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Cells Sep 2023Canonical transient receptor potential 3 (TRPC3) channel is a non-selective cation permeable channel that plays an essential role in calcium signalling. TRPC3 is highly... (Review)
Review
Canonical transient receptor potential 3 (TRPC3) channel is a non-selective cation permeable channel that plays an essential role in calcium signalling. TRPC3 is highly expressed in the brain and also found in endocrine tissues and smooth muscle cells. The channel is activated directly by binding of diacylglycerol downstream of G-protein coupled receptor activation. In addition, TRPC3 is regulated by endogenous factors including Ca ions, other endogenous lipids, and interacting proteins. The molecular and structural mechanisms underlying activation and regulation of TRPC3 are incompletely understood. Recently, several high-resolution cryogenic electron microscopy structures of TRPC3 and the closely related channel TRPC6 have been resolved in different functional states and in the presence of modulators, coupled with mutagenesis studies and electrophysiological characterisation. Here, we review the recent literature which has advanced our understanding of the complex mechanisms underlying modulation of TRPC3 by both endogenous and exogenous factors. TRPC3 plays an important role in Ca homeostasis and entry into cells throughout the body, and both pathological variants and downstream dysregulation of TRPC3 channels have been associated with a number of diseases. As such, TRPC3 may be a valuable therapeutic target, and understanding its regulatory mechanisms will aid future development of pharmacological modulators of the channel.
Topics: Brain; Calcium Signaling; Cardiac Electrophysiology; Homeostasis; Mutagenesis
PubMed: 37759438
DOI: 10.3390/cells12182215 -
The Journal of Biological Chemistry Apr 2024Extracellular ATP activates P2 purinergic receptors. Whether purinergic signaling is functionally coupled to cellular senescence is largely unknown. We find that...
Extracellular ATP activates P2 purinergic receptors. Whether purinergic signaling is functionally coupled to cellular senescence is largely unknown. We find that oxidative stress induced release of ATP and caused senescence in human lung fibroblasts. Inhibition of P2 receptors limited oxidative stress-induced senescence, while stimulation with exogenous ATP promoted premature senescence. Pharmacological inhibition of P2Y11 receptor (P2Y11R) inhibited premature senescence induced by either oxidative stress or ATP, while stimulation with a P2Y11R agonist was sufficient to induce cellular senescence. Our data show that both extracellular ATP and a P2Y11R agonist induced calcium (Ca) release from the endoplasmic reticulum (ER) and that either inhibition of phospholipase C or intracellular Ca chelation impaired ATP-induced senescence. We also find that Ca that was released from the ER, following ATP-mediated activation of phospholipase C, entered mitochondria in a manner dependent on P2Y11R activation. Once in mitochondria, excessive Ca promoted the production of reactive oxygen species in a P2Y11R-dependent fashion, which drove development of premature senescence of lung fibroblasts. Finally, we show that conditioned medium derived from senescent lung fibroblasts, which were induced to senesce through the activation of ATP/P2Y11R-mediated signaling, promoted the proliferation of triple-negative breast cancer cells and their tumorigenic potential by secreting amphiregulin. Our study identifies the existence of a novel purinergic signaling pathway that links extracellular ATP to the development of a protumorigenic premature senescent phenotype in lung fibroblasts that is dependent on P2Y11R activation and ER-to-mitochondria calcium signaling.
Topics: Humans; Adenosine Triphosphate; Calcium; Calcium Signaling; Cellular Senescence; Endoplasmic Reticulum; Fibroblasts; Lung; Mitochondria; Oxidative Stress; Reactive Oxygen Species; Receptors, Purinergic P2; Signal Transduction; Type C Phospholipases; Cell Line; Cell Proliferation
PubMed: 38460941
DOI: 10.1016/j.jbc.2024.107145 -
Frontiers in Endocrinology 2023Allopregnanolone (Allo) is a neurosteroid with pleiotropic action in the brain that includes neurogenesis, oligogenesis, human and rodent neural stem cell regeneration,...
