Kir4.1 channels contribute to astrocyte CO2/H+-sensitivity and the drive to breathe
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE247704 | GEO | 2023/12/29
REPOSITORIES: GEO
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Project description:A parafacial region of the medulla called the retrotrapezoid nucleus (RTN) is an important respiratory control center. A group of glutamatergic neurons in this region function as respiratory chemoreceptors by regulating breathing in response to changes in tissue CO2/H+. Cellular mechanisms underlying this function involve H+-inhibition of TASK2 channels and -activation of GPR4 receptors. Evidence also suggests the RTN and greater parafacial region functions as a CO2/H+ sensing network where CO2/H+-activated and -inhibited neurons talk to each other through excitatory and inhibitory interactions. However, contributions of parafacial inhibitory neurons to control of breathing are unknown, and synaptic properties of RTN chemorecpetors have not been characterized. Here, we show the ventral parafacial region contains parvalbumin (Pvalb), cholecystokinin (CCK), neuron-derived neurotrophic factor (Ndnf) and somatostatin (SST) subtypes of interneurons including a subset strongly inhibited by CO2/H+. We also show that chemosensitive RTN neurons receive tonic inhibitory input under control conditions that is withdrawn in a CO2/H+-dependent manner, and chemogenetic inhibition of ventral parafacial inhibitory neurons increases baseline respiratory activity. These results suggest ventral parafacial inhibitory neurons are important determinants of respiratory activity under baseline conditions when the respiratory system is most prone to failure.
2021-05-12 | GSE153172 | GEO
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.
2018-05-01 | GSE111148 | GEO
Project description:Previous studies have suggested that astrocyte activation in the spinal dorsal horn may play an important role in the development of chronic neuropathic pain; but the mechanisms involved in astrocyte activation and their modulatory effects remain unknown. The inward rectifying potassium channel protein 4.1 (Kir4.1) is the most important background K+ channel in astrocytes. However, how Kir4.1 is regulated and contributes to behavioral hyperalgesia in chronic pain is unknown. In this study, single-cell RNA sequencing analysis indicated that the expression of Kir4.1 and Methyl-CpG-binding protein 2 (MeCP2) were both decreased in spinal astrocytes after chronic constriction injury (CCI) in a mouse model. Conditional knockout of the Kir4.1 channel in spinal astrocytes led to hyperalgesia; and overexpression of the Kir4.1 channel in spinal cord relieved CCI-induced hyperalgesia. Expression of spinal Kir4.1 after CCI was regulated by MeCP2. Electrophysiological recording in spinal slices showed that knockdown of Kir4.1 significantly regulated the excitability of astrocytes and then functionally changed the firing patterns of neurons in dorsal spinal cord. Therefore, targeting spinal Kir4.1 maybe an underlying treatment for hyperalgesia in chronic neuropathic pain.
2022-07-24 | GSE208766 | GEO
Project description:CO2-induced vasoreactivity is an important mechanism to remove CO2 from the brain. Our previous work has shown that in brain endothelial cells Gαq and Gα11, that can replace each other and induce a common intracellular pathway, are required for normal vascular reactivity to CO2 stimulation. Additionally, we found different effects on vascular diameter dependent on the brain area. In the cortex, vessel dilate as response to CO2 stimulation, in the retrotrapezoid nucleus (RTN) of the brainstem, vessels constrict upon CO2 stimulation. To examine the potential basis for the opposing effects of CO2 on the vascular reactivity in brainstem compared to other brain areas, we prepared cortical and brainstem vessel fragments of control and Gαq/11beKO mice and performed microarrays to determine mRNA expression.
2019-12-20 | E-MTAB-8521 | biostudies-arrayexpress
Project description:The respiratory rhythm is generated by the preBötzinger complex in the medulla oblongata, and is modulated by neurons in the retrotrapezoid nucleus (RTN), which are essential for accelerating respiration in response to high CO2. Here we identify a LBX1 frameshift (LBX1FS) mutation in patients with congenital central hypoventilation. The mutation alters the C-terminal but not the DNA-binding domain of LBX1. Mice with the analogous mutation recapitulate the breathing deficits found in humans. Furthermore, the mutation only interferes with a small subset of Lbx1 functions, and in particular with development of RTN neurons that coexpress Lbx1 and Phox2b. Genome-wide analyses in a cell culture model show that Lbx1FS and wild-type Lbx1 proteins are mostly bound to similar sites, but that Lbx1FS is unable to cooperate with Phox2b. Thus, our analyses on Lbx1FS (dys)function reveals an unusual pathomechanism; that is, a mutation that selectively interferes with the ability of Lbx1 to cooperate with Phox2b, and thus impairs the development of a small subpopulation of neurons essential for respiratory control.
