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Heo R, Park M, Mun SY, Zhuang W, Jeong J, Park H, Han ET, Han JH, Chun W, Jung WK, Choi IW, Park WS. Vasorelaxant mechanisms of the antidiabetic anagliptin in rabbit aorta: roles of Kv channels and SERCA pump. Acta Diabetol 2024:10.1007/s00592-024-02351-9. [PMID: 39103505 DOI: 10.1007/s00592-024-02351-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 07/29/2024] [Indexed: 08/07/2024]
Abstract
AIMS The present study investigated the vasorelaxant mechanisms of an oral antidiabetic drug, anagliptin, using phenylephrine (Phe)-induced pre-contracted rabbit aortic rings. METHODS Arterial tone measurement was performed in rabbit thoracic aortic rings. RESULTS Anagliptin induced vasorelaxation in a dose-dependent manner. Pre-treatment with the classical voltagedependent K+ (Kv) channel inhibitors 4-aminopyridine and tetraethylammonium significantly decreased the vasorelaxant effect of anagliptin, whereas pre-treatment with the inwardly rectifying K+ (Kir) channel inhibitor Ba2+, the ATP-sensitive K+ (KATP) channel inhibitor glibenclamide, and the large-conductance Ca2+-activated K+ (BKCa) channel inhibitor paxilline did not attenuate the vasorelaxant effect. Furthermore, the vasorelaxant response of anagliptin was effectively inhibited by pre-treatment with the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump inhibitors thapsigargin and cyclopiazonic acid. Neither cAMP/protein kinase A (PKA)-related signaling pathway inhibitors (adenylyl cyclase inhibitor SQ 22536 and PKA inhibitor KT 5720) nor cGMP/protein kinase G (PKG)-related signaling pathway inhibitors (guanylyl cyclase inhibitor ODQ and PKG inhibitor KT 5823) reduced the vasorelaxant effect of anagliptin. Similarly, the anagliptin-induced vasorelaxation was independent of the endothelium. CONCLUSIONS Based on these results, we suggest that anagliptin-induced vasorelaxation in rabbit aortic smooth muscle occurs by activating Kv channels and the SERCA pump, independent of other vascular K+ channels, cAMP/PKA- or cGMP/PKG-related signaling pathways, and the endothelium.
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Affiliation(s)
- Ryeon Heo
- Department of Physiology, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Minju Park
- Department of Physiology, Institute of Medical Sciences, Kangwon National University School of Medicine, 1 Kangwondaehak-Gil, Chuncheon, 24341, South Korea
| | - Seo-Yeong Mun
- Department of Physiology, Institute of Medical Sciences, Kangwon National University School of Medicine, 1 Kangwondaehak-Gil, Chuncheon, 24341, South Korea
| | - Wenwen Zhuang
- Department of Physiology, Institute of Medical Sciences, Kangwon National University School of Medicine, 1 Kangwondaehak-Gil, Chuncheon, 24341, South Korea
| | - Junsu Jeong
- Department of Physiology, Institute of Medical Sciences, Kangwon National University School of Medicine, 1 Kangwondaehak-Gil, Chuncheon, 24341, South Korea
| | - Hongzoo Park
- Department of Urology, Institute of Medical Sciences, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Jin-Hee Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Wanjoo Chun
- Department of Pharmacology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Won-Kyo Jung
- Department of Biomedical Engineering, and Center for Marine-Integrated Biomedical Technology (BK21 Plus), Pukyong National University, Busan, 48513, South Korea
| | - Il-Whan Choi
- Department of Microbiology, College of Medicine, Inje University, Busan, 48516, South Korea
| | - Won Sun Park
- Department of Physiology, Institute of Medical Sciences, Kangwon National University School of Medicine, 1 Kangwondaehak-Gil, Chuncheon, 24341, South Korea.
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Tong J, Wang Q, Gao Z, Liu Y, Lu C. VMP1: a multifaceted regulator of cellular homeostasis with implications in disease pathology. Front Cell Dev Biol 2024; 12:1436420. [PMID: 39100095 PMCID: PMC11294092 DOI: 10.3389/fcell.2024.1436420] [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: 05/22/2024] [Accepted: 07/08/2024] [Indexed: 08/06/2024] Open
Abstract
Vacuole membrane protein 1 (VMP1) is an integral membrane protein that plays a pivotal role in cellular processes, particularly in the regulation of autophagy. Autophagy, a self-degradative mechanism, is essential for maintaining cellular homeostasis by degradation and recycling damaged organelles and proteins. VMP1 involved in the autophagic processes include the formation of autophagosomes and the subsequent fusion with lysosomes. Moreover, VMP1 modulates endoplasmic reticulum (ER) calcium levels, which is significant for various cellular functions, including protein folding and cellular signaling. Recent studies have also linked VMP1 to the cellular response against viral infections and lipid droplet (LD). Dysregulation of VMP1 has been observed in several pathological conditions, including neurodegenerative diseases such as Parkinson's disease (PD), pancreatitis, hepatitis, and tumorogenesis, underscoring its potential as a therapeutic target. This review aims to provide an overview of VMP1's multifaceted roles and its implications in disease pathology.
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Affiliation(s)
- Jia Tong
- The Third Affiliated Hospital of Xinxiang Medical University, Xinxiang, Henan, China
- Henan Key Laboratory of Biological Psychiatry (Xinxiang Medical University), The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, Henan, China
- Henan International Joint Laboratory for Non-Invasive Neural Modulation, Department of Physiology and Pathology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, Henan, China
- Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, Henan, China
| | - Qianqian Wang
- Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, Henan, China
| | - Ziyan Gao
- Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, Henan, China
| | - Yang Liu
- Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, Henan, China
| | - Chengbiao Lu
- Henan International Joint Laboratory for Non-Invasive Neural Modulation, Department of Physiology and Pathology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, Henan, China
- Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, Henan, China
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Kalkusova K, Taborska P, Stakheev D, Rataj M, Smite S, Darras E, Albo J, Bartunkova J, Vannucci L, Smrz D. Impaired Proliferation of CD8 + T Cells Stimulated with Monocyte-Derived Dendritic Cells Previously Matured with Thapsigargin-Stimulated LAD2 Human Mast Cells. J Immunol Res 2024; 2024:5537948. [PMID: 39056014 PMCID: PMC11272405 DOI: 10.1155/2024/5537948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 04/30/2024] [Accepted: 06/22/2024] [Indexed: 07/28/2024] Open
Abstract
CD8+ T cells are essential for adaptive immunity against infection and tumors. Their ability to proliferate after stimulation is crucial to their functionality. Dendritic cells (DCs) are professional antigen-presenting cells that induce their proliferation. Here, we show that thapsigargin-induced LAD2 mast cell (MC) line-released products can impair the ability of monocyte-derived DCs to induce CD8+ T-cell proliferation and the generation of Th1 cytokine-producing T cells. We found that culture medium conditioned with LAD2 MCs previously stimulated with thapsigargin (thapsLAD2) induces maturation of DCs as determined by the maturation markers CD80, CD83, CD86, and HLA-DR. However, thapsLAD2-matured DCs produced no detectable TNFα or IL-12 during the maturation. In addition, although their surface expression of PD-L1 was comparable with the immature or TLR7/8-agonist (R848)-matured DCs, their TIM-3 expression was significantly higher than in immature DCs and even much higher than in R848-matured DCs. In addition, contrary to R848-matured DCs, the thapsLAD2-matured DCs only tended to induce enhanced proliferation of CD4+ T cells than immature DCs. For CD8+ T cells, this tendency was not even detected because thapsLAD2-matured and immature DCs comparably induced their proliferation, which contrasted with the significantly enhanced proliferation induced by R848-matured DCs. Furthermore, these differences were comparably recapitulated in the ability of the tested DCs to induce IFNγ- and IFNγ/TNFα-producing T cells. These findings show a novel mechanism of MC-mediated regulation of adaptive immune responses.
