Cloning of new endothelin B receptor and its physiological significance

1.内皮素受体亚型分析为研究介导兔和人大隐静脉血管收缩的内皮素受体亚型，观察了几种ET受体激动剂和拮抗剂的作用。我们的结果表明ET_A和ET_B受体介导的收缩的药理异质性(ET_A和ET_B受体介导的收缩)。目前可用的数据以及本研究中获得的数据清楚地表明了内皮素类药物反应的药理学异质性，但这些数据还不足以为内皮素受体命名提供确凿的证据。然而，使用ET_B缺陷小鼠的其他药理学数据清楚地表明，ET_B受体的这些药理上的异质性反应已经完全丧失，这表明ET_B受体和ET_B受体来自单个ET_B基因。2.先天性巨结肠症中内皮素B受体的突变分析先天性巨结肠症(HSCR)的特点是末端肠道中缺乏自主神经节细胞，是新生儿肠梗阻的相对常见原因。最近，ET_B基因被证明是HSCR的易感基因，该基因零突变的小鼠产生无神经节细胞的结肠，并在HSCR(门诺氏家系)的高发近交系中显示错义突变。然而，在其他临床病例中没有发现进一步的突变。我们分析了31例分离的HSCR患者ET_B基因的改变，发现了3个新的突变：A到T，T到C和C到A的转变，分别位于第311,325和1170位核苷酸。这些突变导致Asn到Ile，Cys到Arg和Ser到Arg，预计会产生一个不起作用的ET_B受体。这些观察结果表明，ET_B受体功能障碍或功能丧失可能与某些孤立的HSCR患者的病因有关。

1.Analysis of endothelin receptor subtypesTo study endothelin (ET) receptor subtypes which mediate smooth muscle contraction of the rabbit and human saphenous veins, effects of some ET receptor agonists and antagonists were examined. Our results indicated pharmacological heterogeneity (ET_<A1>, ET_<A2> ; ET_<B1>, ET_<B2>) of both ET_A and ET_B recetor-mediated contractions. The currently available data, as well as those obtained in the present study, clearly indicate pharmacological heterogeneity of responses to endothelins, but they are not yet sufficient to provide conclusive evidence for endothelin receptor nomenclature. However, additional pharmacological data using ET_B-deficient mice clearly indicated that these pharmacologically heterogenous responses of ET_B receptor are completely lost, suggesting that ET_<B1> and ET_<B2> receptors are derived from a single ET_B gene.2.Mutation analysis of endothelin B receptor in Hirschsprung diseaseHirschsprung's disease (HSCR) is characterized by the absence of autonomic ganglion cells in the terminal bowel and is a relatively common cause of intestinal obstruction in the newborn. Recently, ET_B gene has been shown as a susceptibility gene for HSCR by the production of aganglionic colon in mice with a null mutation of this gene and by demonstrating a missense mutation in a large inbred kindred with a high incidence of HSCR (Mennonite pedigree). However, no further mutations have been demonstrated in other clinical cases. We analyzed alterations of the ET_B gene in 31 isolated patients of HSCR.Three novel mutations were detected : A to T, T to C and C to A transitions at nucleotide 311,325 and 1170, respectively. These mutations resulted in Asn to Ile, Cys to Arg and Ser to Arg, predicted to produce a non-functional ET_B receptor. These observations indicate that dysfunction or loss of function of ET_B receptor may be involved in the aetiology of some isolated patients with HSCR.