The guanine nucleotide exchange factor RapGEF2 is required for ERK-dependent immediate-early gene (Egr1) activation during fear memory formation.

The MAP kinase ERK is important for neuronal plasticity underlying associative learning, yet specific molecular pathways for neuronal ERK activation are undetermined. RapGEF2 is a neuron-specific cAMP sensor that mediates ERK activation. We investigated whether it is required for cAMP-dependent ERK activation leading to other downstream neuronal signaling events occurring during associative learning, and if RapGEF2-dependent signaling impairments affect learned behavior. Camk2α-cre+/-::RapGEF2fl/fl mice with depletion of RapGEF2 in hippocampus and amygdala exhibit impairments in context- and cue-dependent fear conditioning linked to corresponding impairment in Egr1 induction in these two brain regions. Camk2α-cre+/-::RapGEF2fl/fl mice show decreased RapGEF2 expression in CA1 and dentate gyrus associated with abolition of pERK and Egr1, but not of c-Fos induction, following fear conditioning, impaired freezing to context after fear conditioning, and impaired cAMP-dependent long-term potentiation at perforant pathway and Schaffer collateral synapses in hippocampal slices ex vivo. RapGEF2 expression is largely eliminated in basolateral amygdala, also involved in fear memory, in Camk2α-cre+/-::RapGEF2fl/fl mice. Neither Egr1 nor c-fos induction in BLA after fear conditioning, nor cue-dependent fear learning, are affected by ablation of RapGEF2 in BLA. However, Egr1 induction (but not that of c-fos) in BLA is reduced after restraint stress-augmented fear conditioning, as is freezing to cue after restraint stress-augmented fear conditioning, in Camk2α-cre+/-::RapGEF2fl/fl mice. Cyclic AMP-dependent GEFs have been genetically associated as risk factors for schizophrenia, a disorder associated with cognitive deficits. Here we show a functional link between one of them, RapGEF2, and cognitive processes involved in associative learning in amygdala and hippocampus.

Human endogenous retrovirus K contributes to a stem cell niche in glioblastoma.

Human endogenous retroviruses (HERVs) are ancestral viral relics that constitute nearly 8% of the human genome. Although normally silenced, the most recently integrated provirus HERV-K (HML-2) can be reactivated in certain cancers. Here, we report pathological expression of HML-2 in malignant gliomas in both cerebrospinal fluid and tumor tissue that was associated with a cancer stem cell phenotype and poor outcomes. Using single-cell RNA-Seq, we identified glioblastoma cellular populations with elevated HML-2 transcripts in neural progenitor-like cells (NPC-like) that drive cellular plasticity. Using CRISPR interference, we demonstrate that HML-2 critically maintained glioblastoma stemness and tumorigenesis in both glioblastoma neurospheres and intracranial orthotopic murine models. Additionally, we demonstrate that HML-2 critically regulated embryonic stem cell programs in NPC-derived astroglia and altered their 3D cellular morphology by activating the nuclear transcription factor OCT4, which binds to an HML-2-specific long-terminal repeat (LTR5Hs). Moreover, we discovered that some glioblastoma cells formed immature retroviral virions, and inhibiting HML-2 expression with antiretroviral drugs reduced reverse transcriptase activity in the extracellular compartment, tumor viability, and pluripotency. Our results suggest that HML-2 fundamentally contributes to the glioblastoma stem cell niche. Because persistence of glioblastoma stem cells is considered responsible for treatment resistance and recurrence, HML-2 may serve as a unique therapeutic target.

Chronic social defeat alters brain vascular-associated cell gene expression patterns leading to vascular dysfunction and immune system activation.

Brain vascular integrity is critical for brain health, and its disruption is implicated in many brain pathologies, including psychiatric disorders. Brain-vascular barriers are a complex cellular landscape composed of endothelial, glial, mural, and immune cells. Yet currently, little is known about these brain vascular-associated cells (BVACs) in health and disease. Previously, we demonstrated that 14 days of chronic social defeat (CSD), a mouse paradigm that produces anxiety and depressive-like behaviors, causes cerebrovascular damage in the form of scattered microbleeds. Here, we developed a technique to isolate barrier-related cells from the mouse brain and subjected the isolated cells to single-cell RNA sequencing. Using this isolation technique, we found an enrichment in BVAC populations, including distinct subsets of endothelial and microglial cells. In CSD compared to non-stress, home-cage control, differential gene expression patterns disclosed biological pathways involving vascular dysfunction, vascular healing, and immune system activation. Overall, our work demonstrates a unique technique to study BVAC populations from fresh brain tissue and suggests that neurovascular dysfunction is a key driver of psychosocial stress-induced brain pathology.

