Transcriptomic analysis in cerebral microvessels from the brain of endothelial-specific Crif1 deficiency mouse
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ABSTRACT: Endothelial cells (ECs) in cerebral vessels are considered the primary targets in acute hemorrhagic brain injuries. EC dysfunction can aggravate neuronal injuries by causing secondary inflammatory responses and blood-brain barrier (BBB) disruption. ECs comprising the BBB are known to have a higher mitochondrial volume compared with peripheral ECs. In previous study, we reported Tek-CRIF1-knockout (KO) mice, with EC-specific deletion of the mitochondrial OxPhos-related gene, Crif1, also known as Gadd45gip1 (encoding GADD45G-interacting protein 1), display profound BBB defects accompanied by reduced expression of junctional proteins in ECs. To identify signaling pathways involved in linking EC-specific mitochondrial dysfunction and BBB disruption, we first performed RNA sequencing using isolated cerebral vessels from Tek-CRIF1 mice. This transcriptome analyses of the Tek-CRIF1-KO mouse revealed significant changes in some signaling, a pathway intimately involved in BBB maintenance.
Project description:CRIF1 is a mitochondrial protein essential for the synthesis and formation of the OxPhos complex in the inner mitochondrial membrane. Beta cell specific Crif1 haploinsufficiency resulted in defect of first phase insulin secretion, and caused islet cell composition change as well as proliferation of beta cell for a compensation to maintain metabolic homeostasis. These results suggest that mitochondrial OxPhos function of beta cell has roles for beta cell compensation as well as insulin secretion.
Project description:Foxp3low inflammatory non-suppressive (INS)-regulatory T cells (Tregs) were discovered recently. Unlike conventional Tregs, they produce proinflammatory-cytokines, exhibit reduced suppressiveness, and promote rather than impair anti-tumor immunity. The role of mitochondria in Foxp3low INS-Treg formation in vivo is unclear. We showed that the Foxp3low INS-Treg equivalents in human tumors demonstrate attenuated expression of CRIF1, a vital mitochondrial regulator. Mice with CRIF1 deficiency in Tregs bore Foxp3low INS-Tregs with mitochondrial dysfunction. The -ketoglutarate-mTORC1 axis was enhanced in these cells. This promoted proinflammatory-cytokine expression by inducing EOMES and SATB1 expression. Moreover, chromatin openness of the regulatory regions of the Ifng and Il4 genes was increased, which facilitated EOMES/SATB1 binding. The increased -ketoglutarate-derived 2-hydroxyglutarate downregulated Foxp3 expression by methylating the Foxp3-gene regulatory regions. Furthermore, CRIF1-deficiency-induced Foxp3low INS-Tregs suppressed tumor growth in an IFN- dependent manner. Thus, CRIF1-mediated mitochondrial homeostasis is critical for inducing Foxp3low INS-Tregs that promote anti-tumor immunity.
Project description:Foxp3low inflammatory non-suppressive (INS)-regulatory T cells (Tregs) were discovered recently. Unlike conventional Tregs, they produce proinflammatory-cytokines, exhibit reduced suppressiveness, and promote rather than impair anti-tumor immunity. The role of mitochondria in Foxp3low INS-Treg formation in vivo is unclear. We showed that the Foxp3low INS-Treg equivalents in human tumors demonstrate attenuated expression of CRIF1, a vital mitochondrial regulator. Mice with CRIF1 deficiency in Tregs bore Foxp3low INS-Tregs with mitochondrial dysfunction. The -ketoglutarate-mTORC1 axis was enhanced in these cells. This promoted proinflammatory-cytokine expression by inducing EOMES and SATB1 expression. Moreover, chromatin openness of the regulatory regions of the Ifng and Il4 genes was increased, which facilitated EOMES/SATB1 binding. The increased -ketoglutarate-derived 2-hydroxyglutarate downregulated Foxp3 expression by methylating the Foxp3-gene regulatory regions. Furthermore, CRIF1-deficiency-induced Foxp3low INS-Tregs suppressed tumor growth in an IFN- dependent manner. Thus, CRIF1-mediated mitochondrial homeostasis is critical for inducing Foxp3low INS-Tregs that promote anti-tumor immunity.
