RESUMO
Ligand-induced cellular signaling involved in interleukin 10 (IL-10) production by lamina propria macrophages (LPMs) during their interactions with commensal bacteria is not clearly understood. We previously showed, using mice lacking a C-type lectin MGL1/CD301a, that this molecule on colonic LPMs plays an important role in the induction of IL-10 upon interaction with commensal bacteria, Streptococcus sp. In the present report, we show that the physical engagement of MGL1/CD301a on LPMs with in-situ isolated Streptococcus sp. bacteria leads to IL-10 messenger RNA (mRNA) induction. Spleen tyrosine kinase (Syk), caspase recruitment domain 9 (CARD9) and extracellular signal-regulated kinase (ERK), but not NF-κB pathway, are shown to be indispensable for IL-10 mRNA induction after stimulation with heat-killed Streptococcus sp. Guanidine hydrochloride treatment of Streptococcus sp., which is known to extract bacterial cell surface glycan-rich components, abolished bacterial binding to recombinant MGL1/CD301a. The extract contained materials which bound rMGL1 in ELISA and appeared to induce IL-10 mRNA expression in LPMs in vitro. Lectin blotting showed that the extract contained glycoproteins that are considered as putative ligands for MGL1. Some human commensal Lactobacillus species also induced IL-10 mRNA expression by colonic LPMs in vitro, which depends on the presence of MGL1/CD301a and CARD9. The present results are the first to show that MGL1/CD301a acts as a signal transducer during colonic host-microbe interactions.
Assuntos
Assialoglicoproteínas , Interleucina-10 , Animais , Assialoglicoproteínas/genética , Assialoglicoproteínas/metabolismo , Bactérias/genética , Proteínas Adaptadoras de Sinalização CARD/metabolismo , Interleucina-10/genética , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Macrófagos/metabolismo , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
The aim of this study is to evaluate the effect of heat shock protein 90 (Hsp90) inhibition, and to identify molecular pathways responsible for anti-proliferative effect on adult T cell leukemia/lymphoma (ATL) cells. For Hsp90 inhibition, we used geldanamycin derivates, 17-AAG (17-allylamino-17-demethoxygeldanamycin) and 17-DMAG (17-(dimethylaminoethylamino) 17-demethoxygeldanamycin) in this study. The inhibitory concentration (IC(50)) of 17-AAG in an ATL cell line, designated as TaY, and two HTLV-1 transformed cell lines (MT-2 and MT-4) was 300-700 nM, and that of 17-DMAG was 150-200nM. Fresh ATL cells obtained from patients were more sensitive to both 17-AAG and 17-DMAG. Gene expression analysis of TaY cells revealed up-regulation of HSPA1A encoding Hsp70, a hallmark of Hsp90 inhibition. Genes regulating cell proliferation or anti-apoptosis (i.e. BCL2 and BIRC5), genes related to cytokines or chemokines (i.e. IL9 and CCL27), and notably TCF7L2, a down-stream effecter of beta-catenin were remarkably down-regulated. Down-regulation of TCF7L2 mRNA was noted in the three cell lines and two patient specimens after Hsp90 inhibition. Hsp90 inhibitors dephosphorylate AKT, thereby, activate GSK-3beta, which phosphorylates beta-catenin for ubiquitination. This indicates the possibility that beta-catenin/TCF7L2 pathway plays an important role in Hsp90 inhibitor-induced cell death in ATL cells and HTLV-1 transformed cells. Our results have provided new insights into the complex molecular pharmacology of Hsp90 inhibitors, and suggest that Hsp90 inhibitors might be beneficial as anti-proliferative agents in treating ATL patients.
