Galectin-1 promotes KSHV-mediated PDGFRA activation on mesenchymal stem cells

GAMBARTE TUDELA, J; RAJAMAHENDRAN, R; MASONE, D; GARCÍA, P.A.; BANNOUD, N.; RABINOVICH, G.A.; CERLIANI, J.P.; CROCI, D.O.

Mar del Plata

Congreso; Reunión anual de la Sociedad Argentina de Investigación Clínica (SAIC); 2019

Sociedad Argentina de Investigación Clínica (SAIC), Sociedad de Farmacología Experimental (SAFE), Sociedad Argentina de Biología (SAB), Sociedad Argentina de Protozoología (SAP), Asociación Argentina de Nanomedicinas (NANOMED-ar)

Galectin-1(Gal-1)contributes to tumor immune-scape by inducing apoptosis in Tcells,promoting tolerogenic dendritic cells and favoring angiogenesis by binding glycoepitopes on VEGFR2 in endothelial cells. Kaposi Sarcoma(KS) is characterized by the proliferation of spindle cells and deregulated angiogenesis. Recent reports have shown that KSHV usurps sarcomagenic PDGFRA signaling to drive KS. This study aimed to investigate the influence of Gal1-N-glycaninteractions in KSHV-mediated sarcomagenic signaling of PDGFRA. To address this, wefirst differentiate bone marrow-derived MSC from B6 mice (CD105+, CD140b+, SCA-1+, CD90.1+, CD11b+, CD34-, CD45-, CD31-, and MHC-II-) and explore their glycophenotype by using a panel of biotinylated lectins (SNA, PNA, HPA, PHA-L, LEL, ConA, ECL, PHA-E). mMSC exhibited high levels of complex N-glycanswith polylactosamine elongations evidencing permissive glycoepitopes for Gal-1 binding(P<0.05). In this sense, PE-conjugated rGal-1bound toprimary-differentiated mMSC and OP9 cells (a murine MSCline) in a dose and carbohydrate-dependent manner (p<0.05). Moreover, colocalization analysis revealed that Gal-1 interacted directly with PDGFRA and more important, with phosphorylated PDGFRA suggesting that this lectin could bind and activate PDGFRA in MSCs. To better define the role of Gal1 in PDGFRA activation and signaling, we performed WB analysis of mMSCs and OP9 cells incubated with rGal-1(0,5-3 uM; 5-40min). Our results have shown that Gal-1 activates PDGFRA signaling inducing Akt, Erk, and STAT-3 phosphorylation (p<0,05). In a bioinformatic approach, we simulate PDGFRA dynamics in a model plasma membrane in the presence of dimeric Gal-1. Preliminary data of coordination analysis showed that after 250 ns Gal-1 and PDGFRA appear associated in a stable complex that affects the lipidic composition of the membrane, suggesting that this interaction could be mediated by lipid rafts. Finally,in order to determine whether KSHV could increase Gal1-mediatedPDGFRA signaling, we evaluated the glycan profile of mMSCs transfected with vGCPR (one of the virus gene activated in late KSHV infection). We observed increasing exposure of glycostructures permissive for Gal-1 binding on mMSC transfected cells (p<0.05), which it was associated with higher binding of this lectin (p<0.05).Taken together, these data support the hypothesis that KSHV infection of MSCs could increase oncogenic signaling of PDGFRAtrough a Gal-1-Glycan dependent mechanism promoting virally-induced sarcomatogenesis.