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Trus M, Atlas D. Non-ionotropic voltage-gated calcium channel signaling. Channels (Austin) 2024; 18:2341077. [PMID: 38601983 PMCID: PMC11017947 DOI: 10.1080/19336950.2024.2341077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 04/04/2024] [Indexed: 04/12/2024] Open
Abstract
Voltage-gated calcium channels (VGCCs) are the major conduits for calcium ions (Ca2+) within excitable cells. Recent studies have highlighted the non-ionotropic functionality of VGCCs, revealing their capacity to activate intracellular pathways independently of ion flow. This non-ionotropic signaling mode plays a pivotal role in excitation-coupling processes, including gene transcription through excitation-transcription (ET), synaptic transmission via excitation-secretion (ES), and cardiac contraction through excitation-contraction (EC). However, it is noteworthy that these excitation-coupling processes require extracellular calcium (Ca2+) and Ca2+ occupancy of the channel ion pore. Analogous to the "non-canonical" characterization of the non-ionotropic signaling exhibited by the N-methyl-D-aspartate receptor (NMDA), which requires extracellular Ca2+ without the influx of ions, VGCC activation requires depolarization-triggered conformational change(s) concomitant with Ca2+ binding to the open channel. Here, we discuss the contributions of VGCCs to ES, ET, and EC coupling as Ca2+ binding macromolecules that transduces external stimuli to intracellular input prior to elevating intracellular Ca2+. We emphasize the recognition of calcium ion occupancy within the open ion-pore and its contribution to the excitation coupling processes that precede the influx of calcium. The non-ionotropic activation of VGCCs, triggered by the upstroke of an action potential, provides a conceptual framework to elucidate the mechanistic aspects underlying the microseconds nature of synaptic transmission, cardiac contractility, and the rapid induction of first-wave genes.
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Affiliation(s)
- Michael Trus
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Daphne Atlas
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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2
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McCarthy CI, Kavalali ET. Nano-organization of synaptic calcium signaling. Biochem Soc Trans 2024; 52:1459-1471. [PMID: 38752834 DOI: 10.1042/bst20231385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/17/2024] [Accepted: 05/03/2024] [Indexed: 06/27/2024]
Abstract
Recent studies suggest an exquisite structural nano-organization within single synapses, where sites of evoked fusion - marked by clustering of synaptic vesicles, active zone proteins and voltage-gated calcium channels - are directly juxtaposed to postsynaptic receptor clusters within nanocolumns. This direct nanometer scale alignment between presynaptic fusion apparatus and postsynaptic receptors is thought to ensure the fidelity of synaptic signaling and possibly allow multiple distinct signals to occur without interference from each other within a single active zone. The functional specificity of this organization is made possible by the inherent nano-organization of calcium signals, where all the different calcium sources such as voltage-gated calcium channels, intracellular stores and store-operated calcium entry have dedicated local targets within their nanodomain to ensure precision of action. Here, we discuss synaptic nano-organization from the perspective of calcium signals, where some of the principal findings from early work in the 1980s continue to inspire current studies that exploit new genetic tools and super-resolution imaging technologies.
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Affiliation(s)
- Clara I McCarthy
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, U.S.A
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, U.S.A
| | - Ege T Kavalali
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, U.S.A
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, U.S.A
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3
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Szabo B. Presynaptic Adrenoceptors. Handb Exp Pharmacol 2024. [PMID: 38755350 DOI: 10.1007/164_2024_714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Presynaptic α2-adrenoceptors are localized on axon terminals of many noradrenergic and non-noradrenergic neurons in the peripheral and central nervous systems. Their activation by exogenous agonists leads to inhibition of the exocytotic release of noradrenaline and other transmitters from the neurons. Most often, the α2A-receptor subtype is involved in this inhibition. The chain of molecular events between receptor occupation and inhibition of the exocytotic release of transmitters has been determined. Physiologically released endogenous noradrenaline elicits retrograde autoinhibition of its own release. Some clonidine-like α2-receptor agonists have been used to treat hypertension. Dexmedetomidine is used for prolonged sedation in the intensive care; It also has a strong analgesic effect. The α2-receptor antagonist mirtazapine increases the noradrenaline concentration in the synaptic cleft by interrupting physiological autoinhibion of release. It belongs to the most effective antidepressive drugs. β2-Adrenoceptors are also localized on axon terminals in the peripheral and central nervous systems. Their activation leads to enhanced transmitter release, however, they are not activated by endogenous adrenaline.
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Affiliation(s)
- Bela Szabo
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.
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4
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Sun X, Yazejian B, Peskoff A, Grinnell AD. Experimentally monitored calcium dynamics at synaptic active zones during neurotransmitter release in neuron-muscle cell cultures. Eur J Neurosci 2024; 59:2293-2319. [PMID: 38483240 DOI: 10.1111/ejn.16289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 01/04/2024] [Accepted: 02/01/2024] [Indexed: 05/08/2024]
Abstract
Ca2+-dependent K+ (BK) channels at varicosities in Xenopus nerve-muscle cell cultures were used to quantify experimentally the instantaneous active zone [Ca2+]AZ resulting from different rates and durations of Ca2+ entry in the absence of extrinsic buffers and correlate this with neurotransmitter release. Ca2+ tail currents produce mean peak [Ca2+]AZ ~ 30 μM; with continued influx, [Ca2+]AZ reaches ~45-60 μM at different rates depending on Ca2+ driving force and duration of influx. Both IBK and release are dependent on Ca2+ microdomains composed of both N- and L-type Ca channels. Domains collapse with a time constant of ~0.6 ms. We have constructed an active zone (AZ) model that approximately fits this data, and depends on incorporation of the high-capacity, low-affinity fixed buffer represented by phospholipid charges in the plasma membrane. Our observations suggest that in this preparation, (1) some BK channels, but few if any of the Ca2+ sensors that trigger release, are located within Ca2+ nanodomains while a large fraction of both are located far enough from Ca channels to be blockable by EGTA, (2) the IBK is more sensitive than the excitatory postsynaptic current (EPSC) to [Ca2+]AZ (K1/2-26 μM vs. ~36 μM [Ca2+]AZ); (3) with increasing [Ca2+]AZ, the IBK grows with a Hill coefficient of 2.5, the EPSC with a coefficient of 3.9; (4) release is dependent on the highest [Ca2+] achieved, independent of the time to reach it; (5) the varicosity synapses differ from mature frog nmjs in significant ways; and (6) BK channels are useful reporters of local [Ca2+]AZ.
