Helicobacter pylori lipopolysaccharide activates Rac1 and transcription of NADPH oxidase Nox1 and its organizer NOXO1 in guinea pig gastric mucosal cells
Helicobacter pylori lipopolysaccharide activates Rac1 and transcription of NADPH oxidase Nox1 and its organizer NOXO1 in guinea pig gastric mucosal cells
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DOI：
10.1152/ajpcell.00319.2004
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发表时间：
2005-02-01
影响因子：
5.5
通讯作者：
Rokutan, K
中科院分区：
文献类型：
--
作者：
Kawahara, T;Kohjima, M;Rokutan, K
豚鼠胃粘膜细胞原代培养表达gp91（phox）的同源物NADPH氧化酶1(Nox1)，并以类似于100 nmol的速率产生超氧阴离子（O-2(-)）。Mg蛋白（-1）。h（-1）对I型毒株幽门螺杆菌脂多糖（LPS）的响应。O-2（-）产生的上调也增强了幽门螺杆菌lps刺激的肿瘤坏死因子- α或环氧合酶-2 mRNA的表达，这表明Nox1在幽门螺杆菌相关疾病的发病机制中可能起作用。放线菌素D和环己亚胺可抑制幽门螺杆菌lps刺激的胃粘膜细胞O-2（-）的产生，表明这种诱导作用在转录水平上受到调控。LPS处理不仅提高了Nox1 mRNA的表达量，还诱导了Nox1活性所需的新型p47（phox）同源物——信息编码、nox组织蛋白1 （NOXO1）的表达。此外，幽门螺杆菌LPS激活了Rac1；即，它将Rac1转换为gtp绑定状态。一种磷酸肌苷3-激酶抑制剂LY-294002可以阻断幽门螺杆菌lps诱导的Rac1激活和O-2（-）生成，而不干扰Nox1和NOXO1 mRNA的表达。被LY-294002抑制的O-2（-）的产生通过转染腺病毒载体完全恢复，腺病毒载体编码组成活性的Rac1而不是非活性的Rac1或组成活性的Cdc42。这些发现表明，Rac1在Nox1激活中起着至关重要的作用。因此，幽门螺杆菌lps刺激胃粘膜细胞产生O-2（-）似乎需要两个不同的事件：1)Nox1和NOXO1的转录上调和2)Rac1的激活。
Primary cultures of guinea pig gastric mucosal cells express NADPH oxidase 1 (Nox1), a homolog of gp91(phox), and produce superoxide anion (O-2(-)) at a rate of similar to 100 nmol . mg protein(-1) . h(-1) in response to Helicobacter pylori (H. pylori) lipopolysaccharide (LPS) from virulent type I strains. The upregulated O-2(-) production also enhances H. pylori LPS-stimulated tumor necrosis factor-alpha or cyclooxygenase-2 mRNA expression, which suggests a potential role for Nox1 in the pathogenesis of H. pylori-associated diseases. The H. pylori LPS-stimulated O-2(-) production in cultured gastric mucosal cells was inhibited by actinomycin D as well as cycloheximide, suggesting that the induction is regulated at the transcriptional level. The LPS treatment not only increased the Nox1 mRNA to a greater extent but also induced expression of the message-encoding, Nox-organizing protein 1 (NOXO1), a novel p47(phox) homolog required for Nox1 activity. In addition, H. pylori LPS activated Rac1; i.e., it converted Rac1 to the GTP-bound state. A phosphoinositide 3-kinase inhibitor, LY-294002, blocked H. pylori LPS-induced Rac1 activation and O-2(-) generation without interfering with the expression of Nox1 and NOXO1 mRNA. O-2(-) production inhibited by LY-294002 was completely restored by transfection of an adenoviral vector encoding a constitutively active Rac1 but not an inactive Rac1 or a constitutively active Cdc42. These findings indicate that Rac1 plays a crucial role in Nox1 activation. Thus the H. pylori LPS-stimulated O-2(-) production in gastric mucosal cells appears to require two distinct events: 1) transcriptional upregulation of Nox1 and NOXO1 and 2) activation of Rac1.