Charmandari Evangelia, Kino Tomoshige, Souvatzoglou Emmanuil, Vottero Alessandra, Bhattacharyya Nisan, Chrousos George P
Pediatric and Reproductive Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Clin Endocrinol Metab. 2004 Apr;89(4):1939-49. doi: 10.1210/jc.2003-030450.
Glucocorticoid resistance is a rare, familial, or sporadic condition characterized by partial end-organ insensitivity to glucocorticoids. The clinical spectrum of the condition ranges from completely asymptomatic to severe hyperandrogenism, fatigue, and/or mineralocorticoid excess. The molecular basis of glucocorticoid resistance in several families and sporadic cases has been ascribed to mutations in the human glucocorticoid receptor-alpha (hGRalpha) gene, which impair the ability of the receptor to transduce the glucocorticoid signal. We systematically investigated the molecular mechanisms through which natural, ligand-binding domain hGRalpha mutants, including hGRalphaI559N, hGRalphaV571A, hGRalphaD641V, hGRalphaV729I, and hGRalphaI747M, produce a defective signal and determined whether their differential effects on hGRalpha function might account for the type of genetic transmission of the disorder and the variable clinical phenotype of the affected subjects. Our findings suggest that all five mutant receptors studied have ligand-binding domains with decreased intrinsic transcriptional activity. Unlike hGRalphaI559N and I747M previously shown to exert a dominant negative effect upon the transcriptional activity of hGRalpha, hGRalphaV571A, D641V, and V729I do not have such an effect. All five mutants studied demonstrate varying degrees of decreased affinity for the ligand in a standard dexamethasone binding assay, but preserve their ability to bind DNA. The nondominant negative mutants, hGRalphaV571A, D641V, and V729I, show delayed translocation into the nucleus after exposure to ligand. Finally, hGRalphaI559N, V571A, D641V, and V729I display an abnormal interaction with the glucocorticoid receptor-interacting protein-1 coactivator in vitro, as this was previously shown also for hGRalphaI747M. We conclude that each of the above hGRalpha mutations imparts different functional defects upon the glucocorticoid signal transduction pathway, which explains the autosomal recessive or dominant transmission of the disorder, but might only explain in part its variable clinical phenotype.
糖皮质激素抵抗是一种罕见的、家族性或散发性疾病，其特征为终末器官对糖皮质激素存在部分不敏感。该疾病的临床谱范围从完全无症状到严重高雄激素血症、疲劳和/或盐皮质激素过多。在几个家族性和散发性病例中，糖皮质激素抵抗的分子基础已归因于人类糖皮质激素受体α（hGRα）基因的突变，这些突变损害了受体转导糖皮质激素信号的能力。我们系统地研究了天然的、配体结合域hGRα突变体（包括hGRαI559N、hGRαV571A、hGRαD641V、hGRαV729I和hGRαI747M）产生缺陷信号的分子机制，并确定它们对hGRα功能的不同影响是否可能解释该疾病的遗传传递类型以及受影响个体的可变临床表型。我们的研究结果表明，所研究的所有五个突变受体的配体结合域均具有降低的内在转录活性。与先前显示对hGRα转录活性具有显性负效应的hGRαI559N和I747M不同，hGRαV571A、D641V和V729I没有这种效应。在所研究的所有五个突变体中，在标准地塞米松结合试验中对配体的亲和力均有不同程度的降低，但保留了它们结合DNA的能力。非显性负性突变体hGRαV571A、D641V和V
