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Abstract
The discovery of NAADP-evoked Ca2+ release in sea urchin eggs and then as a ubiquitous Ca2+ mobilizing messenger has introduced several novel paradigms to our understanding of Ca2+ signalling, not least in providing a link between cell stimulation and Ca2+ release from lysosomes and other acidic Ca2+ storage organelles. In addition, the hallmark concentration-response relationship of NAADP-mediated Ca2+ release, shaped by striking activation/desensitization mechanisms, influences its actions as an intracellular messenger. There has been recent progress in our understanding of the molecular mechanisms underlying NAADP-evoked Ca2+ release, such as the identification of the endo-lysosomal two-pore channel family of cation channels (TPCs) as their principal target and the identity of NAADP-binding proteins that complex with them. The NAADP/TPC signalling axis has gained recent prominence in pathophysiology for their roles in such disease processes as neurodegeneration, tumorigenesis and cellular viral entry.
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Affiliation(s)
- Antony Galione
- Department of Pharmacology, University of Oxford, Oxford, UK.
| | - Lianne C Davis
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Lora L Martucci
- Department of Pharmacology, University of Oxford, Oxford, UK
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Kelu JJ, Webb SE, Galione A, Miller AL. TPC2-mediated Ca 2+ signaling is required for the establishment of synchronized activity in developing zebrafish primary motor neurons. Dev Biol 2018; 438:57-68. [PMID: 29577882 DOI: 10.1016/j.ydbio.2018.02.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 02/21/2018] [Accepted: 02/21/2018] [Indexed: 10/17/2022]
Abstract
During the development of the early spinal circuitry in zebrafish, spontaneous Ca2+ transients in the primary motor neurons (PMNs) are reported to transform from being slow and uncorrelated, to being rapid, synchronized and patterned. In this study, we demonstrated that in intact zebrafish, Ca2+ release via two-pore channel type 2 (TPC2) from acidic stores/endolysosomes is required for the establishment of synchronized activity in the PMNs. Using the SAIGFF213A;UAS:GCaMP7a double-transgenic zebrafish line, Ca2+ transients were visualized in the caudal PMNs (CaPs). TPC2 inhibition via molecular, genetic or pharmacological means attenuated the CaP Ca2+ transients, and decreased the normal ipsilateral correlation and contralateral anti-correlation, indicating a disruption in normal spinal circuitry maturation. Furthermore, treatment with MS-222 resulted in a complete (but reversible) inhibition of the CaP Ca2+ transients, as well as a significant decrease in the concentration of the Ca2+ mobilizing messenger, nicotinic acid adenine diphosphate (NAADP) in whole embryo extract. Together, our new data suggest a novel function for NAADP/TPC2-mediated Ca2+ signaling in the development, coordination, and maturation of the spinal network in zebrafish embryos.
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Affiliation(s)
- Jeffrey J Kelu
- Division of Life Science&State Key Laboratory of Molecular Neuroscience, HKUST, Hong Kong
| | - Sarah E Webb
- Division of Life Science&State Key Laboratory of Molecular Neuroscience, HKUST, Hong Kong
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Andrew L Miller
- Division of Life Science&State Key Laboratory of Molecular Neuroscience, HKUST, Hong Kong.
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Gerasimenko JV, Charlesworth RM, Sherwood MW, Ferdek PE, Mikoshiba K, Parrington J, Petersen OH, Gerasimenko OV. Both RyRs and TPCs are required for NAADP-induced intracellular Ca²⁺ release. Cell Calcium 2015; 58:237-45. [PMID: 26100948 PMCID: PMC4539342 DOI: 10.1016/j.ceca.2015.05.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 05/15/2015] [Accepted: 05/17/2015] [Indexed: 11/29/2022]
Abstract
Antibody against RyR1 reduced NAADP-evoked Ca2+ release by 81%. Combined inhibition of RyR1 and RyR3 (or RyR3-KO) reduced responses to NAADP by >90%. Knockout of TPC2 (or antibody against TPC2) reduced responses to NAADP by 64%. Combined inhibition of TPC2 and TPC1 reduced responses by 86%. In acidic stores inhibition of either pair of RyR1/3 or TPC1/2 abolished responses.
