Helicobacter pylori East Asian type CagA hijacks more SHIP2 by its EPIYA-D motif to potentiate the oncogenicity.

Abstract

CagA is a significant oncogenic factor injected into host cells by Helicobacter pylori, which is divided into two subtypes: East Asian type (CagA^E), characterized by the EPIYA-D motif, and western type (CagA^W), harboring the EPIYA-C motif. CagA^E has been reported to have higher carcinogenicity than CagA^W, although the underlying reason is not fully understood. SHIP2 is an intracellular phosphatase that can be recruited by CagA to perturb the homeostasis of intracellular signaling pathways. In this study, we found that SHIP2 contributes to the higher oncogenicity of CagA^E. Co-Immunoprecipitation and Pull-down assays showed that CagA^E bind more SHIP2 than CagA^W. Immunofluorescence staining showed that a higher amount of SHIP2 recruited by CagA^E to the plasma membrane catalyzes the conversion of PI(3,4,5)P₃ into PI(3,4)P₂. This alteration causes higher activation of Akt signaling, which results in enhanced IL-8 secretion, migration, and invasion of the infected cells. SPR analysis showed that this stronger interaction between CagA^E and SHIP2 stems from the higher affinity between the EPIYA-D motif of CagA^E and the SH2 domain of SHIP2. Structural analysis revealed the crucial role of the Phe residue at the Y + 5 position in EPIYA-D. After mutating Phe of CagA^E into Asp (the corresponding residue in the EPIYA-C motif) or Ala, the activation of downstream Akt signaling was reduced and the malignant transformation of infected cells was alleviated. These findings revealed that CagA^E hijacks SHIP2 through its EPIYA-D motif to enhance its carcinogenicity, which provides a better understanding of the higher oncogenic risk of H. pylori CagA^E.