Schlafen-8 is essential for lymphatic endothelial cell activation in experimental autoimmune encephalomyelitis.

Schlafen-8 (Slfn8) is a member of the Schlafen family of proteins, which harbor helicase domains and are induced by LPS and interferons. It has been reported that the Schlafen family are involved in various cellular functions, including proliferation, differentiation and regulation of virus replication. Slfn8 has been implicated in T-cell differentiation in the thymus. However, the roles of Slfn8 in the immune system remains unclear. In this study, we generated Slfn8 knockout mice (Slfn8-/-) and investigated the immunological role of Slfn8 using the T-cell-mediated autoimmune model experimental autoimmune encephalomyelitis (EAE). We found that the clinical score was reduced in Slfn8-/- mice. IL-6 and IL-17A cytokine production, which are associated with EAE onset and progression, were decreased in the lymph nodes of Slfn8-/- mice. Immune cell populations in Slfn8-/- mice, including macrophages, neutrophils, T cells and B cells, did not reveal significant differences compared with wild-type mice. In vitro activation of Slfn8-/- T cells in response to TCR stimulation also did not reveal significant differences. To confirm the involvement of non-hematopoietic cells, we isolated CD45- CD31+ endothelial cells and CD45-CD31- gp38+ fibroblastic reticular cells by FACS sorting. We showed that the levels of IL-6 and Slfn8 mRNA in CD45- CD31+ endothelial cells were increased after EAE induction. In contrast, the level of IL-6 mRNA after EAE induction was markedly decreased in CD31+ endothelial cells from Slfn8-/- mice. These results indicate that Slfn8 may play a role in EAE by regulating inflammation in endothelial cells.

Antitumor effect of Batf2 through IL-12 p40 up-regulation in tumor-associated macrophages.

The development of effective treatments against cancers is urgently needed, and the accumulation of CD8+ T cells within tumors is especially important for cancer prognosis. Although their mechanisms are still largely unknown, growing evidence has indicated that innate immune cells have important effects on cancer progression through the production of various cytokines. Here, we found that basic leucine zipper transcription factor ATF-like 2 (Batf2) has an antitumor effect. An s.c. inoculated tumor model produced fewer IL-12 p40+ macrophages and activated CD8+ T cells within the tumors of Batf2-/- mice compared with WT mice. In vitro studies also revealed that the IL-12 p40 expression was significantly lower in Batf2-/- macrophages following their stimulation by toll-like receptor ligands, such as R848. Additionally, we found that BATF2 interacts with p50/p65 and promotes IL-12 p40 expression. In conclusion, Batf2 has an antitumor effect through the up-regulation of IL-12 p40 in tumor-associated macrophages, which eventually induces CD8+ T-cell activation and accumulation within the tumor.

Identification of an atypical monocyte and committed progenitor involved in fibrosis.

Monocytes and macrophages comprise a variety of subsets with diverse functions. It is thought that these cells play a crucial role in homeostasis of peripheral organs, key immunological processes and development of various diseases. Among these diseases, fibrosis is a life-threatening disease of unknown aetiology. Its pathogenesis is poorly understood, and there are few effective therapies. The development of fibrosis is associated with activation of monocytes and macrophages. However, the specific subtypes of monocytes and macrophages that are involved in fibrosis have not yet been identified. Here we show that Ceacam1+Msr1+Ly6C-F4/80-Mac1+ monocytes, which we term segregated-nucleus-containing atypical monocytes (SatM), share granulocyte characteristics, are regulated by CCAAT/enhancer binding protein ß (C/EBPß), and are critical for fibrosis. Cebpb deficiency results in a complete lack of SatM. Furthermore, the development of bleomycin-induced fibrosis, but not inflammation, was prevented in chimaeric mice with Cebpb-/- haematopoietic cells. Adoptive transfer of SatM into Cebpb-/- mice resulted in fibrosis. Notably, SatM are derived from Ly6C-FcεRI+ granulocyte/macrophage progenitors, and a newly identified SatM progenitor downstream of Ly6C-FcεRI+ granulocyte/macrophage progenitors, but not from macrophage/dendritic-cell progenitors. Our results show that SatM are critical for fibrosis and that C/EBPß licenses differentiation of SatM from their committed progenitor.

Identification of novel Arabidopsis thaliana upstream open reading frames that control expression of the main coding sequences in a peptide sequence-dependent manner.

Upstream open reading frames (uORFs) are often found in the 5'-leader regions of eukaryotic mRNAs and can negatively modulate the translational efficiency of the downstream main ORF. Although the effects of most uORFs are thought to be independent of their encoded peptide sequences, certain uORFs control translation of the main ORF in a peptide sequence-dependent manner. For genome-wide identification of such peptide sequence-dependent regulatory uORFs, exhaustive searches for uORFs with conserved amino acid sequences have been conducted using bioinformatic analyses. However, whether the conserved uORFs identified by these bioinformatic approaches encode regulatory peptides has not been experimentally determined. Here we analyzed 16 recently identified Arabidopsis thaliana conserved uORFs for the effects of their amino acid sequences on the expression of the main ORF using a transient expression assay. We identified five novel uORFs that repress main ORF expression in a peptide sequence-dependent manner. Mutational analysis revealed that, in four of them, the C-terminal region of the uORF-encoded peptide is critical for the repression of main ORF expression. Intriguingly, we also identified one exceptional sequence-dependent regulatory uORF, in which the stop codon position is not conserved and the C-terminal region is not important for the repression of main ORF expression.