Activation of macrophages by inflammatory stimuli leads to reprogramming of mitochondrial metabolism to support the production of pro-inflammatory cytokines. Hallmarks of this metabolic rewiring are downregulation of a-ketoglutarate formation via isocitrate dehydrogenase (IDH) and accumulation of glutamine-derived succinate, which enhances the inflammatory response via the activity of succinate dehydrogenase (SDH). Here, we identify the nuclear receptor Nur77 (Nr4a1) as a key regulator of the pro-inflammatory metabolic switch in macrophages. Nur77-deficient macrophages fail to downregulate IDH expression and accumulate higher levels of succinate and other downstream TCA cycle metabolites in response to an inflammatory stimulus. Consequently, these macrophages produce more nitric oxide and pro-inflammatory cytokines in an SDH-dependent manner. In vivo, bone marrow Nur77 deficiency exacerbates atherosclerosis development and leads to increased systemic succinate levels. In conclusion, Nur77 supports an anti-inflammatory metabolic state in macrophages that protects against chronic inflammatory diseases such as atherosclerosis. Overall design: Gene expression profiling by RNA-seq was performed in triplicate in RAW264.7 mouse macrophage stable cell lines with doxycycline-inducible overexpression of HA-tagged NUR77 or GFP as control.
Nuclear Receptor Nur77 Limits the Macrophage Inflammatory Response through Transcriptional Reprogramming of Mitochondrial Metabolism.
Cell line, Treatment, Subject
View SamplesThe vascular endothelium forms a physical barrier between blood and the surrounding tissue. Its constant exposure to haemodynamic shear stress controls endothelial barrier function which is of major importance for vascular homeostasis. The role of long non-coding RNAs (lncRNAs) in this process remains elusive. Here we identify the shear stress-induced lncRNA LASSIE (linc00520) as a stabilizer of adherens junctions (AJs) in endothelial cells (ECs), that is indispensable for normal endothelial barrier function and shear stress sensing. Silencing of LASSIE in ECs resulted in impaired cell survival, loss of cell-cell contacts and failure to align in the direction of flow. RNA affinity purification followed by mass spectrometry identified several junction proteins associated with LASSIE, including the endothelial adhesion protein PECAM-1 and intermediate filament (IF) protein nestin. Proteomic analysis of VE-cadherin-associated proteins showed that LASSIE silencing reduces VE-cadherin interaction with nestin and microtubule (MT)-associated cytoskeletal proteins. We confirmed that LASSIE silencing results in a decreased connection between VE-Cadherin and the cytoskeleton, resulting in loss of barrier function and shear stress sensing. Together, this study identifies the shear stress-induced lncRNA LASSIE as a critical link between AJs and the IF cytoskeleton, which is indispensable for normal EC junction stabilization and shear stress sensing.
Long non-coding RNA LASSIE regulates shear stress sensing and endothelial barrier function.
Specimen part
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