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Affiliation(s)
- Xiaoping Sun
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Bruce Yazejian
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Arthur Peskoff
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Alan D Grinnell
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
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Scala M, Khan K, Beneteau C, Fox RG, von Hardenberg S, Khan A, Joubert M, Fievet L, Musquer M, Le Vaillant C, Holsclaw JK, Lim D, Berking AC, Accogli A, Giacomini T, Nobili L, Striano P, Zara F, Torella A, Nigro V, Cogné B, Salick MR, Kaykas A, Eggan K, Capra V, Bézieau S, Davis EE, Wells MF. Biallelic loss-of-function variants in CACHD1 cause a novel neurodevelopmental syndrome with facial dysmorphism and multisystem congenital abnormalities. Genet Med 2024; 26:101057. [PMID: 38158856 DOI: 10.1016/j.gim.2023.101057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 12/22/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024] Open
Abstract
PURPOSE We established the genetic etiology of a syndromic neurodevelopmental condition characterized by variable cognitive impairment, recognizable facial dysmorphism, and a constellation of extra-neurological manifestations. METHODS We performed phenotypic characterization of 6 participants from 4 unrelated families presenting with a neurodevelopmental syndrome and used exome sequencing to investigate the underlying genetic cause. To probe relevance to the neurodevelopmental phenotype and craniofacial dysmorphism, we established two- and three-dimensional human stem cell-derived neural models and generated a stable cachd1 zebrafish mutant on a transgenic cartilage reporter line. RESULTS Affected individuals showed mild cognitive impairment, dysmorphism featuring oculo-auriculo abnormalities, and developmental defects involving genitourinary and digestive tracts. Exome sequencing revealed biallelic putative loss-of-function variants in CACHD1 segregating with disease in all pedigrees. RNA sequencing in CACHD1-depleted neural progenitors revealed abnormal expression of genes with key roles in Wnt signaling, neurodevelopment, and organ morphogenesis. CACHD1 depletion in neural progenitors resulted in reduced percentages of post-mitotic neurons and enlargement of 3D neurospheres. Homozygous cachd1 mutant larvae showed mandibular patterning defects mimicking human facial dysmorphism. CONCLUSION Our findings support the role of loss-of-function variants in CACHD1 as the cause of a rare neurodevelopmental syndrome with facial dysmorphism and multisystem abnormalities.
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Affiliation(s)
- Marcello Scala
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy; Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, University of Genoa, Genoa, Italy; Medical Genetics Unit, IRCCS Giannina Gaslini Institute, Genoa, Italy
| | - Kamal Khan
- Stanley Manne Children's Research Institute, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL
| | - Claire Beneteau
- CHU Nantes, Department of Medical Genetics, CHU Nantes, 9 quai Moncousu, Nantes, France; CHU Nantes, UF of Fœtopathology and Genetics, Nantes, France; CHU de Bordeaux, Service de Génétique Médicale, Bordeaux, France
| | - Rachel G Fox
- Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA
| | | | - Ayaz Khan
- Stanley Manne Children's Research Institute, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL
| | - Madeleine Joubert
- CHU Nantes, UF of Fœtopathology and Genetics, Nantes, France; CHU Nantes, Department of Anatomical Pathology, Nantes, France
| | - Lorraine Fievet
- Center for Human Disease Modeling, Duke University Medical Center, Durham, NC
| | - Marie Musquer
- CHU Nantes, UF of Fœtopathology and Genetics, Nantes, France; CHU Nantes, Department of Anatomical Pathology, Nantes, France
| | | | | | - Derek Lim
- Department of Clinical Genetics, Birmingham Women's and Children's NHS Foundation Trust and Birmingham Health Partners, Birmingham, United Kingdom; Department of Medicine, University of Birmingham, Birmingham, United Kingdom
| | | | - Andrea Accogli
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Thea Giacomini
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy; Child Neuropsychiatry Unit, IRCCS G. Gaslini Institute, Genoa, Italy
| | - Lino Nobili
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy; Child Neuropsychiatry Unit, IRCCS G. Gaslini Institute, Genoa, Italy
| | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy; Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, University of Genoa, Genoa, Italy
| | - Federico Zara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy; Medical Genetics Unit, IRCCS Giannina Gaslini Institute, Genoa, Italy
| | - Annalaura Torella
- Department of Precision Medicine, University of Campania "Luigi Vanvitelli," Naples, Italy; Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Vincenzo Nigro
- Department of Precision Medicine, University of Campania "Luigi Vanvitelli," Naples, Italy; Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Benjamin Cogné
- CHU Nantes, Department of Medical Genetics, CHU Nantes, 9 quai Moncousu, Nantes, France; Nantes Université, CHU de Nantes, CNRS, INSERM, l'institut du thorax, Nantes, France
| | | | | | - Kevin Eggan
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA
| | - Valeria Capra
- Medical Genetics Unit, IRCCS Giannina Gaslini Institute, Genoa, Italy
| | - Stéphane Bézieau
- CHU Nantes, Department of Medical Genetics, CHU Nantes, 9 quai Moncousu, Nantes, France; Nantes Université, CHU de Nantes, CNRS, INSERM, l'institut du thorax, Nantes, France
| | - Erica E Davis
- Stanley Manne Children's Research Institute, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL; Department of Pediatrics and Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
| | - Michael F Wells
- Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA; Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA.
