molecular mechanism of abnormal growth hormone action

生长激素异常作用的分子机制

基本信息

批准号：
09470221
负责人：
KAJI Hidesuke
金额：
$ 1.86万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09470221/
关键词：
growth hormone growth hormone gene growth hormone binding protein growth hormone receptor growth hormone receptor gene insulin like growth factor growth failure 成長ホルモン結合蛋白 (GHBP)成長ホルモン安定体遺伝子インスリン様成長因子 (IGF-1)成長ホルモン結合蛋白(GHBp)インスリン

项目摘要

(1) A heterozygous missense mutation R77C in the GH-1 gene was identified in our patient. This mutant GH not only failed to stimulate tyrosine phosphorylation by itself, but also inhibited the activity of the wild-type GH as an antagonist. There are still unresolved problems why the patient's father did not express the mutant GH in his serum despite the presence of a genomic mutation in his allele. To exclude the possibility of genomic implinting, we investigated the genotype of GH-1 gene in his grand mother. Since there was no mutation, somatic mosaicism may be more likely cause.(2) We have reported a novel heterozygous donor splice site mutation in intron 9 of the GH receptor (GHR) gene in siblings who showed partial GH insensitivity and high serum GH-binding protein (GHBP) levels. This mutation caused the splicing abnormality and produced the truncated GHR consisting of 277 amino acids (GHR-277), which lacked most of the intracellular domain of GHR, including both box 1 and 2. in this study we have characterized the function of GHR-277 expression in COS-7 or CHO cells in vitro. Scatchard analysis revealed that GHR-277 possessed twice the number of binding sites compared to wild-type full-length GHR (GHR-fl). The GHBP level in culture medium of GHR-277-expressing cells was approximately 3 times higher than that in GHR-fl expressing cells. The ligand induced internalization was significantly reduced comapred with that of GHR-fl. Moreover, in GH-induced tyrosine phosphorylation of STAT5, GHR-277 exerted a dominant negative effect when GHR-277 and GHR-fl were cotransfected. These in vitro results would well explain the clinical characteristics in our patients.(3) In a patient with a possible GH insensitivity syndrome, we found a heterozygous missense mutation C422F.However, functional study of this mutant GHR did not support this mutation as a cause of his growth failure.

（1）在我们的患者中鉴定出GH-1基因中的杂合错义突变R77C。这种突变的GH不仅无法刺激酪氨酸磷酸化，而且还抑制了野生型GH作为拮抗剂的活性。仍然存在尚未解决的问题，为什么患者的父亲在他的等位基因中存在基因组突变，但他的血清中没有表达突变的GH。为了排除基因组含义的可能性，我们在他的祖母中调查了GH-1基因的基因型。由于没有突变，因此可能是原因。（2）我们报道了在兄弟姐妹的GH受体（GHR）基因的内含子9中的新型杂合供体剪接位点突变，这些兄弟姐妹表现出局部GH不敏感性和高血清GH GH结合蛋白（GHBP）水平。该突变引起剪接异常，并产生由277种氨基酸（GHR-277）组成的截短GHR，该氨基酸缺乏GHR的大部分细胞内结构域，包括Box 1和2。在这项研究中，我们表征了GHR-277表达在COS-7或CHO细胞中GHR-277表达的功能。 Scatchard分析表明，与野生型全长GHR（GHR-FL）相比，GHR-277的结合位点数量是结合位点的两倍。表达GHR-277细胞的培养基中的GHBP水平是GHR-FL表达细胞中的GHBP水平。配体诱导的内在化与GHR-FL的内在化显着降低了。此外，在GH诱导的STAT5酪氨酸磷酸化中，GHR-277在共转染GHR-277和GHR-FL时产生了显着的负面影响。这些体外结果可以很好地解释我们患者的临床特征。（3）在患有GH不敏感综合征的患者中，我们发现杂合的错义突变C422F.CONTER，该突变GHR的功能性研究并不支持该突变作为其生长失败的原因。