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Affiliation(s)
- Katerina Kalkusova
- Department of ImmunologySecond Faculty of MedicineCharles University and University Hospital Motol, Prague, Czech Republic
| | - Pavla Taborska
- Department of ImmunologySecond Faculty of MedicineCharles University and University Hospital Motol, Prague, Czech Republic
| | - Dmitry Stakheev
- Department of ImmunologySecond Faculty of MedicineCharles University and University Hospital Motol, Prague, Czech Republic
| | - Michal Rataj
- Department of ImmunologySecond Faculty of MedicineCharles University and University Hospital Motol, Prague, Czech Republic
| | - Sindija Smite
- Department of ImmunologySecond Faculty of MedicineCharles University and University Hospital Motol, Prague, Czech Republic
| | - Elea Darras
- Department of ImmunologySecond Faculty of MedicineCharles University and University Hospital Motol, Prague, Czech Republic
| | - Julia Albo
- Department of ImmunologySecond Faculty of MedicineCharles University and University Hospital Motol, Prague, Czech Republic
| | - Jirina Bartunkova
- Department of ImmunologySecond Faculty of MedicineCharles University and University Hospital Motol, Prague, Czech Republic
| | - Luca Vannucci
- Laboratory of ImmunotherapyInstitute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Daniel Smrz
- Department of ImmunologySecond Faculty of MedicineCharles University and University Hospital Motol, Prague, Czech Republic
- Laboratory of ImmunotherapyInstitute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
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Geng Z, Zhang M, Huang B, Zhang X, Wang Z. A novel nanoparticle fluorescent probe based on a water-soluble conjugated polymer for real-time monitoring of ATP fluctuation and configuration of the Golgi apparatus during the inhibition of glycolysis. Anal Chim Acta 2024; 1304:342572. [PMID: 38637042 DOI: 10.1016/j.aca.2024.342572] [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: 12/11/2023] [Revised: 03/23/2024] [Accepted: 04/01/2024] [Indexed: 04/20/2024]
Abstract
BACKGROUND Adenosine 5'-triphosphate (ATP) plays an important role in cell metabolism and has been regarded as an indicator of cell survival and damage. Golgi apparatus participates in the signal transduction processes of substance transport, ion homeostasis and stress when extracellular substances enter cells. Till now, there is no fluorescent probe for monitoring Golgi ATP level fluctuation and visualizing the configuration change of the Golgi apparatus during the inhibition of glycolysis. RESULTS Herein, we report the synthesis of a novel water-soluble cationic polythiophene derivative (PEMTEA) that can be employed as a fluorescent sensor for measuring ATP in the Golgi apparatus. PEMTEA self-assembles into PT-NP nanoparticles in aqueous solution with a diameter of approximately 2 nm. PT-NP displays high sensitivity and superb selectivity towards ATP with a detection limit of 90 nM and a linear detection range from 0 to 3.0 μM. The nanoparticles show low toxicity to HepG2 cells and good photostability in the Golgi apparatus. With the stimulation of Ca2+, PT-NP was practically applied to real-time monitor of endogenous ATP levels in the Golgi apparatus through fluorescence microscopy. Finally, we studied the relationship between the concentration of ATP and configuration of the Golgi apparatus during the inhibition of glycolysis using PT-NP. SIGNIFICANCE We have demonstrated that PT-NP can not only indicate the fluctuation and distribution of ATP in the Golgi apparatus, but also give the information of the configuration change of the Golgi apparatus at the single-cell level during the inhibition of glycolysis.
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Affiliation(s)
- Zhirong Geng
- College of Pharmacy, Jiangsu Joint International Laboratory of Animal-Derived Chinese Medicine and Functional Peptides, Nanjing University of Chinese Medicine, Nanjing, 210023, PR China; State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing, 210023, PR China.
| | - Miaomiao Zhang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing, 210023, PR China
| | - Binghuan Huang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing, 210023, PR China
| | - Xiaohong Zhang
- College of Pharmacy, Jiangsu Joint International Laboratory of Animal-Derived Chinese Medicine and Functional Peptides, Nanjing University of Chinese Medicine, Nanjing, 210023, PR China
| | - Zhilin Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing, 210023, PR China.
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Kodakandla G, Akimzhanov AM, Boehning D. Regulatory mechanisms controlling store-operated calcium entry. Front Physiol 2023; 14:1330259. [PMID: 38169682 PMCID: PMC10758431 DOI: 10.3389/fphys.2023.1330259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 12/08/2023] [Indexed: 01/05/2024] Open
Abstract
Calcium influx through plasma membrane ion channels is crucial for many events in cellular physiology. Cell surface stimuli lead to the production of inositol 1,4,5-trisphosphate (IP3), which binds to IP3 receptors (IP3R) in the endoplasmic reticulum (ER) to release calcium pools from the ER lumen. This leads to the depletion of ER calcium pools, which has been termed store depletion. Store depletion leads to the dissociation of calcium ions from the EF-hand motif of the ER calcium sensor Stromal Interaction Molecule 1 (STIM1). This leads to a conformational change in STIM1, which helps it to interact with the plasma membrane (PM) at ER:PM junctions. At these ER:PM junctions, STIM1 binds to and activates a calcium channel known as Orai1 to form calcium release-activated calcium (CRAC) channels. Activation of Orai1 leads to calcium influx, known as store-operated calcium entry (SOCE). In addition to Orai1 and STIM1, the homologs of Orai1 and STIM1, such as Orai2/3 and STIM2, also play a crucial role in calcium homeostasis. The influx of calcium through the Orai channel activates a calcium current that has been termed the CRAC current. CRAC channels form multimers and cluster together in large macromolecular assemblies termed "puncta". How CRAC channels form puncta has been contentious since their discovery. In this review, we will outline the history of SOCE, the molecular players involved in this process, as well as the models that have been proposed to explain this critical mechanism in cellular physiology.
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Affiliation(s)
- Goutham Kodakandla
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, United States
| | - Askar M. Akimzhanov
- Department of Biochemistry and Molecular Biology, McGovern Medical School, Houston, TX, United States
| | - Darren Boehning
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, United States
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Rajeev P, Singh N, Kechkar A, Butler C, Ramanan N, Sibarita JB, Jose M, Nair D. Nanoscale regulation of Ca2+ dependent phase transitions and real-time dynamics of SAP97/hDLG. Nat Commun 2022; 13:4236. [PMID: 35869063 PMCID: PMC9307800 DOI: 10.1038/s41467-022-31912-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 07/08/2022] [Indexed: 11/20/2022] Open
Abstract
Synapse associated protein-97/Human Disk Large (SAP97/hDLG) is a conserved, alternatively spliced, modular, scaffolding protein critical in regulating the molecular organization of cell-cell junctions in vertebrates. We confirm that the molecular determinants of first order phase transition of SAP97/hDLG is controlled by morpho-functional changes in its nanoscale organization. Furthermore, the nanoscale molecular signatures of these signalling islands and phase transitions are altered in response to changes in cytosolic Ca2+. Additionally, exchange kinetics of alternatively spliced isoforms of the intrinsically disordered region in SAP97/hDLG C-terminus shows differential sensitivities to Ca2+ bound Calmodulin, affirming that the molecular signatures of local phase transitions of SAP97/hDLG depends on their nanoscale heterogeneity and compositionality of isoforms. SAP97/hDLG is a ubiquitous, alternatively spliced, and conserved modular scaffolding protein involved in the organization cell junctions and excitatory synapses. Here, authors confirm that SAP97/hDLG condenses in to nanosized molecular domains in both heterologous cells and hippocampal pyramidal neurons. Authors demonstrate that in vivo and in vitro condensation, molecular signatures of nanoscale condensates and exchange kinetics of SAP97/hDLG is modulated by the local availability of alternatively spliced isoforms. Additionally, SAP97/hDLG isoforms exhibits a differential sensitivity to Ca2+ bound Calmodulin, resulting in altered properties of nanocondensates and their real-time regulation
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Schulte A, Blum R. Shaped by leaky ER: Homeostatic Ca2+ fluxes. Front Physiol 2022; 13:972104. [PMID: 36160838 PMCID: PMC9491824 DOI: 10.3389/fphys.2022.972104] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 08/16/2022] [Indexed: 11/21/2022] Open
Abstract
At any moment in time, cells coordinate and balance their calcium ion (Ca2+) fluxes. The term ‘Ca2+ homeostasis’ suggests that balancing resting Ca2+ levels is a rather static process. However, direct ER Ca2+ imaging shows that resting Ca2+ levels are maintained by surprisingly dynamic Ca2+ fluxes between the ER Ca2+ store, the cytosol, and the extracellular space. The data show that the ER Ca2+ leak, continuously fed by the high-energy consuming SERCA, is a fundamental driver of resting Ca2+ dynamics. Based on simplistic Ca2+ toolkit models, we discuss how the ER Ca2+ leak could contribute to evolutionarily conserved Ca2+ phenomena such as Ca2+ entry, ER Ca2+ release, and Ca2+ oscillations.
