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Somogyi A, Kirkham ED, Lloyd-Evans E, Winston J, Allen ND, Mackrill JJ, Anderson KE, Hawkins PT, Gardiner SE, Waller-Evans H, Sims R, Boland B, O'Neill C. The synthetic TRPML1 agonist ML-SA1 rescues Alzheimer-related alterations of the endosomal-autophagic-lysosomal system. J Cell Sci 2023; 136:jcs259875. [PMID: 36825945 PMCID: PMC10112969 DOI: 10.1242/jcs.259875] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Accepted: 02/13/2023] [Indexed: 02/25/2023] Open
Abstract
Abnormalities in the endosomal-autophagic-lysosomal (EAL) system are an early event in Alzheimer's disease (AD) pathogenesis. However, the mechanisms underlying these abnormalities are unclear. The transient receptor potential channel mucolipin 1(TRPML1, also known as MCOLN1), a vital endosomal-lysosomal Ca2+ channel whose loss of function leads to neurodegeneration, has not been investigated with respect to EAL pathogenesis in late-onset AD (LOAD). Here, we identify pathological hallmarks of TRPML1 dysregulation in LOAD neurons, including increased perinuclear clustering and vacuolation of endolysosomes. We reveal that induced pluripotent stem cell (iPSC)-derived human cortical neurons expressing APOE ε4, the strongest genetic risk factor for LOAD, have significantly diminished TRPML1-induced endolysosomal Ca2+ release. Furthermore, we found that blocking TRPML1 function in primary neurons by depleting the TRPML1 agonist PI(3,5)P2 via PIKfyve inhibition, recreated multiple features of EAL neuropathology evident in LOAD. This included increased endolysosomal Ca2+ content, enlargement and perinuclear clustering of endolysosomes, autophagic vesicle accumulation and early endosomal enlargement. Strikingly, these AD-like neuronal EAL defects were rescued by TRPML1 reactivation using its synthetic agonist ML-SA1. These findings implicate defects in TRPML1 in LOAD EAL pathogenesis and present TRPML1 as a potential therapeutic target.
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Affiliation(s)
- Aleksandra Somogyi
- School of Biochemistry and Cell Biology, BioSciences Institute, University College Cork, T12 YT20 Cork, Ireland
- Department of Pharmacology and Therapeutics, Western Gateway Building, University College Cork, T12 XF62 Cork, Ireland
- Cork Neuroscience Centre (CNSC), University College Cork, T12 YT20 Cork, Ireland
| | - Emily D Kirkham
- School of Biosciences, Sir Martin Evans building, Cardiff University, CF10 3AX Cardiff, UK
| | - Emyr Lloyd-Evans
- School of Biosciences, Sir Martin Evans building, Cardiff University, CF10 3AX Cardiff, UK
| | - Jincy Winston
- UK Dementia Research Institute, Hadyn Ellis Building, Cardiff University, CF24 4HQ Cardiff, UK
| | - Nicholas D Allen
- School of Biosciences, Sir Martin Evans building, Cardiff University, CF10 3AX Cardiff, UK
| | - John J Mackrill
- Department of Physiology, School of Medicine, University College Cork, T12 YT20 Cork, Ireland
| | - Karen E Anderson
- The Babraham Institute, Babraham Research Campus, CB22 3AT Cambridge, UK
| | - Phillip T Hawkins
- The Babraham Institute, Babraham Research Campus, CB22 3AT Cambridge, UK
| | - Sian E Gardiner
- Medicines Discovery Institute, Main Building, Cardiff University, CF10 3AT Cardiff, UK
| | - Helen Waller-Evans
- Medicines Discovery Institute, Main Building, Cardiff University, CF10 3AT Cardiff, UK
| | - Rebecca Sims
- Division of Psychological Medicine and Clinical Neuroscience, Cardiff University, C14 4XN Cardiff, UK
| | - Barry Boland
- Department of Pharmacology and Therapeutics, Western Gateway Building, University College Cork, T12 XF62 Cork, Ireland
- Cork Neuroscience Centre (CNSC), University College Cork, T12 YT20 Cork, Ireland
| | - Cora O'Neill
- School of Biochemistry and Cell Biology, BioSciences Institute, University College Cork, T12 YT20 Cork, Ireland
- Cork Neuroscience Centre (CNSC), University College Cork, T12 YT20 Cork, Ireland
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Zhang C, Maslar D, Minckley TF, LeJeune KD, Qin Y. Spontaneous, synchronous zinc spikes oscillate with neural excitability and calcium spikes in primary hippocampal neuron culture. J Neurochem 2021; 157:1838-1849. [PMID: 33638177 DOI: 10.1111/jnc.15334] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 02/23/2021] [Indexed: 12/19/2022]
