Project description:Neuronal synapse formation and remodeling is essential to central nervous system (CNS) development and is dysfunctional in neurodevelopmental diseases. Innate immune signals regulate tissue remodeling in the periphery, but how this impacts CNS synapses is largely unknown. Here we show that the IL-1 family cytokine Interleukin-33 (IL-33) is produced by developing astrocytes and is developmentally required for normal synapse numbers and neural circuit function in the spinal cord and thalamus. We find that IL-33 signals primarily to microglia under physiologic conditions, that it promotes microglial synapse engulfment, and that it can drive microglial-dependent synapse depletion in vivo. These data reveal a cytokine-mediated mechanism required to maintain synapse homeostasis during CNS development. Overall design: 16 samples total consisting of 4 biological replicates per group of flow sorted IL-33pos and neg astrocytes from thalamus or spinal cord at P15 (IL-33mCherry reporter from M. Colonna lab)
Project description:Neuronal synapse formation and remodeling is essential to central nervous system (CNS) development and is dysfunctional in neurodevelopmental diseases. Innate immune signals regulate tissue remodeling in the periphery, but how this impacts CNS synapses is largely unknown. Here we show that the IL-1 family cytokine Interleukin-33 (IL-33) is produced by developing astrocytes and is developmentally required for normal synapse numbers and neural circuit function in the spinal cord and thalamus. We find that IL-33 signals primarily to microglia under physiologic conditions, that it promotes microglial synapse engulfment, and that it can drive microglial-dependent synapse depletion in vivo. These data reveal a cytokine-mediated mechanism required to maintain synapse homeostasis during CNS development. Overall design: 13 samples consisting of 3-4 biological replicates each of flow sorted astrocytes (Aldh1l1-GFP+) and microglia (CD11b+) from spinal cord P9-P12 Il33 KO and littermates control mice (Pichery et al., 2012; J Immunology)
Project description:Astrocytes, the most abundant cells in the central nervous system, promote synapse formation and help refine neural connectivity. Although they are allocated to spatially distinct regional domains during development, it is unknown whether region-restricted astrocytes are functionally heterogeneous. Here we show that postnatal spinal cord astrocytes express several region-specific genes, and that ventral astrocyte-encoded Semaphorin3a (Sema3a) is required for proper motor neuron and sensory neuron circuit organization. Loss of astrocyte-encoded Sema3a led to dysregulated α−motor neuron axon initial segment orientation, markedly abnormal synaptic inputs, and selective death of α−but not of adjacent γ−motor neurons. Additionally, a subset of TrkA+ sensory afferents projected to ectopic ventral positions. These findings demonstrate that stable maintenance of a positional cue by developing astrocytes influences multiple aspects of sensorimotor circuit formation. More generally, they suggest that regional astrocyte heterogeneity may help to coordinate postnatal neural circuit refinement. 12 total samples consisting of three biological replicates each of flow sorted postnatal day 7 dorsal spinal cord astrocytes, ventral spinal cord astrocytes, dorsal SC non astrocytes, and ventral SC non astrocytes
Project description:The Khakh laboratory used Aldh1l1-Cre/ERT2 transgenic mouse line crossed with RiboTag mice to sequence actively translated mRNAs and compare striatal and hippocampal astrocyte transcriptomes from adults. Overall design: Whole striata and hippocampii were extracted from 4 adult (P63) male and female Aldh1l1-Cre/ERT2 x Ribotag mice. After homogenization, RNA was purified from (i) cleared lysate as the input and control, and (ii) astrocyte-specific ribosome-associated RNA precipitated via a hemagglutinin (HA) tag.
