q000196:embryology; D001923:Brain Chemistry; D004622:Embryo, Mammalian / Q000737:chemistry*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007422:Intestines / Q000737:chemistry / Q000196:embryology; D008099:Liver / Q000737:chemistry / Q000196:embryology; D008297:Male; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D018168:Receptors, Retinoic Acid / Q000032:analysis* / Q000235:genetics; D000072482:Retinoic Acid Receptor alpha; D000097768:Retinoic Acid Receptor gamma
chemical_list: D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D000097768:Retinoic Acid Receptor gamma; C000607071:RARA protein, human; C082925:retinoic acid receptor beta