Immunological synapse formation inhibits, via NF-κB and FOXO1, the apoptosis of dendritic cells

Abstract

The immunological synapse (IS) is a cell-cell junction formed between CD4(+) T cells and dendritic cells (DCs). Here we show in vitro and in vivo that IS formation inhibits apoptosis of DCs. Consistent with these results, IS formation induced antiapoptotic signaling events, including activation of the kinase Akt1 and localization of the prosurvival transcription factor NF-kappaB and the proapoptotic transcription factor FOXO1 to the nucleus and cytoplasm, respectively. Inhibition of phosphatidylinositol 3-OH kinase and Akt1 partially prevented the antiapoptotic effects of IS formation. Direct stimulation of the IS component CD40 on DCs leads to the activation of Akt1, suggesting the involvement of this receptor in the antiapoptotic effects observed upon IS formation.

A Novel MEK-ERK-AMPK Signaling Axis Controls Chemokine Receptor CCR7-dependent Survival in Human Mature Dendritic Cells

“…Two-photon Microscopy and Analysis of Apoptotic CFSE-labeled Dendritic Cells in the Lymph Nodes-The method has been described in detail previously (10,25,26,31). Briefly, CFSE-labeled splenic mDCs (10 8 mDCs/ml) were dissolved in 20 l of RPMI and injected subcutaneously along with LPS (1 g/ml) into the hind footpad of recipient C57BL/6 mice (2 ϫ 10 6 mDCs per footpad).…”

“…Briefly, CFSE-labeled splenic mDCs (10 8 mDCs/ml) were dissolved in 20 l of RPMI and injected subcutaneously along with LPS (1 g/ml) into the hind footpad of recipient C57BL/6 mice (2 ϫ 10 6 mDCs per footpad). After 36 h, when the mDCs have already reached the popliteal LNs (PLNs) (26,32), treated or control animals were injected intraperitoneally, respectively, with the AMPK activator A769662 (3.6 mg/25 g of mice in DMSO) or with vehicle control DMSO. 40.5 h after initiation of the experiment, the mice were injected intravenously with SR-FLIVO (SR, abs 565 nm; em Ͼ600 nm), and after an additional 1 h, the mice were sacrificed, and the popliteal LNs were extracted from the mice and subsequently subjected to twophoton confocal analysis to visualize among the injected CFSEmDCs those that present SR-FLIVO staining (see "Results").…”

“…Monocytes were purified using anti-CD14 magnetic beads (Miltenyi) following the manufacturer's protocol and then induced to differentiate to DCs by adding GM-CSF and IL4 for 7 days as indicated previously (10,11,(25)(26)(27). The DCs were induced to mature by adding TNF␣ as indicated previously (10,11,(25)(26)(27).…”

“…Subsequently, the mDCs were harvested and plated for 40 min on polyornithine-coated coverslips. Apoptotic nuclear morphology was assessed using Hoechst 33342 staining as indicated previously (10,11,25,26) or by analyzing the loss of nuclear DNA content by flow cytometry using propidium iodide as indicated elsewhere (28,29).…”

SCIMP, a Transmembrane Adaptor Protein Involved in Major Histocompatibility Complex Class II Signaling

“…This leads to cross talk between APCs and T cells, required for efficient antigen presentation. In addition, formation of IS in DCs results in apoptosis inhibition and prolonged life span (40). Antigen presentation inducing activation of naive T cells is a primary function of DCs.…”