Background: Chemokine receptor CCR7 promotes survival in mature dendritic cells (mDCs). Results: Activated AMP-dependent kinase (AMPK) induces apoptosis in mDCs; CCR7 uses the kinases MEK1/2-ERK1/2 to regulate phosphorylation of AMPK on Ser-485 and consequently its inhibition. Conclusion: CCR7 uses a novel MEK1/2-ERK1/2-AMPK signaling axis to induce survival in mDCs. Significance: AMPK is a potential target to regulate mDC-mediated immune responses.

The immunological synapse (IS) is a superstructure formed during T cell activation at the zone of contact between T cells and dendritic cells (DCs). The IS includes specific molecular components in the T cell and DCs sides that may result in different functionality. Most of the studies on the IS have focused on the T cell side of this structure and, in contrast, the information available on the IS of DCs is sparse. Autophagy is a cellular process involved in the clearance of damaged proteins and organelles via lysosomal degradation. Mitophagy is the selective autophagy of damaged mitochondria. In this study, it is shown that IS formation induces clustering of mitochondria in the IS of DCs and partial depolarization of these organelles. At the IS of the DCs also accumulate autophagy and mitophagy markers, even when the kinase complex mTORC1, an inhibitor of the autophagy, is active. Together the results presented indicate that IS formation induces local clustering of mitochondria and mitophagy, which could be a homeostatic mechanism to control the quality of mitochondria in this region. The data underline the complexity of the regulatory mechanisms operating in the IS of DCs.