Production of superoxide anion and its physiological roles in gastric mucosal cells

我们证明，原代培养的豚鼠胃窝细胞表达了所有的吞噬细胞NADPH氧化酶成分（p22-, p67-， p47-和p40-phox），并能自发释放超氧阴离子。我们还发现，坑细胞表达非吞噬细胞特异性gp91-phox同源物（Mox1），但不表达gp91-phox。从幽门螺杆菌中提取的脂多糖显著提高了Mox1氧化酶的活性。过氧化氢酶可显著抑制窝细胞的生长。通过超氧化物歧化酶加过氧化氢酶或n -乙酰半胱氨酸清除超氧化物阴离子和相关氧化剂，通过二苯基碘激活caspase 3样蛋白酶抑制Mox1氧化酶，显著增强染色质凝聚和DNA断裂。这种加速的细胞凋亡被caspase抑制剂z-Val-Ala-Asp-CH_2F完全阻断。mox1衍生的活性氧中间体组成性激活核因子kB (NF-kB)， NF-kB诱骗物寡脱氧核苷酸对该活性的抑制加速了它们的自发凋亡。这些结果表明，由窝细胞Mox1氧化酶产生的超氧阴离子可能在调节窝细胞的自发凋亡和细胞增殖中起重要作用。

We demonstrated that primary cultures of guinea pig gastric pit cells expressed all of the phagocyte NADPH oxidase components (p22-, p67-, p47-, and p40-phoxes) and could spontaneously release superoxide anion. We also identified that pit cells express a nonphagocyte-specific gp91-phox homolog (Mox1), but not gp91-phox. Lipopolysaccharide from Helico bacter pylori markedly enhanced the Mox1 oxidase activity. Inclusion of catalase significantly inhibited pit cell growth. Scavenging superoxide anion and related oxidants by superoxide dismutase plus catalase or N-acetyl cysteine and inhibiting Mox1 oxidase by diphenylene iodonium activated caspase 3-like proteases and markedly enhanced chromatin condensation and DNA fragmentation. This accelerated apoptosis was completely blocked by a caspase inhibitor, z-Val-Ala-Asp-CH_2F.Mox1-derived reactive oxygen intermediates constitutively activated nuclear factor kB (NF-kB), and inhibition of this activity by NF-kB decoy oligodeoxynucleotide accelerated their spontaneous apoptosis. These results suggest that superoxide anion produced by the pit cell Mox1 oxidase may play a crucial role in the regulation of their spontaneous apoptosis as well as cell proliferation.