An integrin-tetraspanin interaction required for cellular innate immune responses of an insect, Manduca sexta

Shufei Zhuang, Lisha Kelo, James B. Nardi, Michael R. Kanost

Research output: Contribution to journalArticle

Abstract

In their encounters with foreign intruders, the cells of the insect innate immune system, like those of the mammalian immune system, exhibit both humoral and cell-mediated responses. Some intruders can be dispatched by the humoral immune system alone, but many must be phagocytosed by individual hemocytes or encapsulated by interacting hemocytes. Surface proteins of hemocytes control the abrupt transition of hemocytes from resting, nonadherent cells to activated, adherent cells during these cell-mediated responses.Two of these surface proteins, an integrin and a tetraspanin, interact during this adhesive transition. As demonstrated with a hemocyte adhesion assay and a surface plasmon resonance assay, the large extracellular loop of tetraspanin D76 binds to a hemocyte-specific integrin of Manduca sexta. The interaction between the large extracellular loop domain and hemocyte-specific integrin is interrupted not only by a monoclonal antibody (MS13) that binds to a domain of β-integrin known to be a ligand-binding site for cell adhesion but also by double-stranded β-integrin RNA. Transfected S2 cells expressing tetraspanin mediate adhesion of hemocytes. A monoclonal antibody to tetraspanin D76 perturbs the cell-mediated immune response of encapsulation. These studies involving antibody blocking, RNA interference, and binding assays imply a trans interaction of integrin and tetraspanin on hemocyte surfaces.

Original languageEnglish (US)
Pages (from-to)22563-22572
Number of pages10
JournalJournal of Biological Chemistry
Volume282
Issue number31
DOIs
StatePublished - Aug 3 2007

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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