B7-1 and B7-2: Similar costimulatory ligands with different biochemical, oligomeric and signaling properties

Sumeena Bhatia, Michael Edidin, Steven C. Almo, Stanley G. Nathenson

Research output: Contribution to journalArticle

79 Scopus citations

Abstract

B7-1 and B7-2 are homologous costimulatory ligands expressed on the surface of antigen presenting cells (APCs). Binding of these molecules to the T cell costimulatory receptors, CD28 and CTLA-4, is essential for the activation and regulation of T cell immunity. Despite strong structural similarities, B7-1 and B7-2 exhibit different biochemical features, and their binding to the costimulatory receptors results in distinct T cell functional outcomes. Using photobleaching based fluorescence resonance energy transfer (FRET), our previous studies have demonstrated that B7-1 and B7-2 have different cell surface oligomeric states. While B7-1 is present as a dimer, B7-2 exists as a monomer on the cell surface suggesting that the unique cell surface oligomeric states of the costimulatory ligands may play a key role in the regulation of T cell responses. Moreover, signaling via B7-1 and B7-2 in dendritic cells has been reported to be dependent on their simultaneous expression, raising the possibility that their direct interaction or their involvement in synergistic signaling pathways may play a role in the function of antigen presenting cells. We discuss physiological relevance of distinct oligomeric states of B7-1 and B7-2 and address whether these molecules can associate with one another on the cell surface to form hetero-oligomers. Our findings suggest that B7-1 and B7-2 do not form hetero-oligomers, underscoring the biological relevance of dimeric and monomeric state of B7-1 and B7-2, respectively.

Original languageEnglish (US)
Pages (from-to)70-75
Number of pages6
JournalImmunology Letters
Volume104
Issue number1-2
DOIs
StatePublished - Apr 15 2006

Keywords

  • B7-1 and B7-2
  • FRET
  • Oligomerization
  • T cell costimulation

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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