"Boldog E, Bakken TE, Hodge RD, Novotny M, Aevermann BD, Baka J, Bordé S, Close JL, Diez-Fuertes F, Ding SL, Faragó N, Kocsis AK, Kovács B, Maltzer Z, McCorrison JM, Miller JA, Molnár G, Oláh G, Ozsvár A, Rózsa M, Shehata SI, Smith KA, Sunkin SM, Tran D
PMID: 30150662 | DOI: 10.1038/s41593-018-0205-2
We describe convergent evidence from transcriptomics, morphology, and physiology for a specialized GABAergic neuron subtype in human cortex. Using unbiased single-nucleus RNA sequencing, we identify ten GABAergic interneuron subtypes with combinatorial gene signatures in human cortical layer 1 and characterize a group of human interneurons with anatomical features never described in rodents, having large 'rosehip'-like axonal boutons and compact arborization. These rosehip cells show an immunohistochemical profile (GAD1+CCK+, CNR1-SST-CALB2-PVALB-) matching a single transcriptomically defined cell type whose specific molecular marker signature is not seen in mouse cortex. Rosehip cells in layer 1 make homotypic gap junctions, predominantly target apical dendritic shafts of layer 3 pyramidal neurons, and inhibit backpropagating pyramidal action potentials in microdomains of the dendritic tuft. These cells are therefore positioned for potent local control of distal dendritic computation in cortical pyramidal neurons.
Zhang, ZZ;Zeng, LP;Chen, J;Wu, YF;Wang, YT;Xia, L;Yang, QG;Wang, F;Chen, GH;
PMID: 35574247 | DOI: 10.1155/2022/1483101
A mounting body of evidence suggests that prenatal inflammation may enhance the rate of age-associated cognitive decline and may involve aberrant amounts of synaptic proteins in the hippocampus, including synaptotagmin-1 (Syt1) and activity-regulated cytoskeleton-associated protein (Arc). However, little is known about the specific impact of adolescent environmental enrichment (EE) on age-associated cognitive decline and the changes in synaptic proteins caused by prenatal inflammation. In this study, CD-1 mice in late pregnancy were given intraperitoneal doses of lipopolysaccharide (LPS, 50 μg/kg) or normal saline. Offspring arising from LPS dams were divided into a LPS group and a LPS plus EE (LPS-E) group. The LPS-E mice were exposed to EE from 2 months of age until the end of the experiment (3 or 15 months old). The Morris water maze (MWM) was used to assess the spatial learning and memory capacities of experimental mice, while western blotting and RNA-scope were used to determine the expression levels of Arc and Syt1 in the hippocampus at the protein and mRNA levels, respectively. Analysis revealed that at 15 months of age, the control mice experienced a reduction in cognitive ability and elevated expression levels of Arc and Syt1 genes when compared to control mice at 3 months of age. The LPS-E group exhibited better cognition and lower protein and mRNA levels of Arc and Syt1 than mice in the LPS group of the same age. However, the enriched environment mitigated but did not counteract, the effects of prenatal inflammation on cognitive and synaptic proteins when tested at either 3 or 15 months of age. Our findings revealed that long-term environmental enrichment improved the expression levels of synaptic proteins in CD-1 mice and that this effect was linked to the dysfunctional cognition caused by prenatal inflammation; this process may also be involved in the reduction of hippocampal Arc and Syt1 gene expression.
Auguste, YSS;Ferro, A;Kahng, JA;Xavier, AM;Dixon, JR;Vrudhula, U;Nichitiu, AS;Rosado, D;Wee, TL;Pedmale, UV;Cheadle, L;
PMID: 36171430 | DOI: 10.1038/s41593-022-01170-x
Oligodendrocyte precursor cells (OPCs) give rise to myelinating oligodendrocytes throughout life, but the functions of OPCs are not limited to oligodendrogenesis. Here we show that OPCs contribute to thalamocortical presynapse elimination in the developing and adult mouse visual cortex. OPC-mediated synapse engulfment increases in response to sensory experience during neural circuit refinement. Our data suggest that OPCs may regulate synaptic connectivity in the brain independently of oligodendrogenesis.
