Helicobacter exploits integrin for type IV secretion and kinase activation.

Area of Science:

• Microbiology
• Cell Biology
• Pathogenesis

Background:

• Integrins are crucial mammalian receptors in cellular functions and disease.
• Helicobacter pylori, a gastric pathogen and carcinogen, injects CagA oncoprotein into host cells.
• The host cell receptor for H. pylori CagA injection remained unidentified.

Purpose of the Study:

• To identify the host cell receptor utilized by H. pylori for CagA delivery.
• To elucidate the mechanism of CagA injection by H. pylori into gastric epithelial cells.
• To investigate the role of integrins in H. pylori-induced pathogenesis.

Main Methods:

• Characterization of Helicobacter pylori CagL protein as a specialized adhesin.
• Investigation of CagL binding to integrin alpha5beta1 on gastric epithelial cells.
• Analysis of the arginine-glycine-aspartate (RGD) motif's role in CagL-integrin interaction.
• Assessment of CagA delivery and host cell signaling activation (FAK, Src).

Main Results:

• H. pylori CagL protein binds to and activates the integrin alpha5beta1 receptor.
• The binding is mediated by an arginine-glycine-aspartate (RGD) motif on CagL.
• This interaction facilitates the injection of CagA oncoprotein into gastric epithelial cells.
• Activation of focal adhesion kinase (FAK) and Src signaling pathways was observed.

Conclusions:

• Integrin alpha5beta1 is the host cell receptor exploited by H. pylori for CagA delivery.
• The CagL-integrin alpha5beta1 interaction is a critical step in H. pylori pathogenesis.
• CagL serves as a molecular tool for studying integrin signaling in H. pylori infection.