Project description:Blood-brain barrier (BBB) critically regulate the homeostasis of central nervous system (CNS). This barrier property allows cerebral vessels to meet the extremely high metabolic demand of neural activities and meanwhile protect sensitive neurons from toxic plasma components, blood immune cells and xenobiotics. Therefore, a comprehensive inventory of the molecular determinants of BBB would substantially facilitate understanding of the pathogenesis of neurological disorders involving BBB dysfunction and promote development of novel CNS drug delivery strategies. Here, we established the proteome activity landscapes of adult mouse brain, lung and liver ECs. In this study, we produced a comprehensive molecular atlas of adult mouse BBB and revealed novel insights into adult BBB in health and Alzheimer’s disease.
Project description:With advances in single-cell genomics, molecular signatures of cells comprising the brain vasculature are revealed in unprecedented detail, yet the ageing-associated cell subtype transcriptomic changes which may contribute to neurovascular dysfunction in neurodegenerative diseases remain elusive. Here, we performed single-cell transcriptomic profiling of brain endothelial cells (EC) in young adult and aged mice to characterize their ageing-associated genome-wide expression changes. We identified zonation-dependent transcriptomic changes in aged brain EC subtypes, with capillary ECs exhibiting the most transcriptomic alterations. Pathway enrichment analysis revealed altered immune/cytokine signaling in ECs of all vascular segments, while functional changes impacting the blood-brain barrier (BBB) and glucose/energy metabolism were most prominently implicated in ECs of the capillary bed – the primary site where ECs and other neurovascular unit (NVU) cell types closely interact and coordinate to regulate BBB and cerebral blood flow in health and diseased conditions. Furthermore, an overrepresentation of Alzheimer’s disease (AD)-associated genes identified from GWAS studies was evident among the human orthologs of differentially expressed genes of aged capillary ECs but not other EC subtypes. Importantly, for numerous EC-enriched differentially expressed genes with important functional roles at the BBB and/or association with AD, we found concordant expression changes in human aged or AD brains. Finally, we demonstrated that treatment with exenatide, a glucagon-like peptide-1 receptor (GLP-1R) agonist, strongly reverses transcriptomic changes in ECs and largely reduces BBB leakage in the aged brain. Thus, our study revealed novel vascular ageing-associations of AD in the brain capillary endothelium, and provides insights into detailed transcriptomic alterations underlying brain EC ageing that are complex with subtype specificity yet amenable to pharmacological interventions.
Project description:The receptor tyrosine kinase Mer (gene name Mertk) acts in vascular endothelial cells (ECs) to tighten the blood-brain barrier (BBB) subsequent to viral infection. Correspondingly, we found that Mer regulates the expression and activity of a large cohort of cytoskeletal and BBB proteins, together with endothelial nitric oxide synthase, in brain ECs. We further found that Mer controls the expression of multiple angiogenic genes, and that EC-specific Mertk gene inactivation results in perturbed vascular sprouting and a compromised BBB after induced photothrombotic stroke. Unexpectedly, stroke lesions in the brain were also markedly reduced in the absence of EC Mer, which was linked to reduced plasma expression of fibrinogen, prothrombin, and other effectors of blood coagulation. Together, these results demonstrate that Mer is a central regulator of angiogenesis, BBB integrity, and blood coagulation in the mature vasculature. They may also account for disease severity following infection with the coronavirus SARS-CoV-2.
