Choi, BR;Johnson, KR;Maric, D;McGavern, DB;
PMID: 37248420 | DOI: 10.1038/s41590-023-01521-1
Cerebrovascular injury (CVI) is a common pathology caused by infections, injury, stroke, neurodegeneration and autoimmune disease. Rapid resolution of a CVI requires a coordinated innate immune response. In the present study, we sought mechanistic insights into how central nervous system-infiltrating monocytes program resident microglia to mediate angiogenesis and cerebrovascular repair after an intracerebral hemorrhage. In the penumbrae of human stroke brain lesions, we identified a subpopulation of microglia that express vascular endothelial growth factor A. These cells, termed 'repair-associated microglia' (RAMs), were also observed in a rodent model of CVI and coexpressed interleukin (IL)-6Ra. Cerebrovascular repair did not occur in IL-6 knockouts or in mice lacking microglial IL-6Ra expression and single-cell transcriptomic analyses revealed faulty RAM programming in the absence of IL-6 signaling. Infiltrating CCR2+ monocytes were the primary source of IL-6 after a CVI and were required to endow microglia with proliferative and proangiogenic properties. Faulty RAM programming in the absence of IL-6 or inflammatory monocytes resulted in poor cerebrovascular repair, neuronal destruction and sustained neurological deficits that were all restored via exogenous IL-6 administration. These data provide a molecular and cellular basis for how monocytes instruct microglia to repair damaged brain vasculature and promote functional recovery after injury.
Single-cell and single-nucleus RNA-seq uncovers shared and distinct axes of variation in dorsal LGN neurons in mice, non-human primates, and humans
Bakken, TE;van Velthoven, CT;Menon, V;Hodge, RD;Yao, Z;Nguyen, TN;Graybuck, LT;Horwitz, GD;Bertagnolli, D;Goldy, J;Yanny, AM;Garren, E;Parry, S;Casper, T;Shehata, SI;Barkan, ER;Szafer, A;Levi, BP;Dee, N;Smith, KA;Sunkin, SM;Bernard, A;Phillips, J;Hawrylycz, MJ;Koch, C;Murphy, GJ;Lein, E;Zeng, H;Tasic, B;
PMID: 34473054 | DOI: 10.7554/eLife.64875
Abundant evidence supports the presence of at least three distinct types of thalamocortical (TC) neurons in the primate dorsal lateral geniculate nucleus (dLGN) of the thalamus, the brain region that conveys visual information from the retina to the primary visual cortex (V1). Different types of TC neurons in mice, humans, and macaques have distinct morphologies, distinct connectivity patterns, and convey different aspects of visual information to the cortex. To investigate the molecular underpinnings of these cell types, and how these relate to differences in dLGN between human, macaque, and mice, we profiled gene expression in single nuclei and cells using RNA-sequencing. These efforts identified four distinct types of TC neurons in the primate dLGN: magnocellular (M) neurons, parvocellular (P) neurons, and two types of koniocellular (K) neurons. Despite extensively documented morphological and physiological differences between M and P neurons, we identified few genes with significant differential expression between transcriptomic cell types corresponding to these two neuronal populations. Likewise, the dominant feature of TC neurons of the adult mouse dLGN is high transcriptomic similarity, with an axis of heterogeneity that aligns with core vs. shell portions of mouse dLGN. Together, these data show that transcriptomic differences between principal cell types in the mature mammalian dLGN are subtle relative to the observed differences in morphology and cortical projection targets. Finally, alignment of transcriptome profiles across species highlights expanded diversity of GABAergic neurons in primate versus mouse dLGN and homologous types of TC neurons in primates that are distinct from TC neurons in mouse.
Urrutia AA, Afzal A, Nelson J, Davidoff O, Gross KW, Haase VH.
