Translation in astrocyte distal processes sets molecular heterogeneity at the gliovascular interface

Cell Discovery

2017 Mar 28

Boulay AC, Saubaméa B, Adam N, Chasseigneaux S, Mazaré N, Gilbert A, Bahin M, Bastianelli L, Blugeon C, Perrin S, Pouch J, Ducos B, Le Crom S, Genovesio A, Chrétien F, Declèves X, Laplanche JL, Cohen-Salmon M.
PMID: 28377822 | DOI: 10.1038/celldisc.2017.5

Astrocytes send out long processes that are terminated by endfeet at the vascular surface and regulate vascular functions as well as homeostasis at the vascular interface. To date, the astroglial mechanisms underlying these functions have been poorly addressed. Here we demonstrate that a subset of messenger RNAs is distributed in astrocyte endfeet. We identified, among this transcriptome, a pool of messenger RNAs bound to ribosomes, the endfeetome, that primarily encodes for secreted and membrane proteins. We detected nascent protein synthesis in astrocyte endfeet. Finally, we determined the presence of smooth and rough endoplasmic reticulum and the Golgi apparatus in astrocyte perivascular processes and endfeet, suggesting for local maturation of membrane and secreted proteins. These results demonstrate for the first time that protein synthesis occurs in astrocyte perivascular distal processes that may sustain their structural and functional polarization at the vascular interface.

Reactive astrocytes acquire neuroprotective as well as deleterious signatures in response to Tau and Aß pathology

Nature communications

2022 Jan 10

Jiwaji, Z;Tiwari, SS;Avilés-Reyes, RX;Hooley, M;Hampton, D;Torvell, M;Johnson, DA;McQueen, J;Baxter, P;Sabari-Sankar, K;Qiu, J;He, X;Fowler, J;Febery, J;Gregory, J;Rose, J;Tulloch, J;Loan, J;Story, D;McDade, K;Smith, AM;Greer, P;Ball, M;Kind, PC;Matthews, PM;Smith, C;Dando, O;Spires-Jones, TL;Johnson, JA;Chandran, S;Hardingham, GE;
PMID: 35013236 | DOI: 10.1038/s41467-021-27702-w

Alzheimer's disease (AD) alters astrocytes, but the effect of Aß and Tau pathology is poorly understood. TRAP-seq translatome analysis of astrocytes in APP/PS1 ß-amyloidopathy and MAPTP301S tauopathy mice revealed that only Aß influenced expression of AD risk genes, but both pathologies precociously induced age-dependent changes, and had distinct but overlapping signatures found in human post-mortem AD astrocytes. Both Aß and Tau pathology induced an astrocyte signature involving repression of bioenergetic and translation machinery, and induction of inflammation pathways plus protein degradation/proteostasis genes, the latter enriched in targets of inflammatory mediator Spi1 and stress-activated cytoprotective Nrf2. Astrocyte-specific Nrf2 expression induced a reactive phenotype which recapitulated elements of this proteostasis signature, reduced Aß deposition and phospho-tau accumulation in their respective models, and rescued brain-wide transcriptional deregulation, cellular pathology, neurodegeneration and behavioural/cognitive deficits. Thus, Aß and Tau induce overlapping astrocyte profiles associated with both deleterious and adaptive-protective signals, the latter of which can slow patho-progression.

Parabrachial Interleukin-6 Reduces Body Weight and Food Intake and Increases Thermogenesis to Regulate Energy Metabolism.

Cell Rep.

2019 Mar 12

Mishra D, Richard JE, Maric I, Porteiro B, Häring M, Kooijman S, Musovic S, Eerola K, López-Ferreras L, Peris E, Grycel K, Shevchouk OT, Micallef P, Olofsson CS, Wernstedt Asterholm I, Grill HJ, Nogueiras R, Skibicka KP.
PMID: 30865890 | DOI: 10.1016/j.celrep.2019.02.044

