A novel tRNA-derived fragment tRF-3023b suppresses inflammation in RAW264.7 cells by targeting Cul4a through NF-κB signaling.

The role of transfer RNA (tRNA)-derived fragment (tRF) in various diseases has been established. However, the effect of tRF-3023b on inflammation remains unclear. Inflammation was imitated in RAW264.7 cells by adding Lipopolysaccharide (LPS). Cells were first divided into control, LPS, and LPS + Bulleyaconitine A (BLA) groups. The contents of TNF-α, IL-6, and MCP-1 were quantified using ELISA. The levels of cyclooxygenase-2 (COX2), inducible nitric oxide synthase (iNOS), and the phosphorylation of nuclear factor-kappa B (NF-κB)-P65 (p-P65) were detected by Western blotting. RNA sequencing was utilized to find differentially expressed tRFs (DE-tRFs) among three groups. The levels of various tRFs were checked by quantitative real-time PCR (qRT-PCR). Cell cycle and apoptosis were checked by flow cytometry. Dluciferase reporter assay was applied to predict and confirm the interaction between tRF-3023b and Cullin 4A (Cul4a), subsequently RNA pull-down followed by mass spectrometry analysis were conducted. BLA treatment decreased the contents of TNF-α, IL-6, MCP-1, and the expression levels of COX2, iNOS, p-P65. We found 6 DE-tRFs in LPS + BLA group compared to LPS group, tRF-3023b was high expression in control and BLA groups, and the lowest in LPS group. Cul4a was a direct target of tRF-3023b. tRF-3023b mimic affected the cell cycle distribution, promoted cells apoptosis, and suppressed the TNF-α, IL-6, MCP-1, COX2, iNOS and p-P65. The suppression of Cul4a affected the cell cycle distribution, resulted in an increase of cell apoptosis while a decrease of TNF-α, IL-6, MCP-1, COX2, iNOS and p-P65. Furthermore, Cul4a overexpression reversed the effect of tRF-3023b mimic. Cul4a knockdown reversed the effect of tRF-3023b inhibitor. Our study positions tRF-3023b as a compelling candidate, through its interaction with Cul4a, the underlying mechanism on inflammation maybe related to NF-κB pathway. The study provides a basis for exploring new therapeutic strategies for inflammation.

Role of CD34 in inflammatory bowel disease.

Inflammatory bowel disease (IBD) is caused by a variety of pathogenic factors, including chronic recurrent inflammation of the ileum, rectum, and colon. Immune cells and adhesion molecules play an important role in the course of the disease, which is actually an autoimmune disease. During IBD, CD34 is involved in mediating the migration of a variety of immune cells (neutrophils, eosinophils, and mast cells) to the inflammatory site, and its interaction with various adhesion molecules is involved in the occurrence and development of IBD. Although the function of CD34 as a partial cell marker is well known, little is known on its role in IBD. Therefore, this article describes the structure and biological function of CD34, as well as on its potential mechanism in the development of IBD.

Membrane-anchored stalk domain of influenza HA enhanced immune responses in mice.

Current strategies for influenza virus vaccines primarily aim to elicit immune responses towards the globular head domain of the hemagglutinin (HA) protein so that binding of the virus to membrane receptors on the host cells is inhibited. In the present study, we show a novel strategy to generate immunity against the highly conserved region of the influenza virus. The globular head domain was replaced by different linkers to generate a headless HA (stalk domain) and then coexpressed with influenza M1 proteinin Tni insect cells. The expression was validated by western blot analysis, and stalk domain with peptides (GGGGS)4 linkers was identified to anchor in a stable way to the cell membrane. An immunoelectron microscope showed that stalk domain with (GGGGS)4 linkers were steadily incorporated to the surface of influenza virus-like particles (VLPs). Mice immunized with these VLPs exhibited enhanced systemic antibody responses with increased binding avidity and study found high titers of ADCC antibodies to the influenza virus, these VLPs also induced mucosal immune responses and produced antigen-specific IgG and IgA in nasal and lung washes. In addition, antigen-specific IgG antibody-secreting cells (ASCs) increased significantly in the spleen and lymph node. The results of this study suggest that the headless HA is a useful target in developing a universal vaccine against influenza virus.