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Chichorro JG, Gambeta E, Baggio DF, Zamponi GW. Voltage-gated Calcium Channels as Potential Therapeutic Targets in Migraine. THE JOURNAL OF PAIN 2024:104514. [PMID: 38522594 DOI: 10.1016/j.jpain.2024.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 03/06/2024] [Accepted: 03/12/2024] [Indexed: 03/26/2024]
Abstract
Migraine is a complex and highly incapacitating neurological disorder that affects around 15% of the general population with greater incidence in women, often at the most productive age of life. Migraine physiopathology is still not fully understood, but it involves multiple mediators and events in the trigeminovascular system and the central nervous system. The identification of calcitonin gene-related peptide as a key mediator in migraine physiopathology has led to the development of effective and highly selective antimigraine therapies. However, this treatment is neither accessible nor effective for all migraine sufferers. Thus, a better understanding of migraine mechanisms and the identification of potential targets are still clearly warranted. Voltage-gated calcium channels (VGCCs) are widely distributed in the trigeminovascular system, and there is accumulating evidence of their contribution to the mechanisms associated with headache pain. Several drugs used in migraine abortive or prophylactic treatment target VGCCs, which probably contributes to their analgesic effect. This review aims to summarize the current evidence of VGGC contribution to migraine physiopathology and to discuss how current pharmacological options for migraine treatment interfere with VGGC function. PERSPECTIVE: Calcitonin gene-related peptide (CGRP) represents a major migraine mediator, but few studies have investigated the relationship between CGRP and VGCCs. CGRP release is calcium channel-dependent and VGGCs are key players in familial migraine. Further studies are needed to determine whether VGCCs are suitable molecular targets for treating migraine.
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Affiliation(s)
- Juliana G Chichorro
- Biological Sciences Sector, Department of Pharmacology, Federal University of Parana, Curitiba, Parana, Brazil.
| | - Eder Gambeta
- Cumming School of Medicine, Department of Clinical Neuroscience, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Darciane F Baggio
- Biological Sciences Sector, Department of Pharmacology, Federal University of Parana, Curitiba, Parana, Brazil
| | - Gerald W Zamponi
- Cumming School of Medicine, Department of Clinical Neuroscience, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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7
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Blömer LA, Giacalone E, Abbas F, Filipis L, Tegolo D, Migliore M, Canepari M. Kinetics and functional consequences of BK channels activation by N-type Ca 2+ channels in the dendrite of mouse neocortical layer-5 pyramidal neurons. Front Cell Neurosci 2024; 18:1353895. [PMID: 38419657 PMCID: PMC10899506 DOI: 10.3389/fncel.2024.1353895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 01/24/2024] [Indexed: 03/02/2024] Open
Abstract
The back-propagation of an action potential (AP) from the axon/soma to the dendrites plays a central role in dendritic integration. This process involves an intricate orchestration of various ion channels, but a comprehensive understanding of the contribution of each channel type remains elusive. In this study, we leverage ultrafast membrane potential recordings (Vm) and Ca2+ imaging techniques to shed light on the involvement of N-type voltage-gated Ca2+ channels (VGCCs) in layer-5 neocortical pyramidal neurons' apical dendrites. We found a selective interaction between N-type VGCCs and large-conductance Ca2+-activated K+ channels (BK CAKCs). Remarkably, we observe that BK CAKCs are activated within a mere 500 μs after the AP peak, preceding the peak of the Ca2+ current triggered by the AP. Consequently, when N-type VGCCs are inhibited, the early broadening of the AP shape amplifies the activity of other VGCCs, leading to an augmented total Ca2+ influx. A NEURON model, constructed to replicate and support these experimental results, reveals the critical coupling between N-type and BK channels. This study not only redefines the conventional role of N-type VGCCs as primarily involved in presynaptic neurotransmitter release but also establishes their distinct and essential function as activators of BK CAKCs in neuronal dendrites. Furthermore, our results provide original functional validation of a physical interaction between Ca2+ and K+ channels, elucidated through ultrafast kinetic reconstruction. This insight enhances our understanding of the intricate mechanisms governing neuronal signaling and may have far-reaching implications in the field.
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Affiliation(s)
- Laila Ananda Blömer
- LIPhy, CNRS, Université Grenoble Alpes, Grenoble, France
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France
| | - Elisabetta Giacalone
- Institute of Biophysics, National Research Council, Palermo, Italy
- Dipartimento Matematica e Informatica, Universitá degli Studi di Palermo, Palermo, Italy
| | - Fatima Abbas
- LIPhy, CNRS, Université Grenoble Alpes, Grenoble, France
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France
| | - Luiza Filipis
- LIPhy, CNRS, Université Grenoble Alpes, Grenoble, France
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France
| | - Domenico Tegolo
- Dipartimento Matematica e Informatica, Universitá degli Studi di Palermo, Palermo, Italy
| | - Michele Migliore
- Institute of Biophysics, National Research Council, Palermo, Italy
| | - Marco Canepari
- LIPhy, CNRS, Université Grenoble Alpes, Grenoble, France
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France
- Institut National de la Santé et Recherche Médicale, Paris, France
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Oh KH, Xiong A, Choe JY, Richmond JE, Kim H. Active Zone Trafficking of CaV2/UNC-2 Channels Is Independent of β/CCB-1 and α2δ/UNC-36 Subunits. J Neurosci 2023; 43:5142-5157. [PMID: 37160370 PMCID: PMC10343168 DOI: 10.1523/jneurosci.2264-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 03/28/2023] [Accepted: 05/02/2023] [Indexed: 05/11/2023] Open
Abstract
The CaV2 voltage-gated calcium channel is the major conduit of calcium ions necessary for neurotransmitter release at presynaptic active zones (AZs). The CaV2 channel is a multimeric complex that consists of a pore-forming α1 subunit and two auxiliary β and α2δ subunits. Although auxiliary subunits are critical for channel function, whether they are required for α1 trafficking is unresolved. Using endogenously fluorescent protein-tagged CaV2 channel subunits in Caenorhabditis elegans, we show that UNC-2/α1 localizes to AZs even in the absence of CCB-1/β or UNC-36/α2δ, albeit at low levels. When UNC-2 is manipulated to be trapped in the endoplasmic reticulum (ER), CCB-1 and UNC-36 fail to colocalize with UNC-2 in the ER, indicating that they do not coassemble with UNC-2 in the ER. Moreover, blocking ER-associated degradation does not further increase presynaptic UNC-2 channels in ccb-1 or unc-36 mutants, indicating that UNC-2 levels are not regulated in the ER. An unc-2 mutant lacking C-terminal AZ protein interaction sites with intact auxiliary subunit binding sites displays persistent presynaptic UNC-2 localization and a prominent increase of UNC-2 channels in nonsynaptic axonal regions, underscoring a protective role of auxiliary subunits against UNC-2 degradation. In the absence of UNC-2, presynaptic CCB-1 and UNC-36 are profoundly diminished to barely detectable levels, indicating that UNC-2 is required for the presynaptic localization of CCB-1 and UNC-36. Together, our findings demonstrate that although the pore-forming subunit does not require auxiliary subunits for its trafficking and transport to AZs, it recruits auxiliary subunits to stabilize and expand calcium channel signalosomes.SIGNIFICANCE STATEMENT Synaptic transmission in the neuron hinges on the coupling of synaptic vesicle exocytosis with calcium influx. This calcium influx is mediated by CaV2 voltage-gated calcium channels. These channels consist of one pore-forming α1 subunit and two auxiliary β and α2δ subunits. The auxiliary subunits enhance channel function and regulate the overall level of channels at presynaptic terminals. However, it is not settled how these auxiliary subunits regulate the overall channel level. Our study in C. elegans finds that although the auxiliary subunits do not coassemble with α1 and aid trafficking, they are recruited to α1 and stabilize the channel complex at presynaptic terminals. Our study suggests that drugs that target the auxiliary subunits can directly destabilize and have an impact on CaV2 channels.
