Sharma R P, Kim Y W
Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
Exp Mol Pathol. 1995 Jun;62(3):180-9. doi: 10.1006/exmp.1995.1020.
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.
维甲酸受体（RARs）是核转录因子，可被全反式维甲酸或9-顺式维甲酸激活，存在于所有组织中，但主要存在于发育中的胎儿、分裂的肿瘤细胞和成人皮肤中。已描述了这些受体的三种形式，即α、β和γ。在本文中，我们报告了通过与反义信使核糖核酸杂交确定的RARα和β的存在，以及使用单特异性多克隆抗体在人类早期胚胎的各种组织中对三种形式的RARs进行的组织化学定位。在一个54天大的胚胎中，RARα主要在肝脏和大脑中表达，在肠道中的表达略少。RARβ在大脑中表达最高，其次在肠道和肝脏中有局限性表达。其他器官，即肾上腺、肾脏和睾丸，未显示出可测量的RARβ量。对一个43天大胚胎前部切片的免疫组织化学定位表明，RARα存在于神经上皮细胞以及原始咽囊、背主动脉和心包内衬的细胞中。RARβ在相同组织中的分布略少，而在所有检查的组织中，RARγ的表达是三种RAR中最低的。结果表明，RARα和β在人类胚胎发育的早期阶段出现，且它们的表达局限于某些类型的组织。