Project description:Diversified neurons are essential for sensorimotor function, but whether astrocytes become specialized to optimize circuit performance remains unclear. Large fast α-motor neurons (FαMNs) of spinal cord innervate fast-twitch muscles that generate peak strength. We report that ventral horn astrocytes express the inward rectifying K+ channel Kir4.1 (aka, Kcnj10) around MNs in a VGLUT1-dependent manner. Loss-of astrocyte-encoded Kir4.1 selectively altered FαMN size, function and led to reduced peak strength. Overexpression of Kir4.1 in astrocytes was sufficient to increase MN size through activation of the PI3K/mTOR/pS6 pathway. Kir4.1 was downregulated cell-autonomously in astrocytes derived from amyotrophic lateral sclerosis (ALS) patients with SOD1 mutation. However, astrocyte Kir4.1 was dispensable for FαMN survival even in the mutant SOD1 background. These findings show that astrocyte Kir4.1 is essential for maintenance of peak strength and suggest that Kir4.1 downregulation uncouples symptoms of muscle weakness from MN cell death in ALS. Overall design: 8 samples total consisting of 4 biological replicates per group (Aldh1l1-cre:Kir4.1-floxed/floxed vs cre-negative) of flow sorted Aldh1l1-GFP+ astrocytes from spinal cord at P12-P14
Project description:During development of the mammalian central nervous system (CNS), neurons and glial cells (astrocytes and oligodendrocytes) are generated from common neural precursor cells (NPCs). However, neurogenesis precedes gliogenesis, which normally commences at later stages of fetal telencephalic development. Astrocyte differentiation of mouse NPCs at embryonic day (E) 14.5 (relatively late gestation) is induced by activation of the transcription factor STAT3, whereas at E11.5 (mid-gestation) NPCs do not differentiate into astrocytes even when stimulated by STAT3-activating cytokines such as leukemia inhibitory factor (LIF). This can be explained in part by the fact that astrocyte-specific gene promoters are highly methylated in NPCs at E11.5, but other mechanisms are also likely to play a role. We therefore sought to identify genes involved in the inhibition of astrocyte differentiation of NPCs at midgestation. We first examined gene expression profiles in E11.5 and E14.5 NPCs, using Affymetrix GeneChip analysis, applying the Percellome method to normalize gene expression level. We then conducted in situ hybridization analysis for selected genes found to be highly expressed in NPCs at midgestation. Among these genes, we found that N-myc and high mobility group AT-hook 2 (Hmga2) were highly expressed in the E11.5 but not the E14.5 ventricular zone of mouse brain, where NPCs reside. Transduction of N-myc and Hmga2 by retroviruses into E14.5 NPCs, which normally differentiate into astrocytes in response to LIF, resulted in suppression of astrocyte differentiation. However, sustained expression of N-myc and Hmga2 in E11.5 NPCs failed to maintain the hypermethylated status of an astrocyte-specific gene promoter. Taken together, our data suggest that astrocyte differentiation of NPCs is regulated not only by DNA methylation but also by genes whose expression is controlled spatio-temporally during brain development. Keywords: Cell type comparison Overall design: Neuroepithelial cells(NPCs) were prepared from telencephalons of E11.5 and E14.5 mice and cultured in N2-supplemented Dulbecco's Modified Eagle's Medium with F12 (GIBCO) containing 10 ng/ml basic FGF (R&D Systems) (N2/DMEM/F12/bFGF) on culture dishes (Nunc) or chamber slide (Nunc) which had been precoated with poly-L-ornithine (Sigma) and fibronectin (Sigma). E11.5 NPCs were cultured for one day and E14.5 NPCs were for four days.
Project description:MartínJiménez2017 - Genome-scale reconstruction of the human astrocyte metabolic network
This model is described in the article:
of the Human Astrocyte Metabolic Network.
Salazar-Barreto D, Barreto GE, González J.
Front Aging Neurosci 2017; 9: 23
Astrocytes are the most abundant cells of the central
nervous system; they have a predominant role in maintaining
brain metabolism. In this sense, abnormal metabolic states have
been found in different neuropathological diseases.
Determination of metabolic states of astrocytes is difficult to
model using current experimental approaches given the high
number of reactions and metabolites present. Thus, genome-scale
metabolic networks derived from transcriptomic data can be used
as a framework to elucidate how astrocytes modulate human brain
metabolic states during normal conditions and in
neurodegenerative diseases. We performed a Genome-Scale
Reconstruction of the Human Astrocyte Metabolic Network with
the purpose of elucidating a significant portion of the
metabolic map of the astrocyte. This is the first global
high-quality, manually curated metabolic reconstruction network
of a human astrocyte. It includes 5,007 metabolites and 5,659
reactions distributed among 8 cell compartments,
(extracellular, cytoplasm, mitochondria, endoplasmic reticle,
Golgi apparatus, lysosome, peroxisome and nucleus). Using the
reconstructed network, the metabolic capabilities of human
astrocytes were calculated and compared both in normal and
ischemic conditions. We identified reactions activated in these
two states, which can be useful for understanding the
astrocytic pathways that are affected during brain disease.
Additionally, we also showed that the obtained flux
distributions in the model, are in accordance with
literature-based findings. Up to date, this is the most
complete representation of the human astrocyte in terms of
inclusion of genes, proteins, reactions and metabolic pathways,
being a useful guide for in-silico analysis of several
metabolic behaviors of the astrocyte during normal and
This model is hosted on
and identified by:
To cite BioModels Database, please use:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
Public Domain Dedication for more information.