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Affiliation(s)
- Annemarie Schulte
- Department of Neurology, University Hospital of Würzburg, Würzburg, Germany
- Department of Anesthesiology, Intensive Care, Emergency Medicine and Pain Therapy, University Hospital of Würzburg, Würzburg, Germany
| | - Robert Blum
- Department of Neurology, University Hospital of Würzburg, Würzburg, Germany
- *Correspondence: Robert Blum,
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Milenina LS, Krutetskaya ZI, Antonov VG, Krutetskaya NI. Sigma-1 Receptor Ligands Chlorpromazine and Trifluoperazine Attenuate Ca 2+ Responses in Rat Peritoneal Macrophages. CELL AND TISSUE BIOLOGY 2022; 16:233-244. [PMID: 35668825 PMCID: PMC9136207 DOI: 10.1134/s1990519x22030075] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 11/23/2022]
Abstract
Sigma-1 receptors are ubiquitous multifunctional ligand-regulated molecular chaperones in the endoplasmic reticulum membrane with a unique history, structure, and pharmacological profile. Sigma-1 receptors bind ligands of different chemical structure and pharmacological action and modulate a wide range of cellular processes in health and disease, including Ca2+ signaling. To elucidate the involvement of sigma-1 receptors in the processes of Ca2+ signaling in macrophages we studied the effect of sigma-1 receptor ligands, phenothiazine neuroleptics chlorpromazine and trifluoperazine, on Ca2+ responses induced by inhibitors of endoplasmic Ca2+-ATPases thapsigargin and cyclopiazonic acid, as well as by disulfide-containing immunomodulators Glutoxim and Molixan in rat peritoneal macrophages. Using Fura-2AM microfluorimetry we showed for the first time that chlorpromazine and trifluoperazine inhibit both phases of Ca2+ responses induced by Glutoxim, Molixan, thapsigargin, and cyclopiazonic acid in rat peritoneal macrophages. The data obtained indicate the participation of sigma-1 receptors in a complex signaling cascade caused by Glutoxim or Molixan and leading to an increase in intracellular Ca2+ concentration in macrophages. The results also indicate the involvement of sigma-1 receptors in the regulation of store-dependent Ca2+entry in macrophages.
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Affiliation(s)
- L. S. Milenina
- Department of Biophysics, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Z. I. Krutetskaya
- Department of Biophysics, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - V. G. Antonov
- Department of Clinical Biochemistry and Laboratory Diagnostics, Kirov Military Medical Academy, 194044 St. Petersburg, Russia
| | - N. I. Krutetskaya
- Department of Biophysics, St. Petersburg State University, 199034 St. Petersburg, Russia
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Lee SK, Kweon YC, Lee AR, Lee YY, Park CY. Metastasis enhancer PGRMC1 boosts store-operated Ca2+ entry by uncoiling Ca2+ sensor STIM1 for focal adhesion turnover and actomyosin formation. Cell Rep 2022; 38:110281. [DOI: 10.1016/j.celrep.2021.110281] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 11/05/2021] [Accepted: 12/23/2021] [Indexed: 12/22/2022] Open
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Seo MS, An JR, Kang M, Heo R, Park H, Han ET, Han JH, Chun W, Park WS. Mechanisms underlying the vasodilatory effects of canagliflozin in the rabbit thoracic aorta: Involvement of the SERCA pump and Kv channels. Life Sci 2021; 287:120101. [PMID: 34715136 DOI: 10.1016/j.lfs.2021.120101] [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: 05/09/2021] [Revised: 10/13/2021] [Accepted: 10/24/2021] [Indexed: 10/20/2022]
Abstract
AIMS Canagliflozin is an anti-diabetic agent and sodium glucose co-transporter-2 inhibitor. Despite numerous clinical trials demonstrating its beneficial effects on blood pressure, the cellular mechanisms underlying the effects of canagliflozin on vascular reactivity have yet to be clarified. We investigated the vasodilatory effect of canagliflozin on aortic rings isolated from rabbits. MAIN METHODS We used rabbit thoracic aortic rings and its arterial tone was tested by using wire myography system. KEY FINDINGS Canagliflozin caused concentration-dependent vasodilation in aortic rings pre-constricted with phenylephrine or high K+. However, the degree of canagliflozin-induced vasodilation of the aortic rings pre-constricted with high K+ was less than that of rings pre-constricted with phenylephrine. Application of 4-aminopyridine, a voltage-dependent K+ (Kv) channel inhibitor, reduced canagliflozin-induced vasodilation. However, pre-incubation of an inwardly rectifying K+ channel inhibitor, a large-conductance Ca2+-activated K+ channel inhibitor, and an ATP-sensitive K+ inhibitor did not modulate the vasodilatory effects of canagliflozin. Indeed, canagliflozin increased Kv currents in aortic smooth muscle cells. Pre-treatment with thapsigargin or cyclopiazonic acid, a sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump inhibitors, reduced the vasodilatory effects of canagliflozin. Conversely, pre-treatment with a Ca2+ channel inhibitor, adenylyl cyclase/PKA inhibitors, and guanylyl cyclase/PKG inhibitors did not modulate the vasodilatory effects of canagliflozin. Endothelium removal, and pre-treatment with the nitric oxide synthase inhibitor L-NAME, and small- and intermediate-conductance Ca2+-activated K+ channel inhibitor apamin and TRAM-34, did not diminish the vasodilatory effects of canagliflozin. SIGNIFICANCE Our results indicate that canagliflozin induces vasodilation, which is dependent on the robust SERCA activity and Kv channel activation.
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Affiliation(s)
- Mi Seon Seo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, South Korea
| | - Jin Ryeol An
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, South Korea
| | - Minji Kang
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, South Korea
| | - Ryeon Heo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, South Korea
| | - Hongzoo Park
- Department of Urology, Kangwon National University School of Medicine, Chuncheon 24341, South Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon 24341, South Korea
| | - Jin-Hee Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon 24341, South Korea
| | - Wanjoo Chun
- Department of Pharmacology, Kangwon National University School of Medicine, Chuncheon 24341, South Korea
| | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, South Korea.
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11
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Wang F, Fan LH, Li A, Dong F, Hou Y, Schatten H, Sun QY, Ou XH. Effects of various calcium transporters on mitochondrial Ca 2+ changes and oocyte maturation. J Cell Physiol 2021; 236:6548-6558. [PMID: 33704771 DOI: 10.1002/jcp.30327] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/22/2021] [Accepted: 02/04/2021] [Indexed: 11/10/2022]
Abstract
Ca2+ participates in many important cellular processes, but the underlying mechanisms are still poorly understood, especially during oocyte maturation. First, we confirmed that calcium in the culture medium was essential for oocyte maturation. Next, various inhibitors of Ca2+ channels were applied to investigate their roles in mitochondrial Ca2+ changes and oocyte maturation. Our results showed that Trmp7, Orai, T-type Ca2+ channels and Na+ /Ca2+ exchanger complex (NCLX) were important for oocyte maturation. Trmp7 inhibition delayed germinal vesicle breakdown. Orai and NCLX inhibition significantly weakened the distribution of mitochondrial Ca2+ around the nucleus compared to the Ctrl group. Interestingly, even T-type Ca2+ channels-specific inhibitor Mibefradil blocked germinal vesicle breakdown; mitochondrial Ca2+ surrounding the nucleus still was maintained at a high level without spindle formation. Two calcium transporter inhibitors, Thapsigargin and Ruthenium Red, which have been confirmed to inhibit oocyte activation, did not significantly affect oocyte maturation. Increasing the knowledge of calcium transport may provide a basis to build on for improving oocyte in vitro maturation in human assisted reproduction clinics.
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Affiliation(s)
- Feng Wang
- Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, China
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
| | - Li-Hua Fan
- Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, China
| | - Ang Li
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Feng Dong
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Yi Hou
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Heide Schatten
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, USA
| | - Qing-Yuan Sun
- Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, China
| | - Xiang-Hong Ou
- Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, China
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12
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Yamashita M, Prakriya M. Interrogating permeation and gating of Orai channels using chemical modification of cysteine residues. Methods Enzymol 2021; 652:213-239. [PMID: 34059283 DOI: 10.1016/bs.mie.2021.02.012] [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] [Indexed: 11/20/2022]
Abstract
Chemical modification of ion channels using the substituted cysteine accessibility method has a rich and successful history in elucidating the structural basis of ion channel function. In this approach, cysteine residues are introduced in regions of interest into the protein and their accessibility to water soluble thiol-reactive reagents is determined by monitoring ion channel activity. Because a wide range of these reagents are available with differing size, charge, and membrane solubility, the physio-chemical environment of the introduced cysteine residue and therefore the protein domain of interest can be probed with great precision. The approach has been widely employed for determining the secondary structure of specific ion channel domains, the location and nature of the channel gate, and the conformational rearrangements in the channel pore that underlie the opening/closing of the pore. In this chapter, we describe the use of these and related approaches to probe the functional architecture and gating of store-operated Orai1 channels.
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Affiliation(s)
- Megumi Yamashita
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, IL, United States
| | - Murali Prakriya
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, IL, United States.