Proteostasis Modulation in Germline Missense von Hippel Lindau Disease.

PURPOSE: Missense mutated von Hippel Lindau (VHL) protein (pVHL) maintains intrinsic function but undergoes proteasomal degradation and tumor initiation and/or progression in VHL disease. Vorinostat can rescue missense mutated pVHL and arrest tumor growth in preclinical models. We asked whether short-term oral vorinostat could rescue pVHL in central nervous system hemangioblastomas in patients with germline missense VHL. PATIENTS AND METHODS: We administered oral vorinostat to 7 subjects (ages 46.0 ± 14.5 years) and then removed symptomatic hemangioblastomas surgically (ClinicalTrials.gov identifier NCT02108002). RESULTS: Vorinostat was tolerated without serious adverse events by all patients. pVHL expression was elevated in neoplastic stromal cells compared with untreated hemangioblastomas from same patients. We found transcriptional suppression of downstream hypoxia-inducible factor (HIF) effectors. Mechanistically, vorinostat prevented Hsp90 recruitment to mutated pVHL in vitro. The effects of vorinostat on the Hsp90-pVHL interaction, pVHL rescue, and transcriptional repression of downstream HIF effectors was independent of the location of the missense mutation on the VHL locus. We confirmed a neoplastic stromal cell-specific effect in suppression of protumorigenic pathways with single-nucleus transcriptomic profiling. CONCLUSIONS: We found that oral vorinostat treatment in patients with germline missense VHL mutations has a potent biologic effect that warrants further clinical study. These results provide biologic evidence to support the use of proteostasis modulation for the treatment of syndromic solid tumors involving protein misfolding. Proteostasis modulation with vorinostat rescues missense mutated VHL protein. Further clinical trials are needed to demonstrate tumor growth arrest.

A regulatory network of Sox and Six transcription factors initiate a cell fate transformation during hearing regeneration in adult zebrafish.

Using adult zebrafish inner ears as a model for sensorineural regeneration, we ablated the mechanosensory receptors and characterized the single-cell epigenome and transcriptome at consecutive time points during hair cell regeneration. We utilized deep learning on the regeneration-induced open chromatin sequences and identified cell-specific transcription factor (TF) motif patterns. Enhancer activity correlated with gene expression and identified potential gene regulatory networks. A pattern of overlapping Sox- and Six-family TF gene expression and binding motifs was detected, suggesting a combinatorial program of TFs driving regeneration and cell identity. Pseudotime analysis of single-cell transcriptomic data suggested that support cells within the sensory epithelium changed cell identity to a "progenitor" cell population that could differentiate into hair cells. We identified a 2.6 kb DNA enhancer upstream of the sox2 promoter that, when deleted, showed a dominant phenotype that resulted in a hair-cell-regeneration-specific deficit in both the lateral line and adult inner ear.

Zrsr2 Is Essential for the Embryonic Development and Splicing of Minor Introns in RNA and Protein Processing Genes in Zebrafish.

ZRSR2 (zinc finger CCCH-type, RNA binding motif and serine/arginine rich 2) is an essential splicing factor involved in 3' splice-site recognition as a component of both the major and minor spliceosomes that mediate the splicing of U2-type (major) and U12-type (minor) introns, respectively. Studies of ZRSR2-depleted cell lines and ZRSR2-mutated patient samples revealed its essential role in the U12-dependent minor spliceosome. However, the role of ZRSR2 during embryonic development is not clear, as its function is compensated for by Zrsr1 in mice. Here, we utilized the zebrafish model to investigate the role of zrsr2 during embryonic development. Using CRISPR/Cas9 technology, we generated a zrsr2-knockout zebrafish line, termed zrsr2hg129/hg129 (p.Trp167Argfs*9) and examined embryo development in the homozygous mutant embryos. zrsr2hg129/hg129 embryos displayed multiple developmental defects starting at 4 days post fertilization (dpf) and died after 8 dpf, suggesting that proper Zrsr2 function is required during embryonic development. The global transcriptome analysis of 3 dpf zrsr2hg129/hg129 embryos revealed that the loss of Zrsr2 results in the downregulation of essential metabolic pathways and the aberrant retention of minor introns in about one-third of all minor intron-containing genes in zebrafish. Overall, our study has demonstrated that the role of Zrsr2 as a component of the minor spliceosome is conserved and critical for proper embryonic development in zebrafish.