2022-10-07 | GSE214975 | GEO
Project description:The respiratory rhythm is generated by the preBötzinger complex in the medulla oblongata, and is modulated by neurons in the retrotrapezoid nucleus (RTN), which are essential for accelerating respiration in response to high CO2. Here we identify a LBX1 frameshift (LBX1FS) mutation in patients with congenital central hypoventilation. The mutation alters the C-terminal but not the DNA-binding domain of LBX1. Mice with the analogous mutation recapitulate the breathing deficits found in humans. Furthermore, the mutation only interferes with a small subset of Lbx1 functions, and in particular with development of RTN neurons that coexpress Lbx1 and Phox2b. Genome-wide analyses in a cell culture model show that Lbx1FS and wild-type Lbx1 proteins are mostly bound to similar sites, but that Lbx1FS is unable to cooperate with Phox2b. Thus, our analyses on Lbx1FS (dys)function reveals an unusual pathomechanism; that is, a mutation that selectively interferes with the ability of Lbx1 to cooperate with Phox2b, and thus impairs the development of a small subpopulation of neurons essential for respiratory control.
2022-10-17 | GSE215415 | GEO
Project description:Pitt-Hopkins syndrome (PTHS) is a rare autism spectrum-like disorder characterized by intellectual disability, developmental delays and breathing problems involving episodes of hyperventilation followed by apnea. PTHS is caused by functional haploinsufficiency of the gene encoding transcription factor 4 (Tcf4). Despite the severity of this disease, virtually nothing is known regarding mechanisms contributing to PTHS behavioral abnormalities, and candidate therapeutic targets are lacking. Here, we show that a Tcf4 truncation (Tcf4tr/+) mouse model of PTHS recapitulates respiratory phenotypes observed in PTHS patients. The basis of this behavior deficit involves selective loss of putative expiratory parafacial neurons and compromised function of neurons in the retrotrapezoid nucleus that regulate breathing in response to tissue CO2/H+. We also show that central Nav1.8 channels can be targeted pharmacologically to improve respiratory function at the cellular and behavioral levels in Tcf4tr/+ mice, thus establishing Nav1.8 as a high priority target with therapeutic potential in PTHS.
2021-09-02 | GSE174417 | GEO
Project description:One way by which astrocytes modulate oligodendrocytes’ activity is by delivering neurotransmitters and leukemia inhibitory factor (Lif) in the medium that bind oligodendrocyte receptors. Most of these receptors are involved in intercellular Ca2+-signaling (ICS). However, not much is known about the interactions between myelination (MYE) and ICS genes and how astrocyte nearness modulates the oligodendrocyte genomic myelination fabric. We profiled the transcriptomes of immortalized oligodendrocyte precursor cells (Oli-neu) when cultured alone or co-cultured with cortical astrocytes. The astrocytes were plated in cell culture insert systems that did not allow formation of gap junction channels with oligodendrocytes but permitted exchange of soluble factors via the culture medium. Remarkably, astrocyte proximity induced a larger increase of the overall expression level and interlinkage of MYE genes than the differentiating 10d treatment with 1 mM dibutyryl cAMP that turns Oli-neu cells into myelin-associated glycoprotein-positive oligodendrocyte-like cells. Moreover, more MYE and ICS genes were turned on and fewer turned off by astrocyte proximity than by differentiating treatment. Lif receptor was up-regulated by astrocyte proximity but not by the differentiating treatment. We have identified the responsible transcriptomic networks by which the intercellular ICS gene web controls MYE gene web, with genes encoding the gap junction proteins (connexins, Cx) Cx29, Cx32 and Cx47 playing central roles. The novel Prominent Gene Analysis (that refines iteratively the functional webs to optimize the interconnectivity and expression stability of the associated genes) was used to select and rank the most relevant MYE and ICS genes and build the corresponding gene webs. Determine the modifications of the myelination transcriptome induced in Oli- neu control cells by differentiating treatment and proximity of cortical astrocytes. Four culture dishes of each of control, differentiated and in the astrocyte proximity Oli-neu cells were profiled using Duke mouse 30K and 36k oligonucleotide arrays in the "multiple yellow" hybrization design.
2009-10-26 | E-GEOD-18726 | biostudies-arrayexpress
Project description:MartínJiménez2017 - Genome-scale reconstruction of the human astrocyte metabolic network
This model is described in the article:
Genome-Scale Reconstruction
of the Human Astrocyte Metabolic Network.
Martín-Jiménez CA,
Salazar-Barreto D, Barreto GE, González J.
Front Aging Neurosci 2017; 9: 23
Abstract:
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
pathologic states.
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MODEL1608180000.
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2017-05-18 | MODEL1608180000 | BioModels
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
2014-05-02 | E-GEOD-55054 | biostudies-arrayexpress