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Sage SO, Harper AGS. Calcium sequestration by human platelet acidic organelles is regulated by the actin cytoskeleton and autocrine 5-hydroxytryptamine. Cell Calcium 2021; 101:102522. [PMID: 34968774 DOI: 10.1016/j.ceca.2021.102522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 11/25/2021] [Accepted: 12/20/2021] [Indexed: 11/16/2022]
Abstract
Human platelets regulate agonist-evoked Ca2+ signalling through Ca2+ release from and sequestration into acidic organelles. Previous studies have pharmacologically characterised the presence of a Ca2+-H+ exchanger in these organelles. This exchanger appears to regulate a secondary plateau phase in agonist-evoked cytosolic Ca2+ signals in fura-2-loaded human platelets. Here we demonstrate that cytochalasin D treatment removes the secondary plateau in ADP-evoked Ca2+ signals elicited in the absence of external Ca2+. This effect was reversed by pretreatment with nigericin, a K+/H+ exchanger that short-circuits the Ca2+-H+ exchanger. Using Fluo-5N- or Lysosensor Green-loaded cells, cytochalasin D was found to enhance Ca2+ sequestration into acidic organelles by preventing their alkalinisation. Additional experiments demonstrated that ADP-evoked alkalinisation of acidic organelles and subsequent slowing of acidic organellar Ca2+ sequestration was mediated by autocrine 5-HT signalling. Enhancing this 5-HT signalling using fluoxetine overcame the inhibitory effect of cytochalasin D on ADP-evoked Ca2+ signals, indicating that cytochalasin D interferes with 5-HT autocrine signalling. The ability of Cytochalasin D to interfere with autocrine 5-HT signalling was downstream of the 5-HT2A receptor as secretion of [3H]-5-HT from ADP-stimulated human platelets was not reduced. These data provide the first evidence that the pH gradient across acidic organelles is dynamically regulated upon human platelet activation, and that this can play a significant role in controlling human platelet function by modulating Ca2+-H+ exchange and so [Ca2+]i.
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Affiliation(s)
- Stewart O Sage
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Alan G S Harper
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom; School of Medicine, David Wetherall Building, Keele University, Keele, Staffordshire, ST5 5BG United Kingdom.
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Hasuzawa N, Moriyama S, Wang L, Nagayama A, Ashida K, Moriyama Y, Nomura M. Quinacrine is not a vital fluorescent probe for vesicular ATP storage. Purinergic Signal 2021; 17:725-735. [PMID: 34713379 DOI: 10.1007/s11302-021-09820-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 09/27/2021] [Indexed: 10/20/2022] Open
Abstract
Quinacrine, a fluorescent amphipathic amine, has been used as a vital fluorescent probe to visualize vesicular storage of ATP in the field of purinergic signaling. However, the mechanism(s) by which quinacrine represents vesicular ATP storage remains to be clarified. The present study investigated the validity of the use of quinacrine as a vial fluorescent probe for ATP-storing organelles. Vesicular nucleotide transporter (VNUT), an essential component for vesicular storage and ATP release, is present in very low density lipoprotein (VLDL)-containing secretory vesicles in hepatocytes. VNUT gene knockout (Vnut-/-) or clodronate treatment, a VNUT inhibitor, disappeared vesicular ATP release (Tatsushima et al., Biochim Biophys Acta Molecular Basis of Disease 2021, e166013). Upon incubation of mice's primary hepatocytes, quinacrine accumulates in a granular pattern into the cytoplasm, sensitive to 0.1-μM bafilomycin A1, a vacuolar ATPase (V-ATPase) inhibitor. Neither Vnut-/- nor treatment of clodronate affected quinacrine granular accumulation. In vitro, quinacrine is accumulated into liposomes upon imposing inside acidic transmembranous pH gradient (∆pH) irrespective of the presence or absence of ATP. Neither ATP binding on VNUT nor VNUT-mediated uptake of ATP was affected by quinacrine. Consistently, VNUT-mediated uptake of quinacrine was negligible or under the detection limit. From these results, it is concluded that vesicular quinacrine accumulation is not due to a consequence of its interaction with ATP but due to ∆pH-driven concentration across the membranes as an amphipathic amine. Thus, quinacrine is not a vital fluorescent probe for vesicular ATP storage.