Losurdo M, Davidsson J, Sk�ld MK
PMID: 32290212 | DOI: 10.3390/brainsci10040229
Traumatic brain injury (TBI) commonly results in primary diffuse axonal injury (DAI) and associated secondary injuries that evolve through a cascade of pathological mechanisms. We aim at assessing how myelin and oligodendrocytes react to head angular-acceleration-induced TBI in a previously described model. This model induces axonal injuries visible by amyloid precursor protein (APP) expression, predominantly in the corpus callosum and its borders. Brain tissue from a total of 27 adult rats was collected at 24 h, 72 h and 7 d post-injury. Coronal sections were prepared for immunohistochemistry and RNAscope� to investigate DAI and myelin changes (APP, MBP, Rip), oligodendrocyte lineage cell loss (Olig2), oligodendrocyte progenitor cells (OPCs) (NG2, PDGFRa) and neuronal stress (HSP70, ATF3). Oligodendrocytes and OPCs numbers (expressed as percentage of positive cells out of total number of cells) were measured in areas with high APP expression. Results showed non-statistically significant trends with a decrease in oligodendrocyte lineage cells and an increase in OPCs. Levels of myelination were mostly unaltered, although Rip expression differed significantly between sham and injured animals in the frontal brain. Neuronal stress markers were induced at the dorsal cortex and habenular nuclei. We conclude that rotational injury induces DAI and neuronal stress in specific areas. We noticed indications of oligodendrocyte death and regeneration without statistically significant changes at the timepoints measured, despite indications of axonal injuries and neuronal stress. This might suggest that oligodendrocytes are robust enough to withstand this kind of trauma, knowledge important for the understanding of thresholds for cell injury and post-traumatic recovery potential
Garcia-Alonso, L;Lorenzi, V;Mazzeo, CI;Alves-Lopes, JP;Roberts, K;Sancho-Serra, C;Engelbert, J;Marečková, M;Gruhn, WH;Botting, RA;Li, T;Crespo, B;van Dongen, S;Kiselev, VY;Prigmore, E;Herbert, M;Moffett, A;Chédotal, A;Bayraktar, OA;Surani, A;Haniffa, M;Vento-Tormo, R;
PMID: 35794482 | DOI: 10.1038/s41586-022-04918-4
Gonadal development is a complex process that involves sex determination followed by divergent maturation into either testes or ovaries1. Historically, limited tissue accessibility, a lack of reliable in vitro models and critical differences between humans and mice have hampered our knowledge of human gonadogenesis, despite its importance in gonadal conditions and infertility. Here, we generated a comprehensive map of first- and second-trimester human gonads using a combination of single-cell and spatial transcriptomics, chromatin accessibility assays and fluorescent microscopy. We extracted human-specific regulatory programmes that control the development of germline and somatic cell lineages by profiling equivalent developmental stages in mice. In both species, we define the somatic cell states present at the time of sex specification, including the bipotent early supporting population that, in males, upregulates the testis-determining factor SRY and sPAX8s, a gonadal lineage located at the gonadal-mesonephric interface. In females, we resolve the cellular and molecular events that give rise to the first and second waves of granulosa cells that compartmentalize the developing ovary to modulate germ cell differentiation. In males, we identify human SIGLEC15+ and TREM2+ fetal testicular macrophages, which signal to somatic cells outside and inside the developing testis cords, respectively. This study provides a comprehensive spatiotemporal map of human and mouse gonadal differentiation, which can guide in vitro gonadogenesis.
J Neurosci. 2014 Mar 26;34(13):4481-93.
Farris S, Lewandowski G, Cox CD, Steward O.
PMID: 24671994 | DOI: 10.1523/JNEUROSCI.4944-13.2014.
Arc is an immediate early gene that is unique among neuronal mRNAs because its transcripts are transported into dendrites and accumulate near activated synapses, presumably to be translated locally. These qualities pose Arc as playing an important, yet not fully understood, role in the activity-dependent modifications of synapses that are thought to underlie memory storage. Here we show in vivo in rats that newly synthesized Arc mRNA accumulates at activated synapses and that synaptic activity simultaneously triggers mRNA decay that eliminates Arc mRNA from inactive dendritic domains. Arc mRNA degradation occurs throughout the dendrite and requires both NMDA receptor activation and active translation. Synaptic activation did not lead to decreases in another dendritic mRNA (αCaMKII), indicating that there is not a general activation of mRNA degradation in dendrites. These data reveal a novel mechanism for controlling mRNA distribution within dendrites and highlight activity-dependent mRNA degradation as a regulatory process involved in synaptic plasticity.
