Unknown,Transcriptomics,Genomics,Proteomics

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AcLDL-induced gene expression in wildtype and IRAK4 KI mouse macrophages

ABSTRACT: Exciting discoveries related to IL-1R/TLR signaling in development of atherosclerosis plaque have triggered intense interest in the molecular mechanisms by which innate immune signaling modulates the onset and development of atherosclerosis. Previous studies have clearly shown the definitive role of proinflammatory cytokine IL-1 in the development of atherosclerosis. Recent studies have provided direct evidence supporting a link between innate immunity and atherogenesis. While it is still controversial about whether infectious pathogens contribute to cardiovascular diseases, direct genetic evidence indicates the importance of IL-1R/TLR signaling in atherogenesis. In this study, we examined the role of IRAK4 kinase activity in modified LDL-mediated signaling using bone marrow-derived macrophage as well as in vivo model of atherosclerosis. First, we found that the IRAK4 kinase activity was required for modified LDL-induced NFÎºB activation and expression of a subset of proinflammatory genes, but not for the activation of MAPKs in bonemarrow-derived macrophage. IRAK4 kinase inactive knock-in (IRAK4KI) mice were bred onto ApoE-/- mice to generate IRAK4KI/ApoE-/- mice. Importantly, the aortic sinus lesion formation was impaired in IRAK4KI/ApoE-/- mice compared to that in ApoE-/- mice. Furthermore, proinflammatory cytokine production was reduced in the aortic sinus region of IRAK4KI/ApoE-/- mice compared to that in ApoE-/- mice. Taken together, our results indicate that the IRAK4 kinase plays an important role in modified LDL-mediated signaling and the development of atherosclerosis, suggesting that pharmacological inhibition of IRAK4 kinase activity might be a feasible approach in the development of anti-atherosclerosis drugs. To identify global changes in gene expression, we examined gene expression profiles of macrophages from wild-type and IRAK4 kinase-inactive knock-in mice in response to acLDL stimulation using the Illumina microarray with probes for 23,000 transcripts. Bone marrow-derived macrophages from wild-type and IRAK4 kinase-inactive knock-in mice were treated with acLDL for 24 hours.

ORGANISM(S): Mus musculus

SUBMITTER: Pieter Faber

PROVIDER: E-GEOD-24894 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: The co-stimulatory CD40-CD40L dyad is an important driver of atherosclerosis. CD40 exerts divergent, cell-specific roles, which differentially impact atherogenesis. Objectives: We here investigate the role of the most prominent CD40-expressing cell-type, the B-cell, in atherosclerosis. Methods: B-cell subset specific CD40-expression of patients with mild and severe coronary artery disease (CAD) was determined by mass-cytometry and correlated to CAD severity. Underlying mechanisms were elucidated using B-cell CD40-deficient CD19Cre-CD40flfl-ApoE-/-(CD40BKO) mice and control littermates (CD40BWT). Results: Patients with severe CAD had similar CD40 expression levels on most B-cell subsets but showed a profound decrease in CD40 on putative B1 cells. This was associated with increased atherosclerotic plaque burden and decreased plaque fibrosis. Likewise, CD40BKO mice exhibited an increased plaque area and more advanced staging of atherosclerosis. Absence of CD40 on B-cells caused a decrease in immunoglobulin (Ig) producing cells, including germinal center-, plasma-, but especially B1 cells, thereby reducing levels of (anti-ox/MDA-LDL) IgG and protective (anti-ox/MDA-LDL) IgM. Transcriptomics analysis revealed that the absence of CD40 on B1b cells caused altered gene expression pathways related to lipid uptake (Cd36, Ldlr), cellular stress and metabolism (Nr4a1, Hif1a), and cell death (Naip5/6, Ccnd2). Indeed, in vitro analysis showed that B1bCD40KO cells took up excessive amounts of ac/oxLDL, exhibited defective BCR signaling, and were prone to apoptosis, especially in hyperlipidemic conditions. Transfer of wild-type B1b cells in CD40BKO mice prevented the increase in atherosclerosis. Conclusions: Patients with severe CAD had similar CD40 expression levels on most B-cell subsets but showed a profound decrease in CD40 on putative B1 cells. This was associated with increased atherosclerotic plaque burden and decreased plaque fibrosis. Likewise, CD40BKO mice exhibited an increased plaque area and more advanced staging of atherosclerosis. Absence of CD40 on B-cells caused a decrease in immunoglobulin (Ig) producing cells, including germinal center-, plasma-, but especially B1 cells, thereby reducing levels of (anti-ox/MDA-LDL) IgG and protective (anti-ox/MDA-LDL) IgM. Transcriptomics analysis revealed that the absence of CD40 on B1b cells caused altered gene expression pathways related to lipid uptake (Cd36, Ldlr), cellular stress and metabolism (Nr4a1, Hif1a), and cell death (Naip5/6, Ccnd2). Indeed, in vitro analysis showed that B1bCD40KO cells took up excessive amounts of ac/oxLDL, exhibited defective BCR signaling, and were prone to apoptosis, especially in hyperlipidemic conditions. Transfer of wild-type B1b cells in CD40BKO mice prevented the increase in atherosclerosis.

