Dataset Information

Opposite effects of miR-155 in the initial and later stages of lipopolysaccharide (LPS)-induced inflammatory response.

ABSTRACT: Although microRNA-155 (miR-155) is considered a pro-inflammatory mediator, cumulative evidence indicates that it also has anti-inflammatory effects in macrophages and dendritic cells. In this study, we identified the dramatic expression changes of more than half of potential miR-155-targeted genes upon lipopolysaccharide (LPS) stimulation; 223 genes were down-regulated and 85 genes were up-regulated, including suppressor of cytokine signaling 1 (SOCS1) and transforming growth factor-β-activated kinase 1-binding protein 2 (TAB2), two well-known genes involved in miR-155-mediated regulation of the Toll-like receptor 4 (TLR4) signaling pathway. We also found that miR-155 acted as an anti-inflammatory mediator in the initial stage of LPS-induced inflammatory response mainly through repressing TAB2 protein translation, and as a pro-inflammatory mediator by down-regulating SOCS1 in the later stage. Meanwhile, overexpression of TAB2 3' untranslated region (UTR) in macrophages promoted the development of endotoxin tolerance by competing for binding with miR-155, which resulted in an elevated expression level of SOCS1 protein. These findings provide new insights for understanding the regulatory mechanisms in fine-tuning of LPS-induced innate immune response.

SUBMITTER: Liu Y

PROVIDER: S-EPMC8284089 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:BackgroundMicroRNA miR-155 is implicated in modulation of the inflammatory processes in various pathological conditions. In our previous studies, we demonstrated that in vivo inhibition of miR-155 promotes functional recovery after mouse experimental stroke. In the present study, we explored if this beneficial effect is associated with miR-155 inhibition-induced alterations in post-stroke inflammatory response.MethodsIntravenous injections of a specific miR-155 inhibitor were initiated at 48 h after mouse distal middle cerebral artery occlusion (dMCAO). Temporal changes in the expression of cytokines and key molecules associated with cytokine signaling were assessed at 7, 14, and 21 days after dMCAO, using mouse cytokine gene and protein arrays and Western blot analyses. Electron and immunofluorescence confocal microscopy techniques were used to evaluate the ultrastructural changes, as well as altered expression of specific phenotypic markers, at different time points after dMCAO.ResultsIn the inhibitor-injected mice (inhibitor group), there was a significant decrease in CCL12 and CXCL3 cytokine expression at 7 days and significantly increased levels of major cytokines IL-10, IL-4, IL-6, MIP-1α, IL-5, and IL-17 at 14 days after dMCAO. These temporal changes correlated with altered expression of miR-155 target proteins SOCS-1, SHIP-1, and C/EBP-β and phosphorylation levels of cytokine signaling regulator STAT-3. Electron microscopy showed decreased number of phagocytically active peri-vascular microglia/macrophages in the inhibitor samples. Immunofluorescence and Western blot of these samples demonstrated that expression of leukocyte/ macrophage marker CD45 and phagocytosis marker CD68 was reduced at 7 days, and in contrast, significantly increased at 14 days after dMCAO, as compared to controls.ConclusionsBased on our findings, we propose that in vivo miR-155 inhibition following mouse stroke significantly alters the time course of the expression of major cytokines and inflammation-associated molecules, which could influence inflammation process and tissue repair after experimental cerebral ischemia.

Project description:Atherosclerosis is the leading cause of death from vascular diseases worldwide, and endothelial cell (EC) dysfunction is the key cause of atherosclerosis. miR-155 was found to induce endothelial injury and to trigger atherosclerosis. In addition, brain and muscle ARNT-like protein-1 (Bmal1) has been found to be closely related to EC function. Therefore, the present study aimed to explore the mechanism underlying the regulation of Bmal1 by miR-155 in the induction of EC apoptosis and inflammatory response in atherosclerosis. The atherosclerosis model in apolipoprotein E (ApoE)- / - mice was established. miR-155 and Bmal1 expression was quantified by RT-qPCR and western blot analysis, respectively. The role of miR-155 and Bmal1 in atherosclerosis was evaluated through changes in cardiac function, plaque area, cardiomyocyte apoptosis, and inflammatory factor levels in mice. Moreover, the regulatory relationship between them was identified by dual-luciferase reporter gene assay to explore the mechanism of action of miR-155. After the modeling, the expression of miR-155 was upregulated and Bmal1 was downregulated in aorta, and there was a significant linear correlation between them. Upregulation of miR-155 increased the atherosclerotic plaque area, cell apoptosis, total cholesterol (TC) and triglyceride (TG), as well as weakened aortic diastolic function. However, opposite changes occurred after downregulation of miR-155 or an increase in Bmal1. In addition, the microRNA.org website predicted that there were targeted binding sites between miR-155 and Bmal1, which was verified with a dual-luciferase reporter gene assay. miR-155 was able to inhibit the expression by targeting Bmal1. Moreover, a rescue experiment showed that Bmal1 hindered the promotion of miR-155 in regards to atherosclerosis. In conclusion, miR-155 induces EC apoptosis and inflammatory response, weakens aortic diastolic function, and promotes the progression of atherosclerosis through targeted inhibition of Bmal1.

Dataset Information

Opposite effects of miR-155 in the initial and later stages of lipopolysaccharide (LPS)-induced inflammatory response.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets