Involvement of syntaxin 7 in human gastric epithelial cell vacuolation induced by the Helicobacter pylori-produced cytotoxin VacA.

The Helicobacter pylori-produced cytotoxin VacA induces intracellular vacuolation. The formed vacuole is assumed to be a hybrid of late endosome and lysosome. To elucidate the molecular mechanism of VacA-induced vacuolation, we examined the participation of syntaxin 7 in the human gastric epithelial cell line AGS. Immunocytochemistry revealed that endogenous syntaxin 7 was localized to vacuoles induced by VacA. Northern and Western blotting demonstrated that VacA intoxication increased syntaxin 7 mRNA and protein expression, respectively, in a time-dependent manner. Transient transfection of dominant-negative mutant syntaxin 7, which lacks a carboxyl-terminal transmembrane domain, inhibited VacA-induced vacuolation. In contrast, transient transfection of wild-type syntaxin 7, dominant-negative mutant syntaxin 1a, or dominant-negative mutant syntaxin 4 did not alter VacA-induced vacuolation. Furthermore, under VacA treatment, neutral red dye uptake, a parameter of VacA-induced vacuolation, was inhibited in cells stably transfected with mutant syntaxin 7 but not in cells stably transfected with wild-type syntaxin 7, mutant syntaxin 1a, or mutant syntaxin 4. Sequential immunocytochemical observation confirmed that expression of mutant syntaxin 7 did not affect VacA attachment to or internalization into AGS cells. We suggest that syntaxin 7 is involved in the intracellular vacuolation induced by VacA.

Suzuki J ，Ohnishi H ，Wada A ，Hirayama T ，Ohno H ，Ueda N ，Yasuda H ，Iiri T ，Wada Y ，Futai M ，Mashima H ... -  《JOURNAL OF BIOLOGICAL CHEMISTRY》

Involvement of vesicle-associated membrane protein 7 in human gastric epithelial cell vacuolation induced by Helicobacter pylori-produced VacA.

Mashima H ，Suzuki J ，Hirayama T ，Yoshikumi Y ，Ohno H ，Ohnishi H ，Yasuda H ，Fujita T ，Omata M ... -  《-》

Dynamin is involved in human epithelial cell vacuolation caused by the Helicobacter pylori-produced cytotoxin VacA.

:The Helicobacter pylori-produced cytotoxin VacA induces intracellular vacuolation. To elucidate the molecular mechanism of vacuole formation by VacA, we examined the participation of dynamin, a GTPase functioning in intracellular vesicle formation, in human HeLa cells. Immunocytochemistry revealed that endogenous dynamin was localized to vacuoles induced by VacA. In cells transiently transfected with a GTPase-defective (dominant-negative) dynamin mutant, VacA failed to induce vacuolation. In contrast, VacA did induce vacuolation in cells transiently transfected with wild-type dynamin. Furthermore, under VacA treatment, neutral red dye uptake, a parameter of VacA-induced vacuolation, was inhibited in cells stably transfected with the dominant-negative dynamin mutant. In contrast, uptake was markedly enhanced in cells stably transfected with wild-type dynamin. Moreover, VacA cytopathic effects on the viability of HeLa cells were inhibited in cells stably transfected with dominant-negative dynamin-1. Sequential immunocytochemical observation confirmed that expression of dominant-negative dynamin did not affect VacA attachment to or internalization into HeLa cells. We suggest that dynamin is involved in the intracellular vacuolation induced by VacA.

Suzuki J ，Ohnsihi H ，Shibata H ，Wada A ，Hirayama T ，Iiri T ，Ueda N ，Kanamaru C ，Tsuchida T ，Mashima H ，Yasuda H ，Fujita T ... -  《JOURNAL OF CLINICAL INVESTIGATION》

Clustering and redistribution of late endocytic compartments in response to Helicobacter pylori vacuolating toxin.

Li Y ，Wandinger-Ness A ，Goldenring JR ，Cover TL ... -  《MOLECULAR BIOLOGY OF THE CELL》

Helicobacter pylori vacuolating cytotoxin induces activation of the proapoptotic proteins Bax and Bak, leading to cytochrome c release and cell death, independent of vacuolation.

Yamasaki E ，Wada A ，Kumatori A ，Nakagawa I ，Funao J ，Nakayama M ，Hisatsune J ，Kimura M ，Moss J ，Hirayama T ... -  《JOURNAL OF BIOLOGICAL CHEMISTRY》