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Sphingomyelin is important for the cellular entry and intracellular localization of Helicobacter pylori VacA

Vijay R Gupta1, Brenda A Wilson, Steven R Blanke

  • 1Department of Microbiology, Institute for Genomic Biology, University of Illinois, B103 CLSL, 601 South Goodwin Avenue, Urbana, IL 61801, USA.

Cellular Microbiology
|June 16, 2010
PubMed

Insights

Sphingomyelin (SM) on cell surfaces is crucial for Helicobacter pylori vacuolating toxin (VacA) entry. Longer acyl chains in SM enhance VacA uptake and vacuolation, suggesting SM

Area of Science:

  • Cell Biology
  • Microbiology
  • Biochemistry

Background:

  • Plasma membrane sphingomyelin (SM) facilitates Helicobacter pylori vacuolating toxin (VacA) binding to epithelial cells.
  • The role of SM in VacA cellular entry and trafficking remains incompletely understood.

Purpose of the Study:

  • To investigate the importance of SM acyl chain length in VacA cellular entry and intracellular trafficking.
  • To elucidate the mechanisms by which SM influences VacA-mediated cellular effects.

Main Methods:

  • Enrichment of epithelial cells with synthetic SM variants of varying acyl chain lengths.
  • Characterization of VacA binding, uptake, and trafficking using microscopy and biochemical assays.
  • Analysis of VacA association with detergent-resistant membranes (DRMs).

Main Results:

  • VacA binding was independent of SM acyl chain length.
  • Cells enriched with longer acyl chain SM variants (C12-SM, C18-SM) showed increased sensitivity to VacA-induced vacuolation compared to shorter variants (C2-SM, C6-SM).
  • VacA trafficking differed based on SM enrichment: Cdc42-dependent pinocytosis and Rab7/Lamp1 localization in C18-SM cells versus Cdc42-independent uptake and Rab11 localization in C2-SM cells.
  • VacA associated with DRMs in C18-SM-enriched cells and non-DRMs in C2-SM-enriched cells.

Conclusions:

  • SM is essential for targeting VacA to membrane rafts, which are critical for subsequent Cdc42-dependent pinocytic entry.
  • The acyl chain length of SM significantly influences VacA cellular entry pathways and intracellular trafficking.
  • These findings provide insights into the molecular mechanisms of VacA pathogenesis.

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