Fibroblast apoptosis induced by Porphyromonas gingivalis is stimulated by a gingipain and caspase-independent pathway that involves apoptosis-inducing factor
Fibroblast apoptosis induced by Porphyromonas gingivalis is stimulated by a gingipain and caspase-independent pathway that involves apoptosis-inducing factor
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DOI：
10.1111/j.1462-5822.2007.00987.x
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发表时间：
2007-11-01
影响因子：
3.4
通讯作者：
Graves, Dana T.
中科院分区：
文献类型：
--
作者：
Desta, Tesfahun;Graves, Dana T.
牙龈卟啉单胞菌是一种口腔细菌，可导致许多与成纤维细胞死亡增加相关的牙齿感染的病理学。本文提出的研究表明，牙龈卟啉单胞菌通过凋亡而不是坏死刺激细胞死亡。与以前的研究不同，细胞凋亡的诱导不依赖于蛋白水解活性，也不依赖于半胱天冬酶活性，因为pancaspase抑制剂Z-VAD-favorite几乎没有影响。此外，牙龈卟啉单胞菌下调caspase-3 mRNA水平和caspase-3活性。这种下调的结果是肿瘤坏死因子-α诱导的细胞凋亡显着减少，这是caspase-3依赖性的。免疫荧光和免疫印迹分析显示牙龈卟啉单胞菌诱导的牙周炎诱导因子（AIF）从细胞质易位到细胞核。进行siRNA研究，并证明当AIF沉默时，牙龈卟啉单胞菌刺激的细胞死亡显著减少（P < 0.05）。用H-89（一种阻断AIF活化的蛋白激酶A抑制剂）处理人牙龈成纤维细胞也减少牙龈卟啉单胞菌诱导的细胞凋亡（P < 0.05）。这些结果表明牙龈卟啉单胞菌通过涉及蛋白激酶A和AIF的途径引起成纤维细胞凋亡，不依赖于细菌蛋白水解活性，也不依赖于涉及半胱天冬酶-3的经典凋亡途径。
Porphyromonas gingivalis is an oral bacterium that causes pathology in a number of dental infections that are associated with increased fibroblast cell death. Studies presented here demonstrated that P. gingivalis stimulates cell death by apoptosis rather than necrosis. Unlike previous studies apoptosis was induced independent of proteolytic activity and was also independent of caspase activity because a pancaspase inhibitor, Z-VAD-fmk, had little effect. Moreover, P. gingivalis downregulated caspase-3 mRNA levels and caspase-3 activity. The consequence of this downregulation was a significant reduction in tumour necrosis factor-alpha-induced apoptosis, which is caspase-3-dependent. Immunofluorescence and immunoblot analysis revealed P. gingivalis-induced translocation of apoptosis-inducing factor (AIF) from the cytoplasm to the nucleus. siRNA studies were undertaken and demonstrated that P. gingivalis stimulated cell death was significantly reduced when AIF was silenced (P < 0.05). Treatment of human gingival fibroblasts with H-89, a protein kinase A inhibitor that blocks AIF activation also reduced P. gingivalis-induced apoptosis (P < 0.05). These results indicate that P. gingivalis causes fibroblast apoptosis through a pathway that involves protein kinase A and AIF, is not dependent upon bacterial proteolytic activity and is also independent of the classic apoptotic pathways involving caspase-3.