Knedlík Tomáš, Vorlová Barbora, Navrátil Václav, Tykvart Jan, Sedlák František, Vaculín Šimon, Franěk Miloslav, Šácha Pavel, Konvalinka Jan
Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Prague Czech Republic.
Department of Biochemistry Faculty of Science Charles University Prague Czech Republic.
FEBS Open Bio. 2017 Aug 29;7(9):1362-1378. doi: 10.1002/2211-5463.12276. eCollection 2017 Sep.
Glutamate carboxypeptidase II (GCPII), also known as prostate-specific membrane antigen (PSMA) or folate hydrolase, is a metallopeptidase expressed predominantly in the human brain and prostate. GCPII expression is considerably increased in prostate carcinoma, and the enzyme also participates in glutamate excitotoxicity in the brain. Therefore, GCPII represents an important diagnostic marker of prostate cancer progression and a putative target for the treatment of both prostate cancer and neuronal disorders associated with glutamate excitotoxicity. For the development of novel therapeutics, mouse models are widely used. However, although mouse GCPII activity has been characterized, a detailed comparison of the enzymatic activity and tissue distribution of the mouse and human GCPII orthologs remains lacking. In this study, we prepared extracellular mouse GCPII and compared it with human GCPII. We found that mouse GCPII possesses lower catalytic efficiency but similar substrate specificity compared with the human protein. Using a panel of GCPII inhibitors, we discovered that inhibition constants are generally similar for mouse and human GCPII. Furthermore, we observed highest expression of GCPII protein in the mouse kidney, brain, and salivary glands. Importantly, we did not detect GCPII in the mouse prostate. Our data suggest that the differences in enzymatic activity and inhibition profile are rather small; therefore, mouse GCPII can approximate human GCPII in drug development and testing. On the other hand, significant differences in GCPII tissue expression must be taken into account when developing novel GCPII-based anticancer and therapeutic methods, including targeted anticancer drug delivery systems, and when using mice as a model organism.
谷氨酸羧肽酶II（GCPII），也被称为前列腺特异性膜抗原（PSMA）或叶酸水解酶，是一种主要在人类大脑和前列腺中表达的金属肽酶。GCPII在前列腺癌中的表达显著增加，并且该酶也参与大脑中的谷氨酸兴奋性毒性作用。因此，GCPII是前列腺癌进展的重要诊断标志物，也是治疗前列腺癌和与谷氨酸兴奋性毒性相关的神经疾病的潜在靶点。在新型治疗药物的研发中，小鼠模型被广泛使用。然而，尽管小鼠GCPII的活性已得到表征，但小鼠和人类GCPII直系同源物的酶活性和组织分布的详细比较仍然缺乏。在本研究中，我们制备了细胞外小鼠GCPII并将其与人类GCPII进行比较。我们发现，与人类蛋白相比，小鼠GCPII具有较低的催化效率，但底物特异性相似。使用一组GCPII抑制剂，我们发现小鼠和人类GCPII的抑制常数总体上相似。此外，我们观察到GCPII蛋白在小鼠肾脏、大脑和唾液腺中的表达最高。重要的是，我们在小鼠前列腺中未检测到GCPII。我们的数据表明，酶活性和抑制谱的差异相当小；因此，在药物研发和测试中，小鼠GCPII可以近似人类GCPII。另一方面，在开发基于GCPII的新型抗癌和治疗方法（包括靶向抗癌药物递送系统）以及将小鼠用作模式生物时，必须考虑GCPII组织表达的显著差异。