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Affiliation(s)
- Kelly H Oh
- Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064
| | - Ame Xiong
- Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064
| | - Jun-Yong Choe
- Department of Chemistry, East Carolina University, Greenville, North Carolina 27858
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois, Chicago, Illinois 60607
| | - Hongkyun Kim
- Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064
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9
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Corzo-López A, Leyva-Leyva M, Castillo-Viveros V, Fernández-Gallardo M, Muñoz-Herrera D, Sandoval A, González-Ramírez R, Felix R. Molecular mechanisms of nuclear transport of the neuronal voltage-gated Ca 2+ channel β 3 auxiliary subunit. Neuroscience 2023:S0306-4522(23)00181-1. [PMID: 37169165 DOI: 10.1016/j.neuroscience.2023.04.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 04/01/2023] [Accepted: 04/19/2023] [Indexed: 05/13/2023]
Abstract
Previous studies have shown that in addition to its role within the voltage-gated calcium channel complex in the plasma membrane, the neuronal CaVβ subunit can translocate to the cell nucleus. However, little is known regarding the role this protein could play in the nucleus, nor the molecular mechanism used by CaVβ to enter this cell compartment. This report shows evidence that CaVβ3 has nuclear localization signals (NLS) that are not functional, suggesting that the protein does not use a classical nuclear import pathway. Instead, its entry into the nucleus could be associated with another protein that would function as a carrier, using a mechanism known as a piggyback. Mass spectrometry assays and bioinformatic analysis allowed the identification of proteins that could be participating in the entry of CaVβ3 into the nucleus. Likewise, through proximity ligation assays (PLA), it was found that members of the heterogeneous nuclear ribonucleoproteins (hnRNPs) and B56δ, a regulatory subunit of the protein phosphatase 2A (PP2A), could function as proteins that regulate this piggyback mechanism. On the other hand, bioinformatics and site-directed mutagenesis assays allowed the identification of a functional nuclear export signal (NES) that controls the exit of CaVβ3 from the nucleus, which would allow the completion of the nuclear transport cycle of the protein. These results reveal a novel mechanism for the nuclear transport cycle of the neuronal CaVβ3 subunit.
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Affiliation(s)
- Alejandra Corzo-López
- Department of Cell Biology, Centre for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - Margarita Leyva-Leyva
- Department of Molecular Biology and Histocompatibility, "Dr. Manuel Gea González" General Hospital, Mexico City, Mexico
| | - Valeria Castillo-Viveros
- Department of Cell Biology, Centre for Research and Advanced Studies (Cinvestav), Mexico City, Mexico; Department of Developmental Genetics and Molecular Physiology, Institute of Biotechnology, National Autonomous University of Mexico, Cuernavaca, Mexico
| | | | - David Muñoz-Herrera
- Department of Cell Biology, Centre for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - Alejandro Sandoval
- School of Medicine FES Iztacala, National Autonomous University of Mexico (UNAM), Tlalnepantla, Mexico
| | - Ricardo González-Ramírez
- Department of Molecular Biology and Histocompatibility, "Dr. Manuel Gea González" General Hospital, Mexico City, Mexico
| | - Ricardo Felix
- Department of Cell Biology, Centre for Research and Advanced Studies (Cinvestav), Mexico City, Mexico.