Chronic low-grade inflammation and increased serum levels of the cytokine IL-6 accompany obesity. For brain-produced IL-6, the mechanisms by which it controls energy balance and its role in obesity remain unclear. Here, we show that brain-produced IL-6 is decreased in obese mice and rats in a neuroanatomically and sex-specific manner. Reduced IL-6 mRNA localized to lateral parabrachial nucleus (lPBN) astrocytes, microglia, and neurons, including paraventricular hypothalamus-innervating lPBN neurons. IL-6 microinjection into lPBN reduced food intake and increased brown adipose tissue (BAT) thermogenesis in male lean and obese rats by increasing thyroid and sympathetic outflow to BAT. Parabrachial IL-6 interacted with leptin to reduce feeding. siRNA-mediated reduction of lPBN IL-6 leads to increased weight gain and adiposity, reduced BAT thermogenesis, and increased food intake. Ambient cold exposure partly normalizes the obesity-induced suppression of lPBN IL-6. These results indicate that lPBN-produced IL-6 regulates feeding and metabolism and pinpoints (patho)physiological contexts interacting with lPBN IL-6.

Inhibition of the cGAS-STING pathway ameliorates the premature senescence hallmarks of Ataxia-Telangiectasia brain organoids

Aging cell

2021 Sep 01

Aguado, J;Chaggar, HK;Gómez-Inclán, C;Shaker, MR;Leeson, HC;Mackay-Sim, A;Wolvetang, EJ;
PMID: 34459078 | DOI: 10.1111/acel.13468

Ataxia-telangiectasia (A-T) is a genetic disorder caused by the lack of functional ATM kinase. A-T is characterized by chronic inflammation, neurodegeneration and premature ageing features that are associated with increased genome instability, nuclear shape alterations, micronuclei accumulation, neuronal defects and premature entry into cellular senescence. The causal relationship between the detrimental inflammatory signature and the neurological deficiencies of A-T remains elusive. Here, we utilize human pluripotent stem cell-derived cortical brain organoids to study A-T neuropathology. Mechanistically, we show that the cGAS-STING pathway is required for the recognition of micronuclei and induction of a senescence-associated secretory phenotype (SASP) in A-T olfactory neurosphere-derived cells and brain organoids. We further demonstrate that cGAS and STING inhibition effectively suppresses self-DNA-triggered SASP expression in A-T brain organoids, inhibits astrocyte senescence and neurodegeneration, and ameliorates A-T brain organoid neuropathology. Our study thus reveals that increased cGAS and STING activity is an important contributor to chronic inflammation and premature senescence in the central nervous system of A-T and constitutes a novel therapeutic target for treating neuropathology in A-T patients.

Divergent transcriptional regulation of astrocyte reactivity across disorders

Nature

2022 May 25

Burda, JE;O'Shea, TM;Ao, Y;Suresh, KB;Wang, S;Bernstein, AM;Chandra, A;Deverasetty, S;Kawaguchi, R;Kim, JH;McCallum, S;Rogers, A;Wahane, S;Sofroniew, MV;
PMID: 35614216 | DOI: 10.1038/s41586-022-04739-5

Astrocytes respond to injury and disease in the central nervous system with reactive changes that influence the outcome of the disorder1-4. These changes include differentially expressed genes (DEGs) whose contextual diversity and regulation are poorly understood. Here we combined biological and informatic analyses, including RNA sequencing, protein detection, assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) and conditional gene deletion, to predict transcriptional regulators that differentially control more than 12,000 DEGs that are potentially associated with astrocyte reactivity across diverse central nervous system disorders in mice and humans. DEGs associated with astrocyte reactivity exhibited pronounced heterogeneity across disorders. Transcriptional regulators also exhibited disorder-specific differences, but a core group of 61 transcriptional regulators was identified as common across multiple disorders in both species. We show experimentally that DEG diversity is determined by combinatorial, context-specific interactions between transcriptional regulators. Notably, the same reactivity transcriptional regulators can regulate markedly different DEG cohorts in different disorders; changes in the access of transcriptional regulators to DNA-binding motifs differ markedly across disorders; and DEG changes can crucially require multiple reactivity transcriptional regulators. We show that, by modulating reactivity, transcriptional regulators can substantially alter disorder outcome, implicating them as therapeutic targets. We provide searchable resources of disorder-related reactive astrocyte DEGs and their predicted transcriptional regulators. Our findings show that transcriptional changes associated with astrocyte reactivity are highly heterogeneous and are customized from vast numbers of potential DEGs through context-specific combinatorial transcriptional-regulator interactions.

