Adams J S, Beeker T G, Hongo T, Clemens T L
Division of Endocrinology and Metabolism, Cedars-Sinai Medical Center-UCLA School of Medicine 90048.
J Bone Miner Res. 1990 Dec;5(12):1265-9. doi: 10.1002/jbmr.5650051212.
The capacity of the v-myc-transformed, chicken myelomonocytic cell line HD-11 to metabolize 25-hydroxyvitamin D3 (25-OHD3) was examined. HD-11 cells produced and secreted a metabolite of 25-OHD3 that was bound with high affinity by receptor for 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. On normal-phase HPLC, this metabolite cochromatographed with authentic 1,25-(OH)2D3 in both hexane- and methylene chloride-based solvent systems. The 25-OHD3 1-hydroxylation reaction was substrate saturable with a Km of 73 nM 25-OHD3 and a maximal velocity of 167 fmol per 10(6) cells per h. This reaction was inhibited by ketoconazole, a recognized inhibitor of cytochrome P450 mixed-function oxidases including the authentic, renal 25-OHD3 1-hydroxylase. On the other hand, HD-11 cell 1,25-(OH)2D3 production was not affected by the antioxidant DPPD, a known inhibitor of free radical-generated 1,25-(OH)2D3. In addition to synthesizing 1,25-(OH)2D3, this monocyte-macrophage cell line also has the potential to be a target for the hormone; HD-11 cells express high-affinity receptor for 1,25-(OH)2D3 (Kin = 0.06 nM).
研究了v-myc转化的鸡骨髓单核细胞系HD-11代谢25-羟基维生素D3（25-OHD3）的能力。HD-11细胞产生并分泌一种25-OHD3的代谢产物，该产物能与1,25-二羟基维生素D3[1,25-(OH)2D3]受体高亲和力结合。在正相高效液相色谱上，在基于己烷和二氯甲烷的溶剂系统中，这种代谢产物与纯品1,25-(OH)2D3共洗脱。25-OHD3 1-羟化反应对底物具有饱和性，Km为73 nM 25-OHD3，最大速度为每10(6)个细胞每小时167 fmol。该反应被酮康唑抑制，酮康唑是一种公认的细胞色素P450混合功能氧化酶抑制剂，包括真正的肾25-OHD3 1-羟化酶。另一方面，HD-11细胞1,25-(OH)2D3的产生不受抗氧化剂DPPD的影响，DPPD是自由基生成的1,25-(OH)2D3的已知抑制剂。除了合成1,25-(OH)2D3外，这种单核巨噬细胞系也有可能成为该激素的作用靶点；HD-11细胞表达1,25-(OH)2D3的高亲和力受体（Kin = 0.06 nM）。