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10
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Alekseeva MG, Dyakov IN, Bushkova KK, Mavletova DA, Yunes RA, Chernyshova IN, Masalitin IA, Koshenko TA, Nezametdinova VZ, Danilenko VN. Study of the binding of ΔFN3.1 fragments of the Bifidobacterium longum GT15 with TNFα and prevalence of domain-containing proteins in groups of bacteria of the human gut microbiota. MICROBIOME RESEARCH REPORTS 2023; 2:10. [PMID: 38047275 PMCID: PMC10688814 DOI: 10.20517/mrr.2023.06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/25/2023] [Accepted: 03/31/2023] [Indexed: 12/05/2023]
Abstract
Aim: This study is mainly devoted to determining the ability of ∆FN3.1 protein fragments of Bifidobacterium (B.) longum subsp. longum GT15, namely two FN3 domains (2D FN3) and a C-terminal domain (CD FN3), to bind to tumor necrosis factor-alpha (TNF-α). Methods: Fragments of the fn3 gene encoding the 2D FN3 and CD FN3 were cloned in Escherichia (E.) coli. In order to assess the binding specificity between 2D FN3 and CD FN3 to TNFα, we employed the previously developed sandwich ELISA system to detect any specific interactions between the purified protein and any of the studied cytokines. The trRosetta software was used to build 3D models of the ∆FN3.1, 2D FN3, and CD FN3 proteins. The detection of polymorphism in the amino acid sequences of the studied proteins and the analysis of human gut-derived bacterial proteins carrying FN3 domains were performed in silico. Results: We experimentally showed that neither 2D FN3 nor CD FN3 alone can bind to TNFα. Prediction of the 3D structures of ΔFN3.1, 2D FN3, and CD FN3 suggested that only ΔFN3.1 can form a pocket allowing binding with TNFα to occur. Polymorphism analysis of amino acid sequences of ΔFN3.1 proteins in B. longum strains uncovered substitutions that can alter the conformation of the spatial structure of the ΔFN3.1 protein. We also analyzed human gut-derived bacterial proteins harboring FN3 domains which allowed us to differentiate between those containing motifs of cytokine receptors (MCRs) in their FN3 domains and those lacking them. Conclusion: Only the complete ∆FN3.1 protein can selectively bind to TNFα. Analysis of 3D models of the 2D FN3, CD FN3, and ΔFN3.1 proteins showed that only the ΔFN3.1 protein is potentially capable of forming a pocket allowing TNFα binding to occur. Only FN3 domains containing MCRs exhibited sequence homology with FN3 domains of human proteins.
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Affiliation(s)
- Maria G. Alekseeva
- Laboratory of Genetics of Microorganisms, Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia
| | - Ilya N. Dyakov
- Laboratory of Immunoglobulin biosynthesis, Mechnikov Research Institute of Vaccines and Sera, Moscow 105064, Russia
| | - Kristina K. Bushkova
- Laboratory of Immunoglobulin biosynthesis, Mechnikov Research Institute of Vaccines and Sera, Moscow 105064, Russia
| | - Dilara A. Mavletova
- Laboratory of Genetics of Microorganisms, Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia
| | - Roman A. Yunes
- Laboratory of Genetics of Microorganisms, Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia
| | - Irina N. Chernyshova
- Laboratory of Immunoglobulin biosynthesis, Mechnikov Research Institute of Vaccines and Sera, Moscow 105064, Russia
| | - Ilya A. Masalitin
- Laboratory of Immunoglobulin biosynthesis, Mechnikov Research Institute of Vaccines and Sera, Moscow 105064, Russia
| | - Tatiana A. Koshenko
- Laboratory of Genetics of Microorganisms, Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia
| | - Venera Z. Nezametdinova
- Laboratory of Genetics of Microorganisms, Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia
| | - Valery N. Danilenko
- Laboratory of Genetics of Microorganisms, Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia
- Caspian International School of Medicine, Caspian University, Almaty 050000, Kazakhstan
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11
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Chen X, Chen S, Li Z, Zhu R, Jia Z, Ban J, Zhen R, Chen X, Pan X, Ren Q, Yue L, Niu S. Effect of semaglutide and empagliflozin on cognitive function and hippocampal phosphoproteomic in obese mice. Front Pharmacol 2023; 14:975830. [PMID: 37007007 PMCID: PMC10063902 DOI: 10.3389/fphar.2023.975830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 03/03/2023] [Indexed: 03/19/2023] Open
Abstract
Objective: Based on the 4D label-free phosphoproteomic technique, we examined the differences in cognitive function and hippocampal phosphorylated protein expression in high-fat diet-induced obese mice after the intervention of semaglutide and empagliflozin, as well as the effects of both on protein activity and function in obese mice’s hippocampal tissues and the signaling pathways involved.Methods: Thirty-two C57BL/6JC male mice were assigned to two groups randomly: A control group (group C, 10% of energy is from fat, n = 8) and a high-fat diet group (group H, 60% of energy is from fat, n = 24). The high-fat diet-induced obese mice were screened after 12 weeks of feeding based on the criterion that the bodyweight of mice in fat rich diet group was greater than or equal to 20% of the average body weight of the mice in the blank control group. Group H separate into group H (n = 8), group Semaglutide (group S, n = 8), and group empagliflozin (group E, n = 8). For a total of 12 weeks, group S received 30 nmol/kg/d bodyweight of semaglutide intraperitoneally, group E received 10 mg/kg/d bodyweight of empagliflozin via gavage, and groups C and H received equal amounts of saline by intraperitoneal injection and gavage. At the end of treatment, the mice were appraised for cognitive function employing the Morris water maze (MWM), and serum fasting glucose, lipids, and inflammatory parameters were measured. The 4D label-free phosphoproteomics method was employed to screen the differential phosphoproteins and loci in hippocampal tissues of mice in different treatment groups, and bioinformatics was used to analyze the biological processes, signaling pathways, and related protein–protein interaction (PPI) network analysis of these differentially phosphorylated proteins.Results: In comparison to normal controls, The escape latency of obese mice induced by high-fat diet was prolonged, the percentage of swimming time in the target quadrant was reduced, and the number of times of crossing the platform was reduced, whereas semaglutide and empagliflozin treatment reduced escape latency, increase the percentage of swim time in the target quadrant and increase the frequency of passing through the platform area, although there is little difference in the effect of the two drugs. The phosphoproteomic results showed 20,493 unique phosphorylated peptides, representing 21,239 phosphorylation sites and 4,290 phosphorylated proteins. Further analysis revealed that the proteins corresponding to these differentially phosphorylated sites are jointly distributed in signaling pathways such as dopaminergic synapses and axon guidance, and are involved in biological processes such as neuronal projection development, synaptic plasticity, and axonogenesis. Notably, the key factors voltage-dependent L-type calcium channel subunit alpha-1D (CACNA1D), voltage-dependent P/Q-type calcium channel subunit alpha-1A (CACNA1A), and voltage-dependent N-type calcium channel subunit alpha-1B (CACNA1B) were all found to be involved in the dopaminergic synapse pathway, and their expression was upregulated by semaglutide and empagliflozin.Conclusion: We found for the first time that a high-fat diet decreased CACNA1D, CACNA1A, and CACNA1B protein serine phosphorylation, which may affect neuronal development, synaptic plasticity, and cognitive function in mice. Notably, semaglutide and empagliflozin increased the phosphorylation of these proteins.