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13
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Christensen SB, Simonsen HT, Engedal N, Nissen P, Møller JV, Denmeade SR, Isaacs JT. From Plant to Patient: Thapsigargin, a Tool for Understanding Natural Product Chemistry, Total Syntheses, Biosynthesis, Taxonomy, ATPases, Cell Death, and Drug Development. PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS 2021; 115:59-114. [PMID: 33797641 DOI: 10.1007/978-3-030-64853-4_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Thapsigargin, the first representative of the hexaoxygenated guaianolides, was isolated 40 years ago in order to understand the skin-irritant principles of the resin of the umbelliferous plant Thapsia garganica. The pronounced cytotoxicity of thapsigargin is caused by highly selective inhibition of the intracellular sarco-endoplasmic Ca2+-ATPase (SERCA) situated on the membrane of the endo- or sarcoplasmic reticulum. Thapsigargin is selective to the SERCA pump and to a minor extent the secretory pathway Ca2+/Mn2+ ATPase (SPCA) pump. Thapsigargin has become a tool for investigation of the importance of SERCA in intracellular calcium homeostasis. In addition, complex formation of thapsigargin with SERCA has enabled crystallization and structure determination of calcium-free states by X-ray crystallography. These results led to descriptions of the mechanism of action and kinetic properties of SERCA and other ATPases. Inhibition of SERCA depletes Ca2+ from the sarco- and endoplasmic reticulum provoking the unfolded protein response, and thereby has enabled new studies on the mechanism of cell death. Development of protocols for selective transformation of thapsigargin disclosed the chemistry and facilitated total synthesis of the molecule. Conversion of trilobolide into thapsigargin offered an economically feasible sustainable source of thapsigargin, which enables a future drug production. Principles for prodrug development were used by conjugating a payload derived from thapsigargin with a hydrophilic peptide selectively cleaved by proteases in the tumor. Mipsagargin was developed in order to obtain a drug for treatment of cancer diseases characterized by the presence of prostate specific membrane antigen (PSMA) in the neovascular tissue of the tumors. Even though mipsagargin showed interesting clinical effects the results did not encourage funding and consequently the attempt to register the drug has been abandoned. In spite of this disappointing fact, the research performed to develop the drug has resulted in important scientific discoveries concerning the chemistry, biosynthesis and biochemistry of sesquiterpene lactones, the mechanism of action of ATPases including SERCA, mechanisms for cell death caused by the unfolded protein response, and the use of prodrugs for cancer-targeting cytotoxins. The presence of toxins in only some species belonging to Thapsia also led to a major revision of the taxonomy of the genus.
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Affiliation(s)
- Søren Brøgger Christensen
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark.
| | - Henrik Toft Simonsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Bld 223, 2800, Kgs. Lyngby, Denmark
| | - Nikolai Engedal
- Department of Tumor Biology, Institute for Cancer Research, University Hospital, Montebello, 0379, Oslo, Norway
| | - Poul Nissen
- Department of Molecular Biology and Genetics, Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Gustav Wieds Vej 10C, 8000, Aarhus C, Denmark
| | - Jesper Vuust Møller
- Department of Biomedicine, Aarhus University, Ole Worms Allé 3, Bld 1182, Room 114, 8000, Aarhus C, Denmark
| | - Samuel R Denmeade
- Department of Oncology, Prostate Cancer Program, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins Maryland, The Johns Hopkins University School of Medicine, Baltimore, The Bunting-Blaustein Cancer Research Building, 1650 Orleans Street, Baltimore, MD, 21231, USA
| | - John T Isaacs
- Department of Oncology, Prostate Cancer Program, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins Maryland, The Johns Hopkins University School of Medicine, Baltimore, The Bunting-Blaustein Cancer Research Building, 1650 Orleans Street, Baltimore, MD, 21231, USA
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14
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Bakowski D, Murray F, Parekh AB. Store-Operated Ca 2+ Channels: Mechanism, Function, Pharmacology, and Therapeutic Targets. Annu Rev Pharmacol Toxicol 2020; 61:629-654. [PMID: 32966177 DOI: 10.1146/annurev-pharmtox-031620-105135] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Calcium (Ca2+) release-activated Ca2+ (CRAC) channels are a major route for Ca2+ entry in eukaryotic cells. These channels are store operated, opening when the endoplasmic reticulum (ER) is depleted of Ca2+, and are composed of the ER Ca2+ sensor protein STIM and the pore-forming plasma membrane subunit Orai. Recent years have heralded major strides in our understanding of the structure, gating, and function of the channels. Loss-of-function and gain-of-function mutants combined with RNAi knockdown strategies have revealed important roles for the channel in numerous human diseases, making the channel a clinically relevant target. Drugs targeting the channels generally lack specificity or exhibit poor efficacy in animal models. However, the landscape is changing, and CRAC channel blockers are now entering clinical trials. Here, we describe the key molecular and biological features of CRAC channels, consider various diseases associated with aberrant channel activity, and discuss targeting of the channels from a therapeutic perspective.
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Affiliation(s)
| | - Fraser Murray
- Pandeia Therapeutics, Oxford OX4 4GP, United Kingdom
| | - Anant B Parekh
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford OX1 3PT, United Kingdom; , .,Current affiliation: National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
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15
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Wang F, Li A, Meng TG, Wang LY, Wang LJ, Hou Y, Schatten H, Sun QY, Ou XH. Regulation of [Ca 2+] i oscillations and mitochondrial activity by various calcium transporters in mouse oocytes. Reprod Biol Endocrinol 2020; 18:87. [PMID: 32799904 PMCID: PMC7429721 DOI: 10.1186/s12958-020-00643-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 08/10/2020] [Indexed: 12/12/2022] Open
Abstract
Oocyte activation inefficiency is one of the reasons for female infertility and Ca2+ functions play a critical role in the regulation of oocyte activation. We used various inhibitors of Ca2+ channels located on the membrane, including sarcoplasmic/ endoplasmic reticulum Ca2+ATPases (SERCAs, the main Ca2+ pumps which decrease the intracellular Ca2+ level by refilling Ca2+ into the sarcoplasmic reticulum), transient receptor potential (TRP) ion channel subfamily member 7 (TRPM7, a Ca2+/Mg2+-permeable non-selective cation channel), T-type Ca2+ channels and calcium channel Orai1, to investigate their roles in [Ca2+]i oscillation patterns and mitochondrial membrane potential during oocyte activation by real-time recording. Our results showed that SERCAs, TRPM7 and T-type Ca2+ channels were important for initiation and maintenance of [Ca2+]i oscillations, which was required for mitochondrial membrane potential elevation during oocyte activation, as well as oocyte cytoskeleton stability and subsequent embryo development. Increasing the knowledge of calcium transport may provide a theoretical basis for improving oocyte activation in human assisted reproduction clinics.
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Affiliation(s)
- Feng Wang
- Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, 510317 China
- grid.9227.e0000000119573309China State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Ang Li
- grid.9227.e0000000119573309China State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Tie-Gang Meng
- Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, 510317 China
- grid.9227.e0000000119573309China State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Le-Yun Wang
- grid.9227.e0000000119573309China State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Li-Juan Wang
- grid.9227.e0000000119573309China State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Yi Hou
- grid.9227.e0000000119573309China State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Heide Schatten
- grid.134936.a0000 0001 2162 3504Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211 USA
| | - Qing-Yuan Sun
- Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, 510317 China
- grid.9227.e0000000119573309China State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Xiang-Hong Ou
- Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, 510317 China
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16
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The integrated stress response induces R-loops and hinders replication fork progression. Cell Death Dis 2020; 11:538. [PMID: 32678076 PMCID: PMC7366693 DOI: 10.1038/s41419-020-2727-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 06/25/2020] [Indexed: 12/15/2022]
Abstract
The integrated stress response (ISR) allows cells to rapidly shutdown most of their protein synthesis in response to protein misfolding, amino acid deficiency, or virus infection. These stresses trigger the phosphorylation of the translation initiation factor eIF2alpha, which prevents the initiation of translation. Here we show that triggering the ISR drastically reduces the progression of DNA replication forks within 1 h, thus flanking the shutdown of protein synthesis with immediate inhibition of DNA synthesis. DNA replication is restored by compounds that inhibit eIF2alpha kinases or re-activate eIF2alpha. Mechanistically, the translational shutdown blocks histone synthesis, promoting the formation of DNA:RNA hybrids (R-loops), which interfere with DNA replication. R-loops accumulate upon histone depletion. Conversely, histone overexpression or R-loop removal by RNaseH1 each restores DNA replication in the context of ISR and histone depletion. In conclusion, the ISR rapidly stalls DNA synthesis through histone deficiency and R-loop formation. We propose that this shutdown mechanism prevents potentially detrimental DNA replication in the face of cellular stresses.