Boldine modulates glial transcription and functional recovery in a murine model of contusion spinal cord injury

bioRxiv : the preprint server for biology

2023 Feb 15

Toro, CA;Johnson, K;Hansen, J;Siddiq, MM;Vásquez, W;Zhao, W;Graham, ZA;Sáez, JC;Iyengar, R;Cardozo, CP;
PMID: 36824813 | DOI: 10.1101/2023.02.15.528337

Membrane channels such as connexins (Cx), pannexins (Panx) and P2X 7 receptors (P2X 7 R) are permeable to calcium ions and other small molecules such as ATP and glutamate. Release of ATP and glutamate through these channels is a key mechanism driving tissue response to traumas such as spinal cord injury (SCI). Boldine, an alkaloid isolated from the Chilean boldo tree, blocks both Cx hemichannels (HC) and Panx. To test if boldine could improve function after SCI, boldine or vehicle was administered to treat mice with a moderate severity contusion-induced SCI. Boldine led to greater spared white matter and increased locomotor function as determined by the Basso Mouse Scale and horizontal ladder rung walk tests. Boldine treatment reduced immunostaining for markers of activated microglia (Iba1) and astrocytic (GFAP) markers while increasing that for axon growth and neuroplasticity (GAP-43). Cell culture studies demonstrated that boldine blocked glial HC, specifically Cx26 and Cx30, in cultured astrocytes and blocked calcium entry through activated P2X 7 R. RT-qPCR studies showed that boldine treatment reduced expression of the chemokine Ccl2, cytokine IL-6 and microglial gene CD68, while increasing expression of the neurotransmission genes Snap25 and Grin2b, and Gap-43. Bulk RNA sequencing (of the spinal cord revealed that boldine modulated a large number of genes involved in neurotransmission in in spinal cord tissue just below the lesion epicenter at 14 days after SCI. Numbers of genes regulated by boldine was much lower at 28 days after injury. These results indicate that boldine treatment ameliorates injury and spares tissue to increase locomotor function.

Neurovascular injury with complement activation and inflammation in COVID-19

Brain : a journal of neurology

2022 Jul 29

Lee, MH;Perl, DP;Steiner, J;Pasternack, N;Li, W;Maric, D;Safavi, F;Horkayne-Szakaly, I;Jones, R;Stram, MN;Moncur, JT;Hefti, M;Folkerth, RD;Nath, A;
PMID: 35788639 | DOI: 10.1093/brain/awac151

The underlying mechanisms by which severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) leads to acute and long-term neurological manifestations remains obscure. We aimed to characterize the neuropathological changes in patients with coronavirus disease 2019 and determine the underlying pathophysiological mechanisms. In this autopsy study of the brain, we characterized the vascular pathology, the neuroinflammatory changes and cellular and humoral immune responses by immunohistochemistry. All patients died during the first wave of the pandemic from March to July 2020. All patients were adults who died after a short duration of the infection, some had died suddenly with minimal respiratory involvement. Infection with SARS-CoV-2 was confirmed on ante-mortem or post-mortem testing. Descriptive analysis of the pathological changes and quantitative analyses of the infiltrates and vascular changes were performed. All patients had multifocal vascular damage as determined by leakage of serum proteins into the brain parenchyma. This was accompanied by widespread endothelial cell activation. Platelet aggregates and microthrombi were found adherent to the endothelial cells along vascular lumina. Immune complexes with activation of the classical complement pathway were found on the endothelial cells and platelets. Perivascular infiltrates consisted of predominantly macrophages and some CD8+ T cells. Only rare CD4+ T cells and CD20+ B cells were present. Astrogliosis was also prominent in the perivascular regions. Microglial nodules were predominant in the hindbrain, which were associated with focal neuronal loss and neuronophagia. Antibody-mediated cytotoxicity directed against the endothelial cells is the most likely initiating event that leads to vascular leakage, platelet aggregation, neuroinflammation and neuronal injury. Therapeutic modalities directed against immune complexes should be considered.

