RESUMO
The genome of vertebrates contains endogenous retroviruses (ERVs) that are largely nonfunctional relicts of ancestral germline infection by exogenous retroviruses. However, in some mouse strains ERVs are actively involved in disease. Here we report that nucleic acid-recognizing Toll-like receptors 3, 7, and 9 (TLR 3, TLR7, and TLR9) are essential for the control of ERVs. Loss of TLR7 function caused spontaneous retroviral viremia that coincided with the absence of ERV-specific antibodies. Importantly, additional TLR3 and TLR9 deficiency led to acute T cell lymphoblastic leukemia, underscoring a prominent role for TLR3 and TLR9 in surveillance of ERV-induced tumors. Experimental ERV infection induced a TLR3-, TLR7-, and TLR9-dependent group of "acute-phase" genes previously described in HIV and SIV infections. Our study suggests that in addition to their role in innate immunity against exogenous pathogens, nucleic acid-recognizing TLRs contribute to the immune control of activated ERVs and ERV-induced tumors.
Assuntos
Retrovirus Endógenos/genética , Ácidos Nucleicos/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Receptores Toll-Like/genética , Receptores Toll-Like/metabolismo , Viremia/genética , Animais , Anticorpos Antivirais/genética , Anticorpos Antivirais/imunologia , Linhagem Celular , Retrovirus Endógenos/imunologia , Retrovirus Endógenos/metabolismo , Imunidade Inata/genética , Imunidade Inata/imunologia , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ácidos Nucleicos/imunologia , Ácidos Nucleicos/metabolismo , Oncogenes/genética , Oncogenes/imunologia , Leucemia-Linfoma Linfoblástico de Células T Precursoras/imunologia , Leucemia-Linfoma Linfoblástico de Células T Precursoras/metabolismo , Receptores Toll-Like/imunologia , Viremia/imunologia , Viremia/metabolismoRESUMO
BACKGROUND: T cells play a central role in many inflammatory diseases, hence the identification and validation of T cell-specific target genes will increase the understanding of T cell function in pathologic inflammatory situations. RNA interference (RNAi), with its ability to induce specific gene silencing in mammalian cells, represents a powerful technology to investigate and validate the function of pharmaceutical target genes in vitro and in vivo. The aim of the present study was to systematically explore RNAi-mediated gene-silencing of known T cell-specific model signaling molecules in primary murine T cells in vitro and in vivo. RESULTS: We demonstrate that siRNA delivery and subsequent silencing of T cell specific genes is substantially increased, if murine T cells were activated prior siRNA transfection. Silencing of ZAP70, p56Lck as well as PLC-gamma1 protein expression resulted in impaired function of T cells in vitro. Furthermore, delayed type hypersensitivity (DTH) was ameliorated in vivo after adoptive transfer of ZAP70-silenced T cells. CONCLUSION: The combination of RNAi-mediated gene silencing and adoptive transfer of gene-silenced T cells, thus, may allow the identification and analysis of T cell-specific targets for therapeutic intervention. Additionally, this model system may represent an alternative to conventional time consuming and cost intensive gene targeting approaches.