Project description:Endothelial cells (ECs) are constantly submitted in vivo to hemodynamical forces derived from the blood circulation, including shear stress (SS). EC are able to detect SS and consequently adapt their phenotype, thus affecting many endothelial functions. If a plethora of shear stress-regulated molecular networks have been described in peripheral EC, less is known about the molecular responses of microvascular brain ECs which constitute the blood-brain barrier (BBB). In this work, we investigated the response of human cerebral microvascular ECs to laminar physiological shear stress using the well characterized hCMEC/D3 cell line. Interestingly, we showed that hCMEC/D3 cells responded to shear stress by aligning perpendicularly to the flow direction, contrary to peripheral endothelial cells which aligned in the flow direction. Whole proteomic profiles were compared between hCMEC/D3 cells cultured either in static condition or under 5 or 10 dyn.cm-2 SS for three days. 3592 proteins were identified and expression levels were significantly affected for 3% of them upon both SS conditions. Pathway analyses were performed which revealed that most proteins overexpressed by SS refer to the antioxidant defense, probably mediated by activation of the NRF2 transcriptional factor. Regarding down-regulated proteins, most of them participate to the pro-inflammatory response, cell motility and proliferation. These findings confirm the induction of EC quiescence by laminar physiological SS and reveal a strong neuroprotective effect of SS on hCMEC/D3 cells, suggesting a similar effect on the BBB. Our results also showed that SS did not significantly increase expression levels nor did it affect the localization of junctional proteins or the functional activity of several ABC transporters (P-glycoprotein and MRPs). This work provides new insights on the response of microvascular brain EC to SS and on the importance of SS for optimizing in vitro BBB models.
Project description:CR6-interacting factor-1 (CRIF1) interacting with large mitoribosome subunits is essential for the maturation and insertion of oxidative phosphorylation (OxPhos) polypeptides into the mitochondrial inner membrane. Recently, it has reported that the genetic ablation of Crif1 in a tissue-specific manner results in mitochondrial stress response (MSR) including mitochondrial unfolded protein response (UPRmt). In this study, we aim to obtain a comprehensive understanding of systemic energy metabolism in response to hepatic mitochondrial dysfunction. Through the liver-specific Crif1 deficient mice (LKO), we explore the adaptive response not only in the liver but also in inguinal white adipose tissue (iWAT). Moreover, RNA sequencing in liver, iWAT, skeletal muscle, and hypothalamus suggest that hepatic mitochondrial dysfunction enhance metabolic pathways, including glycolysis, fatty acid elongation and degradation, and 1C metabolism in liver and insulin signaling in iWAT. RNA sequencing also suggests that hepato-mitokines, GDF15 and FGF21 are highly increased in liver of LKO mice. To identify the role of hepato-mitokines, we generate double knockout mice (LKO/Gdf15-/- and LKO/Fgf21-/-), suggesting that GDF15 is responsible for the regulation of the body and fat mass and FGF21 has a critical role for the insulin sensitivity and energy expenditure in this mice.
Project description:The therapeutic potential of neurotrophic factors has been hampered by their inability to achieve adequate tissue penetration. Brain blood vessels, however, could be an alternative target for neuro-salvage therapies by virtue of their close proximity to neurons. Here we show that hemizygous deletion of Rac1 in mouse endothelial cells (ECs) attenuates brain injury and edema following focal cerebral ischemia. To explore the mechanisms whereby decrease of Rac1 in ECs provide neuroprotection, ECs were derived from Rac1+/+ and Rac1+/- mice. Microarray analysis was performed to determine the differential gene expression between Rac1+/+ and Rac1+/- ECs. Rac1+/+ and Rac1+/- ECs were cultured to subconfluence. Total RNA was extracted and reverse transcribed. Rac1+/+ (n = 2) and Rac1+/- (n = 2) EC cDNAs were labeled with Cy3 and Cy5, respectively, and equimolar mixtures of labeled Rac1+/+ and Rac1+/- probes were hybridized to 2 slides (sample #21648, #21649). Additionally, Rac1+/+ (n = 2) and Rac1+/- (n=2) EC cDNAs labeled with Cy5 and Cy3 (dye-swapping) were hybridized to 2 slides (sample #21650, #21651). Comparison of signal intensities between Rac1+/+ (channel 2) and Rac1+/- (channel 1) was conducted on each slide (sample), and the ratio of intensities from 4 slides were statistically assessed for each gene feature to investigate differential gene expression.