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Affiliation(s)
- Xiaoyi Chen
- Department of Internal Medicine, Hebei North University, Zhangjiakou, China
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
| | - Shuchun Chen
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- *Correspondence: Shuchun Chen,
| | - Zelin Li
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
| | - Ruiyi Zhu
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
| | - Zhuoya Jia
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
| | - Jiangli Ban
- Department of Internal Medicine, Hebei North University, Zhangjiakou, China
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
| | - Ruoxi Zhen
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
| | - Xing Chen
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
| | - Xiaoyu Pan
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
| | - Qingjuan Ren
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
| | - Lin Yue
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
| | - Shu Niu
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
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12
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Török F, Tezcan K, Filippini L, Fernández-Quintero ML, Zanetti L, Liedl KR, Drexel RS, Striessnig J, Ortner NJ. Germline de novo variant F747S extends the phenotypic spectrum of CACNA1D Ca2+ channelopathies. Hum Mol Genet 2023; 32:847-859. [PMID: 36208199 PMCID: PMC9941835 DOI: 10.1093/hmg/ddac248] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/22/2022] [Accepted: 09/30/2022] [Indexed: 11/14/2022] Open
Abstract
Germline gain-of-function missense variants in the pore-forming Cav1.3 α1-subunit (CACNA1D gene) confer high risk for a severe neurodevelopmental disorder with or without endocrine symptoms. Here, we report a 4-week-old new-born with the novel de novo missense variant F747S with a so far not described prominent jittering phenotype in addition to symptoms previously reported for CACNA1D mutations including developmental delay, elevated aldosterone level and transient hypoglycemia. We confirmed the pathogenicity of this variant in whole-cell patch-clamp experiments with wild-type and F747S mutant channels heterologously expressed together with α2δ1 and cytosolic β3 or membrane-bound β2a subunits. Mutation F747S caused the quantitatively largest shift in the voltage dependence of activation (-28 mV) reported so far for CACNA1D germline mutations. It also shifted inactivation to more negative voltages, slowed the time course of current inactivation and slowed current deactivation upon repolarization with both co-expressed β-subunits. In silico modelling and molecular docking, simulations revealed that this gain-of-function phenotype can be explained by formation of a novel inter-domain hydrogen bond between mutant residues S747 (IIS6) with N1145 (IIIS6) stabilizing selectively the activated open channel state. F747S displayed 2-6-fold increased sensitivity for the L-type Ca2+ channel blocker isradipine compared to wild type. Our data confirm the pathogenicity of the F747S variant with very strong gain-of-function gating changes, which may contribute to the novel jittering phenotype. Increased sensitivity for isradipine suggests this drug for potential symptomatic off-label treatment for carriers of this mutation.
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Affiliation(s)
- Ferenc Török
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Kamer Tezcan
- Department of Genetics, Kaiser Permanente, Sacramento, CA 95825, USA
| | - Ludovica Filippini
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Monica L Fernández-Quintero
- Department of General, Inorganic and Theoretical Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Lucia Zanetti
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Klaus R Liedl
- Department of General, Inorganic and Theoretical Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Raphaela S Drexel
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Jörg Striessnig
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Nadine J Ortner
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
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13
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Cunningham KL, Littleton JT. Mechanisms controlling the trafficking, localization, and abundance of presynaptic Ca 2+ channels. Front Mol Neurosci 2023; 15:1116729. [PMID: 36710932 PMCID: PMC9880069 DOI: 10.3389/fnmol.2022.1116729] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 12/26/2022] [Indexed: 01/14/2023] Open
Abstract
Voltage-gated Ca2+ channels (VGCCs) mediate Ca2+ influx to trigger neurotransmitter release at specialized presynaptic sites termed active zones (AZs). The abundance of VGCCs at AZs regulates neurotransmitter release probability (Pr ), a key presynaptic determinant of synaptic strength. Given this functional significance, defining the processes that cooperate to establish AZ VGCC abundance is critical for understanding how these mechanisms set synaptic strength and how they might be regulated to control presynaptic plasticity. VGCC abundance at AZs involves multiple steps, including channel biosynthesis (transcription, translation, and trafficking through the endomembrane system), forward axonal trafficking and delivery to synaptic terminals, incorporation and retention at presynaptic sites, and protein recycling. Here we discuss mechanisms that control VGCC abundance at synapses, highlighting findings from invertebrate and vertebrate models.
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Affiliation(s)
- Karen L. Cunningham
- The Picower Institute for Learning and Memory, Department of Biology, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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14
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Role of the Ca2+ channel α2δ-1 auxiliary subunit in proliferation and migration of human glioblastoma cells. PLoS One 2022; 17:e0279186. [PMID: 36520928 PMCID: PMC9754164 DOI: 10.1371/journal.pone.0279186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 12/01/2022] [Indexed: 12/23/2022] Open
Abstract
The overexpression of α2δ-1 is related to the development and degree of malignancy of diverse types of cancer. This protein is an auxiliary subunit of voltage-gated Ca2+ (CaV) channels, whose expression favors the trafficking of the main pore-forming subunit of the channel complex (α1) to the plasma membrane, thereby generating an increase in Ca2+ entry. Interestingly, TLR-4, a protein belonging to the family of toll-like receptors that participate in the inflammatory response and the transcription factor Sp1, have been linked to the progression of glioblastoma multiforme (GBM). Therefore, this report aimed to evaluate the role of the α2δ-1 subunit in the progression of GBM and investigate whether Sp1 regulates its expression after the activation of TLR-4. To this end, the expression of α2δ-1, TLR-4, and Sp1 was assessed in the U87 human glioblastoma cell line, and proliferation and migration assays were conducted using different agonists and antagonists. The actions of α2δ-1 were also investigated using overexpression and knockdown strategies. Initial luciferase assays and Western blot analyses showed that the activation of TLR-4 favors the transcription and expression of α2δ-1, which promoted the proliferation and migration of the U87 cells. Consistent with this, overexpression of α2δ-1, Sp1, and TLR-4 increased cell proliferation and migration, while their knockdown with specific siRNAs abrogated these actions. Our data also suggest that TLR-4-mediated regulation of α2δ-1 expression occurs through the NF-kB signaling pathway. Together, these findings strongly suggest that the activation of TLR-4 increases the expression of α2δ-1 in U87 cells, favoring their proliferative and migratory potential, which might eventually provide a theoretical basis to examine novel biomarkers and molecular targets for the diagnosis and treatment of GBM.