PMID: 27683416 | DOI: 10.1182/blood-2016-05-713545
A classic response to systemic hypoxia is the increased production of red blood cells due to hypoxia-inducible factor (HIF)-mediated induction of erythropoietin (EPO). EPO is a glycoprotein hormone that is essential for normal erythropoiesis and is predominantly synthesized by peritubular renal interstitial fibroblast-like cells, which express cellular markers characteristic of neuronal cells and pericytes. To investigate whether the ability to synthesize EPO is a general functional feature of pericytes, we used conditional gene targeting to examine the von Hippel-Lindau/prolyl-4-hydroxylase domain (PHD)/HIF axis in cell-expressing neural glial antigen 2, a known molecular marker of pericytes in multiple organs. We found that pericytes in the brain synthesized EPO in mice with genetic HIF activation and were capable of responding to systemic hypoxia with the induction of Epo. Using high-resolution multiplex in situ hybridization, we determined that brain pericytes represent an important cellular source of Epo in the hypoxic brain (up to 70% of all Epo-expressing cells). We furthermore determined that Epo transcription in brain pericytes was HIF-2 dependent and cocontrolled by PHD2 and PHD3, oxygen- and 2-oxoglutarate-dependent prolyl-4-hydroxylases that regulate HIF activity. In summary, our studies provide experimental evidence that pericytes in the brain have the ability to function as oxygen sensors and respond to hypoxia with EPO synthesis. Our findings furthermore suggest that the ability to synthesize EPO may represent a functional feature of pericytes in the brain and kidney.
Du L, Hu X, Yang W, Yasheng H, Liu S, Zhang W, Zhou Y, Cui W, Zhu J, Qiao Z, Maoying Q, Chu Y, Zhou H, Wang Y, Mi W.
PMID: 31087583 | DOI: 10.1002/glia.23639
Interleukin-33 (IL-33) and its receptor ST2 contribute to spinal glial activation and chronic pain. A recent study showed that peripheral IL-33 plays a pivotal role in the pathogenesis of chronic itch induced by poison ivy. However, how IL-33/ST2 signaling in the spinal cord potentially mediates chronic itch remains elusive. Here, we determined that St2-/- substantially reduced scratching behaviors in 2,4-dinitrofluorobenzene (DNFB)-induced allergic contact dermatitis (ACD) as well as acetone and diethylether followed by water-induced dry skin in mice. Intrathecal administration of the neutralizing anti-ST2 or anti-IL-33 antibody remarkably decreased the scratching response in DNFB-induced ACD mice. Expression of spinal IL-33 and ST2 significantly increased in ACD mice, as evidenced by increased mRNA and protein levels. Immunofluorescence and in situ hybridization demonstrated that increased expression of spinal IL-33 was predominant in oligodendrocytes and astrocytes, whereas ST2 was mainly expressed in astrocytes. Further studies showed that in ACD mice, the activation of astrocytes and increased phosphorylation of signal transducer and activator of transcription 3 (STAT3) were markedly attenuated by St2-/- . Intrathecal injection of Janus Kinase 2 Inhibitor AG490 significantly alleviated scratching behaviors in ACD mice. rIL-33 pretreatment exacerbated gastrin-releasing peptide (GRP)-evoked scratching behaviors. This increased gastrin-releasing peptide receptor (GRPR) expression was abolished by St2-/- . Tnf-α upregulation was suppressed by St2-/- . Our results indicate that the spinal IL-33/ST2 signaling pathway contributes to chronic itch via astrocytic JAK2-STAT3 cascade activation, promoting TNF-α release to regulate the GRP/GRPR signaling-related itch response. Thus, these findings provide a potential therapeutic option for treating chronic pruritus.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
Velazquez-Sanchez, C;Muresan, L;Marti-Prats, L;Belin, D;
PMID: 36635597 | DOI: 10.1038/s41386-022-01522-y
Some compulsive disorders have been considered to stem from the loss of control over coping strategies, such as displacement. However, the cellular mechanisms involved in the acquisition of coping behaviours and their subsequent compulsive manifestation in vulnerable individuals have not been elucidated. Considering the role of the locus coeruleus (LC) noradrenaline-dependent system in stress and related excessive behaviours, we hypothesised that neuroplastic changes in the LC may be associated with the acquisition of an adjunctive polydipsic water drinking, a prototypical displacement behaviour, and the ensuing development of compulsion in vulnerable individuals. Thus, male Sprague Dawley rats were characterised for their tendency, or not, to develop compulsive polydipsic drinking in a schedule-induced polydipsia (SIP) procedure before their fresh brains were harvested. A new quantification tool for RNAscope assays revealed that the development of compulsive adjunctive behaviour was associated with a low mRNA copy number of the plasticity marker Arc in the LC which appeared to be driven by specific adaptations in an ensemble of tyrosine hydroxylase (TH)+, zif268- neurons. This ensemble was specifically engaged by the expression of compulsive adjunctive behaviour, not by stress, because its functional recruitment was not observed in individuals that no longer had access to the water bottle before sacrifice, while it consistently correlated with the levels of polydipsic water drinking only when it had become compulsive. Together these findings suggest that downregulation of Arc mRNA levels in a population of a TH+/zif268- LC neurons represents a signature of the tendency to develop compulsive coping behaviours.