Antibody Response to HML-2 May Be Protective in Amyotrophic Lateral Sclerosis.

OBJECTIVES: Reactivation of HERV-K(HML-2) has been found in subsets of individuals with amyotrophic lateral sclerosis (ALS). This study examines the antibody response against HML-2 in ALS and analyzes its clinical relevance. METHODS: Antibodies to HML-2 envelope (env) were analyzed using a peptide array for epitope mapping and by a peptide enzyme-linked immunosorbent assay (ELISA) in 242 healthy donors, and 243 ALS and 85 multiple sclerosis (MS) individuals. Extracellular levels of HML-2 were analyzed by digital polymerase chain reaction (PCR). RESULTS: Antibodies in the sera of ALS individuals recognized more HML-2 env peptides compared to healthy controls (p < 0.0001). ALS individuals had higher levels of HML-2 than healthy donors (p = 0.02) and higher antibody levels against a select HML-2 env peptide compared to healthy donors or individuals with multiple sclerosis (p < 0.0001). 55.14% of ALS compared to 21.16% of healthy donors and 13.10% of MS individuals had antibodies against the HML-2 peptide (AUC = 0.769, p < 0.0001). Levels of extracellular HML-2 DNA in serum (p = 0.02) and the number of HML-2 env peptides recognized by ALS sera (p = 0.02) correlated with disease duration. Among ALS individuals, lower levels of HML-2 antibodies were associated with a definite diagnosis per EL Escorial criteria (p = 0.03), and with a lower predicted (p = 0.02) and observed survival (p = 0.03). INTERPRETATION: There is a differential antibody response against specific epitopes of HML-2 env in ALS and controls, suggesting epitope spreading, likely due to persistent antigenic exposure following reactivation of the viral genes. Low levels of antibodies to HML-2 env in ALS are associated with poor prognosis and decreased survival probability. ANN NEUROL 2022;92:782-792.

Pituitary adenomas evade apoptosis via noxa deregulation in Cushing's disease.

Sporadic pituitary adenomas occur in over 10% of the population. Hormone-secreting adenomas, including those causing Cushing's disease (CD), cause severe morbidity and early mortality. Mechanistic studies of CD are hindered by a lack of in vitro models and control normal human pituitary glands. Here, we surgically annotate adenomas and adjacent normal glands in 25 of 34 patients. Using single-cell RNA sequencing (RNA-seq) analysis of 27594 cells, we identify CD adenoma transcriptomic signatures compared with adjacent normal cells, with validation by bulk RNA-seq, DNA methylation, qRT-PCR, and immunohistochemistry. CD adenoma cells include a subpopulation of proliferating, terminally differentiated corticotrophs. In CD adenomas, we find recurrent promoter hypomethylation and transcriptional upregulation of PMAIP1 (encoding pro-apoptotic BH3-only bcl-2 protein noxa) but paradoxical noxa downregulation. Using primary CD adenoma cell cultures and a corticotroph-enriched mouse cell line, we find that selective proteasomal inhibition with bortezomib stabilizes noxa and induces apoptosis, indicating its utility as an anti-tumor agent.

ERK-dependent induction of the immediate-early gene Egr1 and the late gene Gpr50 contribute to two distinct phases of PACAP Gs-GPCR signaling for neuritogenesis.

