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Cross-presentation by intercellular peptide transfer through gap junctions.
Neijssen J, HerbertsC, Drijfhout JW, Reits E, Janssen L, Neefjes J
Nature 2005 Mar 3 434(7029):83-8

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Exceptional
F1000 Factor 9.9

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Etienne Joly
IFR 30, France
IMMUNOLOGY

New Finding

Through wonderfully simple approaches, the authors demonstrate unequivocally that antigenic peptides can be transferred to immediately adjacent cells through gap junctions established via expression of connexin molecules. This finding not only unveils a potential molecular process for cross presentation of antigens by dendritic cells and other professional APCs, but also gives interesting perspectives regarding the potential of the immune system's capacity to control viral infections and for tumours to evade it.

Evaluated 4 Apr 2005

Valeri Vasioukhin
Fred Hutchinson Cancer Research Center, United States of America
CELL BIOLOGY

New Finding

This paper demonstrates that gap junctions can be used not only for the intercellular transport of small molecules but also for the transport of peptides. Moreover, gap junction-mediated peptide transport appears to be important during a process called cross-presentation, when the antigenic peptides are transferred from the virus-infected cells to the professional antigen presenting cells.

Evaluated 1 Apr 2005

Vivian Tang
Harvard Medical School, United States of America
CELL BIOLOGY

New Finding

This powerful paper combines superb basic techniques of immunolgy, cell biology, and channel physiology to demonstrate that cell-cell coupling through connexin 43 gap junctions can support efficient transfer of intracellular antigenic peptides from a cell infected with a virus to uninfected neighboring antigen-presenting cells (APC), a process called cross-presentaton. It is somewhat surprising that peptides up to 9 amino acids in length show efficient cell-cell transfer, suggesting that some unidentified binding steps must be present. Indeed, a recent Letter {1} points out that large channels such as bacterial porin LamB and OmpF have extended binding zones for their substrates. It will be interestingly to follow future investigations into the mechanism underlying macromolecular cell-cell communication through gap junctions. {1} Berezhkovskii and Bezrukov, Biophys J 2005, 88:L17-L19 [PMID:15626697].

Evaluated 22 Mar 2005

Frank Momburg
German Cancer Research Center (DKFZ), Germany
IMMUNOLOGY

New Finding

I found this article most interesting because it provides evidence for a novel and unexpected mechanism of antigen cross-presentation through MHC class I molecules. It is shown that antigenic peptides can travel from the cytoplasm of an infected cell to the cytoplasm of an antigen presenting cell through intercellular gap junctions. Inactivation of gap junctions is observed in tumor cells and may represent another strategy to escape MHC class I peptide-dependent immune responses by cytotoxic T cells.

Evaluated 22 Mar 2005
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[Cao Xuân Hiếu]

Figure 1 'Cross-presentation' by peptide transfer through gap junctions. a, Peptides derived from a cell's own proteins are presented on the cell surface (not shown). If the cell is infected by a virus, viral peptides will likewise be presented. The viral proteins are first chopped up in the proteasome; resulting peptides are transported into the endoplasmic reticulum, where they are paired with major histocompatibility complex I (MHC I) molecules and then moved to the cell surface. Killer T cells detect viral peptides and destroy the infected cell. b, Neijssen et al.1 find that peptides up to ten amino acids long (derived from viral or cellular proteins) may also be transferred from one cell to its neighbour through gap junctions. These peptides follow the classical MHC I pathway and are displayed on the surface for recognition by killer T cells. c, Cells farther away probably do not receive enough viral peptides to be displayed.

Source: Nature, 2005

 

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