Mohr E, Bahnsen U, Kiessling C, Richter D
Institut für Zellbiochemie und klinische Neurobiologie, Universitäts-Krankenhaus Eppendorf, Hamburg, FRG.
FEBS Lett. 1988 Dec 19;242(1):144-8. doi: 10.1016/0014-5793(88)81003-2.
The genes for the hypothalamic hormones vasopressin and oxytocin are located in close proximity to each other within the rat genome. They are separated by only approx. 11 kbp of DNA sequence and oriented in such a way that their transcription occurs on opposite DNA strands. Although the two genes are structurally very similar including common potential regulatory elements in their putative promotor regions, they are expressed in discrete populations of magnocellular neurons of the hypothalamus. In rats placed under osmotic stress, the vasopressin gene is upregulated; concomitantly transcription of the oxytocin gene is also stimulated. To address the question of whether this coordinated rise in oxytocin-encoding mRNA is the result of switching on oxytocin gene transcription in vasopressinergic neurons, in situ hybridization with double labelled cRNA probes was carried out. Biotinylated and [alpha-35S]CTP labelled antisense cRNA probes specific for either vasopressin or oxytocin mRNA were constructed and hybridized to hypothalamic sections from salt-loaded rats. The results demonstrate that upregulation of oxytocin gene transcription is restricted solely to oxytocinergic cells; no oxytocin gene transcripts can be detected in vasopressinergic neurons.
下丘脑激素血管加压素和催产素的基因在大鼠基因组中彼此紧邻。它们仅被约11千碱基对的DNA序列隔开，并且排列方式使得它们的转录发生在相反的DNA链上。尽管这两个基因在结构上非常相似，包括在其假定启动子区域有共同的潜在调控元件，但它们在下丘脑大细胞神经元的不同群体中表达。在处于渗透应激状态的大鼠中，血管加压素基因上调；同时催产素基因的转录也受到刺激。为了解编码催产素的mRNA这种协同增加是否是血管加压素能神经元中催产素基因转录开启的结果，进行了用双标记cRNA探针的原位杂交。构建了生物素化的和用[α-35S]CTP标记的分别针对血管加压素或催产素mRNA的反义cRNA探针，并将其与盐负荷大鼠的下丘脑切片杂交。结果表明，催产素基因转录的上调仅局限于催产素能细胞；在血管加压素能神经元中未检测到催产素基因转录本。
