Harstad Eric B, Rosenblum Jonathan S, Gorrell Mark D, Achanzar William E, Minimo Lauro, Wu Jiangyue, Rosini-Marthaler Laura, Gullo Russell, Ordway Nicole D, Kirby Mark S, Chadwick Kristina D, Cosma Gregory N, Moyer Carolyn F
Drug Safety Evaluation, Bristol-Myers Squibb Co., New Brunswick, NJ, USA.
Regul Pept. 2013 Sep 10;186:26-35. doi: 10.1016/j.regpep.2013.07.003. Epub 2013 Jul 12.
Dipeptidyl peptidases (DPPs) are proteolytic enzymes that regulate many physiological systems by degrading signaling peptides. DPP8 and DPP9 are distinct from DPP4 in sequence, cellular localization and expression levels, thus implying distinct functions. However, DPP8 and DPP9 expression needs further delineation. We evaluated DPP4, DPP8 and DPP9 expression using three independent methods at the mRNA, protein, and functional levels to better understand the local physiological contribution of each enzyme. Sprague Dawley rats and cynomolgus monkeys were selected for DPP4, DPP8 and DPP9 expression profiling to represent animal species commonly utilized for drug preclinical safety evaluation. A novel Xhibit assay of DPP protease activity was applied in addition to newly available antibodies for immunohistochemical localization. This combined approach can facilitate a functional evaluation of protease expression, which is important for understanding physiological relevance. Few inter-species differences were observed. Tissue mRNA and protein levels generally correlated to functional DPP4 and DPP8/9 enzymatic activity. All three proteins were seen in epithelial cells, lymphoid cells and some endothelial and vascular smooth muscle cells. Combined DPP8/DPP9 enzymatic activity was uniformly intracellular across tissues at approximately 10-fold lower levels than non-renal DPP4. Consistent levels of each DPP were detected among most non-renal tissues in rats and monkeys. DPP4 was ubiquitous, principally detected on cell membranes of epithelial and endothelial cells and was greatest in the kidney. The expression patterns suggest that DPP8 and DPP9 may act similarly across tissues, and that their actions might in part overlap with DPP4.
二肽基肽酶（DPPs）是一类蛋白水解酶，通过降解信号肽来调节多种生理系统。DPP8和DPP9在序列、细胞定位和表达水平上与DPP4不同，因此暗示其功能不同。然而，DPP8和DPP9的表达仍需进一步明确。我们使用三种独立方法在mRNA、蛋白质和功能水平上评估DPP4、DPP8和DPP9的表达，以更好地了解每种酶在局部的生理作用。选择Sprague Dawley大鼠和食蟹猴进行DPP4、DPP8和DPP9的表达谱分析，以代表常用于药物临床前安全性评估的动物物种。除了新获得的用于免疫组织化学定位的抗体外，还应用了一种新型的DPP蛋白酶活性Xhibit测定法。这种联合方法有助于对蛋白酶表达进行功能评估，这对于理解生理相关性很重要。观察到的种间差异很少。组织mRNA和蛋白质水平通常与功能性DPP4和DPP8/9酶活性相关。在上皮细胞、淋巴细胞以及一些内皮细胞和血管平滑肌细胞中均可见到这三种蛋白质。DPP8/DPP9的联合酶活性在各组织中均均匀地存在于细胞内，其水平比非肾组织中的DPP4低约10倍。在大鼠和猴子的大多数非肾组织中检测到每种DPP的水平一致。DPP4普遍存在，主要在上皮细胞和内皮细胞膜上检测到，在肾脏中含量最高。表达模式表明，DPP8和DPP9在各组织中的作用可能相似，并且它们的作用可能部分与DPP4重叠。
