PubMed · 2564697
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H K Kimelberg, M D Norenberg. 1989. Astrocytes.. https://doi.org/10.1038/scientificamerican0489-66
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Endothelial cells and astrocytes are critical structural and functional components of the blood-brain barrier. In many neuroinflammatory diseases, endothelial cells are among the first to respond to inflammatory stimuli and release extracellular vesicles (EVs). However, whether inflammatory stimulation alters EV RNA cargo and subsequently regulates astrocyte function remains unclear. In this study, we performed integrated RNA sequencing and proteomic analyses to investigate the effects of TNFα-stimulated endothelial EVs on astrocytes. RNA profiling revealed significant alterations in EV cargo after TNFα stimulation, including 867 upregulated and 577 downregulated mRNAs, 317 upregulated and 15 downregulated lncRNAs, and 88 upregulated and 62 downregulated miRNAs. The results of functional enrichment analysis suggested that altered EV RNAs may primarily promote inflammatory responses, cell migration, and RNA splicing in astrocytes while reducing their regulatory effects on neuronal projection and calcium homeostasis. Further integrative analysis of EV RNAs and astrocytic proteomics revealed key overlapping targets, including upregulated expression of ICAM1, SOD2, TFPI2, and TNFAIP8, whereas NFKBIA expression was consistently decreased. Network analysis revealed NF-κB as the central regulatory node. Reduced levels of EV-derived NFKBIA mRNA were associated with decreased IκBα protein levels in astrocytes, which promoted NF-κB activation and inflammatory cytokine release. Finally, overexpression of IκBα in astrocytes significantly attenuated TNFα EV-induced IL-1β and IL-6 secretion. Collectively, these findings demonstrate that TNFα-stimulated endothelial EVs coordinately regulate astrocyte function through mRNA, lncRNA, and miRNA cargo and that the IκBα/NF-κB axis may be a key mechanism underlying endothelial EV-mediated inflammatory disruption of the blood-brain barrier.
Astrocytes contribute to the development and regulation of the higher-level functions of the brain, the critical targets of evolution. However, how astrocytes evolve in primates is unsettled. Here, we obtain human, chimpanzee, and macaque induced pluripotent stem-cell-derived astrocytes (iAstrocytes). Human iAstrocytes are bigger and more complex than the non-human primate iAstrocytes. We identify new loci contributing to the increased human astrocyte. We show that genes and pathways implicated in long-range intercellular signaling are activated in the human iAstrocytes and partake in controlling iAstrocyte complexity. Genes downregulated in human iAstrocytes frequently relate to neurological disorders and were decreased in adult brain samples. Through regulome analysis and machine learning, we uncover that functional activation of enhancers coincides with a previously unappreciated, pervasive gain of "stripe" transcription factor binding sites. Altogether, we reveal the transcriptomic signature of primate astrocyte evolution and a mechanism driving the acquisition of the regulatory potential of enhancers.
Interleukin-11 (IL-11) is a pleiotropic cytokine with important effects on hematopoietic and other cells. IL-11 was originally described as a product of stromal cell lines and fibroblasts. Using RT-PCR, Northern blotting, and ELISA we demonstrated that the human U373 and U87 glioblastoma cell lines expressed IL-11 and its encoding mRNA when stimulated with IL-1 beta, phorbol ester, and calcium ionophore. The neuroblastoma cell line SH-SY5Y did not express IL-11 mRNA in response to these agents. Cerebral expression of IL-11 by glial cells is important because IL-11 has been shown to have effects on neuronal electrophysiology, has overlapping functions with the neuroactive cytokine interleukin-6, and is part of the gp130-associated neuropoietic family of cytokines.