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Affiliation(s)
- Nao Hasuzawa
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, 830-0011, Japan
| | - Sawako Moriyama
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, 830-0011, Japan
| | - Lixiang Wang
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, 830-0011, Japan
| | - Ayako Nagayama
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, 830-0011, Japan
| | - Kenji Ashida
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, 830-0011, Japan
| | - Yoshinori Moriyama
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, 830-0011, Japan.
| | - Masatoshi Nomura
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, 830-0011, Japan
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Miyake S, Takihara Y, Yokota S, Takamura Y, Inatani M. Effect of Microtubule Disruption on Dynamics of Acidic Organelles in the Axons of Primary Cultured Retinal Ganglion Cells. Curr Eye Res 2017; 43:77-83. [PMID: 28937869 DOI: 10.1080/02713683.2017.1370117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
PURPOSE Axonal transport is fundamental to autophagy in neuronal cells. To understand its biological significance in various conditions, it is necessary to monitor the process of autophagy. However, monitoring methods are often limited to static analyses, such as protein expression and histological observations. Autophagy has multistep process and is highly dynamic; therefore, additional techniques are necessary to study autophagy. In this study, we quantified the dynamics of autophagy-related organelle transport under conditions of dynamic instability and catastrophic disruption of microtubules using in vitro live imaging. MATERIALS AND METHODS Retinal ganglion cells (RGCs) were isolated from postnatal day 3 Sprague-Dawley rats by immunopanning. After 7 days of culture, acidic organelles were stained by LysoTracker. Dynamics of acidic organelles was quantified using kymographs. Colchicine was used to induce microtubule disruption. Movement of acidic organelles was observed at five time points: before, and at 6, 24, 72, and 120 h after colchicine stimulation. Ethidium homodimer-1 (EthD-1) was used to determine cell viability. RESULTS The status of axonal transport of acidic organelles (n = 363) from 27 RGCs was classified into four categories: anterograde (1.4%), retrograde (90%), stationary (8.0%), and fluttering (0.28%). Six hours after the induction of microtubule disruption in 14 of 27 RGCs, almost all acidic organelles (n = 236) were stationary. All acidic components had completely stopped moving 24 h later. At 72 h after stimulation, axonal fragmentation, and shrinking and disappearance of soma were observed in 71% of RGCs. Finally, the remaining RGCs became positive for EthD-1. In the control (13 of 27 RGCs), axonal transport was maintained for 120 h and EthD-1-positive RGCs were not observed. CONCLUSION Almost all acidic organelles were transported retrogradely along the axon, which was inhibited by colchicine. Understanding the dynamics of acidic organelles may provide useful parameters for characterizing autophagy of neuronal cells in pathophysiological conditions.
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Affiliation(s)
- Seiji Miyake
- a Department of Ophthalmology, Faculty of Medical Sciences , University of Fukui , Fukui , Japan
| | - Yuji Takihara
- a Department of Ophthalmology, Faculty of Medical Sciences , University of Fukui , Fukui , Japan.,b Cancer Science Institute of Singapore , National University of Singapore , Medical Drive , Singapore
| | - Satoshi Yokota
- a Department of Ophthalmology, Faculty of Medical Sciences , University of Fukui , Fukui , Japan.,c Department of Ophthalmology and Visual Sciences , Kyoto University Graduate School of Medicine , Kyoto , Japan
| | - Yoshihiro Takamura
- a Department of Ophthalmology, Faculty of Medical Sciences , University of Fukui , Fukui , Japan
| | - Masaru Inatani
- a Department of Ophthalmology, Faculty of Medical Sciences , University of Fukui , Fukui , Japan
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Thomé MP, Filippi-Chiela EC, Villodre ES, Migliavaca CB, Onzi GR, Felipe KB, Lenz G. Ratiometric analysis of Acridine Orange staining in the study of acidic organelles and autophagy. J Cell Sci 2016; 129:4622-4632. [PMID: 27875278 DOI: 10.1242/jcs.195057] [Citation(s) in RCA: 141] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 11/07/2016] [Indexed: 01/06/2023] Open
Abstract
Acridine Orange is a cell-permeable green fluorophore that can be protonated and trapped in acidic vesicular organelles (AVOs). Its metachromatic shift to red fluorescence is concentration-dependent and, therefore, Acridine Orange fluoresces red in AVOs, such as autolysosomes. This makes Acridine Orange staining a quick, accessible and reliable method to assess the volume of AVOs, which increases upon autophagy induction. Here, we describe a ratiometric analysis of autophagy using Acridine Orange, considering the red-to-green fluorescence intensity ratio (R/GFIR) to quantify flow cytometry and fluorescence microscopy data of Acridine-Orange-stained cells. This method measured with accuracy the increase in autophagy induced by starvation or rapamycin, and the reduction in autophagy produced by bafilomycin A1 or the knockdown of Beclin1 or ATG7. Results obtained with Acridine Orange, considering R/GFIR, correlated with the conversion of the unlipidated form of LC3 (LC3-I) into the lipidated form (LC3-II), SQSTM1 degradation and GFP-LC3 puncta formation, thus validating this assay to be used as an initial and quantitative method for evaluating the late step of autophagy in individual cells, complementing other methods.