OBJECTIVE
Allopregnanolone (Allo) is a neurosteroid with pleiotropic action in the brain that includes neurogenesis, oligogenesis, human and rodent neural stem cell regeneration, increased glucose metabolism, mitochondrial respiration and biogenesis, improved cognitive function, and reduction of both inflammation and Alzheimer's disease (AD) pathology. Because the breadth of Allo-induced responses requires activation of multiple systems of biology in the absence of an Allo-specific nuclear receptor, analyses were conducted in both neurons and astrocytes to identify unifying systems and signaling pathways.
METHODS
Mechanisms of Allo action were investigated in embryonic hippocampal neurons and astrocytes cultured in an Aging Model (AM) media. Cellular morphology, mitochondrial function, and transcriptomics were investigated followed by mechanistic pathway analyses.
RESULTS
In hippocampal neurons, Allo significantly increased neurite outgrowth and synaptic protein expression, which were paralleled by upregulated synaptogenesis and long-term potentiation gene expression profiles. Mechanistically, Allo induced Ca/CREB signaling cascades. In parallel, Allo significantly increased maximal mitochondrial respiration, mitochondrial membrane potential, and Complex IV activity while reducing oxidative stress, which required both the GABA and L-type Ca channels. In astrocytes, Allo increased ATP generation, mitochondrial function and dynamics while reducing oxidative stress, inflammasome indicators, and apoptotic signaling. Mechanistically, Allo regulation of astrocytic mitochondrial function required both the GABA and L-type Ca channels. Furthermore, Allo activated NRF1-TFAM signaling and increased the DRP1/OPA1 protein ratio, which led to increased mitochondrial biogenesis and dynamics.
CONCLUSION
Collectively, the cellular, mitochondrial, transcriptional, and pharmacological profiles provide evidence in support of calcium signaling as a unifying mechanism for Allo pleiotropic actions in the brain.
Topics: Humans; Calcium Signaling; Astrocytes; Pregnanolone; Neurons; gamma-Aminobutyric Acid
PubMed: 38189047
DOI: 10.3389/fendo.2023.1286931 -
Molecular Psychiatry Nov 2023Neuroinflammatory disorders preferentially impair the higher cognitive and executive functions of the prefrontal cortex (PFC). This includes such challenging disorders... (Review)
Review
Neuroinflammatory disorders preferentially impair the higher cognitive and executive functions of the prefrontal cortex (PFC). This includes such challenging disorders as delirium, perioperative neurocognitive disorder, and the sustained cognitive deficits from "long-COVID" or traumatic brain injury. There are no FDA-approved treatments for these symptoms; thus, understanding their etiology is important for generating therapeutic strategies. The current review describes the molecular rationale for why PFC circuits are especially vulnerable to inflammation, and how α2A-adrenoceptor (α2A-AR) actions throughout the nervous and immune systems can benefit the circuits in PFC needed for higher cognition. The layer III circuits in the dorsolateral PFC (dlPFC) that generate and sustain the mental representations needed for higher cognition have unusual neurotransmission and neuromodulation. They are wholly dependent on NMDAR neurotransmission, with little AMPAR contribution, and thus are especially vulnerable to kynurenic acid inflammatory signaling which blocks NMDAR. Layer III dlPFC spines also have unusual neuromodulation, with cAMP magnification of calcium signaling in spines, which opens nearby potassium channels to rapidly weaken connectivity and reduce neuronal firing. This process must be tightly regulated, e.g. by mGluR3 or α2A-AR on spines, to prevent loss of firing. However, the production of GCPII inflammatory signaling reduces mGluR3 actions and markedly diminishes dlPFC network firing. Both basic and clinical studies show that α2A-AR agonists such as guanfacine can restore dlPFC network firing and cognitive function, through direct actions in the dlPFC, but also by reducing the activity of stress-related circuits, e.g. in the locus coeruleus and amygdala, and by having anti-inflammatory actions in the immune system. This information is particularly timely, as guanfacine is currently the focus of large clinical trials for the treatment of delirium, and in open label studies for the treatment of cognitive deficits from long-COVID.