Ribeiro, M;Ayupe, AC;Beckedorff, FC;Levay, K;Rodriguez, S;Tsoulfas, P;Lee, JK;Nascimento-Dos-Santos, G;Park, KK;
PMID: 35738417 | DOI: 10.1016/j.expneurol.2022.114147
Following injury in the central nervous system, a population of astrocytes occupy the lesion site, form glial bridges and facilitate axon regeneration. These astrocytes originate primarily from resident astrocytes or NG2+ oligodendrocyte progenitor cells. However, the extent to which these cell types give rise to the lesion-filling astrocytes, and whether the astrocytes derived from different cell types contribute similarly to optic nerve regeneration remain unclear. Here we examine the distribution of astrocytes and NG2+ cells in an optic nerve crush model. We show that optic nerve astrocytes partially fill the injury site over time after a crush injury. Viral mediated expression of a growth-promoting factor, ciliary neurotrophic factor (CNTF), in retinal ganglion cells (RGCs) promotes axon regeneration without altering the lesion size or the degree of lesion-filling GFAP+ cells. Strikingly, using inducible NG2CreER driver mice, we found that CNTF overexpression in RGCs increases the occupancy of NG2+ cell-derived astrocytes in the optic nerve lesion. An EdU pulse-chase experiment shows that the increase in NG2 cell-derived astrocytes is not due to an increase in cell proliferation. Lastly, we performed RNA-sequencing on the injured optic nerve and reveal that CNTF overexpression in RGCs results in significant changes in the expression of distinct genes, including those that encode chemokines, growth factor receptors, and immune cell modulators. Even though CNTF-induced axon regeneration has long been recognized, this is the first evidence of this procedure affecting glial cell fate at the optic nerve crush site. We discuss possible implication of these results for axon regeneration.
The Journal of neuroscience : the official journal of the Society for Neuroscience
Fudge, JL;Kelly, EA;Hackett, TA;
PMID: 36280261 | DOI: 10.1523/JNEUROSCI.1453-22.2022
The central extended amygdala (CEA) and ventral pallidum (VP) are involved in diverse motivated behaviors based on rodent models. These structures are conserved, but expanded, in higher primates including human. Corticotropin releasing factor (CRF), a canonical 'stress molecule' associated with the CEA and VP circuitry across species, is dynamically regulated by stress and drugs of abuse and misuse. CRF's effects on circuits critically depend on its colocation with primary 'fast' transmitters, making this crucial for understanding circuit effects. We surveyed the distribution and colocalization of CRF-, VGluT2- (vesicular glutamate transporter 2) and VGAT- (vesicular GABA transporter) mRNA in specific subregions of the CEA and VP in young male monkeys. Although CRF-containing neurons were clustered in the lateral central bed nucleus (BSTLcn), the majority were broadly dispersed throughout other CEA subregions, and the VP. CRF/VGAT-only neurons were highest in the BSTLcn, lateral central amygdala nucleus (CeLcn), and medial central amygdala nucleus (CeM) (74%, 73%, and 85%, respectively). In contrast, lower percentages of CRF/VGAT only neurons populated the sublenticular extended amygdala (SLEAc), ventrolateral bed nucleus (BSTLP), and VP (53%, 54%, 17%, respectively), which had higher complements of CRF/VGAT/VGluT2 labeled neurons (33%, 29%, 67%, respectively). Thus, the majority of CRF-neurons at the 'poles' (BSTLcn and CeLcn/CeM) of the CEA are inhibitory, while the 'extended' BSTLP and SLEAc subregions, and neighboring VP, have a more complex profile with admixtures of 'multiplexed' excitatory CRF neurons. CRF's colocalization with its various fast transmitters is likely circuit-specific, and relevant for understanding CRF actions on specific target sites.SIGNIFICANCE STATEMENT:The central extended amygdala (CEA) and ventral pallidum (VP) regulate multiple motivated behaviors through differential downstream projections. The stress neuropeptide corticotropin releasing factor (CRF) is enriched in the CEA, and is thought to 'set the gain' through modulatory effects on co-expressed primary transmitters. Using protein and transcript assays in monkey, we found that CRF neurons are broadly and diffusely distributed in CEA and VP. CRF mRNA+ neurons colocalize with VGAT (GABA) and VGluT2 (glutamate) mRNAs in different proportions depending on subregion. CRF mRNA was also co-expressed in a subpopulation of VGAT/VGluT2 mRNA ('multiplexed') cells which were most prominent in the VP and 'pallidal'-like parts of the CEA. Heterogeneous CRF and fast transmitter co-expression across CEA/VP subregions implies circuit-specific effects.
