CD40 signaling in human dendritic cells is initiated within membrane rafts

• Published in: The EMBO journal 2000-07, Vol.19 (13), p.3304-3313
• Main Authors: Vidalain, Pierre-Olivier, Azocar, Olga, Servet-Delprat, Christine, Rabourdin-Combe, Chantal, Gerlier, Denis, Manié, Serge
• Format: Article
• Language: English
• Subjects: Adaptive immunology; Biochemistry, Molecular Biology; CD40 antigen; CD40 Antigens - metabolism; CD40 signaling; Cell Membrane - metabolism; Cells, Cultured; dendritic cells; Dendritic Cells - immunology; Dendritic Cells - metabolism; Enzyme Activation; Enzyme Precursors - metabolism; Humans; Immunology; Interleukin 1 Receptor Antagonist Protein; Interleukin-1 - biosynthesis; Interleukin-12 - biosynthesis; Intracellular Signaling Peptides and Proteins; Life Sciences; membrane rafts; Membranes; Molecular Networks; Phosphorylation; Protein-Tyrosine Kinases - metabolism; Sialoglycoproteins - biosynthesis; Signal Transduction; Src kinases; src-Family Kinases - metabolism; Syk Kinase; TRAF
• ISSN: 0261-4189; 1460-2075; 1460-2075
• DOI: 10.1093/emboj/19.13.3304

Despite CD40's role in stimulating dendritic cells (DCs) for efficient specific T‐cell stimulation, its signal transduction components in DCs are still poorly documented. We show that CD40 receptors on human monocyte‐derived DCs associate with sphingolipid‐ and cholesterol‐rich plasma membrane microdomains, termed membrane rafts. Following engagement, CD40 utilizes membrane raft‐associated Lyn Src family kinase, and possibly other raft‐associated Src family kinases, to initiate tyrosine phosphorylation of intracellular substrates. CD40 engagement also leads to a membrane raft‐restricted recruitment of tumor necrosis factor (TNF) receptor‐associated factor (TRAF) 3 and, to a lesser extent, TRAF2, to CD40's cytoplasmic tail. Thus, the membrane raft structure plays an integral role in proximal events of CD40 signaling in DCs. We demonstrate that stimulation of Src family kinase within membrane rafts initiates a pathway implicating ERK activation, which leads to interleukin (IL)‐1α/β and IL‐1Ra mRNA production and contributes to p38‐dependent IL‐12 mRNA production. These results provide the first evidence that membrane rafts play a critical role in initiation of CD40 signaling in DCs, and delineate the outcome of CD40‐mediated pathways on cytokine production.