Intracellular Ca2+ release is mostly mediated by inositol trisphosphate, but intracellular cyclic-ADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate (NAADP) are important messengers in many systems. Whereas cADPR generally activates type 2 ryanodine receptors (RyR2s), the NAADP-activated Ca2+ release mechanism is less clear. Using knockouts and antibodies against RyRs and Two-Pore Channels (TPCs), we have compared their relative importance for NAADP-induced Ca2+ release from two-photon permeabilized pancreatic acinar cells. In these cells, cholecystokinin-elicited Ca2+ release is mediated by NAADP. TPC2-KO reduced NAADP-induced Ca2+ release by 64%, but the combination of TPC2-KO and an antibody against TPC1, significantly reduced Ca2+ release by 86% (64% vs. 86%, p < 0.0002). In RyR3-KO, NAADP-evoked Ca2+ release reduced by ∼50% but, when combined with antibodies against RyR1, responses were 90% inhibited. Antibodies against RyR2 had practically no effect on NAADP-evoked Ca2+ release, but reduced release in response to cADPR by 55%. Antibodies to RyR1 inhibited NAADP-induced Ca2+ liberation by 81%, but only reduced cADPR responses by 30%. We conclude that full NAADP-mediated Ca2+ release requires both TPCs and RyRs. The sequence of relative importance for NAADP-elicited Ca2+ release from the all stores is RyR1 > TPC2 > RyR3 > TPC1 >> RyR2. However, when assessing NAADP-induced Ca2+ release solely from the acidic stores (granules/endosomes/lysosomes), antibodies against TPC2 and TPC1 virtually abolished the Ca2+ liberation as did antibodies against RyR1 and RyR3. Our results indicate that the primary, but very small, NAADP-elicited Ca2+ release via TPCs from endosomes/lysosomes triggers the detectable Ca2+-induced Ca2+ release via RyR1 and RyR3 occurring from the granules and the ER.
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Affiliation(s)
- Julia V Gerasimenko
- Medical Research Council Group, Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, UK
| | - Richard M Charlesworth
- Medical Research Council Group, Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, UK
| | - Mark W Sherwood
- Laboratory for Developmental Neurobiology, Riken Brain Science Institute, Wako City, Saitama, Japan
| | - Pawel E Ferdek
- Medical Research Council Group, Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, UK
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, Riken Brain Science Institute, Wako City, Saitama, Japan; Ca(2+) Oscillation Project, ICORP-SORST, JST, Wako City, Saitama, Japan
| | - John Parrington
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Ole H Petersen
- Medical Research Council Group, Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, UK
| | - Oleg V Gerasimenko
- Medical Research Council Group, Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, UK.
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Abstract
Calcium ion (Ca(2+)) is an important second messenger in trypanosomatids and essential for their survival although prolonged high intracellular Ca(2+) levels lead to cell death. As other eukaryotic cells, trypanosomes use two sources of Ca(2+) for generating signals: Ca(2+) release from intracellular stores and Ca(2+) entry across the plasma membrane. Ca(2+) release from intracellular stores is controlled by the inositol 1,4,5-trisphosphate receptor (IP3R) that is located in acidocalcisomes, acidic organelles that are the primary Ca(2+) reservoir in these cells. A plasma membrane Ca(2+)-ATPase controls the cytosolic Ca(2+) levels and a number of pumps and exchangers are responsible for Ca(2+) uptake and release from intracellular compartments. The trypanosomatid genomes contain a wide variety of signaling and regulatory proteins that bind Ca(2+) as well as many Ca(2+)-binding proteins that await further characterization. The mitochondrial Ca(2+) transporters of trypanosomatids have an important role in the regulation of cell bioenergetics and flagellar Ca(2+) appears to have roles in sensing the environment. In trypanosomatids in which an intracellular life cycle is present, Ca(2+) signaling is important for host cell invasion.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30620, USA; Departamento de Patologia Clínica, State University of Campinas, Campinas, SP 13083, Brazil.
| | - Guozhong Huang
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30620, USA
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