Gap junctions in cells of the immune system: structure, regulation and possible functional roles

Abstract

Gap junction channels are sites of cytoplasmic communication between contacting cells. In vertebrates, they consist of protein subunits denoted connexins (Cxs) which are encoded by a gene family. According to their Cx composition, gap junction channels show different gating and permeability properties that define which ions and small molecules permeate them. Differences in Cx primary sequences suggest that channels composed of different Cxs are regulated differentially by intracellular pathways under specific physiological conditions. Functional roles of gap junction channels could be defined by the relative importance of permeant substances, resulting in coordination of electrical and/or metabolic cellular responses. Cells of the native and specific immune systems establish transient homo-and heterocellular contacts at various steps of the immune response. Morphological and functional studies reported during the last three decades have revealed that many intercellular contacts between cells in the immune response present gap junctions or "gap junction-like" structures. Partial characterization of the molecular composition of some of these plasma membrane structures and regulatory mechanisms that control them have been published recently. Studies designed to elucidate their physiological roles suggest that they might permit coordination of cellular events which favor the effective and timely response of the immune system. Correspondence

Gap Junctions at the Dendritic Cell-T Cell Interface Are Key Elements for Antigen-Dependent T Cell Activation

“…Also, formation of heterocellular gap junctions between allogeneic DCs and T cells in cocultures has been suggested using morphological techniques (8,22). To investigate whether gap junctional communication might also occur between isogeneic T cells and DCs, we cocultured DCs purified from spleen with naive TCR-transgenic CD4 ϩ T cells (TCR AND) in the presence of the specific peptide PCC 87-103 , which is recognized in the context of I-E k .…”

“…The heterocellular interaction mediated by cell adhesion molecules has also been suggested to favor the formation of intercellular junctions, such as gap junctions between DCs and T cells (8).…”

Role of connexin-based gap junction channels and hemichannels in ischemia-induced cell death in nervous tissue

“…Cultured microglia treated with interferon-γ plus TNF-α or bacterial lipopolisaccharide show upregulation of Cx43 expression and form functional gap junctions [41]. In general, gap junction channels expressed by microglia may help to coordinate inflammatory responses [124].…”

Human T-cell lymphotropic virus type 1–transformed cells induce angiogenesis and establish functional gap junctions with endothelial cells

“…[37][38][39] There is evidence for the existence of functional gap junctions in endothelial cells 40,41 and normal lymphocytes. 42,43 However, though the endothelium interacts with many cell types, including leukocytes, [44][45][46][47] astrocytes, 48 smooth muscle cells, 49 and cancer cells, 50,51 communication of neoplastic lymphocytes with the endothelium has never been described before.…”