Mice deficient in protein tyrosine phosphatase receptor type Z are resistant to gastric ulcer induction by VacA of Helicobacter pylori

Abstract

The vacuolating cytotoxin VacA produced by Helicobacter pylori causes massive cellular vacuolation in vitro and gastric tissue damage in vivo, leading to gastric ulcers, when administered intragastrically. Here we report that mice deficient in protein tyrosine phosphatase receptor type Z (Ptprz, also called PTP-zeta or RPTP-beta, encoded by Ptprz) do not show mucosal damage by VacA, although VacA is incorporated into the gastric epithelial cells to the same extent as in wild-type mice. Primary cultures of gastric epithelial cells from Ptprz+/+ and Ptprz-/- mice also showed similar incorporation of VacA, cellular vacuolation and reduction in cellular proliferation, but only Ptprz+/+ cells showed marked detachment from a reconstituted basement membrane 24 h after treatment with VacA. VacA bound to Ptprz, and the levels of tyrosine phosphorylation of the G protein-coupled receptor kinase-interactor 1 (Git1), a Ptprz substrate, were higher after treatment with VacA, indicating that VacA behaves as a ligand for Ptprz. Furthermore, pleiotrophin (PTN), an endogenous ligand of Ptprz, also induced gastritis specifically in Ptprz+/+ mice when administered orally. Taken together, these data indicate that erroneous Ptprz signaling induces gastric ulcers.

Prostaglandin E2 Prevents Helicobacter-Induced Gastric Preneoplasia and Facilitates Persistent Infection in a Mouse Model

“…20 Mouse infections were performed orally with ~10 8 bacteria. Primary gastric epithelial cells were isolated as previously described; 21 the immortalized murine gastric epithelial cell line used in this study was also described previously. 7 Both cell types were grown in DMEM/Ham's F12 medium (1:1; Gibco) supplemented with 10% FCS and infected for 12 hours with H. pylori strains G27 or an isogenic mutant lacking the Cag pathogenicity island (PAI), G27 PAI.…”

Helicobacter pylori persistence: biology and disease

“…Although VacA is not necessary for gastric ulcer formation, in H. pylori-colonized Mongolian gerbils its presence increases the risk (53). Mice administered VacA orally develop gastric ulcers (54, S28), but mice deficient in the protein tyrosine phosphatase receptor type Z, polypeptide 1 (Ptprz -/-mice) do not (54). Ptprz is one of several puta- The cagA product is injected into the cytoplasm of the host cell, where tyrosine (Y) residues near its COOH-terminus are phosphorylated.…”

Essential Domain of Receptor Tyrosine Phosphatase β (RPTPβ) for Interaction with Helicobacter pylori Vacuolating Cytotoxin

“…Git1 Phosphorylation-BHK-21 cells (2 ϫ 10 5 ), which lack RPTP␤ but contain its substrate Git1, were cultured on Matrigel-coated plates for 24 h in DMEM containing 10% FCS and then transfected with RPTP␤ mutant expression plasmids (9). After cultivation for 24 h, cells were incubated with or without VacA for 1 h at 37°C and then washed twice with ice-cold PBS; this was followed by treatment with N-lysis buffer (20 mM Tris-HCl, pH 7.5, 137 mM NaCl, 1% Nonidet P-40, 0.1% SDS, 0.2% deoxycholic acid, 1 mM sodium orthovanadate, 1 mM NaF, and protease inhibitor) for 30 min on ice.…”

“…Recent molecular and cellular studies of VacA action have shown that it is a major virulence factor that is involved in the pathogenesis of inflammation in H. pyloriinduced gastritis and ulceration (4 -6). In mice, orally administered VacA causes degeneration of the gastric mucosa and acute inflammation followed by gastric ulcer disease (7)(8)(9). In some eukaryotic cells, VacA induces cytoplasmic vacuolation, leading to death.…”

“…The phosphorylation of Git1, G protein-coupled receptor kinase-interactor 1, may be responsible for epithelial cell detachment caused by VacA by a mechanism different from that leading to vacuolation (9). Mitochondrial damage (17,18) and apoptosis (17)(18)(19)(20) appear to be vacuolation-independent effects of VacA.…”