Project description:Background: Atherosclerosis leads high mortality, highlighting an urgent need for new therapeutic strategies. Protein kinases orchestrate multiple cellular events in atherosclerosis and may provide new therapeutic targets for atherosclerosis. Here, we identified a protein kinase, WEE1 G2 checkpoint kinase (WEE1), promoting inflammatory response in atherosclerosis. Methods: The ApoE-/- mice without macrophage-specific WEE1 deletion (ApoE-/-WEE1f/f) and ApoE-/- mice with macrophage-specific WEE1 deletion (ApoE-/-WEE1MCKO) were generated using bone marrow transplantation. These mice and WEE1 inhibitor MK1775 were used in a high-fat diet (HFD)-induced atherosclerotic model. Human atherosclerotic tissues, mouse primary peritoneal macrophages (MPMs), 293T cells, and recombinant proteins were utilized to investigate the pathogenic role and underlying mechanisms of WEE1. Results: We identified up-regulated p-WEE1 in macrophages in atherosclerotic lesions of HFD-fed ApoE-/- mice. Transcriptome sequencing analysis indicated that WEE1 promotes oxLDL-induced inflammation in macrophages. We then demonstrated that macrophage-specific deletion or pharmacological inhibition of WEE1 attenuates atherosclerosis by reducing inflammation both in vivo and in vitro. The overexpression of wild-type WEE1 or activating-mutant WEE1, but not inactivating-mutant WEE1, exacerbates inflammation in macrophages. Mechanistically, transcriptome sequencing analysis and co-immunoprecipitation followed by quantitative proteomics analysis identified p65 as a binding protein of WEE1. We confirmed that WEE1 directly interacts with the RHD domain of p65 via kinase domain and phosphorylates p65 at S536, thereby facilitating subsequent NF-κB activation and inflammatory response in macrophages. Conclusions: Our findings demonstrated that macrophage WEE1 promotes inflammatory atherosclerosis by directly binding to p65 and phosphorylate it at S536. This study provides WEE1 as a new p65 regulator in inflammation and a potential therapeutic target for atherosclerosis.

Project description:The multi-ligand Receptor for AGE (RAGE) contributes to atherosclerosis in apolipoprotein (ApoE) null mice in both the non-diabetic and diabetic states. Previous studies using soluble RAGE, the extracellular ligand-binding domain of RAGE, or homozygous RAGE null mice showed that blockade or deletion of RAGE resulted in marked reduction in atherosclerotic lesion area and complexity compared to control animals. In parallel, significant down-regulation of inflammatory mediators and matrix metalloproteinases was evident in ApoE null mice aortas devoid of RAGE compared to those of ApoE null RAGE-expressing mice. Although these findings suggested that RAGE triggered pro-atherogenic mechanisms via regulation of inflammatory gene expression, these studies did not reveal the broader pathways by which RAGE contributed to atherosclerosis in ApoE null mice. Therefore, we performed Affymetrix gene expression arrays on aortas of non-diabetic and diabetic ApoE null mice expressing RAGE or devoid of RAGE at nine weeks of age, as this reflected a time point at which frank atherosclerotic lesions were not yet present, but, that we would be able to identify the genes likely involved in diabetes- and RAGE-dependent atherogenesis. The comparisons were as follows: 1. diabetic ApoE null relative to non-diabetic ApoE null; 2. non-diabetic ApoE null / RAGE null relative to non-diabetic ApoE null; 3. diabetic ApoE null / RAGE null relative to non-diabetic ApoE null / RAGE null; and 4. diabetic ApoE null / RAGE null relative to diabetic ApoE null aorta. Our data reveal that there is very little overlap of the genes which are differentially expressed both in the onset of diabetes in ApoE null mice, and in the effect of RAGE deletion in diabetic ApoE null mice. We next performed a Pathway-Express analysis to determine the pathways that were most associated with the onset of diabetes in ApoE null mice and the effect of RAGE gene deletion in diabetic ApoE null mice. Rigorous statistical analysis was undertaken and revealed that the transforming growth factor-beta pathway (tgf-beta) and focal adhesion pathways might be expected to play a significant role in both the mechanism by which diabetes facilitates the formation of atherosclerotic plaques in ApoE null mice, and the mechanism by which deletion of RAGE ameliorates this effect. We focused on three genes of the tgf-betafamily which were found to be up-regulated in diabetic vs. non-diabetic ApoE null aorta, and which were reduced by deletion of RAGE. These included: thrombospondin1 (Thbs1), transforming growth factor-beta (tgf-beta) and rho-associated kinase (ROCK1). Real-time quantitative polymerase chain reaction and Western blotting experiments were performed, as well as ROCK1 activity assays in mouse aorta, and validated the findings of the Affymetrix gene array. Further, confocal microscopy revealed that a principal cell type in the ApoE null aorta expressing these factors was the vascular smooth muscle cell. Our data suggest the novel finding that the observed reduction of accelerated atherosclerosis in diabetic ApoE null / RAGE null vs. diabetic ApoE null mice occurs, all or in part, through the ROCK1 branch of the TGF-betapathway. We have inferred a detailed mechanism for this process. Taken together, these data suggest that suppression of ROCK1 activity in the atherosclerosis-vulnerable vessel wall, especially in diabetes, but in non-diabetes as well, may underlie the beneficial effects of RAGE antagonism and genetic deletion in murine models. These findings highlight logical and novel targets for therapeutic intervention in cardiovascular disease and diabetes. 1. diabetic ApoE null relative to non-diabetic ApoE null; 2. non-diabetic ApoE null / RAGE null relative to non-diabetic ApoE null; 3. diabetic ApoE null / RAGE null relative to non-diabetic ApoE null / RAGE null; and 4. diabetic ApoE null / RAGE null relative to diabetic ApoE null aorta. There were 4 mice in each group initially. However there are only 3 non-diabetic ApoE null / RAGE null mice in the final experimental sample in group 3 due to a failure to generate cRNA from that sample. All samples were normalized to remove chip-dependent regularities using the RMA method. Chips and controls at each combination of genotype and disease sate were normalized together. The statistical significance of differential expression was calculated using the empirical Bayesian LIMMA (LInear Model for MicroArrays) method A cut-off B>0 was used for the statistical significance of gene expression.

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AcLDL-induced gene expression in wildtype and IRAK4 KI mouse macrophages

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