Gs-coupled GPCR-stimulated neuritogenesis in PC12 and NS-1 - cells depends on activation of the MAP kinase ERK. Here, we examine changes in ERK activation (phosphorylation), and the time course of ERK-dependent gene induction, to seek transcriptional determinants for this process. Quenching of ERK activation by inhibition of MEK with U0126 at any time point for at least 24 h following addition of PACAP resulted in arrest of neurite formation. Changes in the transcriptome profile throughout this time period revealed at least two phases of gene induction: an early phase dominated by induction of immediate-early genes, and a later phase of gene induction after 4-6 h of exposure to PACAP with persistent elevation of phospho-ERK levels. Genes induced by PACAP in both phases consisted in those whose induction was dependent on ERK (i.e., blocked by U0126), and some whose induction was blocked by the protein kinase A inhibitor H89. ERK-dependent "late gene" transcripts included Gpr50, implicated earlier in facilitation of NGF-induced neurite formation in NS-1 cells. Gpr50 induction by PACAP, but not NGF, was dependent on the guanine nucleotide exchange factor RapGEF2, which has been shown to be required for PACAP-induced neuritogenesis in NS-1 cells. Expression of a Gpr50-directed shRNA lowered basal levels of Gpr50 mRNA and attenuated Gpr50 mRNA and GPR50 protein induction by PACAP, with a corresponding attenuation of PACAP-induced neuritogenesis. Gs-GPCR-stimulated neuritogenesis first requires immediate-early gene induction, including that of Egr1 (Zif268/NGF1A/Krox24) as previously reported. This early phase of gene induction, however, is insufficient to maintain the neuritogenic process without ERK-dependent induction of additional late genes, including Gpr50, upon continuous exposure to neurotrophic neuropeptide. Early (Egr1) and late (Gpr50) gene induction by NGF, like that for PACAP, was inhibited by U0126, but was independent of RapGEF2, confirming distinct modes of ERK activation by Gs-coupled GPCRs and neurotrophic tyrosine receptor kinases, converging on a final common ERK-dependent signaling pathway for neuritogenesis.

CD47 interactions with exportin-1 limit the targeting of m7G-modified RNAs to extracellular vesicles.

CD47 is a marker of self and a signaling receptor for thrombospondin-1 that is also a component of extracellular vesicles (EVs) released by various cell types. Previous studies identified CD47-dependent functional effects of T cell EVs on target cells, mediated by delivery of their RNA contents, and enrichment of specific subsets of coding and noncoding RNAs in CD47+ EVs. Mass spectrometry was employed here to identify potential mechanisms by which CD47 regulates the trafficking of specific RNAs to EVs. Specific interactions of CD47 and its cytoplasmic adapter ubiquilin-1 with components of the exportin-1/Ran nuclear export complex were identified and confirmed by coimmunoprecipitation. Exportin-1 is known to regulate nuclear to cytoplasmic trafficking of 5'-7-methylguanosine (m7G)-modified microRNAs and mRNAs that interact with its cargo protein EIF4E. Interaction with CD47 was inhibited following alkylation of exportin-1 at Cys528 by its covalent inhibitor leptomycin B. Leptomycin B increased levels of m7G-modified RNAs, and their association with exportin-1 in EVs released from wild type but not CD47-deficient cells. In addition to perturbing nuclear to cytoplasmic transport, transcriptomic analyses of EVs released by wild type and CD47-deficient Jurkat T cells revealed a global CD47-dependent enrichment of m7G-modified microRNAs and mRNAs in EVs released by CD47-deficient cells. Correspondingly, decreasing CD47 expression in wild type cells or treatment with thrombospondin-1 enhanced levels of specific m7G-modified RNAs released in EVs, and re-expressing CD47 in CD47-deficient T cells decreased their levels. Therefore, CD47 signaling limits the trafficking of m7G-modified RNAs to EVs through physical interactions with the exportin-1/Ran transport complex.

CD63+ and MHC Class I+ Subsets of Extracellular Vesicles Produced by Wild-Type and CD47-Deficient Jurkat T Cells Have Divergent Functional Effects on Endothelial Cell Gene Expression.

T cells and endothelial cells engage in bidirectional communication that regulates angiogenesis and T cell transmigration. Extracellular vesicles (EVs) mediate intercellular communication by the transfer of bioactive molecules including RNAs. EVs produced by a given cell type are heterogeneous in their RNA content, but it is unclear how specific EV surface markers relate to their functional effects on target cells. Our previous work established that Jurkat T cell EVs bearing CD63, MHC-I, or CD47 surface markers contain distinct noncoding RNA populations. The present study reveals that CD63+ and MHC-I+ EVs from CD47-deficient Jurkat T cells are enriched in small non-coding RNAs relative to EVs from wild-type Jurkat T cells. CD47-deficient Jurkat T cells secrete more CD63+ and MHC-I+ EVs, but MHC-I+ EVs are selectively taken up more by human umbilical vein endothelial cells. Transcriptomics analysis of endothelial cells treated with CD63+ or MHC-I+ EVs showed surface marker- and CD47-dependent changes in gene expression in the target cells. Gene set enrichment analysis identified CD47-dependent, and surface marker-dependent effects of T cell EVs on VEGF and inflammatory signaling, cell cycle, and lipid and cholesterol metabolism. Thus, subsets of T cell EVs differentially regulate endothelial cell metabolism and inflammatory and angiogenic responses.

