title: Inhibition of CD40-induced N-Ras activation reduces leishmania major infection.
abstract: Leishmania major is a parasite that resides and replicates in macrophages. We previously showed that the parasite enhanced CD40-induced Raf-MEK-ERK signaling but inhibited PI3K-MKK-p38MAPK signaling to proleishmanial effects. As Raf and PI3K have a Ras-binding domain but exert opposite effects on Leishmania infection, we examined whether Ras isoforms had differential roles in Leishmania infection. We observed that L. major enhanced N-Ras and H-Ras expression but inhibited K-Ras expression in macrophages. L. major infection enhanced N-Ras activity but inhibited H-Ras and K-Ras activity. TLR2 short hairpin RNA or anti-TLR2 or anti-lipophosphoglycan Abs reversed the L. major-altered N-Ras and K-Ras expressions. Pam3CSK4, a TLR2 ligand, enhanced N-Ras expression but reduced K-Ras expression, indicating TLR2-regulated Ras expression in L. major infection. Whereas N-Ras silencing reduced L. major infection, K-Ras and H-Ras silencing enhanced the infection both in macrophages in vitro and in C57BL/6 mice. BALB/c-derived macrophages transduced with lentivirally expressed N-Ras short hairpin RNA and pulsed with L. major-expressed MAPK10 enhanced MAPK10-specific Th1-type response. CD40-deficient mice primed with these macrophages had reduced L. major infection, accompanied by higher IFN-γ but less IL-4 production. As N-Ras is activated by Sos, a guanine nucleotide exchange factor, we modeled the N-Ras-Sos interaction and designed two peptides from their interface. Both the cell-permeable peptides reduced L. major infection in BALB/c mice but not in CD40-deficient mice. These data reveal the L. major-enhanced CD40-induced N-Ras activation as a novel immune evasion strategy and the potential for Ras isoform-targeted antileishmanial immunotherapy and immunoprophylaxis.
authors: National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
authors: Sushmita
authors: S
authors: Chakraborty
authors: National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
authors: Ankita
authors: A
authors: Srivastava
authors: National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
authors: Mukesh Kumar
authors: MK
authors: Jha
authors: National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
authors: Arathi
authors: A
authors: Nair
authors: National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
authors: Surya Prakash
authors: SP
authors: Pandey
authors: National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
authors: Neetu
authors: N
authors: Srivastava
authors: National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
authors: Sangeeta
authors: S
authors: Kumari
authors: National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
authors: Shailza
authors: S
authors: Singh
authors: National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
authors: Musti V
authors: MV
authors: Krishnasastry
authors: National Centre for Cell Science, Ganeshkhind, Pune 411007, India sahab@nccs.res.in.
authors: Bhaskar
authors: B
authors: Saha
mesh_terms: D000818:Animals; D019013:CD40 Antigens / Q000235:genetics / Q000276:immunology*; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000276:immunology*; D057131:Immune Evasion / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D007167:Immunotherapy; D018320:Leishmania major / Q000276:immunology*; D016773:Leishmaniasis, Cutaneous / Q000235:genetics / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control; D055666:Lipopeptides / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D017737:Macrophages, Peritoneal / Q000276:immunology / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008817:Mice, Mutant Strains; D048057:Mitogen-Activated Protein Kinase 10 / Q000235:genetics / Q000276:immunology; D020929:Mitogen-Activated Protein Kinase Kinases; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics / Q000276:immunology*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000276:immunology; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000276:immunology; D020839:Son of Sevenless Protein, Drosophila / Q000235:genetics / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology / Q000473:pathology; D051195:Toll-Like Receptor 2; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000276:immunology
chemical_list: D019013:CD40 Antigens; D055666:Lipopeptides; D048057:Mitogen-Activated Protein Kinase 10; D020929:Mitogen-Activated Protein Kinase Kinases; D020559:Monomeric GTP-Binding Proteins; D019869:Phosphatidylinositol 3-Kinases; D016283:Proto-Oncogene Proteins p21(ras); D020839:Son of Sevenless Protein, Drosophila; D051195:Toll-Like Receptor 2; D048051:p38 Mitogen-Activated Protein Kinases; C508075:Pam(3)CSK(4) peptide; C493486:Tlr2 protein, mouse; C495971:Hras protein, mouse; C586503:Nras protein, mouse