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Nature Immunology 8, 569–577 (1 June 2007) | doi:10.1038/ni1470

Activation of the lectin DC-SIGN induces an immature dendritic cell phenotype triggering Rho-GTPase activity required for HIV-1 replication

Ashleigh Hodges , Katherine Sharrocks , Mariola Edelmann , Dilair Baban , Arnaud Moris , Olivier Schwartz , Hal Drakesmith , Kay Davies , Benedikt Kessler , Andrew McMichael & Alison Simmons

DC-SIGN, a C-type lectin expressed on dendritic cells (DCs), can sequester human immunodeficiency virus (HIV) virions in multivesicular bodies. Here, using large-scale gene expression profiling and tyrosine-phosphorylated proteome analyses, we characterized signaling mediated by DC-SIGN after activation by either HIV or a DC-SIGN-specific antibody. Activation of DC-SIGN resulted in downregulation of genes encoding major histocompatibility complex class II, Jagged 1 and interferon-response molecules and upregulation of the gene encoding transcription factor ATF3. Phosphorylated proteome analysis showed that HIV- or antibody-stimulated DC-SIGN signaling was mediated by the Rho guanine nucleotide–exchange factor LARG and led to increased Rho-GTPase activity. Activation of LARG in DCs exposed to HIV was required for the formation of virus–T cell synapses. Thus, HIV sequestration by and stimulation of DC-SIGN helps HIV evade immune responses and spread to cells.