The Warburg effect is necessary to promote glycosylation in the blastema during zebrafish tail regeneration.

Throughout their lifetime, fish maintain a high capacity for regenerating complex tissues after injury. We utilized a larval tail regeneration assay in the zebrafish Danio rerio, which serves as an ideal model of appendage regeneration due to its easy manipulation, relatively simple mixture of cell types, and superior imaging properties. Regeneration of the embryonic zebrafish tail requires development of a blastema, a mass of dedifferentiated cells capable of replacing lost tissue, a crucial step in all known examples of appendage regeneration. Using this model, we show that tail amputation triggers an obligate metabolic shift to promote glucose metabolism during early regeneration similar to the Warburg effect observed in tumor forming cells. Inhibition of glucose metabolism did not affect the overall health of the embryo but completely blocked the tail from regenerating after amputation due to the failure to form a functional blastema. We performed a time series of single-cell RNA sequencing on regenerating tails with and without inhibition of glucose metabolism. We demonstrated that metabolic reprogramming is required for sustained TGF-ß signaling and blocking glucose metabolism largely mimicked inhibition of TGF-ß receptors, both resulting in an aberrant blastema. Finally, we showed using genetic ablation of three possible metabolic pathways for glucose, that metabolic reprogramming is required to provide glucose specifically to the hexosamine biosynthetic pathway while neither glycolysis nor the pentose phosphate pathway were necessary for regeneration.

B-cells are abnormal in psychosocial stress and regulate meningeal myeloid cell activation.

There is increasing interest in how immune cells, including those within the meninges at the blood-brain interface, influence brain function and mood disorders, but little data on humoral immunity in this context. Here, we show that in mice exposed to psychosocial stress, there is increased splenic B cell activation and secretion of the immunoregulatory cytokine interleukin (IL)-10. Meningeal B cells were prevalent in homeostasis but substantially decreased following stress, whereas Ly6Chi monocytes increased, and meningeal myeloid cells showed augmented expression of activation markers. Single-cell RNA sequencing of meningeal B cells demonstrated the induction of innate immune transcriptional programmes following stress, including genes encoding antimicrobial peptides that are known to alter myeloid cell activation. Cd19-/- mice, that have reduced B cells, showed baseline meningeal myeloid cell activation and decreased exploratory behaviour. Together, these data suggest that B cells may influence behaviour by regulating meningeal myeloid cell activation.

Compound heterozygous KCTD7 variants in progressive myoclonus epilepsy.

KCTD7 is a member of the potassium channel tetramerization domain-containing protein family and has been associated with progressive myoclonic epilepsy (PME), characterized by myoclonus, epilepsy, and neurological deterioration. Here we report four affected individuals from two unrelated families in which we identified KCTD7 compound heterozygous single nucleotide variants through exome sequencing. RNAseq was used to detect a non-annotated splicing junction created by a synonymous variant in the second family. Whole-cell patch-clamp analysis of neuroblastoma cells overexpressing the patients' variant alleles demonstrated aberrant potassium regulation. While all four patients experienced many of the common clinical features of PME, they also showed variable phenotypes not previously reported, including dysautonomia, brain pathology findings including a significantly reduced thalamus, and the lack of myoclonic seizures. To gain further insight into the pathogenesis of the disorder, zinc finger nucleases were used to generate kctd7 knockout zebrafish. Kctd7 homozygous mutants showed global dysregulation of gene expression and increased transcription of c-fos, which has previously been correlated with seizure activity in animal models. Together these findings expand the known phenotypic spectrum of KCTD7-associated PME, report a new animal model for future studies, and contribute valuable insights into the disease.

Immunopathogenic CSF TCR repertoire signatures in virus-associated neurologic disease.

