Gene expression of Vit D conversion eyzymes and Ca metaboism in the feto-placental system

钙代谢是内分泌学最感兴趣的领域之一。为了从分子水平上阐明它，人们已经做了大量的研究。然而，胎儿-胎盘系统的调节机制还有待阐明。此外，胎儿维生素D转换酶基因表达的机制与成人器官略有不同。因此，我们的研究项目包括(1)按时间顺序研究人胎盘线粒体中1-α-羟基酶和24R-羟基酶的酶学性质；(2)分析胎儿脑、肺、肾中被认为只存在于肾小管中的1-α-羟基酶和24R-羟基酶。我们发现生物活性维生素D是在胎盘中合成的，是调节胎儿生长的重要物质之一。24R-羟基酶的活性在妊娠20周左右出现，并在节育前略有增加。重度宫内发育迟缓(IUGR)胎盘中，除1-α-羟基酶外，仅有24R-羟基酶表达。我们怀疑这种酶的基因表达可能受到抑制。兔胎儿和新生儿的脑组织、胎盘、肾脏也有1-α-羟基酶的活性。在大脑中，它会一过性增加，并在新生儿年龄后消失。这些新的发现怀疑，维生素D转换酶系统可能与成人和胎儿两种类型的人一致，短暂地出现。我们正试图描述这些胎儿系统的特征，特别是1-α-羟基酶。

Calcium metabolism is one of the most interesting areas in the endocrinology. Much amount of research have been done to clarify it in the molecular levels. However, the regulating mechanisms in the feto-placental systems are to be clarified. In addition, the mechanism of gene expression of Vit D conversion enzymes in the fetus is a little different from the adult organs. So our research project consisted with (1) studying chronologically the enzymatic characterization of 1-alpha-hydroxylase and 24R-hydroxylase in the mitochondria in the human placenta, (2) analyzing the 1-alpha-hydroxylase and 24R-hydroxylase in the fetal brain, lung, kidney, which has been thought to be exist only in the renal tubules.We have found that the biologically active vitamin D was synthesized in the placenta and is one of the important substances regulating the fetal growth. The activity of 24R-hydroxylase appears around pregnancy 20 weeks and slightly increases until partrition. In the placenta of severe type of IUGR (intrauterine growth retardation), however, only 24R-hydroxylase except 1-alpha-hydroxylase was found. We suspect that the gene expression of this enzyme might be inhibited. The activity of rabbit fetus and neonate, and that of 1-alpha-hydroxylase was also found in the brain, placenta, kidney. In the brain it increased transiently and disappeared after the age of the neonate. These new finding suspects that the vitamin D conversion enzyme system might consist with the two types of the adult and the fetus, appearing transiently. We are trying to characterize these fetal systems, especially of 1-alpha-hydroxylase.