Zhu H, Meissner LE, Byrnes C, Tuymetova G, Tifft CJ, Proia RL
PMID: 32179479 | DOI: 10.1016/j.isci.2020.100957
The SUSD4 (Sushi domain-containing protein 4) gene encodes a complement inhibitor that is frequently deleted in 1q41q42 microdeletion syndrome, a multisystem congenital disorder that includes neurodevelopmental abnormalities. To understand SUSD4's role in the mammalian nervous system, we analyzed Susd4 knockout (KO) mice. Susd4 KO mice exhibited significant defects in motor performance and significantly higher levels of anxiety-like behaviors. Susd4 KO brain had abnormal "hairy" basket cells surrounding Purkinje neurons within the cerebellum and significantly reduced dendritic spine density in hippocampal pyramidal neurons. Neurons and oligodendrocyte lineage cells of wild-type mice were found to express Susd4 mRNA. Protein expression of the complement component C1q was increased in the brains of Susd4 KO mice. Our data indicate that SUSD4 plays an important role in neuronal functions, possibly via the complement pathway, and that SUSD4 deletion may contribute to the nervous system abnormalities in patients with 1q41q42 deletions
Aloi, MS;Thompson, SJ;Quartapella, N;Noebels, JL;
PMID: 36417872 | DOI: 10.1016/j.celrep.2022.111696
Mutations in Kv1.1 (Kcna1) voltage-gated potassium channels in humans and mice generate network hyperexcitability, enhancing aberrant postnatal neurogenesis in the dentate subgranular zone, resulting in epilepsy and hippocampal hypertrophy. While Kcna1 loss stimulates proliferation of progenitor cell subpopulations, the identity of extrinsic molecular triggers linking network hyperexcitability to aberrant postnatal neurogenesis remains incomplete. System x-c (Sxc) is an inducible glutamate/cysteine antiporter that regulates extracellular glutamate. Here, we find that the functional unit of Sxc, xCT (Slc7a11), is upregulated in regions of Kcna1 knockout (KO) hippocampus, suggesting a contribution to both hyperplasia and epilepsy. However, Slc7a11 KO suppressed and rescued hippocampal enlargement without altering seizure severity in Kcna1-Slc7a11-KO mice. Microglial activation, but not astrocytosis, was also reduced. Our study identifies Sxc-mediated glutamate homeostasis as an essential non-synaptic trigger coupling aberrant postnatal neurogenesis and neuroimmune crosstalk, revealing that neurogenesis and epileptogenesis in the dentate gyrus are not mutually contingent events.