In this study, we examined and characterized disease-specific TCR signatures in cerebrospinal fluid (CSF) of patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). TCR ß libraries using unique molecular identifier-based methodologies were sequenced in paired peripheral blood mononuclear cells (PBMCs) and CSF cells from HAM/TSP patients and normal healthy donors (NDs). The sequence analysis demonstrated that TCR ß repertoires in CSF of HAM/TSP patients were highly expanded and contained both TCR clonotypes shared with PBMCs and uniquely enriched within the CSF. In addition, we analyzed TCR ß repertoires of highly expanded and potentially immunopathologic HTLV-1 Tax11-19-specific CD8+ T cells from PBMCs of HLA-A*0201+ HAM/TSP and identified a conserved motif (PGLAG) in the CDR3 region. Importantly, TCR ß clonotypes of expanded clones in HTLV-1 Tax11-19-specific CD8+ T cells were also expanded and enriched in the CSF of the same patient. These results suggest that exploring TCR repertoires of CSF and antigen-specific T cells may provide a TCR repertoire signature in virus-associated neurologic disorders.

Cell-penetrating, antioxidant SELENOT mimetic protects dopaminergic neurons and ameliorates motor dysfunction in Parkinson's disease animal models.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor dysfunction for which there is an unmet need for better treatment options. Although oxidative stress is a common feature of neurodegenerative diseases, notably PD, there is currently no efficient therapeutic strategy able to tackle this multi-target pathophysiological process. Based on our previous observations of the potent antioxidant and neuroprotective activity of SELENOT, a vital thioredoxin-like selenoprotein, we designed the small peptide PSELT from its redox active site to evaluate its antioxidant properties in vivo, and its potential polyfunctional activity in PD models. PSELT protects neurotoxin-treated dopaminergic neurons against oxidative stress and cell death, and their fibers against neurotoxic degeneration. PSELT is cell-permeable and acts in multiple subcellular compartments of dopaminergic neurons that are vulnerable to oxidative stress. In rodent models of PD, this protective activity prevented neurodegeneration, restored phosphorylated tyrosine hydroxylase levels, and led to improved motor skills. Transcriptomic analysis revealed that gene regulation by PSELT after MPP+ treatment negatively correlates with that occurring in PD, and positively correlates with that occurring after resveratrol treatment. Mechanistically, a major impact of PSELT is via nuclear stimulation of the transcription factor EZH2, leading to neuroprotection. Overall, these findings demonstrate the potential of PSELT as a therapeutic candidate for treatment of PD, targeting oxidative stress at multiple intracellular levels.

Extracellular vesicles released from the filarial parasite Brugia malayi downregulate the host mTOR pathway.

We have previously shown that the microfilarial (mf) stage of Brugia malayi can inhibit the mammalian target of rapamycin (mTOR; a conserved serine/threonine kinase critical for immune regulation and cellular growth) in human dendritic cells (DC) and we have proposed that this mTOR inhibition is associated with the DC dysfunction seen in filarial infections. Extracellular vesicles (EVs) contain many proteins and nucleic acids including microRNAs (miRNAs) that might affect a variety of intracellular pathways. Thus, EVs secreted from mf may elucidate the mechanism by which the parasite is able to modulate the host immune response during infection. EVs, purified from mf of Brugia malayi and confirmed by size through nanoparticle tracking analysis, were assessed by miRNA microarrays (accession number GSE157226) and shown to be enriched (>2-fold, p-value<0.05, FDR = 0.05) for miR100, miR71, miR34, and miR7. The microarray analysis compared mf-derived EVs and mf supernatant. After confirming their presence in EVs using qPCR for these miRNA targets, web-based target predictions (using MIRPathv3, TarBAse and MicroT-CD) predicted that miR100 targeted mTOR and its downstream regulatory protein 4E-BP1. Our previous data with live parasites demonstrated that mf downregulate the phosphorylation of mTOR and its downstream effectors. Additionally, our proteomic analysis of the mf-derived EVs revealed the presence of proteins commonly found in these vesicles (data are available via ProteomeXchange with identifier PXD021844). We confirmed internalization of mf-derived EVs by human DCs and monocytes using confocal microscopy and flow cytometry, and further demonstrated through flow cytometry, that mf-derived EVs downregulate the phosphorylation of mTOR in human monocytes (THP-1 cells) to the same degree that rapamycin (a known mTOR inhibitor) does. Our data collectively suggest that mf release EVs that interact with host cells, such as DC, to modulate host responses.