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15
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Autism associated mutations in β 2 subunit of voltage-gated calcium channels constitutively activate gene expression. Cell Calcium 2022; 108:102672. [PMID: 36427431 DOI: 10.1016/j.ceca.2022.102672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/23/2022] [Accepted: 11/08/2022] [Indexed: 11/13/2022]
Abstract
Membrane depolarization triggers gene expression through voltage-gated calcium channels (VGCC) in a process called Excitation-transcription (ET) coupling. Mutations in the channel subunits α11.2, or β2d, are associated with neurodevelopmental disorders such as ASD. Here, we found that two mutations S143F and G113S within the rat Cavβ2a corresponding to autistic related mutations Cavβ2dS197F and Cavβ2dG167S in the human Cavβ2d, activate ET-coupling via the RAS/ERK/CREB pathway. Membrane depolarization of HEK293 cells co-expressing α11.2 and α2δ with Cavβ2aS143F or Cavβ2aG113S triggers constitutive transcriptional activation, which is correlated with facilitated channel activity. Similar to the Timothy-associated autistic mutation α11.2G406R, constitutive gene activation is attributed to a hyperpolarizing shift in the activation kinetics of Cav1.2. Pulldown of RasGRF2 and RhoGEF by wt and the Cavβ2a autistic mutants is consistent with Cavβ2/Ras activation in ET coupling and implicates Rho signaling as yet another molecular pathway activated by Cavα11.2/Cavβ2 . Facilitated spontaneous channel activity preceding enhanced gene activation via the Ras/ERK/CREB pathway, appears a general molecular mechanism for Ca2+ channel mediated ASD and other neurodevelopmental disorders.
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16
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Chai Z, Tzingounis AV, Lykotrafitis G. The periodic axon membrane skeleton leads to Na nanodomains but does not impact action potentials. Biophys J 2022; 121:3334-3344. [PMID: 36029000 PMCID: PMC9515372 DOI: 10.1016/j.bpj.2022.08.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 07/07/2022] [Accepted: 08/19/2022] [Indexed: 11/20/2022] Open
Abstract
Recent work has established that axons have a periodic skeleton structure comprising of azimuthal actin rings connected via longitudinal spectrin tetramer filaments. This structure endows the axon with structural integrity and mechanical stability. Additionally, voltage-gated sodium channels follow the periodicity of the active-spectrin arrangement, spaced ∼190 nm segments apart. The impact of this periodic arrangement of sodium channels on the generation and propagation of action potentials is unknown. To address this question, we simulated an action potential using the Hodgkin-Huxley formalism in a cylindrical compartment, but instead of using a homogeneous distribution of voltage-gated sodium channels in the membrane, we applied the experimentally determined periodic arrangement. We found that the periodic distribution of voltage-gated sodium channels does not significantly affect the generation or propagation of action potentials but instead leads to large, localized sodium action currents caused by high-density sodium nanodomains. Additionally, our simulations show that the distance between periodic sodium channel strips could control axonal excitability, suggesting a previously underappreciated mechanism to regulate neuronal firing properties. Together, this work provides a critical new insight into the role of the periodic arrangement of sodium channels in axons, providing a foundation for future experimental studies.
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Affiliation(s)
- Zhaojie Chai
- Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut
| | | | - George Lykotrafitis
- Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut; Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut.
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17
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Martínez-Valencia A, Ramírez-Santiago G, De-Miguel FF. Dynamics of Neuromuscular Transmission Reproduced by Calcium-Dependent and Reversible Serial Transitions in the Vesicle Fusion Complex. Front Synaptic Neurosci 2022; 13:785361. [PMID: 35242023 PMCID: PMC8885725 DOI: 10.3389/fnsyn.2021.785361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 12/30/2021] [Indexed: 11/28/2022] Open
Abstract
Neuromuscular transmission, from spontaneous release to facilitation and depression, was accurately reproduced by a mechanistic kinetic model of sequential maturation transitions in the molecular fusion complex. The model incorporates three predictions. First, calcium-dependent forward transitions take vesicles from docked to preprimed to primed states, followed by fusion. Second, prepriming and priming are reversible. Third, fusion and recycling are unidirectional. The model was fed with experimental data from previous studies, whereas the backward (β) and recycling (ρ) rate constant values were fitted. Classical experiments were successfully reproduced with four transition states in the model when every forward (α) rate constant had the same value, and both backward rate constants were 50–100 times larger. Such disproportion originated an abruptly decreasing gradient of resting vesicles from docked to primed states. By contrast, a three-state version of the model failed to reproduce the dynamics of transmission by using the same set of parameters. Simulations predict the following: (1) Spontaneous release reflects primed to fusion spontaneous transitions. (2) Calcium elevations synchronize the series of forward transitions that lead to fusion. (3) Facilitation reflects a transient increase of priming following the calcium-dependent maturation transitions. (4) The calcium sensors that produce facilitation are those that evoke the transitions form docked to primed states. (5) Backward transitions and recycling restore the resting state. (6) Depression reflects backward transitions and slow recycling after intense release. Altogether, our results predict that fusion is produced by one calcium sensor, whereas the modulation of the number of vesicles that fuse depends on the calcium sensors that promote the early transition states. Such finely tuned kinetics offers a mechanism for collective non-linear transitional adaptations of a homogeneous vesicle pool to the ever-changing pattern of electrical activity in the neuromuscular junction.
