Helicobacter pylori VacA Reduces the Cellular Expression of STAT3 and Pro-survival Bcl-2 Family Proteins, Bcl-2 and Bcl-XL, Leading to Apoptosis in Gastric Epithelial Cells
Helicobacter pylori VacA Reduces the Cellular Expression of STAT3 and Pro-survival Bcl-2 Family Proteins, Bcl-2 and Bcl-XL, Leading to Apoptosis in Gastric Epithelial Cells
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DOI：
10.1007/s10620-010-1420-1
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发表时间：
2011-04-01
影响因子：
3.1
通讯作者：
Kohno, Shigeru
中科院分区：
文献类型：
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作者：
Matsumoto, Ayako;Isomoto, Hajime;Kohno, Shigeru
幽门螺杆菌空泡细胞毒素 VacA 通过线粒体依赖性途径刺激细胞凋亡。 VacA 通过激活促凋亡 B 细胞淋巴瘤 (Bcl)-2 家族蛋白、Bcl-2 相关 X 蛋白 (Bax) 和 Bcl-2 同源拮抗剂/杀伤剂 (Bak) 来诱导细胞凋亡，而 Bcl-2 和 Bcl-X-L 等促存活 Bcl-2 家族成员在 VacA 诱导的细胞凋亡中的含义仍不清楚。信号转导和转录激活因子 3 (STAT3) 是上调 Bcl-2 和 Bcl-X-L 的关键转录因子。本研究旨在阐明 STAT3 和促存活 Bcl-2 和 Bcl-X-L 在内在凋亡中的含义。采用免疫印迹和逆转录酶实时聚合酶链反应 (RT-PCR) 评估 STAT3、Bcl-2 和 Bcl-X-L 的细胞表达。 Bcl-X-L 在胃腺癌细胞系中响应纯化的 VacA。在用每种特定小干扰 RNA (siRNA) 敲低后或在存在药理学抑制剂的情况下，对 VacA 诱导的细胞凋亡进行形态学定量。VacA 以剂量依赖性方式减少 STAT3、Bcl-2 和 Bcl-X-L 的表达。在充分接种 VacA 的情况下，通过 siRNA 敲低 STAT3、Bcl-2 和 Bcl-X-L 会诱导细胞凋亡，程度相似。 VacA 介导的 STAT3 表达减少与细胞空泡形成无关，因为空泡型 ATP 酶抑制剂巴弗洛霉素 A1 不会抑制 VacA 诱导的 STAT3、Bcl-2 和 Bcl-X-L 表达减少。相反，c-JUN NH2 末端激酶 (JNK) 抑制剂 SP600125 将 VacA 诱导的 STAT3 表达减少恢复至基础水平。VacA 诱导的细胞凋亡可能部分与 STAT3 的减少有关，而 STAT3 的减少与 Bcl-2 和 Bcl-X-L 的下调有关，与 JNK 活性相关。
Helicobacter pylori vacuolating cytotoxin, VacA, stimulates apoptosis via a mitochondria-dependent pathway. VacA induces apoptosis via activation of the pro-apoptotic B-cell lymphoma (Bcl)-2 family proteins, Bcl-2-associated X protein (Bax) and Bcl-2 homologous antagonist/killer (Bak), while the implication of such pro-survival Bcl-2 family members as Bcl-2 and Bcl-X-L in the VacA-induced apoptosis remains unknown. Signal transduction and activator of transcription 3 (STAT3) is a pivotal transcription factor that upregulates Bcl-2 and Bcl-X-L.This study was conducted to elicit the implication of STAT3 and pro-survival Bcl-2 and Bcl-X-L in the intrinsic apoptosis.Immunoblot and reverse transcriptase real-time polymerase chain reaction (RT-PCR) were employed to assess the cellular expression of STAT3, Bcl-2, and Bcl-X-L in response to purified VacA in gastric adenocarcinoma cell lines. VacA-induced apoptosis was quantitated morphologically following knockdown by each specific small interfering RNA (siRNA) or in the presence of pharmacological inhibitors.VacA reduced STAT3, Bcl-2, and Bcl-X-L expression in a dose-dependent manner. Knockdown of STAT3, Bcl-2, and Bcl-X-L by siRNA induced apoptosis to a similar extent in the case of sufficient VacA inoculation. The VacA-mediated reduction of STAT3 expression was independent of cellular vacuolization, since a vacuolar-type ATPase inhibitor, bafilomycin A1, did not inhibit VacA-induced reduction of STAT3, Bcl-2, and Bcl-X-L expression. Instead, a c-JUN NH2-terminal kinase (JNK) inhibitor, SP600125, restored the VacA-induced reduction of STAT3 expression to the basal level.VacA-induced apoptosis may be, in part, implicated in the reduction of STAT3 linking to the downregulation of Bcl-2 and Bcl-X-L, in association with JNK activity.