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17
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Draberova L, Draberova H, Potuckova L, Halova I, Bambouskova M, Mohandas N, Draber P. Cytoskeletal Protein 4.1R Is a Positive Regulator of the FcεRI Signaling and Chemotaxis in Mast Cells. Front Immunol 2020; 10:3068. [PMID: 31993060 PMCID: PMC6970983 DOI: 10.3389/fimmu.2019.03068] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 12/16/2019] [Indexed: 12/11/2022] Open
Abstract
Protein 4.1R, a member of the 4.1 family, functions as a bridge between cytoskeletal and plasma membrane proteins. It is expressed in T cells, where it binds to a linker for activation of T cell (LAT) family member 1 and inhibits its phosphorylation and downstream signaling events after T cell receptor triggering. The role of the 4.1R protein in cell activation through other immunoreceptors is not known. In this study, we used 4.1R-deficient (4.1R-KO) and 4.1R wild-type (WT) mice and explored the role of the 4.1R protein in the high-affinity IgE receptor (FcεRI) signaling in mast cells. We found that bone marrow mast cells (BMMCs) derived from 4.1R-KO mice showed normal growth in vitro and expressed FcεRI and c-KIT at levels comparable to WT cells. However, 4.1R-KO cells exhibited reduced antigen-induced degranulation, calcium response, and secretion of tumor necrosis factor-α. Chemotaxis toward antigen and stem cell factor (SCF) and spreading on fibronectin were also reduced in 4.1R-KO BMMCs, whereas prostaglandin E2-mediated chemotaxis was not affected. Antibody-induced aggregation of tetraspanin CD9 inhibited chemotaxis toward antigen in WT but not 4.1R-KO BMMCs, implying a CD9-4.1R protein cross-talk. Further studies documented that in the absence of 4.1R, antigen-mediated phosphorylation of FcεRI β and γ subunits was not affected, but phosphorylation of SYK and subsequent signaling events such as phosphorylation of LAT1, phospholipase Cγ1, phosphatases (SHP1 and SHIP), MAP family kinases (p38, ERK, JNK), STAT5, CBL, and mTOR were reduced. Immunoprecipitation studies showed the presence of both LAT1 and LAT2 (LAT, family member 2) in 4.1R immunocomplexes. The positive regulatory role of 4.1R protein in FcεRI-triggered activation was supported by in vivo experiments in which 4.1R-KO mice showed the normal presence of mast cells in the ears and peritoneum, but exhibited impaired passive cutaneous anaphylaxis. The combined data indicate that the 4.1R protein functions as a positive regulator in the early activation events after FcεRI triggering in mast cells.
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Affiliation(s)
- Lubica Draberova
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Helena Draberova
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Lucie Potuckova
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Ivana Halova
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Monika Bambouskova
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Narla Mohandas
- Red Cell Physiology Laboratory, New York Blood Center, New York, NY, United States
| | - Petr Draber
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
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18
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Ashmore J, Olsen H, Sørensen N, Thrasivoulou C, Ahmed A. Wnts control membrane potential in mammalian cancer cells. J Physiol 2019; 597:5899-5914. [DOI: 10.1113/jp278661] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 10/23/2019] [Indexed: 01/30/2023] Open
Affiliation(s)
- Jonathan Ashmore
- Department of Neuroscience Physiology and Pharmacology and UCL Ear Institute University College London Gower Street London WC1E 6BT UK
| | - Hervør Olsen
- Sophion Bioscience A/S Baltorpvej 154 DK‐2750 Ballerup Denmark
| | - Naja Sørensen
- Sophion Bioscience A/S Baltorpvej 154 DK‐2750 Ballerup Denmark
| | - Christopher Thrasivoulou
- Research Department of Cell & Developmental Biology, Centre for Cell & Molecular Dynamics, Rockefeller Building University Street, University College London London WC1E 6JJ UK
| | - Aamir Ahmed
- Centre for Stem Cells and Regenerative Medicine King's College London, 28th Floor, Tower Wing, Guy's Hospital Great Maze Pond London SE1 9RT UK
- Prostate Cancer Research Centre, Division of Surgery, 3rd Floor Laboratories, Charles Bell House University College London 67 Riding House Street London W1W 7EJ UK
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19
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Lin YP, Bakowski D, Mirams GR, Parekh AB. Selective recruitment of different Ca 2+-dependent transcription factors by STIM1-Orai1 channel clusters. Nat Commun 2019; 10:2516. [PMID: 31175287 PMCID: PMC6555828 DOI: 10.1038/s41467-019-10329-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 04/23/2019] [Indexed: 11/08/2022] Open
Abstract
Store-operated Ca2+ entry, involving endoplasmic reticulum Ca2+ sensing STIM proteins and plasma membrane Orai1 channels, is a widespread and evolutionary conserved Ca2+ influx pathway. This form of Ca2+ influx occurs at discrete loci where peripheral endoplasmic reticulum juxtaposes the plasma membrane. Stimulation evokes numerous STIM1-Orai1 clusters but whether distinct signal transduction pathways require different cluster numbers is unknown. Here, we show that two Ca2+-dependent transcription factors, NFAT1 and c-fos, have different requirements for the number of STIM1-Orai1 clusters and on the Ca2+ flux through them. NFAT activation requires fewer clusters and is more robustly activated than c-fos by low concentrations of agonist. For similar cluster numbers, transcription factor recruitment occurs sequentially, arising from intrinsic differences in Ca2+ sensitivities. Variations in the number of STIM1-Orai1 clusters and Ca2+ flux through them regulate the robustness of signalling to the nucleus whilst imparting a mechanism for selective recruitment of different Ca2+-dependent transcription factors.
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Affiliation(s)
- Yu-Ping Lin
- Department of Physiology, Anatomy and Genetics, Oxford University, Parks Road, Oxford, OX1 3PT, UK
| | - Daniel Bakowski
- Department of Physiology, Anatomy and Genetics, Oxford University, Parks Road, Oxford, OX1 3PT, UK
| | - Gary R Mirams
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, Nottingham University, Nottingham, NG7 2RD, UK
| | - Anant B Parekh
- Department of Physiology, Anatomy and Genetics, Oxford University, Parks Road, Oxford, OX1 3PT, UK.
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20
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Merlot AM, Porter GM, Sahni S, Lim EG, Peres P, Richardson DR. The metastasis suppressor, NDRG1, differentially modulates the endoplasmic reticulum stress response. Biochim Biophys Acta Mol Basis Dis 2019; 1865:2094-2110. [PMID: 30981813 DOI: 10.1016/j.bbadis.2019.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 04/02/2019] [Accepted: 04/09/2019] [Indexed: 01/22/2023]
Abstract
The metastasis suppressor, N-myc downstream regulated gene-1 (NDRG1), is a stress response protein that is involved in the inhibition of multiple oncogenic signaling pathways. Initial studies have linked NDRG1 and the endoplasmic reticulum (ER) stress response. Considering this, we extensively examined the mechanism by which NDRG1 regulates the ER stress response in pancreatic and colon cancer cells. We also examined the anti-cancer agent, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), which induces NDRG1 expression and causes ER stress. The expression of NDRG1 was demonstrated to regulate the three main arms of the ER stress response by: (1) increasing the expression of three major ER chaperones, binding immunoglobulin protein (BiP), calreticulin, and calnexin; (2) suppressing the protein kinase, RNA-activated (PKR)-like ER kinase (PERK); (3) inhibiting the inositol-requiring kinase 1α (IRE1α) arm; and (4) increasing the cleavage of activating transcription factor 6 (ATF6). An important finding was that NDRG1 enhances the anti-proliferative and anti-migratory activity of Dp44mT. This increased efficacy could be related to the following effects in the presence of Dp44mT and NDRG1, namely: markedly increased activation of the PERK target, eukaryotic translation initiation factor 2α (eIF2α); the maintenance of activating transcription factor 4 (ATF4) expression; high cytosolic Ca+2 that increases the sensitivity of cells to apoptosis via activation of the calmodulin-dependent kinase II (CaMKII) signaling cascade; and increased pro-apoptotic C/EBP-homologous protein (CHOP) expression. Collectively, this investigation dissects the molecular mechanisms through which NDRG1 manipulates the ER stress response and its ability to potentiate the activity of the potent anti-cancer agent, Dp44mT.
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Affiliation(s)
- A M Merlot
- Cancer Targets and Therapeutics Group, Lowy Cancer Research Centre, UNSW Centre for Childhood Cancer Research (C25), Faculty of Medicine, The University of New South Wales, Kensington, New South Wales 2031, Australia; Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Medical Foundation Building (K25), The University of Sydney, Sydney, New South Wales 2006, Australia.
| | - G M Porter
- Cancer Targets and Therapeutics Group, Lowy Cancer Research Centre, UNSW Centre for Childhood Cancer Research (C25), Faculty of Medicine, The University of New South Wales, Kensington, New South Wales 2031, Australia; Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Medical Foundation Building (K25), The University of Sydney, Sydney, New South Wales 2006, Australia
| | - S Sahni
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Medical Foundation Building (K25), The University of Sydney, Sydney, New South Wales 2006, Australia
| | - E G Lim
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Medical Foundation Building (K25), The University of Sydney, Sydney, New South Wales 2006, Australia
| | - P Peres
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Medical Foundation Building (K25), The University of Sydney, Sydney, New South Wales 2006, Australia
| | - D R Richardson
- Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Medical Foundation Building (K25), The University of Sydney, Sydney, New South Wales 2006, Australia; Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-8550, Japan.
