Dendritic Cell Migration Toward CCL21 Gradient Requires Functional Cx43

Abstract

Dendritic cells (DCs) travel through lymphatic vessels to transport antigens and present them to T cells in lymph nodes. DCs move directionally toward lymphatics by virtue of their CCR7 and a CCL21 chemotactic gradient. We evaluated in vivo and in bone marrow-derived dendritic cells (BMDCs) whether the gap junction protein Cx43 contributes to CCL21/CCR7-dependent DC migration in wild-type (WT) mice, heterozygous (Cx43+/−) mice and mice expressing a truncated form of Cx43 lacking its regulatory C-terminus (Cx43K258/−). In a model of flank skin inflammation, we found that the recruitment of myeloid DCs (mDCs) to skin draining lymph nodes was reduced in Cx43K258/− mice as compared to WT and Cx43+/− mice. In addition, the migration of Cx43K258/− BMDCs toward CCL21 was abolished in an in vitro chemotactic assay while it was only reduced in Cx43+/− cells. Both mutant genotypes showed defects in the directionality of BMDC migration as compared to WT BMDCs. No difference was found between the three populations of BMDCs in terms of expression of surface markers (CD11c, CD86, CD80, CD40, MHC-II, and CCR7) after differentiation and TLR activation. Finally, examination of the CCR7-induced signaling pathways in BMDCs revealed normal receptor-induced mobilization of intracellular Ca2+. These results demonstrate that full expression of an intact Cx43 is critical to the directionality and rate of DC migration, which may be amenable to regulation of the immune response.

Molecular mechanisms of dendritic cell migration in immunity and cancer

“…In vitro studies using bone marrow-derived DCs (BMDCs) from mice with reduced Cx43 expression revealed defective migration towards CCL21. Moreover, reduced cDC migration to the lymph node in vivo was observed in mice expressing a truncated form of Cx43 [98]. Although there was no direct connection defined between Cx43 and the directional movement of DCs, it has previously been noted that connexin interacts with c-Src kinase involved in CCL21-directed movement [97][98][99].…”

“…Phosphorylation of oligomeric CCR7 by Src at a tyrosine residue creates a binding site for further signalling molecules containing SH2-domains, which is important for efficient cell migration towards CCL21 [97]. The gap junction protein connexin43 (Cx43) expressed in cDCs has also been identified as a potential player in DC migration towards CCL21 [98]. In vitro studies using bone marrow-derived DCs (BMDCs) from mice with reduced Cx43 expression revealed defective migration towards CCL21.…”

“…Moreover, reduced cDC migration to the lymph node in vivo was observed in mice expressing a truncated form of Cx43 [98]. Although there was no direct connection defined between Cx43 and the directional movement of DCs, it has previously been noted that connexin interacts with c-Src kinase involved in CCL21-directed movement [97][98][99]. Human monocyte-derived mature DCs highly express the GPI-anchored protein semaphorin 7A (SEMA7A) which has been shown to promote chemokinedriven DC migration [100].…”

Connexin-Mediated Signaling at the Immunological Synapse

“…The involvement of Cx43 channels in DC-mediated T cell activation is not only limited to its role in facilitating signaling amplification at the IS, but also in DC maturation [53], DC migration to lymph nodes [54] and, as we described below, in promoting the spreading and amplification of antigen cross-presentation pathways.…”

Senolytic activity of small molecular polyphenols from olive restores chondrocyte redifferentiation and cartilage regeneration in osteoarthritis

“…During tissue regeneration and following injury, the dedifferentiation, redifferentiation and senescence processes play finely tuned temporal and spatial roles to reverse the loss of tissue in a precise way 35,36 . Cx43, via channel-dependent and -independent functions, has been involved in different phases of tissue regeneration including in controlling acute and chronic inflammation, cell differentiation, migration, proliferation or cellular reprogramming and lately in cellular senescence [22][23][24]37,38 . Results from our lab and others, demonstrated that Cx43 is a target of interest for the treatment of OA in order to stop cartilage degradation and to restore regeneration.…”