Abstract
Zinc has been suggested to act as an intracellular signaling molecule due to its regulatory effects on numerous protein targets including enzymes, transcription factors, ion channels, neurotrophic factors, and postsynaptic scaffolding proteins. However, intracellular zinc concentration is tightly maintained at steady levels under natural physiological conditions. Dynamic changes in intracellular zinc concentration have only been detected in certain types of cells that are exposed to pathologic stimuli or upon receptor ligand binding. Unlike calcium, the ubiquitous signaling metal ion that can oscillate periodically and spontaneously in various cells, spontaneous zinc oscillations have never been reported. In this work, we made the novel observation that the developing neurons generated spontaneous and synchronous zinc spikes in primary hippocampal cultures using a fluorescent zinc sensor, FluoZin-3. Blocking of glutamate receptor-dependent calcium influx depleted the zinc spikes, suggesting that these zinc spikes were driven by the glutamate-mediated spontaneous neural excitability and calcium spikes that have been characterized in early developing neurons. Simultaneous imaging of calcium or pH together with zinc, we uncovered that a downward pH spike was evoked with each zinc spike and this transient cellular acidification occurred downstream of calcium spikes but upstream of zinc spikes. Our results suggest that spontaneous, synchronous zinc spikes were generated through calcium influx-induced cellular acidification, which liberates zinc from intracellular zinc binding ligands. Given that changes in zinc concentration can modulate activities of proteins essential for synapse maturation and neuronal differentiation, these zinc spikes might act as important signaling roles in neuronal development.
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Affiliation(s)
- Chen Zhang
- Department of Biological Sciences, University of Denver, Denver, CO, USA
| | - Drew Maslar
- Department of Biological Sciences, University of Denver, Denver, CO, USA
| | - Taylor F Minckley
- Department of Biological Sciences, University of Denver, Denver, CO, USA
| | - Kate D LeJeune
- Department of Biological Sciences, University of Denver, Denver, CO, USA
| | - Yan Qin
- Department of Biological Sciences, University of Denver, Denver, CO, USA
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Bootman MD, Allman S, Rietdorf K, Bultynck G. Deleterious effects of calcium indicators within cells; an inconvenient truth. Cell Calcium 2018; 73:82-87. [DOI: 10.1016/j.ceca.2018.04.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 04/03/2018] [Accepted: 04/11/2018] [Indexed: 01/20/2023]
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Abstract
Spontaneous Ca2+ waves, also termed store-overload-induced Ca2+ release (SOICR), in cardiac cells can trigger ventricular arrhythmias especially in failing hearts. SOICR occurs when RyRs are activated by an increase in sarcoplasmic reticulum (SR) luminal Ca2+. Carvedilol is one of the most effective drugs for preventing arrhythmias in patients with heart failure. Furthermore, carvedilol analogues with minimal β-blocking activity also block SOICR showing that SOICR-inhibiting activity is distinct from that for β-block. We show here that carvedilol is a potent inhibitor of cADPR-induced Ca2+ release in sea urchin egg homogenate. In addition, the carvedilol analog VK-II-86 with minimal β-blocking activity also suppresses cADPR-induced Ca2+ release. Carvedilol appeared to be a non-competitive antagonist of cADPR and could also suppress Ca2+ release by caffeine. These results are consistent with cADPR releasing Ca2+ in sea urchin eggs by sensitizing RyRs to Ca2+ involving a luminal Ca2+ activation mechanism. In addition to action on the RyR, we also observed inhibition of inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release by carvedilol suggesting a common mechanism between these evolutionarily related and conserved Ca2+ release channels.