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21
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Ribeiro D, Freitas M, Rocha S, Lima JLFC, Carvalho F, Fernandes E. Calcium Pathways in Human Neutrophils-The Extended Effects of Thapsigargin and ML-9. Cells 2018; 7:cells7110204. [PMID: 30423935 PMCID: PMC6262620 DOI: 10.3390/cells7110204] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 10/23/2018] [Accepted: 10/31/2018] [Indexed: 12/01/2022] Open
Abstract
In neutrophils, intracellular Ca2+ levels are regulated by several transporters and pathways, namely SERCA [sarco(endo)plasmic reticulum Ca2+-ATPase], SOCE (store-operated calcium entry), and ROCE (receptor-operated calcium entry). However, the exact mechanisms involved in the communication among these transporters are still unclear. In the present study, thapsigargin, an irreversible inhibitor of SERCA, and ML-9, a broadly used SOCE inhibitor, were applied in human neutrophils to better understand their effects on Ca2+ pathways in these important cells of the immune system. The thapsigargin and ML-9 effects in the intracellular free Ca2+ flux were evaluated in freshly isolated human neutrophils, using a microplate reader for monitoring fluorimetric kinetic readings. The obtained results corroborate the general thapsigargin-induced intracellular pattern of Ca2+ fluctuation, but it was also observed a much more extended effect in time and a clear sustained increase of Ca2+ levels due to its influx by SOCE. Moreover, it was obvious that ML-9 enhanced the thapsigargin-induced emptying of the internal stores. Indeed, ML-9 does not have this effect by itself, which indicates that, in neutrophils, thapsigargin does not act only on the influx by SOCE, but also by other Ca2+ pathways, that, in the future, should be further explored.
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Affiliation(s)
- Daniela Ribeiro
- LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal.
| | - Marisa Freitas
- LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal.
| | - Sílvia Rocha
- LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal.
| | - José L F C Lima
- LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal.
| | - Félix Carvalho
- UCIBIO, REQUIMTE, Toxicology Department, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal.
| | - Eduarda Fernandes
- LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal.
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22
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Yanda MK, Liu Q, Cebotaru L. A potential strategy for reducing cysts in autosomal dominant polycystic kidney disease with a CFTR corrector. J Biol Chem 2018; 293:11513-11526. [PMID: 29875161 DOI: 10.1074/jbc.ra118.001846] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 05/22/2018] [Indexed: 12/27/2022] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is associated with progressive enlargement of cysts, leading to a decline in function and renal failure that cannot be prevented by current treatments. Mutations in pkd1 and pkd2, encoding the polycystin 1 and 2 proteins, induce growth-related pathways, including heat shock proteins, as occurs in some cancers, raising the prospect that pharmacological interventions that target these pathways might alleviate or prevent ADPKD. Here, we demonstrate a role for VX-809, a corrector of cystic fibrosis transmembrane conductance regulator (CFTR), conventionally used to manage cystic fibrosis in reducing renal cyst growth. VX-809 reduced cyst growth in Pkd1-knockout mice and in proximal, tubule-derived, cultured Pkd1 knockout cells. VX-809 reduced both basal and forskolin-activated cAMP levels and also decreased the expression of the adenylyl cyclase AC3 but not of AC6. VX-809 also decreased resting levels of intracellular Ca2+ but did not affect ATP-stimulated Ca2+ release. Notably, VX-809 dramatically decreased thapsigargin-induced release of Ca2+ from the endoplasmic reticulum (ER). VX-809 also reduced the levels of heat shock proteins Hsp27, Hsp70, and Hsp90 in mice cystic kidneys, consistent with the restoration of cellular proteostasis. Moreover, VX-809 strongly decreased an ER stress marker, the GADD153 protein, and cell proliferation but had only a small effect on apoptosis. Given that administration of VX-809 is safe, this drug potentially offers a new way to treat patients with ADPKD.
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Affiliation(s)
- Murali K Yanda
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Qiangni Liu
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Liudmila Cebotaru
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
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23
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Yanda MK, Liu Q, Cebotaru V, Guggino WB, Cebotaru L. Histone deacetylase 6 inhibition reduces cysts by decreasing cAMP and Ca 2+ in knock-out mouse models of polycystic kidney disease. J Biol Chem 2017; 292:17897-17908. [PMID: 28887310 DOI: 10.1074/jbc.m117.803775] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/31/2017] [Indexed: 11/06/2022] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is associated with progressive enlargement of multiple renal cysts, often leading to renal failure that cannot be prevented by a current treatment. Two proteins encoded by two genes are associated with ADPKD: PC1 (pkd1), primarily a signaling molecule, and PC2 (pkd2), a Ca2+ channel. Dysregulation of cAMP signaling is central to ADPKD, but the molecular mechanism is unresolved. Here, we studied the role of histone deacetylase 6 (HDAC6) in regulating cyst growth to test the possibility that inhibiting HDAC6 might help manage ADPKD. Chemical inhibition of HDAC6 reduced cyst growth in PC1-knock-out mice. In proximal tubule-derived, PC1-knock-out cells, adenylyl cyclase 6 and 3 (AC6 and -3) are both expressed. AC6 protein expression was higher in cells lacking PC1, compared with control cells containing PC1. Intracellular Ca2+ was higher in PC1-knock-out cells than in control cells. HDAC inhibition caused a drop in intracellular Ca2+ and increased ATP-simulated Ca2+ release. HDAC6 inhibition reduced the release of Ca2+ from the endoplasmic reticulum induced by thapsigargin, an inhibitor of endoplasmic reticulum Ca2+-ATPase. HDAC6 inhibition and treatment of cells with the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) reduced cAMP levels in PC1-knock-out cells. Finally, the calmodulin inhibitors W-7 and W-13 reduced cAMP levels, and W-7 reduced cyst growth, suggesting that AC3 is involved in cyst growth regulated by HDAC6. We conclude that HDAC6 inhibition reduces cell growth primarily by reducing intracellular cAMP and Ca2+ levels. Our results provide potential therapeutic targets that may be useful as treatments for ADPKD.
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Affiliation(s)
- Murali K Yanda
- From the Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205 and
| | - Qiangni Liu
- From the Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205 and
| | - Valeriu Cebotaru
- the Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - William B Guggino
- From the Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205 and
| | - Liudmila Cebotaru
- From the Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205 and
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24
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Krutetskaya ZI, Milenina LS, Naumova AA, Butov SN, Antonov VG, Nozdrachev AD. The effect of chlorpromazine on intracellular Ca 2+ concentration in macrophages. DOKL BIOCHEM BIOPHYS 2017; 474:162-164. [PMID: 28726103 DOI: 10.1134/s1607672917030036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Indexed: 11/22/2022]
Abstract
Using Fura-2AM microfluorimetry, it was shown for the first time that neuroleptic chlorpromazine causes intracellular Ca2+ concentration increase in macrophages due to Ca2+ mobilization from intracellular Ca2+ stores and subsequent Ca2+ entry from the external medium. Chlorpromazine-induced Ca2+ entry is inhibited by La3+ and 2-aminoethoxydiphenyl borate and is associated with Ca2+ store depletion.
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Affiliation(s)
- Z I Krutetskaya
- St. Petersburg State University, St. Petersburg, 199034, Russia.
| | - L S Milenina
- St. Petersburg State University, St. Petersburg, 199034, Russia
| | - A A Naumova
- St. Petersburg State University, St. Petersburg, 199034, Russia
| | - S N Butov
- St. Petersburg State University, St. Petersburg, 199034, Russia
| | - V G Antonov
- St. Petersburg State University, St. Petersburg, 199034, Russia
| | - A D Nozdrachev
- St. Petersburg State University, St. Petersburg, 199034, Russia
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25
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Ferreira-Gomes MS, Mangialavori IC, Ontiveros MQ, Rinaldi DE, Martiarena J, Verstraeten SV, Rossi JPFC. Selectivity of plasma membrane calcium ATPase (PMCA)-mediated extrusion of toxic divalent cations in vitro and in cultured cells. Arch Toxicol 2017; 92:273-288. [DOI: 10.1007/s00204-017-2031-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 07/12/2017] [Indexed: 12/26/2022]
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26
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Chang CL, Chen YJ, Liou J. ER-plasma membrane junctions: Why and how do we study them? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1494-1506. [PMID: 28554772 DOI: 10.1016/j.bbamcr.2017.05.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/09/2017] [Accepted: 05/17/2017] [Indexed: 12/17/2022]
Abstract
Endoplasmic reticulum (ER)-plasma membrane (PM) junctions are membrane microdomains important for communication between the ER and the PM. ER-PM junctions were first reported in muscle cells in 1957, but mostly ignored in non-excitable cells due to their scarcity and lack of functional significance. In 2005, the discovery of stromal interaction molecule 1 (STIM1) mediating a universal Ca2+ feedback mechanism at ER-PM junctions in mammalian cells led to a resurgence of research interests toward ER-PM junctions. In the past decade, several major advancements have been made in this emerging topic in cell biology, including the generation of tools for labeling ER-PM junctions and the unraveling of mechanisms underlying regulation and functions of ER-PM junctions. This review summarizes early studies, recently developed tools, and current advances in the characterization and understanding of ER-PM junctions. This article is part of a Special Issue entitled: Membrane Contact Sites edited by Christian Ungermann and Benoit Kornmann.
