JQ1 is a small-molecule inhibitor of the bromodomain and extra terminal (BET) protein family that potently inhibits the bromodomain testis-specific protein (BRDT), which is essential for spermatogenesis. JQ1 treatment produces a reversible contraceptive effect by targeting the activity of BRDT in mouse male germ cells, validating BRDT as a male contraceptive target. Although JQ1 possesses favourable physical properties, it exhibits a short half-life. Because the details of xenobiotic metabolism play important roles in the optimization of drug candidates and in determining the role of metabolism in drug efficacy, we investigated the metabolism of JQ1 in human and mouse liver microsomes. We present the first comprehensive view of JQ1 metabolism in liver microsomes, distinguishing nine JQ1 metabolites, including three monohydroxylated, one de-tert-butylated, two dihydroxylated, one monohydroxylated/dehydrogenated, one monohydroxylated-de-tert-butylated and one dihydroxylated/dehydrogenated variant of JQ1. The dominant metabolite (M1) in both human and mouse liver microsomes is monohydroxylated on the fused three-ring core. Using recombinant cytochrome P450 (CYP) enzymes, chemical inhibitors and the liver S9 fraction of Cyp3a-null mice, we identify enzymes that contribute to the formation of these metabolites. Cytochrome P450 family 3 subfamily A member 4 (CYP3A4) is the main contributor to the production of JQ1 metabolites in vitro, and the CYP3A4/5 inhibitor ketoconazole strongly inhibits JQ1 metabolism in both human and mouse liver microsomes. Our findings suggest that JQ1 half-life and efficacy might be improved in vivo by co-administration of a selective CYP inhibitor, thereby impacting the use of JQ1 as a probe for BRDT activity in spermatogenesis and as a probe or therapeutic in other systems.

中文翻译：

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JQ1（溴结构域和额外末端溴结构域蛋白的抑制剂）在人和小鼠肝微粒体中的代谢†。

JQ1 是溴结构域和额外末端 (BET) 蛋白家族的小分子抑制剂，可有效抑制对精子发生至关重要的溴结构域睾丸特异性蛋白 (BRDT)。JQ1 治疗通过靶向小鼠雄性生殖细胞中 BRDT 的活性产生可逆的避孕效果，验证 BRDT 作为雄性避孕靶点。尽管 JQ1 具有良好的物理性质，但它的半衰期很短。由于异生物质代谢的细节在候选药物的优化和确定代谢在药物疗效中的作用中起着重要作用，我们研究了 JQ1 在人和小鼠肝微粒体中的代谢。我们展示了肝微粒体中 JQ1 代谢的第一个综合视图，区分了九种 JQ1 代谢物，包括三种单羟基化的、JQ1 的一种去叔丁基化、两种二羟基化、一种单羟基化/脱氢、一种单羟基化-去叔丁基化和一种二羟基化/脱氢变体。人和小鼠肝微粒体中的主要代谢物 (M1) 在融合的三环核心上被单羟基化。使用重组细胞色素 P450 (CYP) 酶、化学抑制剂和肝脏 S9 部分Cyp3a缺失的小鼠，我们鉴定了有助于形成这些代谢物的酶。细胞色素 P450 家族 3 亚家族 A 成员 4 (CYP3A4) 是体外产生 JQ1 代谢物的主要贡献者，CYP3A4/5 抑制剂酮康唑强烈抑制人和小鼠肝微粒体中的 JQ1 代谢。我们的研究结果表明，JQ1 的半衰期和功效可能会通过共同给药选择性 CYP 抑制剂而在体内得到改善，从而影响 JQ1 在精子发生中作为 BRDT 活性的探针以及在其他系统中作为探针或治疗剂的使用。