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Affiliation(s)
- Marcos P Thomé
- Departamento de Biofísica, Universidade Federal do Rio Grande do Sul (UFRGS), 91501970, Porto Alegre, Brazil
| | - Eduardo C Filippi-Chiela
- Departamento de Biofísica, Universidade Federal do Rio Grande do Sul (UFRGS), 91501970, Porto Alegre, Brazil.,Faculdade de Medicina, UFRGS, 91501970, Porto Alegre, Brazil
| | - Emilly S Villodre
- Departamento de Biofísica, Universidade Federal do Rio Grande do Sul (UFRGS), 91501970, Porto Alegre, Brazil
| | - Celina B Migliavaca
- Departamento de Biofísica, Universidade Federal do Rio Grande do Sul (UFRGS), 91501970, Porto Alegre, Brazil
| | - Giovana R Onzi
- Departamento de Biofísica, Universidade Federal do Rio Grande do Sul (UFRGS), 91501970, Porto Alegre, Brazil
| | - Karina B Felipe
- Departamento de Biofísica, Universidade Federal do Rio Grande do Sul (UFRGS), 91501970, Porto Alegre, Brazil.,Departamento de Análises Clínicas, Universidade Federal do Paraná (UFPR), 80060000, Curitiba, Brazil
| | - Guido Lenz
- Departamento de Biofísica, Universidade Federal do Rio Grande do Sul (UFRGS), 91501970, Porto Alegre, Brazil .,Centro de Biotecnologia, UFRGS, 91501970, Porto Alegre, Brazil
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Yamabe M, Kumagai T, Shimogawara R, Blay EA, Hino A, Ichimura K, Sato A, Kim HS, Ohta N. Novel synthetic compounds with endoperoxide structure damage juvenile stage of Schistosoma mansoni by targeting lysosome-like organelles. Parasitol Int 2016; 66:917-924. [PMID: 27771462 DOI: 10.1016/j.parint.2016.10.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 10/13/2016] [Accepted: 10/18/2016] [Indexed: 10/20/2022]
Abstract
The new synthetic compound 1,2,6,7-tetraoxaspiro[7.11]nonadecan (N-89), a novel anti-malaria drug candidate, is also a promising drug candidate against schistosomiasis with killing effects against juvenile stage of S. mansoni. In order to investigate how N-89 kills schistosomes, we used a derivative of N-89, 6-(1,2,6,7-tetraoxaspiro[7.11] nonadec-4-yl)hexan-1-ol (N-251), which enables us to conjugate with fluorescent reagents. Firstly, N-251 showed strong killing effects to larvae of S. mansoni in vitro. Ultrastructural analysis showed the disruptions of the lysosome-like organelles or the acetabular glands, followed by cytoplasmic lysis inside the worm body in N-251-treated group under electron microscopy. For rhodamine-conjugated N-251 and organelle markers, we observed that N-251 accumulated in acidic organelle. In addition, LysoTracker signals in these acidic organelles disappeared in N-251-treated group over time. Finally, we observed that the activity of cathepsin B, a lysosome-specific enzyme, was also decreased together with alternation of acidic organelle marker signal by N-251-treated group. These results suggested that our synthesized compounds induced the dysfunction or the disruption of acidic lysosome-like organelles and finally led to worm death.
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Affiliation(s)
- Masafumi Yamabe
- Department of Environmental Parasitology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Takashi Kumagai
- Department of Environmental Parasitology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Rieko Shimogawara
- Department of Environmental Parasitology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Emmanuel Awusah Blay
- Department of Environmental Parasitology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Akina Hino
- Department of Environmental Parasitology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Koichiro Ichimura
- Department of Anatomy and Life Structure, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Akira Sato
- Division of International Infectious Diseases Control, Faculty of Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Hye-Sook Kim
- Division of International Infectious Diseases Control, Faculty of Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Nobuo Ohta
- Department of Environmental Parasitology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
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