Filbin MG, Tirosh I, Hovestadt V, Shaw ML, Escalante LE, Mathewson ND, Neftel C, Frank N, Pelton K, Hebert CM, Haberler C, Yizhak K, Gojo J, Egervari K, Mount C, van Galen P, Bonal DM, Nguyen QD, Beck A, Sinai C, Czech T, Dorfer C, Goumnerova L, Lavarino
PMID: 29674595 | DOI: 10.1126/science.aao4750
Gliomas with histone H3 lysine27-to-methionine mutations (H3K27M-glioma) arise primarily in the midline of the central nervous system of young children, suggesting a cooperation between genetics and cellular context in tumorigenesis. Although the genetics of H3K27M-glioma are well characterized, their cellular architecture remains uncharted. We performed single-cell RNA sequencing in 3321 cells from six primary H3K27M-glioma and matched models. We found that H3K27M-glioma primarily contain cells that resemble oligodendrocyte precursor cells (OPC-like), whereas more differentiated malignant cells are a minority. OPC-like cells exhibit greater proliferation and tumor-propagating potential than their more differentiated counterparts and are at least in part sustained by PDGFRA signaling. Our study characterizes oncogenic and developmental programs in H3K27M-glioma at single-cell resolution and across genetic subclones, suggesting potential therapeutic targets in this disease.
Cell Rep. 2018 Dec 18;25(12):3435-3450.e6.
Wang J, Saraswat D, Sinha AK, Polanco J, Dietz K, O'Bara MA, Pol SU, Shayya HJ, Sim FJ.
PMID: 30566868 | DOI: 10.1016/j.celrep.2018.11.068
Human oligodendrocyte progenitor cells (hOPCs) persist into adulthood as an abundant precursor population capable of division and differentiation. The transcriptional mechanisms that regulate hOPC homeostasis remain poorly defined. Herein, we identify paired related homeobox protein 1 (PRRX1) in primary PDGFαR+ hOPCs. We show that enforced PRRX1 expression results in reversible G1/0 arrest. While both PRRX1 splice variants reduce hOPC proliferation, only PRRX1a abrogates migration. hOPC engraftment into hypomyelinated shiverer/rag2 mouse brain is severely impaired by PRRX1a, characterized by reduced cell proliferation and migration. PRRX1 induces a gene expression signature characteristic of stem cell quiescence. Both IFN-γ and BMP signaling upregulate PRRX1 and induce quiescence. PRRX1 knockdown modulates IFN-γ-induced quiescence. In mouse brain, PRRX1 mRNA was detected in non-dividing OPCs and is upregulated in OPCs following demyelination. Together, these data identify PRRX1 as a regulator of quiescence in hOPCs and as a potential regulator of pathological quiescence.
Dada, LA;Welch, LC;Magnani, ND;Ren, Z;Han, H;Brazee, PL;Celli, D;Flozak, AS;Weng, A;Herrerias, MM;Kryvenko, V;Vadász, I;Runyan, CE;Abdala-Valencia, H;Shigemura, M;Casalino-Matsuda, SM;Misharin, AV;Budinger, GRS;Gottardi, CJ;Sznajder, JI;
PMID: 36626234 | DOI: 10.1172/jci.insight.159331
Persistent symptoms and radiographic abnormalities suggestive of failed lung repair are among the most common symptoms in patients with COVID-19 after hospital discharge. In mechanically ventilated patients with ARDS secondary to SARS-CoV-2 pneumonia, low tidal volumes to reduce ventilator-induced lung injury necessarily elevate blood CO2 levels, often leading to hypercapnia. The role of hypercapnia on lung repair after injury is not completely understood. Here, using a mouse model of hypercapnia exposure, cell lineage-tracing, spatial transcriptomics and 3D-cultures, we show that hypercapnia limits β-catenin signaling in AT2 cells, leading to their reduced proliferative capacity. Hypercapnia alters expression of major Wnts in PDGFRα+-fibroblasts from those maintaining AT2 progenitor activity towards those that antagonize β-catenin signaling thereby limiting progenitor function. Constitutive activation of β-catenin signaling in AT2 cells or treatment of organoid cultures with recombinant WNT3A protein bypasses the inhibitory effects of hypercapnia. Inhibition of AT2 proliferation in hypercapnic patients may contribute to impaired lung repair after injury, preventing sealing of the epithelial barrier, increasing lung flooding, ventilator dependency and mortality. .
