Faculty Profiles - NAKAYAMA Masaaki

Papers - NAKAYAMA Masaaki

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Gangliosides Act as Co-receptors for Salmonella enteritidis FliC and Promote FliC Induction of Human β-Defensin-2 Expression in Caco-2 Cells Reviewed

Ken-ichi Ogushi, Akihiro Wada, Takuro Niidome, Tatsuya Okuda, Rafael Llanes, Masaaki Nakayama, Yoshito Nishi, Hisao Kurazono, Kelly D. Smith, Alan Aderem, Joel Moss, Toshiya Hirayama

Journal of Biological Chemistry 279 ( 13 ) 12213 - 12219 2004.3

Helicobacter pylori VacA activates the p38/activating transcription factor 2-mediated signal pathway in AZ-521 cells. Reviewed International journal

Masaaki Nakayama, Miyuki Kimura, Akihiro Wada, Kinnosuke Yahiro, Ken-ichi Ogushi, Takuro Niidome, Akihiro Fujikawa, Daisuke Shirasaka, Nobuo Aoyama, Hisao Kurazono, Masaharu Noda, Joel Moss, Toshiya Hirayama

The Journal of biological chemistry 279 ( 8 ) 7024 - 7028 2004.2

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Persistent Helicobacter pylori colonization in the stomach induces gastritis and peptic ulcer and interferes with ulcer healing. Most strains of H. pylori produce a cytotoxin, VacA, that induces cytoplasmic vacuolation in epithelial cells with structural and functional changes, leading to gastric injury. VacA is known to cause cell death by mitochondrial damage. We hypothesized that VacA might disrupt other signaling pathways; to that end, we examined the effects of VacA on MAPKs to elucidate their role in the abnormalities seen in VacA-treated cells. VacA stimulated phosphorylation of p38 and Erk1/2, but not JNK, in AZ-521 cells. Both phosphorylation and kinase activation of p38 were maximal 10-30 min after addition of VacA and declined thereafter. Treatment with anti-VacA antibody or the p38 inhibitor SB203580 blocked p38 phosphorylation caused by VacA and inhibited VacA-induced phosphorylation of activating transcription factor 2 (ATF-2), which is implicated in transcriptional control of stress-responsive genes. These data indicate that VacA stimulates a p38/ATF-2-mediated signal pathway. However, 10 microM SB203580, which is sufficient to decrease p38 phosphorylation, did not inhibit VacA-induced cellular vacuolation, decrease in mitochondrial membrane potential, or cytochrome c release from mitochondria. These results suggest that VacA-induced activation of p38/ATF-2-mediated signal pathway is independent of cellular vacuolation, decrease in mitochondrial membrane potential, or cytochrome c release from mitochondria caused by VacA. The cytotoxin may thus act independently on several cellular targets, leading to disruption of signaling, regulatory, and metabolic pathways.

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Protein-tyrosine Phosphatase α, RPTPα, Is a Helicobacter pylori VacA Receptor Reviewed

Kinnosuke Yahiro, Akihiro Wada, Masaaki Nakayama, Takahiro Kimura, Ken-ichi Ogushi, Takuro Niidome, Haruhiko Aoyagi, Ken-ichi Yoshino, Kazuyoshi Yonezawa, Joel Moss, Toshiya Hirayama

Journal of Biological Chemistry 278 ( 21 ) 19183 - 19189 2003.5

High Molecular Weight Factor in FCS Inhibits Helicobacter pylori VacA-Binding to Its Receptor, RPTPβ, on AZ-521 Reviewed

KIMURA Takahiro, WADA Akihiro, NAKAYAMA Masaaki, OGUSHI Ken-ichi, NISHI Yoshito, DE GUZMAN Blanquita B., MOSS Joel, HIRAYAMA Toshiya

Microbiology and Immunology 47 ( 1 ) 105 - 107 2003.1

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Papers - NAKAYAMA Masaaki