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Affiliation(s)
- Chi-Lun Chang
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yu-Ju Chen
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jen Liou
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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27
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Molteni L, Rizzi L, Bresciani E, Possenti R, Petrocchi Passeri P, Ghè C, Muccioli G, Fehrentz JA, Verdié P, Martinez J, Omeljaniuk RJ, Biagini G, Binda A, Rivolta I, Locatelli V, Torsello A. Pharmacological and Biochemical Characterization of TLQP-21 Activation of a Binding Site on CHO Cells. Front Pharmacol 2017; 8:167. [PMID: 28424618 PMCID: PMC5371653 DOI: 10.3389/fphar.2017.00167] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/14/2017] [Indexed: 11/16/2022] Open
Abstract
VGF is a propeptide of 617 amino acids expressed throughout the central and the peripheral nervous system. VGF and peptides derived from its processing have been found in dense core vesicles and are released from neuronal and neuroendocrine cells via the regulated secretory pathway. Among VGF-derived neuropeptides, TLQP-21 (VGF556-576) has raised a huge interest and is one of most studied. TLQP-21 is a multifunctional neuropeptide involved in the control of several physiological functions, potentially including energy homeostasis, pain modulation, stress responsiveness and reproduction. Although little information is available about its receptor and the intracellular mechanisms mediating its biological effects, recent reports suggest that TLQP-21 may bind to the complement receptors C3aR1 and/or gC1qR. The first aim of this study was to ascertain the existence and nature of TLQP-21 binding sites in CHO cells. Secondly, we endeavored to characterize the ligand binding to these sites by using a small panel of VGF-derived peptides. And finally, we investigated the influence of TLQP-21 on selected intracellular signaling pathways. We report that CHO cells express a single class of saturable and specific binding sites for TLQP-21 with an affinity and capacity of Kd = 0.55 ± 0.05 × 10-9 M and Bmax = 81.7 ± 3.9 fmol/mg protein, respectively. Among the many bioactive products derived from the C-terminal region of VGF that we tested, TLQP-21 was the most potent in stimulating intracellular calcium mobilization in CHO cells; this effect is primarily due to its C-terminal fragment (HFHH-10). TLQP-21 induced rapid and transient dephosphorylation of phospholipase Cγ1 and phospholipase A2. Generation of IP3 and diacylglycerol was crucial for TLQP-21 bioactivity. In conclusion, our results suggest that the receptor stimulated by TLQP-21 belongs to the family of the Gq-coupled receptors, and its activation first increases membrane-lipid derived second messengers which thereby induce the mobilization of Ca2+ from the endoplasmic reticulum followed by a slower store-operated Ca2+ entry from outside the cell.
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Affiliation(s)
- Laura Molteni
- Department of Medicine and Surgery, University of Milano-BicoccaMonza, Italy.,PhD Program in Neuroscience, Department of Medicine and Surgery, University of Milano-BicoccaMonza, Italy
| | - Laura Rizzi
- Department of Medicine and Surgery, University of Milano-BicoccaMonza, Italy
| | - Elena Bresciani
- Department of Medicine and Surgery, University of Milano-BicoccaMonza, Italy
| | - Roberta Possenti
- Department of Medicine of Systems, University of Rome "Tor Vergata"Rome, Italy
| | | | - Corrado Ghè
- Department of Drug Science and Technology, University of TurinTurin, Italy
| | - Giampiero Muccioli
- Department of Drug Science and Technology, University of TurinTurin, Italy
| | - Jean-Alain Fehrentz
- Centre National de la Recherche Scientifique, Max Mousseron Institute of Biomolecules UMR5247, University of Montpellier, École Nationale Supérieure de Chimie de MontpellierMontpellier, France
| | - Pascal Verdié
- Centre National de la Recherche Scientifique, Max Mousseron Institute of Biomolecules UMR5247, University of Montpellier, École Nationale Supérieure de Chimie de MontpellierMontpellier, France
| | - Jean Martinez
- Centre National de la Recherche Scientifique, Max Mousseron Institute of Biomolecules UMR5247, University of Montpellier, École Nationale Supérieure de Chimie de MontpellierMontpellier, France
| | | | - Giuseppe Biagini
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy
| | - Anna Binda
- Department of Medicine and Surgery, University of Milano-BicoccaMonza, Italy
| | - Ilaria Rivolta
- Department of Medicine and Surgery, University of Milano-BicoccaMonza, Italy
| | - Vittorio Locatelli
- Department of Medicine and Surgery, University of Milano-BicoccaMonza, Italy
| | - Antonio Torsello
- Department of Medicine and Surgery, University of Milano-BicoccaMonza, Italy
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28
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Merhi A, Delrée P, Marini AM. The metabolic waste ammonium regulates mTORC2 and mTORC1 signaling. Sci Rep 2017; 7:44602. [PMID: 28303961 PMCID: PMC5355986 DOI: 10.1038/srep44602] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 02/09/2017] [Indexed: 12/21/2022] Open
Abstract
Two structurally and functionally distinct mammalian TOR complexes control cell growth and metabolism in physiological and pathological contexts including cancer. Upregulated glutaminolysis is part of the metabolic reprogramming occurring in cancer, providing fuels for growth but also liberating ammonium, a potent neurotoxic waste product. Here, we identify ammonium as a novel dose-dependent signal mediating rapid mTORC2 activation and further regulating mTORC1. We show that ammonium induces rapid RICTOR-dependent phosphorylation of AKT-S473, a process requiring the PI3K pathway and further involving the Src-family kinase YES1, the FAK kinase and the ITGβ1 integrin. Release of calcium from the endoplasmic reticulum store triggers rapid mTORC2 activation, similar to ammonium-induced activation, the latter being conversely prevented by calcium chelation.Moreover, in analogy to growth factors, ammonium triggers the AKT-dependent phosphoinhibition of the TSC complex and of PRAS40, two negative regulators of mTORC1. Consistent with mTORC1 stimulation, ammonium induces the inhibitory phosphorylation of 4EBP1, a negative regulator of protein biogenesis. Ammonium however dually impacts on the phosphorylation of p70S6K1 triggering a transient AKT-independent decrease in the phosphorylation of this second mTORC1 readout. Finally, we reveal ammonium as a dose-dependent stimulator of proliferation. This study underscores an mTORC2 and mTORC1 response to the so-called ammonium waste.
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Affiliation(s)
- Ahmad Merhi
- Biology of Membrane Transport, IBMM, Université Libre de Bruxelles, Rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium.,Institute of Pathology and Genetics, Avenue Georges Lemaître 25, 6041 Gosselies, Belgium.,Tumour Bank, Institute of Pathology and Genetics, Avenue Georges Lemaître 25, 6041 Gosselies, Belgium
| | - Paul Delrée
- Institute of Pathology and Genetics, Avenue Georges Lemaître 25, 6041 Gosselies, Belgium.,Tumour Bank, Institute of Pathology and Genetics, Avenue Georges Lemaître 25, 6041 Gosselies, Belgium
| | - Anna Maria Marini
- Biology of Membrane Transport, IBMM, Université Libre de Bruxelles, Rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium
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29
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Petersen OH, Courjaret R, Machaca K. Ca 2+ tunnelling through the ER lumen as a mechanism for delivering Ca 2+ entering via store-operated Ca 2+ channels to specific target sites. J Physiol 2017; 595:2999-3014. [PMID: 28181236 PMCID: PMC5430212 DOI: 10.1113/jp272772] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/05/2017] [Indexed: 01/02/2023] Open
Abstract
Ca2+ signalling is perhaps the most universal and versatile mechanism regulating a wide range of cellular processes. Because of the many different calcium‐binding proteins distributed throughout cells, signalling precision requires localized rises in the cytosolic Ca2+ concentration. In electrically non‐excitable cells, for example epithelial cells, this is achieved by primary release of Ca2+ from the endoplasmic reticulum via Ca2+ release channels placed close to the physiological target. Because any rise in the cytosolic Ca2+ concentration activates Ca2+ extrusion, and in order for cells not to run out of Ca2+, there is a need for compensatory Ca2+ uptake from the extracellular fluid. This Ca2+ uptake occurs through a process known as store‐operated Ca2+ entry. Ideally Ca2+ entering the cell should not diffuse to the target site through the cytosol, as this would potentially activate undesirable processes. Ca2+ tunnelling through the lumen of the endoplasmic reticulum is a mechanism for delivering Ca2+ entering via store‐operated Ca2+ channels to specific target sites, and this process has been described in considerable detail in pancreatic acinar cells and oocytes. Here we review the most important evidence and present a generalized concept.
