Recently, it was showed that E1E2 complexes can interacts with the first extracellular loop of Claudin-1, whereas soluble E2 did not [7]

Recently, it was showed that E1E2 complexes can interacts with the first extracellular loop of Claudin-1, whereas soluble E2 did not [7]. HCV infection. Interestingly, experiments with peptides derived from each SLAMF3 domain showed that the first N-terminal extracellular domain is essential for interaction with HCV particles. Finally, we showed that recombinant HCV envelop protein E2 can bind SLAMF3 and that anti-SLAMF3 antibodies inhibited specifically this interaction. Overall, our results revealed that SLAMF3 plays a role during HCV entry, likely by enhancing entry of viral particle within hepatocytes. Introduction The hepatitis C virus (HCV) particle entry into cells requires sequential interactions between viral proteins E1/E2 and several cellular factors. The recent development of functional models allowing the studies of Voreloxin Hydrochloride the HCV life cycle, has prompted the identification of several TSPAN31 cell surface proteins involved in HCV entry. Recent data suggest that HCV entry is a slow, complex, multistep process mechanism that depends on several cellular and environmental factors [1]. After initial attachment to the host cell (via GAGs and LDL-R, for example) [2], [3], HCV interacts with scavenger receptor class B type 1 (SR-BI), CD81 and claudin 1 (CLDN1) through its E1/E2 glycoprotein complexes [4], [5], [6], [7]. Other entry factors (such as occludin (OCLDN), receptor tyrosine kinases RTKs including the EGFR and EphA2 are thought to be involved at viral entry late stages [8], [9] by regulating CD81-CLDN1 coreceptor interactions and membrane fusion. Recently, NPC1L1 (a cholesterol sensing receptor expressed on apical surface of hepatocytes as well as enterocytes) [10] and transferin 1 [11] were identified as new HCV entry factor. The use Voreloxin Hydrochloride of these all receptors leads to HCV internalisation by clathrin-mediated endocytosis [12], [13]. However, the viral entry process is far from being fully understood and may involve other Voreloxin Hydrochloride membrane receptors and/or intracellular factors. Recently, we reported the expression by hepatocytes of only one single member from signaling lymphocytic activation molecule family (SLAM), the SLAMF3 (CD229) [14]. SLAM-family proteins have two or four extracellular immunoglobulin (Ig)-like domains, a transmembrane domain and an intracytoplasmic region comprising tyrosine-based motifs. SLAMF3 offers four extracellular Ig-like domains; domains 1 and 3 are very related, as are domains 2 and 4 [15], [16]. It is noteworthy that SLAMF3 is definitely associated with the -2 chain of the AP-2 adaptor complex and is the only SLAM Voreloxin Hydrochloride family member that can be internalized by clathrin-mediated endocytosis [17], [18]. Until recently [13], SLAMF3 manifestation was recorded for Voreloxin Hydrochloride thymocytes, T cells, B cells, dendritic cells, macrophages and natural killer cells. During the formation of the immunological synapse between T cells and antigen-presenting B cells, SLAMF3 relocates at the edge of the contact area between the cells [19]. However, SLAMF3’s exact functions remain unclear. Interestingly, SLAMF1 functions as a measles disease co-receptor with CD46 [20]. As SLAMF3 is the only SLAMF family member that has been recognized in hepatocytes, we examined it’s part in HCV illness. We found that SLAMF3 blockade (with specific antibodies, website-1 derived peptides and specific small interfering (siRNA) inhibits HCV access into hepatocytes. Furthermore, over-expression of SLAMF3 enhanced the hepatocytes permissiveness to HCV. Taken together, our results suggest that hepatocyte SLAMF3 likely participates to viral access like a cofactor. Material and Methods Cells, antibodies and peptides Huh-7 cell collection was a kind gift from Professor Gilles Duverlie (Virology Laboratory, Jules Verne Universit Picardie, Amiens, France). The African Green Monkey kidney fibroblast COS-7 cell collection was purchased from ATCC (Manassas, VA). All cell lines were managed in Dulbecco’s Modified Eagle’s Medium (Life Systems, Invitrogen, Saint Aubin, France) supplemented with 10% fetal calf serum (FCS) (PAA, Velizy-Villacoublay, France), 100 IU/mL penicillin, 100 g/mL streptomycin and 2 mM L-glutamine. Healthy human main hepatocytes PHH (Lonza, Basel, Switzerland) were managed in phenol and serum-free HBCTM Basal Medium. HBCTM SingleQuotsKit comprising 500 L hEGF, 500.