Non-Productive Infection of Glial Cells with SARS-CoV-2 in Hamster Organotypic Cerebellar Slice Cultures

Viruses

2022 Jun 03

Lamoureux, L;Sajesh, B;Slota, JA;Medina, SJ;Mayor, M;Frost, KL;Warner, B;Manguiat, K;Wood, H;Kobasa, D;Booth, SA;
PMID: 35746689 | DOI: 10.3390/v14061218

The numerous neurological syndromes associated with COVID-19 implicate an effect of viral pathogenesis on neuronal function, yet reports of direct SARS-CoV-2 infection in the brain are conflicting. We used a well-established organotypic brain slice culture to determine the permissivity of hamster brain tissues to SARS-CoV-2 infection. We found levels of live virus waned after inoculation and observed no evidence of cell-to-cell spread, indicating that SARS-CoV-2 infection was non-productive. Nonetheless, we identified a small number of infected cells with glial phenotypes; however, no evidence of viral infection or replication was observed in neurons. Our data corroborate several clinical studies that have assessed patients with COVID-19 and their association with neurological involvement.

Sodium Channel SCN3A (NaV1.3) Regulation of Human Cerebral Cortical Folding and Oral Motor Development

Neuron.

2018 Aug 23

Smith RS, Kenny CJ, Ganesh V, Jang A, Borges-Monroy R, Partlow JN, Hill RS, Shin T, Chen AY, Doan RN, Anttonen AK, Ignatius J, Medne L, Bönnemann CG, Hecht JL, Salonen O, Barkovich AJ, Poduri A, Wilke M, de Wit MCY, Mancini GMS, Sztriha L, Im K, Amrom D,
PMID: 30146301 | DOI: 10.1016/j.neuron.2018.07.052

Channelopathies are disorders caused by abnormal ion channel function in differentiated excitable tissues. We discovered a unique neurodevelopmental channelopathy resulting from pathogenic variants in SCN3A, a gene encoding the voltage-gated sodium channelNaV1.3. Pathogenic NaV1.3 channels showed altered biophysical properties including increased persistent current. Remarkably, affected individuals showed disrupted folding (polymicrogyria) of the perisylvian cortex of the brain but did not typically exhibit epilepsy; they presented with prominent speech and oral motor dysfunction, implicating SCN3A in prenatal development of human cortical language areas. The development of this disorder parallels SCN3A expression, which we observed to be highest early in fetal cortical development in progenitor cells of the outer subventricular zone and cortical plate neurons and decreased postnatally, when SCN1A (NaV1.1) expression increased. Disrupted cerebral cortical folding and neuronal migration were recapitulated in ferrets expressing the mutant channel, underscoring the unexpected role of SCN3A in progenitor cells and migrating neurons.

A genetic tool for the longitudinal study of a subset of post-inflammatory reactive astrocytes

Cell reports methods

2022 Aug 22

Agnew-Svoboda, W;Ubina, T;Figueroa, Z;Wong, YC;Vizcarra, EA;Roebini, B;Wilson, EH;Fiacco, TA;Riccomagno, MM;
PMID: 36046623 | DOI: 10.1016/j.crmeth.2022.100276

Astrocytes are vital support cells that ensure proper brain function. In brain disease, astrocytes reprogram into a reactive state that alters many of their cellular roles. A long-standing question in the field is whether downregulation of reactive astrocyte (RA) markers during resolution of inflammation is because these astrocytes revert back to a non-reactive state or die and are replaced. This has proven difficult to answer mainly because existing genetic tools cannot distinguish between healthy versus RAs. Here we describe the generation of an inducible genetic tool that can be used to specifically target and label a subset of RAs. Longitudinal analysis of an acute inflammation model using this tool revealed that the previously observed downregulation of RA markers after inflammation is likely due to changes in gene expression and not because of cell death. Our findings suggest that cellular changes associated with astrogliosis after acute inflammation are largely reversible.

Simultaneous expansion microscopy imaging of proteins and mRNAs via dual-ExM

Scientific reports

2022 Mar 01

Cho, I;Chang, JB;
PMID: 35233025 | DOI: 10.1038/s41598-022-06903-3

Simultaneous nanoscale imaging of mRNAs and proteins of the same specimen can provide better information on the translational regulation, molecular trafficking, and molecular interaction of both normal and diseased biological systems. Expansion microscopy (ExM) is an attractive option to achieve such imaging; however, simultaneous ExM imaging of proteins and mRNAs has not been demonstrated. Here, a technique for simultaneous ExM imaging of proteins and mRNAs in cultured cells and tissue slices, which we termed dual-expansion microscopy (dual-ExM), is demonstrated. First, we verified a protocol for the simultaneous labeling of proteins and mRNAs. Second, we combined the simultaneous labeling protocol with ExM to enable the simultaneous ExM imaging of proteins and mRNAs in cultured cells and mouse brain slices and quantitatively study the degree of signal retention after expansion. After expansion, both proteins and mRNAs can be visualized with a resolution beyond the diffraction limit of light in three dimensions. Dual-ExM is a versatile tool to study complex biological systems, such as the brain or tumor microenvironments, at a nanoscale resolution.