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Affiliation(s)
- Anthony J Morgan
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Konstantina Bampali
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Margarida Ruas
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Cailley Factor
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Thomas G Back
- Department of Chemistry, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - S R Wayne Chen
- The Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
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Abstract
The Ca2+-mobilizing second messenger, NAADP (nicotinic acid adenine dinucleotide phosphate), has been with us for nearly 20 years and yet we still cannot fully agree on the identity of its target Ca2+-release channel. In spite of some recent robust challenges to the idea that two-pore channels (TPCs) represent the elusive "NAADP receptor", evidence continues to accumulate that TPCs are important for NAADP-mediated responses. This article will briefly outline the background and review more recent work pertaining to the TPC story.
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Abstract
Cell homogenates provide a simple and yet powerful means of investigating the actions of Ca(2+)-mobilizing second messengers and their target Ca(2+) stores. The sea urchin egg homogenate is particularly useful and almost unique in retaining robust Ca(2+) responses to all three major messengers, i.e., inositol 1,4,5-trisphosphate (IP3), cyclic ADP-ribose, and nicotinic acid adenine dinucleotide phosphate (NAADP) (Lee and Aarhus. J Biol Chem 270: 2152-2172, 1995). It is not only invaluable for probing the pharmacology and mechanism of action of these messengers, but can also be used to assay Ca(2+) uptake mechanisms (Churchill et al. Cell 111: 703-708, 2002), second messenger production (Morgan et al. Methods in cADPR and NAADP research. In: Putney JW Jr (ed) Methods in calcium signalling, CRC: Boca Raton, FL, 2006), and dynamics of luminal pH (pHL) changes within acidic Ca(2+) stores (Lee and Epel. Dev Biol 98: 446-454, 1983; Morgan and Galione. Biochem J 402: 301-310, 2007). Here, we detail the protocols for preparing and using egg homogenates, wherein eggs are shed and collected into artificial sea water (ASW), dejellied, washed several times in Ca(2+)-free ASW, and then finally washed and resuspended in an intracellular-like medium. Homogenization is effected with a Dounce glass tissue homogenizer (at 50 % (v/v)) and aliquots frozen and stored at -80 °C. For Ca(2+) (or pHL) measurements, homogenate is thawed and sequentially diluted in an intracellular-like medium and the fluorescence of Ca(2+)- or pHL-sensitive dyes monitored in a standard fluorimeter or plate-reader.
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Lam AK, Galione A. The endoplasmic reticulum and junctional membrane communication during calcium signaling. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2013; 1833:2542-59. [DOI: 10.1016/j.bbamcr.2013.06.004] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 06/03/2013] [Accepted: 06/03/2013] [Indexed: 12/13/2022]
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Morgan AJ, Davis LC, Wagner SKTY, Lewis AM, Parrington J, Churchill GC, Galione A. Bidirectional Ca²⁺ signaling occurs between the endoplasmic reticulum and acidic organelles. ACTA ACUST UNITED AC 2013; 200:789-805. [PMID: 23479744 PMCID: PMC3601362 DOI: 10.1083/jcb.201204078] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
After acidic organelles induce signaling to activate ER calcium ion release, local microdomains of high calcium at ER–acidic organelle junctions feed back to activate further acidic organelle calcium release. The endoplasmic reticulum (ER) and acidic organelles (endo-lysosomes) act as separate Ca2+ stores that release Ca2+ in response to the second messengers IP3 and cADPR (ER) or NAADP (acidic organelles). Typically, trigger Ca2+ released from acidic organelles by NAADP subsequently recruits IP3 or ryanodine receptors on the ER, an anterograde signal important for amplification and Ca2+ oscillations/waves. We therefore investigated whether the ER can signal back to acidic organelles, using organelle pH as a reporter of NAADP action. We show that Ca2+ released from the ER can activate the NAADP pathway in two ways: first, by stimulating Ca2+-dependent NAADP synthesis; second, by activating NAADP-regulated channels. Moreover, the differential effects of EGTA and BAPTA (slow and fast Ca2+ chelators, respectively) suggest that the acidic organelles are preferentially activated by local microdomains of high Ca2+ at junctions between the ER and acidic organelles. Bidirectional organelle communication may have wider implications for endo-lysosomal function as well as the generation of Ca2+ oscillations and waves.
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Affiliation(s)
- Anthony J Morgan
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, England, UK.
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