Cholesterol Metabolism: the Main Pathway Acting Downstream of Cytochrome P450 Oxidoreductase in Skeletal Development of the Limb
Cholesterol Metabolism: the Main Pathway Acting Downstream of Cytochrome P450 Oxidoreductase in Skeletal Development of the Limb
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DOI：
10.1128/mcb.01638-08
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发表时间：
2009-05-15
影响因子：
5.3
通讯作者：
Tickle, Cheryll
中科院分区：
文献类型：
--
作者：
Schmidt, Katy;Hughes, Catherine;Tickle, Cheryll
细胞色素P450氧化还原酶(POR)是所有微粒体细胞色素P450酶的专有电子供体，催化多种异源和内生化合物的代谢。最近在Antley-Bixler样综合征患者中发现了POR的点突变，其中包括四肢骨骼缺陷。为了研究P450在肢体和骨骼发育中的功能，我们在小鼠的肢芽间充质中特异性地删除了POR。条件性基因敲除(CKO)小鼠的前肢和后肢较短，骨骼元素较薄，关节融合。POR缺失发生在前肢比后肢更早，另外由于生长、细胞死亡和骨骼分段的改变，还会导致软组织并指以及腕关节元素和指骨的丢失。E12.5小鼠前肢芽的转录分析表明，P450参与了维甲酸、胆固醇和花生四烯酸的代谢。CKO四肢的生化分析证实维甲酸过多。在CKO肢体中，整个胆固醇生物合成途径的基因表达上调，胆固醇缺乏可以解释表型的大部分方面。因此，细胞内依赖POR的胆固醇合成在肢体和骨骼发育过程中是必不可少的。P450活性的调节可能有助于胚胎和发育器官对畸形的易感性。
Cytochrome P450 oxidoreductase (POR) is the obligate electron donor for all microsomal cytochrome P450 enzymes, which catalyze the metabolism of a wide spectrum of xenobiotic and endobiotic compounds. Point mutations in POR have been found recently in patients with Antley-Bixler-like syndrome, which includes limb skeletal defects. In order to study P450 function during limb and skeletal development, we deleted POR specifically in mouse limb bud mesenchyme. Forelimbs and hind limbs in conditional knockout (CKO) mice were short with thin skeletal elements and fused joints. POR deletion occurred earlier in forelimbs than in hind limbs, leading additionally to soft tissue syndactyly and loss of wrist elements and phalanges due to changes in growth, cell death, and skeletal segmentation. Transcriptional analysis of E12.5 mouse forelimb buds demonstrated the expression of P450s involved in retinoic acid, cholesterol, and arachidonic acid metabolism. Biochemical analysis of CKO limbs confirmed retinoic acid excess. In CKO limbs, expression of genes throughout the whole cholesterol biosynthetic pathway was upregulated, and cholesterol deficiency can explain most aspects of the phenotype. Thus, cellular POR-dependent cholesterol synthesis is essential during limb and skeletal development. Modulation of P450 activity could contribute to susceptibility of the embryo and developing organs to teratogenesis.