Topics: Humans; Calcium Signaling; Cognitive Dysfunction; Delirium; Guanfacine; Neuroinflammatory Diseases; Post-Acute COVID-19 Syndrome; Prefrontal Cortex
PubMed: 37029295
DOI: 10.1038/s41380-023-02057-4 -
Cell Communication and Signaling : CCS Sep 2023G protein-coupled receptor heteromerization is believed to exert dynamic regulatory impact on signal transduction. CXC chemokine receptor 4 (CXCR4) and its ligand...
BACKGROUND
G protein-coupled receptor heteromerization is believed to exert dynamic regulatory impact on signal transduction. CXC chemokine receptor 4 (CXCR4) and its ligand CXCL12, both of which are overexpressed in many cancers, play a pivotal role in metastasis. Likewise, lysophosphatidic acid receptor 1 (LPA) is implicated in cancer cell proliferation and migration. In our preliminary study, we identified LPA as a prospective CXCR4 interactor. In the present study, we investigated in detail the formation of the CXCR4-LPA heteromer and characterized the unique molecular features and function of this heteromer.
METHODS
We employed bimolecular fluorescence complementation, bioluminescence resonance energy transfer, and proximity ligation assays to demonstrate heteromerization between CXCR4 and LPA. To elucidate the distinctive molecular characteristics and functional implications of the CXCR4-LPA heteromer, we performed various assays, including cAMP, BRET for G protein activation, β-arrestin recruitment, ligand binding, and transwell migration assays.
RESULTS
We observed that CXCR4 forms heteromers with LPA in recombinant HEK293A cells and the human breast cancer cell line MDA-MB-231. Coexpression of LPA with CXCR4 reduced CXCL12-mediated cAMP inhibition, ERK activation, Gα activation, and β-arrestin recruitment, while CXCL12 binding to CXCR4 remained unaffected. In contrast, CXCR4 had no impact on LPA-mediated signaling. The addition of lysophosphatidic acid (LPA) further hindered CXCL12-induced Gα recruitment to CXCR4. LPA or alkyl-OMPT inhibited CXCL12-induced migration in various cancer cells that endogenously express both CXCR4 and LPA. Conversely, CXCL12-induced calcium signaling and migration were increased in LPAR1 knockout cells, and LPA-selective antagonists enhanced CXCL12-induced Gα signaling and cell migration in the parental MDA-MB-231 cells but not in LPA-deficient cells. Ultimately, complete inhibition of cell migration toward CXCL12 and alkyl-OMPT was only achieved in the presence of both CXCR4 and LPA antagonists.
CONCLUSIONS
The presence and impact of CXCR4-LPA heteromers on CXCL12-induced signaling and cell migration have been evidenced across various cell lines. This discovery provides crucial insights into a valuable regulatory mechanism of CXCR4 through heteromerization. Moreover, our findings propose a therapeutic potential in combined CXCR4 and LPA inhibitors for cancer and inflammatory diseases associated with these receptors, simultaneously raising concerns about the use of LPA antagonists alone for such conditions. Video Abstract.
Topics: Humans; Calcium Signaling; Cell Movement; Chemokine CXCL12; Ligands; Prospective Studies; Receptors, CXCR4; Receptors, Lysophosphatidic Acid
PubMed: 37749552
DOI: 10.1186/s12964-023-01261-7 -
Brain : a Journal of Neurology Aug 2023ATP1A3 encodes the α3 subunit of the sodium-potassium ATPase, one of two isoforms responsible for powering electrochemical gradients in neurons. Heterozygous pathogenic...
