Interactions between human UGT1A1, UGT1A4, and UGT1A6 affect their enzymatic activities
Interactions between human UGT1A1, UGT1A4, and UGT1A6 affect their enzymatic activities
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DOI：
10.1124/dmd.107.016402
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发表时间：
2007-10-01
影响因子：
3.9
通讯作者：
Yokoi, Tsuyoshi
中科院分区：
文献类型：
--
作者：
Fujiwara, Ryoichi;Nakajima, Miki;Yokoi, Tsuyoshi
利用双表达系统（UGT1A1/ UGT1A4、UGT1A1/UGT1A6和UGT1A4/UGT1A6）在HEK293细胞中研究了人udp -葡萄糖醛酸糖基转移酶（UGT） 1A1、UGT1A4和UGT1A6之间的蛋白-蛋白相互作用。UGT1A1（雌二醇和胆红素）、UGT1A4（丙嗪和三氟拉嗪）和UGT1A6（血清素和双氯芬酸）特异性底物被用来确定其他UGT1A亚型的共表达对酶活性的影响。UGT1A4和UGT1A6的共表达降低了ugt1a1催化雌二醇生成3- o -葡糖苷的S-50和V-max值，提高了ugt1a1催化胆红素生成o - o -葡糖苷的Vmax值。UGT1A1的共表达降低了ugt1a4催化丙咪嗪n -葡糖苷生成的Vmax值，但对ugt1a4催化三氟拉嗪n -葡糖苷生成无影响。UGT1A6的共表达对ugt1a4催化丙咪嗪n -葡糖苷生成无影响，但增加了ugt1a4催化三氟拉嗪n -葡糖苷生成的Km和Vmax。UGT1A1和UGT1A4的共表达增加了ugt1a6催化的血清素和双氯芬酸o -葡萄糖醛酸生成的Vmax值。因此，其他UGT1A异构体的共表达对特定活性动力学的影响取决于UGT1A异构体和底物。双表达系统的天然聚丙烯酰胺凝胶电泳分析显示，在约110 kDa处存在多个条带，表明UGTs存在异源二聚体和同源二聚体。总之，我们发现人类UGT1A1， UGT1A4和UGT1A6可能通过异源二聚化相互作用，并且它们对酶活性的影响是复杂的，取决于同工型和底物。
Protein-protein interactions between human UDP-glucuronosyltransferase (UGT) 1A1, UGT1A4, and UGT1A6 were investigated using double expression systems in HEK293 cells (UGT1A1/ UGT1A4, UGT1A1/UGT1A6, and UGT1A4/UGT1A6). The substrates specific for UGT1A1 (estradiol and bilirubin), UGT1A4 (imipramine and trifluoperazine), and UGT1A6 (serotonin and diclofenac) were used to determine the effects of the coexpression of the other UGT1A isoforms on the enzymatic activity. The coexpression of UGT1A4 and UGT1A6 decreased the S-50 and V-max values of UGT1A1-catalyzed estradiol 3-O-glucuronide formation and increased the Vmax value of UGT1A1-catalyzed bilirubin O-glucuronide formation. The coexpression of UGT1A1 decreased the Vmax value of UGT1A4-catalyzed imipramine N-glucuronide formation but had no effect on UGT1A4-catalyzed trifluoperazine N-glucuronide formation. The coexpression of UGT1A6 had no effect on UGT1A4-catalyzed imipramine N-glucuronide formation but increased the Km and Vmax of UGT1A4-catalyzed trifluoperazine N-glucuronide formation. The coexpression of both UGT1A1 and UGT1A4 increased the Vmax values of UGT1A6-catalyzed serotonin and diclofenac O-glucuronide formation. Thus, the effects of the coexpression of other UGT1A isoforms on the kinetics of specific activities were different depending on the UGT1A isoforms and substrates. Native polyacrylamide gel electrophoresis analysis of the double expression systems showed multiple bands at approximately 110 kDa, indicating the existence of heterodimers as well as homodimers of UGTs. In conclusion, we found that human UGT1A1, UGT1A4, and UGT1A6 interact with each other, possibly by heterodimerization, and that their effects on the enzymatic activities are complex depending on the isoforms and substrates.