Chen T L, Hirst M A, Cone C M, Hochberg Z, Tietze H U, Feldman D
J Clin Endocrinol Metab. 1984 Sep;59(3):383-8. doi: 10.1210/jcem-59-3-383.
To investigate further the cellular defects of vitamin D-dependent rickets type II with alopecia, we studied 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] receptors and the response to 1,25-(OH)2D3 in cultured skin fibroblasts from rachitic patients. Our studies included cells from four affected patients from three kindreds and their parents and cells from five normal subjects. We measured total 1,25-(OH)2D3 receptor binding in cell extracts and the capacity of 1,25-(OH)2D3 to induce the enzyme 25-hydroxyvitamin D3-24-hydroxylase (24-hydroxylase) as a marker of functional response. In normal fibroblasts, the 1,25-(OH)2D3 maximal binding capacity was 52 +/- 5 fmol/100 micrograms DNA (mean +/- SE), and the apparent dissociation constant (Kd) was 0.05 +/- 0.01 nM. The maximal induced 24-hydroxylase activity after 1,25-(OH)2D3 treatment was 11.5 +/- 1 fmol/10(6) cells X 30 min, and the dose of 1,25-(OH)2D3 that achieved half-maximal induction was 2.3 +/- 0.3 nM. Fibroblasts from all four rachitic patients had the same defect: no measurable 1,25-(OH)2D3 receptor binding and no detectable response above basal activity even after high doses of 1,25-(OH)2D3. Cells from all parents except one had normal 1,25-(OH)2D3 binding characteristics and normal 24-hydroxylase bioresponse to 1,25-(OH)2D3. One parent despite a normal phenotype had only half the normal level of binding sites and only half the normal bioresponse. In summary, the cultured fibroblasts from four affected children representing three different kindreds with 1,25-(OH)2D3 resistance failed to exhibit detectable 1,25-(OH)2D3 receptors. We postulate that this biochemical defect produced both the inability to respond to 1,25-(OH)2D3 in vitro and the 1,25-(OH)2D3 resistance in vivo. The obligate heterozygotic parents were normal, except for one who had both half the normal number of receptors and half the normal response to 1,25-(OH)2D3. The data confirm the critical role of the receptor in 1,25-(OH)2D3 action and the close coupling of receptor content and functional responsiveness.
为了进一步研究伴有脱发的II型维生素D依赖性佝偻病的细胞缺陷，我们对佝偻病患者培养的皮肤成纤维细胞中的1,25 - 二羟维生素D3 [1,25-(OH)2D3]受体以及对1,25-(OH)2D3的反应进行了研究。我们的研究包括来自三个家族的四名患病患者及其父母的细胞，以及来自五名正常受试者的细胞。我们测量了细胞提取物中总的1,25-(OH)2D3受体结合情况，以及1,25-(OH)2D3诱导25 - 羟维生素D3 - 24 - 羟化酶（24 - 羟化酶）的能力，以此作为功能反应的标志物。在正常成纤维细胞中，1,25-(OH)2D3的最大结合能力为52±5 fmol/100微克DNA（平均值±标准误），表观解离常数（Kd）为0.05±0.01 nM。1,25-(OH)2D3处理后诱导的24 - 羟化酶最大活性为11.5±1 fmol/10^6细胞×30分钟，达到最大诱导活性一半时的1,25-(OH)2D3剂量为2.3±0.3 nM。所有四名佝偻病患者的成纤维细胞都有相同的缺陷：无法检测到1,25-(OH)2D3受体结合，即使给予高剂量的1,25-(OH)2D3，也未检测到高于基础活性的反应。除一名家长外，所有家长的细胞对1,25-(OH)2D3具有正常的结合特性，并且对1,25-(OH)2D3有正常的24 - 羟化酶生物反应。一名家长尽管表型正常，但只有正常水平一半的结合位点和一半的正常生物反应。总之，来自代表三个不同家族且具有1,25-(OH)2D3抵抗性的四名患病儿童的培养成纤维细胞未能表现出可检测到的1,25-(OH)2D3受体。我们推测这种生化缺陷导致了体外对1,25-(OH)