Candesartan could ameliorate the COVID-19 cytokine storm.

BACKGROUND: Angiotensin receptor blockers (ARBs) reducing inflammation and protecting lung and brain function, could be of therapeutic efficacy in COVID-19 patients. METHODS: Using GSEA, we compared our previous transcriptome analysis of neurons injured by glutamate and treated with the ARB Candesartan (GSE67036) with transcriptional signatures from SARS-CoV-2 infected primary human bronchial epithelial cells (NHBE) and lung postmortem (GSE147507), PBMC and BALF samples (CRA002390) from COVID-19 patients. RESULTS: Hundreds of genes upregulated in SARS-CoV-2/COVID-19 transcriptomes were similarly upregulated by glutamate and normalized by Candesartan. Gene Ontology analysis revealed expression profiles with greatest significance and enrichment, including proinflammatory cytokine and chemokine activity, the NF-kappa B complex, alterations in innate and adaptive immunity, with many genes participating in the COVID-19 cytokine storm. CONCLUSIONS: There are similar injury mechanisms in SARS-CoV-2 infection and neuronal injury, equally reduced by ARB treatment. This supports the hypothesis of a therapeutic role for ARBs, ameliorating the COVID-19 cytokine storm.

Analysis of cerebrovascular dysfunction caused by chronic social defeat in mice.

Psychological stress and affective disorders are clinically associated with hypertension and vascular disease, but the biological links between the conditions have not been fully explored. To examine this relationship, we used chronic social defeat (CSD) stress, which produces anxiety-like and depressive-like behavioral declines in susceptible mice. In such mice, CSD also produces cerebrovascular microbleeds in scattered locations. Here, we showed further evidence of vascular pathology and blood-brain barrier breakdown by visualizing plasma immunoglobulins and erythrocytes within the parenchyma and perivascular spaces of CSD brains. To further characterize the impact of stress on the cerebrovasculature, brain endothelial cells (bECs) were isolated, and global gene expression profiles were generated. Bioinformatic analysis of CSD-induced transcriptional changes in bECs showed enrichment in pathways that delineate the vascular response to injury. These pathways followed a temporal sequence of inflammation, oxidative stress, growth factor signaling, and wound healing (i.e., platelet aggregation, hemostasis, fibrinogen deposition, and angiogenesis). Immunohistochemical staining for markers of fibrinogen deposition and angiogenesis confirmed the existence of the markers at the sites of vascular disruptions. Recovery after CSD cessation was marked by recruitment of leukocytes perhaps participating in vascular repair. The data suggest that co-morbidity of affective disorders and vascular diseases may be attributed in part to a common link in altered endothelial cell function.

The vitamin B12 processing enzyme, mmachc, is essential for zebrafish survival, growth and retinal morphology.

Cobalamin C (cblC) deficiency, the most common inborn error of intracellular cobalamin metabolism, is caused by mutations in MMACHC, a gene responsible for the processing and intracellular trafficking of vitamin B12. This recessive disorder is characterized by a failure to metabolize cobalamin into adenosyl- and methylcobalamin, which results in the biochemical perturbations of methylmalonic acidemia, hyperhomocysteinemia and hypomethioninemia caused by the impaired activity of the downstream enzymes, methylmalonyl-CoA mutase and methionine synthase. Cobalamin C deficiency can be accompanied by a wide spectrum of clinical manifestations, including progressive blindness, and, in mice, manifests with very early embryonic lethality. Because zebrafish harbor a full complement of cobalamin metabolic enzymes, we used genome editing to study the loss of mmachc function and to develop the first viable animal model of cblC deficiency. mmachc mutants survived the embryonic period but perished in early juvenile life. The mutants displayed the metabolic and clinical features of cblC deficiency including methylmalonic acidemia, severe growth retardation and lethality. Morphologic and metabolic parameters improved when the mutants were raised in water supplemented with small molecules used to treat patients, including hydroxocobalamin, methylcobalamin, methionine and betaine. Furthermore, mmachc mutants bred to express rod and/or cone fluorescent reporters, manifested a retinopathy and thin optic nerves (ON). Expression analysis using whole eye mRNA revealed the dysregulation of genes involved in phototransduction and cholesterol metabolism. Zebrafish with mmachc deficiency recapitulate the several of the phenotypic and biochemical features of the human disorder, including ocular pathology, and show a response to established treatments.