Zhang Hui, Chen Yiqian, Wadham Carol, McCaughan Geoffrey W, Keane Fiona M, Gorrell Mark D
Centenary Institute and Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
Centenary Institute and Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
Biochim Biophys Acta. 2015 Feb;1853(2):470-80. doi: 10.1016/j.bbamcr.2014.11.029. Epub 2014 Dec 5.
Dipeptidyl peptidase 9 (DPP9) is a ubiquitously expressed member of the DPP4 gene and protease family. Deciphering the biological functions of DPP9 and its roles in pathogenesis has implicated DPP9 in tumor biology, the immune response, apoptosis, intracellular epidermal growth factor-dependent signaling and cell adhesion and migration. We investigated the intracellular distribution of DPP9 chimeric fluorescent proteins and consequent functions of DPP9. We showed that while some DPP9 is associated with mitochondria, the strongest co-localization was with microtubules. Under steady state conditions, DPP9 was not seen at the plasma membrane, but upon stimulation with either phorbol 12-myristate 13-acetate or epidermal growth factor, some DPP9 re-distributed towards the ruffling membrane. DPP9 was seen at the leading edge of the migrating cell and co-localized with the focal adhesion proteins, integrin-β1 and talin. DPP9 gene silencing and treatment with a DPP8/DPP9 specific inhibitor both reduced cell adhesion and migration. Expression of integrin-β1 and talin was decreased in DPP9-deficient and DPP9-enzyme-inactive cells. There was a concomitant decrease in the phosphorylation of focal adhesion kinase and paxillin, indicating that DPP9 knockdown or enzyme inhibition suppressed the associated adhesion signaling pathway, causing impaired cell movement. These novel findings provide mechanistic insights into the regulatory role of DPP9 in cell movement, and may thus implicate DPP9 in tissue and tumor growth and metastasis.
二肽基肽酶9（DPP9）是DPP4基因和蛋白酶家族中广泛表达的成员。解读DPP9的生物学功能及其在发病机制中的作用表明，DPP9参与肿瘤生物学、免疫反应、细胞凋亡、细胞内表皮生长因子依赖性信号传导以及细胞黏附和迁移。我们研究了DPP9嵌合荧光蛋白的细胞内分布以及DPP9的后续功能。我们发现，虽然一些DPP9与线粒体相关，但最强的共定位是与微管。在稳态条件下，在质膜上未观察到DPP9，但在用佛波醇12 - 肉豆蔻酸酯13 - 乙酸酯或表皮生长因子刺激后，一些DPP9重新分布到褶皱膜。在迁移细胞的前沿观察到DPP9，并与粘着斑蛋白整合素-β1和踝蛋白共定位。DPP9基因沉默和用DPP8 / DPP9特异性抑制剂处理均降低了细胞黏附和迁移。在DPP9缺陷型和DPP9酶失活细胞中，整合素-β1和踝蛋白的表达降低。粘着斑激酶和桩蛋白的磷酸化同时降低，表明DPP9敲低或酶抑制抑制了相关的黏附信号通路，导致细胞运动受损。这些新发现为DPP9在细胞运动中的调节作用提供了机制性见解，因此可能表明DPP9参与组织和肿瘤生长及转移。