Batiuk, MY;Tyler, T;Dragicevic, K;Mei, S;Rydbirk, R;Petukhov, V;Deviatiiarov, R;Sedmak, D;Frank, E;Feher, V;Habek, N;Hu, Q;Igolkina, A;Roszik, L;Pfisterer, U;Garcia-Gonzalez, D;Petanjek, Z;Adorjan, I;Kharchenko, PV;Khodosevich, K;
PMID: 36223459 | DOI: 10.1126/sciadv.abn8367
Schizophrenia is one of the most widespread and complex mental disorders. To characterize the impact of schizophrenia, we performed single-nucleus RNA sequencing (snRNA-seq) of >220,000 neurons from the dorsolateral prefrontal cortex of patients with schizophrenia and matched controls. In addition, >115,000 neurons were analyzed topographically by immunohistochemistry. Compositional analysis of snRNA-seq data revealed a reduction in abundance of GABAergic neurons and a concomitant increase in principal neurons, most pronounced for upper cortical layer subtypes, which was substantiated by histological analysis. Many neuronal subtypes showed extensive transcriptomic changes, the most marked in upper-layer GABAergic neurons, including down-regulation in energy metabolism and up-regulation in neurotransmission. Transcription factor network analysis demonstrated a developmental origin of transcriptomic changes. Last, Visium spatial transcriptomics further corroborated upper-layer neuron vulnerability in schizophrenia. Overall, our results point toward general network impairment within upper cortical layers as a core substrate associated with schizophrenia symptomatology.
Smith HL, Freeman OJ, Butcher AJ, Holmqvist S, Humoud I, Sch�tzl T, Hughes DT, Verity NC, Swinden DP, Hayes J, de Weerd L, Rowitch DH, Franklin RJM, Mallucci GR
PMID: 31924446 | DOI: 10.1016/j.neuron.2019.12.014
Recent interest in astrocyte activation states has raised the fundamental question of how these cells, normally essential for synapse and neuronal maintenance, become pathogenic. Here, we show that activation of the unfolded protein response (UPR), specifically phosphorylated protein kinase R-like endoplasmic reticulum (ER) kinase (PERK-P) signaling-a pathway that is widely dysregulated in neurodegenerative diseases-generates a distinct reactivity state in astrocytes that alters the astrocytic secretome, leading to loss of synaptogenic function in vitro. Further, we establish that the same PERK-P-dependent astrocyte reactivity state is harmful to neurons in vivo in mice with prion neurodegeneration. Critically, targeting this signaling exclusively in astrocytes during prion disease is alone sufficient to prevent neuronal loss and significantly prolongs survival. Thus, the astrocyte reactivity state resulting from UPR over-activation is a distinct pathogenic mechanism that can by itself be effectively targeted for neuroprotection
Biological Psychiatry Global Open Science
Jiang, S;Zhang, H;Eiden, L;
| DOI: 10.1016/j.bpsgos.2023.04.001
Background The neuropeptide PACAP is a master regulator of central and peripheral stress responses, yet it is not clear how PACAP projections throughout the brain execute endocrine and behavioral stress responses. Methods We used AAV neuronal tracing, an acute restraint stress (ARS) paradigm, and intersectional genetics, in C57Bl6 mice, to identify PACAP-containing circuits controlling stress-induced behavior and endocrine activation. Results PACAP deletion from forebrain excitatory neurons, including a projection directly from medial prefrontal cortex (mPFC) to hypothalamus, impairs c-fos activation and CRH mRNA elevation in PVN after 2 hr of restraint, without affecting ARS-induced hypophagia, or c-fos elevation in non-hypothalamic brain. Elimination of PACAP within projections from lateral parabrachial nucleus to extended amygdala (EA), on the other hand, attenuates ARS-induced hypophagia, along with EA fos induction, without affecting ARS-induced CRH mRNA elevation in PVN. PACAP projections to EA terminate at PKCδ neurons in both central amygdala (CeA) and oval nuclei of bed nucleus of stria terminalis (BNSTov). Silencing of PKCδ neurons in CeA, but not in BNSTov, attenuates ARS-induced hypophagia. Experiments were carried out in mice of both sexes with n>5 per group. Conclusions A frontocortical descending PACAP projection controls PVN CRH mRNA production, to maintain hypothalamo-pituitary adrenal (HPA) axis activation, and regulate the endocrine response to stress. An ascending PACAPergic projection from eLPBn to PKCδ neurons in central amygdala regulates behavioral responses to stress. Defining two separate limbs of the acute stress response provides broader insight into the specific brain circuitry engaged by the psychogenic stress response.
