Cytochrome b5 and NADH cytochrome b5 reductase: genotype-phenotype correlations for hydroxylamine reduction.
Cytochrome b5 and NADH cytochrome b5 reductase: genotype-phenotype correlations for hydroxylamine reduction.
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DOI：
10.1097/fpc.0b013e3283343296
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发表时间：
2010-01
影响因子：
2.6
通讯作者：
Trepanier LA
中科院分区：
文献类型：
--
作者：
Sacco JC;Trepanier LA
NADH细胞色素b5还原酶（b5 R）和细胞色素b5（b5）催化磺胺甲恶唑羟胺（SMX-HA）还原为母体药物磺胺甲恶唑，这可能导致磺胺超敏反应。因此，羟胺还原的变异性可能在药物不良反应中发挥作用。本研究的目的是描述111例人类肝脏中SMX-HA减少的变异性，并研究其与b5和b5 R cDNA中单核苷酸多态性（SNP）的相关性。测定肝微粒体的SMX-HA还原活性，并通过免疫印迹法对b5和b5 R表达进行半定量。对b5（CYB 5A）和b5 R（CYB 5 R3）基因的编码区进行重新测序。肝脏SMX-HA降低显示个体变异性范围为19倍（0.06-1.11 nmol/min/mg蛋白），离群值中的有效性范围（Vmax/Km）为17倍。SMX-HA减少与b5和b5 R蛋白含量呈正相关（分别为p < 0.0001，r = 0.42; p = 0.01，r = 0.23），两种蛋白的表达相互相关（p < 0.0001; r = 0.74）。CYB 5A（S5 A）中的一种新的cSNP与非常低的活性和蛋白表达相关。两种新型CYB 5 R3 SNP R59 H和R297 H显示非典型SMX-HA还原动力学，并降低SMX-HA还原效率。这些研究表明，虽然CYB 5A和CYB 5 R3中的新型cSNP与显著改变的蛋白质表达和/或羟胺还原活性相关，但这些低频cSNP似乎仅对观察到的总体表型变异性产生最小影响。目前正在研究这些基因其他区域的多态性，以进一步解释羟胺还原的个体差异。
NADH cytochrome b5 reductase (b5R) and cytochrome b5 (b5) catalyze the reduction of sulfamethoxazole hydroxylamine (SMX-HA), which can contribute to sulfonamide hypersensitivity, to the parent drug sulfamethoxazole. Variability in hydroxylamine reduction could thus play a role in adverse drug reactions. The aim of this study was to characterize variability in SMX-HA reduction in 111 human livers, and investigate its association with single nucleotide polymorphisms (SNPs) in b5 and b5R cDNA. Liver microsomes were assayed for SMX-HA reduction activity, and b5 and b5R expression was semi-quantified by immunoblotting. The coding regions of the b5 (CYB5A) and b5R (CYB5R3) genes were resequenced. Hepatic SMX-HA reduction displayed a 19-fold range of individual variability (0.06–1.11 nmol/min/mg protein), and a 17-fold range in efficiency (Vmax/Km) among outliers. SMX-HA reduction was positively correlated with b5 and b5R protein content (p < 0.0001, r = 0.42; p = 0.01, r = 0.23, respectively), and expression of both proteins correlated with one another (p < 0.0001; r = 0.74). A novel cSNP in CYB5A (S5A) was associated with very low activity and protein expression. Two novel CYB5R3 SNPs, R59H and R297H, displayed atypical SMX-HA reduction kinetics and decreased SMX-HA reduction efficiency. These studies indicate that while novel cSNPs in CYB5A and CYB5R3 are associated with significantly altered protein expression and/or hydroxylamine reduction activities, these low frequency cSNPs only appear to minimally impact overall observed phenotypic variability. Work is underway to characterize polymorphisms in other regions of these genes to further account for individual variability in hydroxylamine reduction.