Studies on the expression and metabolic capabilities of human liver cytochrome P450IIIA5 (HLp3).
Studies on the expression and metabolic capabilities of human liver cytochrome P450IIIA5 (HLp3).
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DOI：
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发表时间：
1990-08
影响因子：
3.6
通讯作者：
S. Wrighton;W. Brian;M. A. Sari;M. Iwasaki;F. Guengerich;J. Raucy;D. Molowa;M. Vandenbranden
中科院分区：
文献类型：
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作者：
S. Wrighton;W. Brian;M. A. Sari;M. Iwasaki;F. Guengerich;J. Raucy;D. Molowa;M. Vandenbranden
人类P450III家族至少由四个成员组成，P450IIIA3 (HLp), P450IIIA4 (P450NF), P450IIIA5 （HLp3）和P450IIIA6 （HLp2）。由于缺乏特异性识别该家族个体成员的探针，人们对它们的相对表达知之甚少。我们通过免疫吸收抗P450IIIA5 IgG抗Sepharose 4B制备了P450IIIA5的形式特异性抗体，该抗体与不含P450IIIA5或纯化的P450IIIA3的微粒体结合。免疫印迹分析显示，P450IIIA5在66个人类肝脏中只有19个（29%）的肝脏中表达到可检测水平。P450IIIA5的表达不受患者性别和病史的影响。当检测P450IIIA5在不同年龄组中的表达时，我们发现P450IIIA5在儿童和青少年（19岁及以下）中检测到的比例与其他人群相比有统计学意义上更高（8 / 17,47%,11 / 46,24%）。此外，P450IIIA5在10个人胎儿肝脏中检测到。在被鉴定为P450III家族成员底物的大量化合物中，P450IIIA5被发现能积极代谢硝苯地平、睾酮、雌二醇、3-硫酸脱氢表雄酮和皮质醇，而对红霉素、奎尼丁、17 α -乙炔雌二醇和黄曲霉毒素代谢不佳或不代谢。乙酰甾体孕酮被发现是P450IIIA4和P450IIIA5的有效机制抑制剂。从未经处理和地塞米松、苯巴比妥或3-甲基胆蒽处理的HepG2细胞中分离的微粒体的免疫印迹显示，HepG2细胞中没有P450III家族成员的蛋白表达。总之，我们的研究表明，P450IIIA5在人类发育的所有阶段都存在多态性表达，其代谢能力比P450IIIA4更有限。
The human P450III family has been shown to be composed of at least four members, P450IIIA3 (HLp), P450IIIA4 (P450NF), P450IIIA5 (HLp3), and P450IIIA6 (HLp2). Due to the lack of probes that specifically recognize the individual members of this family, little is known about their relative expression. We prepared a form-specific antibody to P450IIIA5 by immunoabsorption of anti-P450IIIA5 IgG against Sepharose 4B upon which microsomes that did not contain P450IIIA5 or purified P450IIIA3 had been bound. Immunoblot analyses demonstrated that P450IIIA5 was expressed at detectable levels in only 19 of 66 (29%) human livers. The expression of P450IIIA5 was not influenced by the gender or medical history of the patients. When the expression of P450IIIA5 in different age groups was examined, it was observed that P450IIIA5 was detected in a statistically significantly higher percentage of children and adolescents (19 years old and under), as compared with the remaining population (8 of 17, 47%, versus 11 of 46, 24%, respectively). Furthermore, P450IIIA5 was detected in 1 of 10 human fetal livers. Of the large number of compounds identified as substrates of P450III family members, P450IIIA5 was found to actively metabolize nifedipine, testosterone, estradiol, dehydroepiandrosterone 3-sulfate, and cortisol, whereas it metabolized poorly or did not metabolize erythromycin, quinidine, 17 alpha-ethynylestradiol, and aflatoxins. The acetylenic steroid gestodene was found to be an effective mechanism-based inhibitor of both P450IIIA4 and P450IIIA5. Immunoblots of microsomes isolated from untreated and dexamethasone-, phenobarbital-, or 3-methylcholanthrene-treated HepG2 cells that were developed with an antibody that recognizes all the P450III family members demonstrated that no proteins in the P450III family were expressed by the HepG2 cells. In conclusion, our studies indicate that P450IIIA5 is polymorphically expressed at all stages of human development and is more limited in its metabolic capabilities than is P450IIIA4.