Ichihara, R;Shiraki, Y;Mizutani, Y;Iida, T;Miyai, Y;Esaki, N;Kato, A;Mii, S;Ando, R;Hayashi, M;Takami, H;Fujii, T;Takahashi, M;Enomoto, A;
PMID: 35020975 | DOI: 10.1111/pin.13198
Cancer-associated fibroblasts (CAFs), a compartment of the tumor microenvironment, were previously thought to be a uniform cell population that promotes cancer progression. However, recent studies have shown that CAFs are heterogeneous and that there are at least two types of CAFs, that is, cancer-promoting and -restraining CAFs. We previously identified Meflin as a candidate marker of cancer-restraining CAFs (rCAFs) in pancreatic ductal adenocarcinoma (PDAC). The precise nature of rCAFs, however, has remained elusive owing to a lack of understanding of their comprehensive gene signatures. Here, we screened genes whose expression correlated with Meflin in single-cell transcriptomic analyses of human cancers. Among the identified genes, we identified matrix remodeling-associated protein 8 (MXRA8), which encodes a type I transmembrane protein with unknown molecular function. Analysis of MXRA8 expression in human PDAC samples showed that MXRA8 was differentially co-expressed with other CAF markers. Moreover, in patients with PDAC or syngeneic tumors developed in MXRA8-knockout mice, MXRA8 expression did not affect the roles of CAFs in cancer progression, and the biological importance of MXRA8+ CAFs is still unclear. Overall, we identified MXRA8 as a new CAF marker; further studies are needed to determine the relevance of this marker.
Blanco-Suarez E, Liu TF, Kopelevich A, Allen NJ.
PMID: 30344043 | DOI: 10.1016/j.neuron.2018.09.043
In the developing brain, immature synapses contain calcium-permeable AMPA glutamate receptors (AMPARs) that are subsequently replaced with GluA2-containing calcium-impermeable AMPARs as synapses stabilize and mature. Here, we show that this essential switch in AMPARs and neuronal synapse maturation is regulated by astrocytes. Using biochemical fractionation of astrocyte-secreted proteins and mass spectrometry, we identified that astrocyte-secreted chordin-like 1 (Chrdl1) is necessary and sufficient to induce mature GluA2-containing synapses to form. This function of Chrdl1 is independent of its role as an antagonist of bone morphogenetic proteins (BMPs). Chrdl1 expression is restricted to cortical astrocytes in vivo, peaking at the time of the AMPAR switch. Chrdl1 knockout (KO) mice display reduced synaptic GluA2 AMPARs, altered kinetics of synaptic events, and enhanced remodeling in an in vivo plasticity assay. Studies have shown that humans with mutations in Chrdl1 display enhanced learning. Thus astrocytes, via the release of Chrdl1, promote GluA2-dependent synapse maturation and thereby limit synaptic plasticity.
van Bruggen, D;Pohl, F;Langseth, CM;Kukanja, P;Lee, H;Albiach, AM;Kabbe, M;Meijer, M;Linnarsson, S;Hilscher, MM;Nilsson, M;Sundström, E;Castelo-Branco, G;
PMID: 35523173 | DOI: 10.1016/j.devcel.2022.04.016
Oligodendrogenesis in the human central nervous system has been observed mainly at the second trimester of gestation, a much later developmental stage compared to oligodendrogenesis in mice. Here, we characterize the transcriptomic neural diversity in the human forebrain at post-conception weeks (PCW) 8-10. Using single-cell RNA sequencing, we find evidence of the emergence of a first wave of oligodendrocyte lineage cells as early as PCW 8, which we also confirm at the epigenomic level through the use of single-cell ATAC-seq. Using regulatory network inference, we predict key transcriptional events leading to the specification of oligodendrocyte precursor cells (OPCs). Moreover, by profiling the spatial expression of 50 key genes through the use of in situ sequencing (ISS), we identify regions in the human ventral fetal forebrain where oligodendrogenesis first occurs. Our results indicate evolutionary conservation of the first wave of oligodendrogenesis between mice and humans and describe regulatory mechanisms involved in human OPC specification.