ATP1A3 encodes the α3 subunit of the sodium-potassium ATPase, one of two isoforms responsible for powering electrochemical gradients in neurons. Heterozygous pathogenic ATP1A3 variants produce several distinct neurological syndromes, yet the molecular basis for phenotypic variability is unclear. We report a novel recurrent variant, ATP1A3(NM_152296.5):c.2324C>T; p.(Pro775Leu), in nine individuals associated with the primary clinical features of progressive or non-progressive spasticity and developmental delay/intellectual disability. No patients fulfil diagnostic criteria for ATP1A3-associated syndromes, including alternating hemiplegia of childhood, rapid-onset dystonia-parkinsonism or cerebellar ataxia-areflexia-pes cavus-optic atrophy-sensorineural hearing loss (CAPOS), and none were suspected of having an ATP1A3-related disorder. Uniquely among known ATP1A3 variants, P775L causes leakage of sodium ions and protons into the cell, associated with impaired sodium binding/occlusion kinetics favouring states with fewer bound ions. These phenotypic and electrophysiologic studies demonstrate that ATP1A3:c.2324C>T; p.(Pro775Leu) results in mild ATP1A3-related phenotypes resembling complex hereditary spastic paraplegia or idiopathic spastic cerebral palsy. Cation leak provides a molecular explanation for this genotype-phenotype correlation, adding another mechanism to further explain phenotypic variability and highlighting the importance of biophysical properties beyond ion transport rate in ion transport diseases.
Topics: Humans; Mutation; Syndrome; Intellectual Disability; Cerebellar Ataxia; Phenotype; Muscle Spasticity; Cations; Sodium-Potassium-Exchanging ATPase
PubMed: 37043503
DOI: 10.1093/brain/awad124 -
International Journal of Molecular... Dec 2023Dysrhythmia is a term referring to the occurrence of spontaneous and repetitive changes in potentials with parameters deviating from those considered normal. The term... (Review)
Review
Dysrhythmia is a term referring to the occurrence of spontaneous and repetitive changes in potentials with parameters deviating from those considered normal. The term refers to heart anomalies but has a broader meaning. Dysrhythmias may concern the heart, neurological system, digestive system, and sensory organs. Ion currents conducted through ion channels are a universal phenomenon. The occurrence of channel abnormalities will therefore result in disorders with clinical manifestations depending on the affected tissue, but phenomena from other tissues and organs may also manifest themselves. A similar problem concerns the implementation of pharmacotherapy, the mechanism of which is related to the impact on various ion currents. Treatment in this case may cause unfavorable effects on other tissues and organs. Drugs acting through the modulation of ion currents are characterized by relatively low tissue specificity. To assess a therapy's efficacy and safety, the risk of occurrences in other tissues with similar mechanisms of action must be considered. In the present review, the focus is shifted prominently onto a comparison of abnormal electrical activity within different tissues and organs. This review includes an overview of the types of dysrhythmias and the basic techniques of clinical examination of electrophysiological disorders. It also presents a concise overview of the available pharmacotherapy in particular diseases. In addition, the authors review the relevant ion channels and their research technique based on patch clumping.
Topics: Humans; Arrhythmias, Cardiac; Heart; Ion Transport; Research Design; Ion Channels
PubMed: 38203440
DOI: 10.3390/ijms25010263 -
Cell Calcium Jul 2024Calcium (Ca) is a secondary messenger that regulates various cellular processes. However, Ca mishandling could lead to pathological conditions. Orai1 is a Cachannel... (Review)
Review
Calcium (Ca) is a secondary messenger that regulates various cellular processes. However, Ca mishandling could lead to pathological conditions. Orai1 is a Cachannel contributing to the store-operated calcium entry (SOCE) and plays a critical role in Ca homeostasis in several cell types. Dysregulation of Orai1 contributed to severe combined immune deficiency syndrome, some cancers, pulmonary arterial hypertension (PAH), and other cardiorespiratory diseases. During its activation process, Orai1 is mainly regulated by stromal interacting molecule (STIM) proteins, especially STIM1; however, many other regulatory partners have also been recently described. Increasing knowledge about these regulatory partners provides a better view of the downstream signalling pathways of SOCE and offers an excellent opportunity to decipher Orai1 dysregulation in these diseases. These proteins participate in other cellular functions, making them attractive therapeutic targets. This review mainly focuses on Orai1 regulatory partners in the physiological and pathological conditions of the pulmonary circulation and inflammation.