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Affiliation(s)
- Alejandro Martínez-Valencia
- Posgrado en Ciencias Físicas, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | | | - Francisco F. De-Miguel
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
- *Correspondence: Francisco F. De-Miguel,
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18
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Luo JK, Melland H, Nithianantharajah J, Gordon SL. Postsynaptic Neuroligin-1 Mediates Presynaptic Endocytosis During Neuronal Activity. Front Mol Neurosci 2021; 14:744845. [PMID: 34690694 PMCID: PMC8531268 DOI: 10.3389/fnmol.2021.744845] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 09/15/2021] [Indexed: 01/31/2023] Open
Abstract
Fast, high-fidelity neurotransmission and synaptic efficacy requires tightly regulated coordination of pre- and postsynaptic compartments and alignment of presynaptic release sites with postsynaptic receptor nanodomains. Neuroligin-1 (Nlgn1) is a postsynaptic cell-adhesion protein exclusively localised to excitatory synapses that is crucial for coordinating the transsynaptic alignment of presynaptic release sites with postsynaptic AMPA receptors as well as postsynaptic transmission and plasticity. However, little is understood about whether the postsynaptic machinery can mediate the molecular architecture and activity of the presynaptic nerve terminal, and thus it remains unclear whether there are presynaptic contributions to Nlgn1-dependent control of signalling and plasticity. Here, we employed a presynaptic reporter of neurotransmitter release and synaptic vesicle dynamics, synaptophysin-pHluorin (sypHy), to directly assess the presynaptic impact of loss of Nlgn1. We show that lack of Nlgn1 had no effect on the size of the readily releasable or entire recycling pool of synaptic vesicles, nor did it impact exocytosis. However, we observed significant changes in the retrieval of synaptic vesicles by compensatory endocytosis, specifically during activity. Our data extends growing evidence that synaptic adhesion molecules critical for forming transsynaptic scaffolds are also important for regulating activity-induced endocytosis at the presynapse.
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Affiliation(s)
- Jiaqi Keith Luo
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Holly Melland
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.,Melbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Jess Nithianantharajah
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Sarah L Gordon
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.,Melbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
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19
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Kowalczyk A, Gbadamosi O, Kolor K, Sosa J, Andrzejczuk L, Gibson G, Croix C, Chikina M, Aizenman E, Clark N, Kiselyov K. Evolutionary rate covariation identifies SLC30A9 (ZnT9) as a mitochondrial zinc transporter. Biochem J 2021; 478:3205-3220. [PMID: 34397090 PMCID: PMC10491466 DOI: 10.1042/bcj20210342] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 08/12/2021] [Accepted: 08/16/2021] [Indexed: 12/16/2022]
Abstract
Recent advances in genome sequencing have led to the identification of new ion and metabolite transporters, many of which have not been characterized. Due to the variety of subcellular localizations, cargo and transport mechanisms, such characterization is a daunting task, and predictive approaches focused on the functional context of transporters are very much needed. Here we present a case for identifying a transporter localization using evolutionary rate covariation (ERC), a computational approach based on pairwise correlations of amino acid sequence evolutionary rates across the mammalian phylogeny. As a case study, we find that poorly characterized transporter SLC30A9 (ZnT9) coevolves with several components of the mitochondrial oxidative phosphorylation chain, suggesting mitochondrial localization. We confirmed this computational finding experimentally using recombinant human SLC30A9. SLC30A9 loss caused zinc mishandling in the mitochondria, suggesting that under normal conditions it acts as a zinc exporter. We therefore propose that ERC can be used to predict the functional context of novel transporters and other poorly characterized proteins.
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Affiliation(s)
- Amanda Kowalczyk
- Joint Carnegie Mellon University-University of Pittsburgh PhD Program in Computational Biology, Pittsburgh, PA 15213, U.S.A
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15213, U.S.A
| | - Omotola Gbadamosi
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA 15260, U.S.A
| | - Kathryn Kolor
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA 15260, U.S.A
| | - Jahree Sosa
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA 15260, U.S.A
| | - Livia Andrzejczuk
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA 15260, U.S.A
| | - Gregory Gibson
- Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, PA 15260, U.S.A
| | - Claudette Croix
- Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, PA 15260, U.S.A
| | - Maria Chikina
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15213, U.S.A
| | - Elias Aizenman
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, U.S.A
| | - Nathan Clark
- Department of Human Genetics, University of Utah, Utah 84112, U.S.A
| | - Kirill Kiselyov
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA 15260, U.S.A
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20
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Winters BL, Vaughan CW. Mechanisms of endocannabinoid control of synaptic plasticity. Neuropharmacology 2021; 197:108736. [PMID: 34343612 DOI: 10.1016/j.neuropharm.2021.108736] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 01/13/2023]
Abstract
The endogenous cannabinoid transmitter system regulates synaptic transmission throughout the nervous system. Unlike conventional transmitters, specific stimuli induce synthesis of endocannabinoids (eCBs) in the postsynaptic neuron, and these travel backwards to modulate presynaptic inputs. In doing so, eCBs can induce short-term changes in synaptic strength and longer-term plasticity. While this eCB regulation is near ubiquitous, it displays major regional and synapse specific variations with different synapse specific forms of short-versus long-term plasticity throughout the brain. These differences are due to the plethora of pre- and postsynaptic mechanisms which have been implicated in eCB signalling, the intricacies of which are only just being realised. In this review, we shall describe the current understanding and highlight new advances in this area, with a focus on the retrograde action of eCBs at CB1 receptors (CB1Rs).
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Affiliation(s)
- Bryony Laura Winters
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, University of Sydney at Royal North Shore Hospital, NSW, Australia.
| | - Christopher Walter Vaughan
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, University of Sydney at Royal North Shore Hospital, NSW, Australia
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