The complement system drives local inflammatory tissue priming by metabolic reprogramming of synovial fibroblasts

Immunity

2021 Mar 19

Friščić, J;Böttcher, M;Reinwald, C;Bruns, H;Wirth, B;Popp, SJ;Walker, KI;Ackermann, JA;Chen, X;Turner, J;Zhu, H;Seyler, L;Euler, M;Kirchner, P;Krüger, R;Ekici, AB;Major, T;Aust, O;Weidner, D;Fischer, A;Andes, FT;Stanojevic, Z;Trajkovic, V;Herrmann, M;Korb-Pap, A;Wank, I;Hess, A;Winter, J;Wixler, V;Distler, J;Steiner, G;Kiener, HP;Frey, B;Kling, L;Raza, K;Frey, S;Kleyer, A;Bäuerle, T;Hughes, TR;Grüneboom, A;Steffen, U;Krönke, G;Croft, AP;Filer, A;Köhl, J;Klein, K;Buckley, CD;Schett, G;Mougiakakos, D;Hoffmann, MH;
PMID: 33761330 | DOI: 10.1016/j.immuni.2021.03.003

Arthritis typically involves recurrence and progressive worsening at specific predilection sites, but the checkpoints between remission and persistence remain unknown. Here, we defined the molecular and cellular mechanisms of this inflammation-mediated tissue priming. Re-exposure to inflammatory stimuli caused aggravated arthritis in rodent models. Tissue priming developed locally and independently of adaptive immunity. Repeatedly stimulated primed synovial fibroblasts (SFs) exhibited enhanced metabolic activity inducing functional changes with intensified migration, invasiveness and osteoclastogenesis. Meanwhile, human SF from patients with established arthritis displayed a similar primed phenotype. Transcriptomic and epigenomic analyses as well as genetic and pharmacological targeting demonstrated that inflammatory tissue priming relies on intracellular complement C3- and C3a receptor-activation and downstream mammalian target of rapamycin- and hypoxia-inducible factor 1α-mediated metabolic SF invigoration that prevents activation-induced senescence, enhances NLRP3 inflammasome activity, and in consequence sensitizes tissue for inflammation. Our study suggests possibilities for therapeutic intervention abrogating tissue priming without immunosuppression.

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	Description
sense Example: Hs-LAG3-sense	Standard probes for RNA detection are in antisense. Sense probe is reverse complent to the corresponding antisense probe.
Intron# Example: Mm-Htt-intron2	Probe targets the indicated intron in the target gene, commonly used for pre-mRNA detection
Pool/Pan Example: Hs-CD3-pool (Hs-CD3D, Hs-CD3E, Hs-CD3G)	A mixture of multiple probe sets targeting multiple genes or transcripts
No-XSp Example: Hs-PDGFB-No-XMm	Does not cross detect with the species (Sp)
XSp Example: Rn-Pde9a-XMm	designed to cross detect with the species (Sp)
O# Example: Mm-Islr-O1	Alternative design targeting different regions of the same transcript or isoforms
CDS Example: Hs-SLC31A-CDS	Probe targets the protein-coding sequence only
EnEm	Probe targets exons n and m
En-Em	Probe targets region from exon n to exon m
Retired Nomenclature
tvn Example: Hs-LEPR-tv1	Designed to target transcript variant n
ORF Example: Hs-ACVRL1-ORF	Probe targets open reading frame
UTR Example: Hs-HTT-UTR-C3	Probe targets the untranslated region (non-protein-coding region) only
5UTR Example: Hs-GNRHR-5UTR	Probe targets the 5' untranslated region only
3UTR Example: Rn-Npy1r-3UTR	Probe targets the 3' untranslated region only
Pan Example: Pool	A mixture of multiple probe sets targeting multiple genes or transcripts

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