Topics: Humans; ORAI1 Protein; Animals; Stromal Interaction Molecules; Calcium Signaling; Calcium; Vascular Diseases
PubMed: 38735127
DOI: 10.1016/j.ceca.2024.102892 -
Proceedings of the National Academy of... Nov 2023Regulation of stem cells requires coordination of the cells that make up the stem cell niche. Here, we describe a mechanism that allows communication between niche cells...
Regulation of stem cells requires coordination of the cells that make up the stem cell niche. Here, we describe a mechanism that allows communication between niche cells to coordinate their activity and shape the signaling environment surrounding resident stem cells. Using the hematopoietic organ, the lymph gland, we show that cells of the hematopoietic niche, the posterior signaling center (PSC), communicate using gap junctions (GJs) and form a signaling network. This network allows PSC cells to exchange Ca signals repetitively which regulate the hematopoietic niche. Disruption of Ca signaling in the PSC or the GJ-mediated network connecting niche cells causes dysregulation of the PSC and blood progenitor differentiation. Analysis of PSC-derived cell signaling shows that the Hedgehog pathway acts downstream of GJ-mediated Ca signaling to modulate the niche microenvironment. These data show that GJ-mediated communication between hematopoietic niche cells maintains their homeostasis and consequently controls blood progenitor behavior.
Topics: Animals; Drosophila Proteins; Hematopoietic Stem Cells; Calcium Signaling; Hedgehog Proteins; Drosophila; Cell Differentiation; Gap Junctions; Homeostasis; Stem Cell Niche; Hematopoiesis
PubMed: 37903259
DOI: 10.1073/pnas.2303018120 -
Neurobiology of Disease Jul 2023Fluid homeostasis is fundamental for brain function with cerebral edema and hydrocephalus both being major neurological conditions. Fluid movement from blood into brain... (Review)
Review
Fluid homeostasis is fundamental for brain function with cerebral edema and hydrocephalus both being major neurological conditions. Fluid movement from blood into brain is one crucial element in cerebral fluid homeostasis. Traditionally it has been thought to occur primarily at the choroid plexus (CP) as cerebrospinal fluid (CSF) secretion due to polarized distribution of ion transporters at the CP epithelium. However, there are currently controversies as to the importance of the CP in fluid secretion, just how fluid transport occurs at that epithelium versus other sites, as well as the direction of fluid flow in the cerebral ventricles. The purpose of this review is to evaluate evidence on the movement of fluid from blood to CSF at the CP and the cerebral vasculature and how this differs from other tissues, e.g., how ion transport at the blood-brain barrier as well as the CP may drive fluid flow. It also addresses recent promising data on two potential targets for modulating CP fluid secretion, the Na/K/Cl cotransporter, NKCC1, and the non-selective cation channel, transient receptor potential vanilloid 4 (TRPV4). Finally, it raises the issue that fluid secretion from blood is not constant, changing with disease and during the day. The apparent importance of NKCC1 phosphorylation and TRPV4 activity at the CP in determining fluid movement suggests that such secretion may also vary over short time frames. Such dynamic changes in CP (and potentially blood-brain barrier) function may contribute to some of the controversies over its role in brain fluid secretion.
Topics: Extracellular Fluid; TRPV Cation Channels; Brain; Blood-Brain Barrier; Cerebral Ventricles; Choroid Plexus
PubMed: 37209923
DOI: 10.1016/j.nbd.2023.106159