VITAMIN A AS PRECURSOR OF INTRACELLULAR SECOND MESSENGER

在视黄醇的多效性功能中，对免疫系统的影响 系统是值得注意的，反映在几乎完全依赖B 和T细胞在这种类维生素A上的生长和活化。 而 为了寻找作用机制，我们定义了一种代谢物， 视黄醇，14-羟基-反视黄醇（14 HRR），可能是 视黄醇在淋巴细胞中的作用。 待检验的工作假设是 14 HRR作为第二信使分子传递抗原， 受体向细胞质或细胞核产生激活信号 受体分子 这一假设得到了令人兴奋的 发现14 HRR的一个结构上的近亲，脱水反视黄醇， (ARR)，竞争与类似的靶受体结合， 可逆抑制T细胞活化和B细胞生长。 转化的B细胞在12至24小时内停止增殖并死亡， μ M浓度的ARR。 借鉴关于14 HRR的先前工作 根据对拮抗剂ARR的新观察，我们建议继续 几个新维甲酸类化合物分离和结构表征 哺乳动物和昆虫细胞（目标#1）。 14 HRR和13，14二羟基- 视黄醇（DHR），一种新的类维生素A和可能的生物合成中间体， 14 HRR合成，将合成以证明结构和 确定天然化合物的立体化学性质， 生产用于生物实验的3 H标记化合物（目标#2）。 视黄醇经13，14-环氧-视黄醇的生物合成途径 和DHR至14 HRR将进行研究（目标3）。 14 HRR结合蛋白 细胞质和/或细胞核中的蛋白质将通过使用常规的 蛋白质分级分离结合14 HRR结合测定， 通过使用ARR构造的亲和矩阵。 识别 14 HRR结合蛋白的研究可能为研究其作用机制开辟新的前景 并建议替代以前持有的（仍然是首选） 14 HRR作为核转录因子配体的假说 (Aim 4）。

Among the pleiotropic functions of retinol, the effects on the immune system are noteworthy, as reflected in the almost total dependence of B and T cells for growth and activation in culture on this retinoid. While searching for the mechanism of action, we have defined a metabolite of retinol, 14-hydroxy-retro-retinol (14HRR) that is the likely mediator of retinol effects in lymphocytes. The working hypothesis to be tested is that 14HRR acts as a second messenger molecule to transmit antigen- receptor generated activation signal(s) to cytoplasmic or nuclear receptor molecules. this hypothesis has been buoyed by the exciting finding that a close structural relative of 14HRR, anhydro-retro-retinol (ARR), competes for binding to similar target receptors and causes reversible inhibition of T cell activation and B cell growth. Transformed B cells cease to proliferate and die within 12 to 24 h with muM concentrations of ARR. Drawing on the previous body of work on 14HRR and on new observations with the antagonist ARR, we propose to continue the isolation and structural characterization of several new retinoids of mammalian and insect cells (Aim #1). 14HRR and 13,14 dihydroxy- retinol (DHR), a new retinoid and likely biosynthetic intermediate in 14HRR synthesis, will be synthesized to prove the structures and determine the stereochemical properties of the natural compounds and to produce 3H-labeled compounds for biological experimentation (Aim #2). The putative biosynthetic pathway from retinol via 13,14 epoxy-retinol and DHR to 14HRR will be investigated (Aim 3). 14HRR binding proteins in cytoplasm and/or nucleus will be identified by use of conventional protein fractionation in conjunction with assays for 14HRR binding and by use of an affinity matrix constructed with ARR. The identification of 14HRR binding proteins may open new vistas on the mechanism of action and suggest alternatives to the previously held (and still preferred) hypothesis that 14HRR acts as ligand for a nuclear transcription factor (Aim 4).