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Affiliation(s)
- Ole H Petersen
- MRC Group, School of Biosciences and Systems Immunity Research Institute, Cardiff University, Cardiff, CF10 3AX, UK
| | - Raphael Courjaret
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, PO Box 24144, Doha, Qatar
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, PO Box 24144, Doha, Qatar
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30
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Navas-Navarro P, Rojo-Ruiz J, Rodriguez-Prados M, Ganfornina MD, Looger LL, Alonso MT, García-Sancho J. GFP-Aequorin Protein Sensor for Ex Vivo and In Vivo Imaging of Ca(2+) Dynamics in High-Ca(2+) Organelles. Cell Chem Biol 2016; 23:738-45. [PMID: 27291400 DOI: 10.1016/j.chembiol.2016.05.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/05/2016] [Accepted: 05/10/2016] [Indexed: 11/17/2022]
Abstract
Proper functioning of organelles such as the ER or the Golgi apparatus requires luminal accumulation of Ca(2+) at high concentrations. Here we describe a ratiometric low-affinity Ca(2+) sensor of the GFP-aequorin protein (GAP) family optimized for measurements in high-Ca(2+) concentration environments. Transgenic animals expressing the ER-targeted sensor allowed monitoring of Ca(2+) signals inside the organelle. The use of the sensor was demonstrated under three experimental paradigms: (1) ER Ca(2+) oscillations in cultured astrocytes, (2) ex vivo functional mapping of cholinergic receptors triggering ER Ca(2+) release in acute hippocampal slices from transgenic mice, and (3) in vivo sarcoplasmic reticulum Ca(2+) dynamics in the muscle of transgenic flies. Our results provide proof of the suitability of the new biosensors to monitor Ca(2+) dynamics inside intracellular organelles under physiological conditions and open an avenue to explore complex Ca(2+) signaling in animal models of health and disease.
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Affiliation(s)
- Paloma Navas-Navarro
- Instituto de Biología y Genética Molecular (IBGM), University of Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), c/ Sanz y Forés 3, 47003 Valladolid, Spain
| | - Jonathan Rojo-Ruiz
- Instituto de Biología y Genética Molecular (IBGM), University of Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), c/ Sanz y Forés 3, 47003 Valladolid, Spain
| | - Macarena Rodriguez-Prados
- Instituto de Biología y Genética Molecular (IBGM), University of Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), c/ Sanz y Forés 3, 47003 Valladolid, Spain
| | - María Dolores Ganfornina
- Instituto de Biología y Genética Molecular (IBGM), University of Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), c/ Sanz y Forés 3, 47003 Valladolid, Spain
| | - Loren L Looger
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147, USA
| | - María Teresa Alonso
- Instituto de Biología y Genética Molecular (IBGM), University of Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), c/ Sanz y Forés 3, 47003 Valladolid, Spain.
| | - Javier García-Sancho
- Instituto de Biología y Genética Molecular (IBGM), University of Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), c/ Sanz y Forés 3, 47003 Valladolid, Spain.
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31
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Merlot AM, Shafie NH, Yu Y, Richardson V, Jansson PJ, Sahni S, Lane DJ, Kovacevic Z, Kalinowski DS, Richardson DR. Mechanism of the induction of endoplasmic reticulum stress by the anti-cancer agent, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT): Activation of PERK/eIF2α, IRE1α, ATF6 and calmodulin kinase. Biochem Pharmacol 2016; 109:27-47. [DOI: 10.1016/j.bcp.2016.04.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 04/04/2016] [Indexed: 11/25/2022]
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32
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Chang CL, Liou J. Homeostatic regulation of the PI(4,5)P2-Ca(2+) signaling system at ER-PM junctions. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:862-873. [PMID: 26924250 DOI: 10.1016/j.bbalip.2016.02.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 02/17/2016] [Accepted: 02/19/2016] [Indexed: 10/22/2022]
Abstract
The phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2)-Ca(2+) signaling system is important for cell activation in response to various extracellular stimuli. This signaling system is initiated by receptor-induced hydrolysis of PI(4,5)P2 in the plasma membrane (PM) to generate the soluble second messenger inositol 1,4,5-trisphosphate (IP3). IP3 subsequently triggers the release of Ca(2+) from the endoplasmic reticulum (ER) store to the cytosol to activate Ca(2+)-mediated responses, such as secretion and proliferation. The consumed PM PI(4,5)P2 and ER Ca(2+) must be quickly restored to sustain signaling responses, and to maintain the homeostasis of PI(4,5)P2 and Ca(2+). Since phosphatidylinositol (PI), the precursor lipid for PM PI(4,5)P2, is synthesized in the ER membrane, and a Ca(2+) influx across the PM is required to refill the ER Ca(2+) store, efficient communications between the ER and the PM are critical for the homeostatic regulation of the PI(4,5)P2-Ca(2+) signaling system. This review describes the major findings that established the framework of the PI(4,5)P2-Ca(2+) signaling system, and recent discoveries on feedback control mechanisms at ER-PM junctions that sustain the PI(4,5)P2-Ca(2+) signaling system. Particular emphasis is placed on the characterization of ER-PM junctions where efficient communications between the ER and the PM occur, and the activation mechanisms of proteins that dynamically localize to ER-PM junctions to provide the feedback control during PI(4,5)P2-Ca(2+) signaling, including the ER Ca(2+) sensor STIM1, the extended synaptotagmin E-Syt1, and the PI transfer protein Nir2. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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Affiliation(s)
- Chi-Lun Chang
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jen Liou
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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33
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Drop in endo/sarcoplasmic calcium precedes the unfolded protein response in Brefeldin A-treated vascular smooth muscle cells. Eur J Pharmacol 2015; 764:328-339. [DOI: 10.1016/j.ejphar.2015.07.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 07/08/2015] [Accepted: 07/10/2015] [Indexed: 11/22/2022]
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Abstract
Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca(2+) from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca(2+) sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca(2+) from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca(2+) depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease.
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Affiliation(s)
- Murali Prakriya
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
| | - Richard S Lewis
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
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35
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Differential calcium handling by the cis and trans regions of the Golgi apparatus. Biochem J 2015; 466:455-65. [PMID: 25511127 DOI: 10.1042/bj20141358] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
High Ca2+ content in the Golgi apparatus (Go) is essential for protein processing and sorting. In addition, the Go can shape the cytosolic Ca2+ signals by releasing or sequestering Ca2+. We generated two new aequorin-based Ca2+ probes to specifically measure Ca2+ in the cis/cis-to-medial-Go (cGo) or the trans-Go (tGo). Ca2+ homoeostasis in these compartments and in the endoplasmic reticulum (ER) has been studied and compared. Moreover, the relative size of each subcompartment was estimated from aequorin consumption. We found that the cGo accumulates Ca2+ to high concentrations (150-300 μM) through the sarco plasmic/endoplasmic reticulum Ca2+-ATPase (SERCA). The tGo, in turn, is divided into two subcompartments: tGo1 and tGo2. The subcompartment tGo1 contains 20% of the aequorin and has a high internal [Ca2+]; Ca2+ is accumulated in this subcompartment via the secretory pathway Ca2+-ATPase 1 (SPCA-1) at a very high affinity (K50=30 nM). The subcompartment tGo2 contains 80% of aequorin, has a lower [Ca2+] and no SPCA-1 activity; Ca2+ uptake happens through SERCA and is slower than in tGo1. The two tGo subcompartments, tGo1 and tGo2, are diffusionally isolated. Inositol trisphosphate mobilizes Ca2+ from the cGo and tGo2, but not from tGo1, whereas caffeine releases Ca2+ from all the Golgi regions, and nicotinic acid dinucleotide phosphate and cADP ribose from none.
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36
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Vasudevan SR, Singh N, Churchill GC. Scaffold hopping with virtual screening from IP3 to a drug-like partial agonist of the inositol trisphosphate receptor. Chembiochem 2014; 15:2774-82. [PMID: 25399672 DOI: 10.1002/cbic.201402440] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Indexed: 11/06/2022]
Abstract
Inositol 1,4,5-trisphosphate (IP3 ) is a universal signalling molecule that releases calcium from stores within cells by activating the IP3 receptor. Although chemical tools that modulate the IP3 receptor exist, none is ideal due to trade offs between potency, selectivity and cell permeability, and their chemical properties make them challenging starting points for optimisation. Therefore, to find new leads, we used virtual screening to scaffold hop from IP3 by using the program ROCS to perform a 3D ligand-based screen of the ZINC database of purchasable compounds. We then used the program FRED to dock the top-ranking hits into the IP3 binding pocket of the receptor. We tested the 12 highest-scoring hits in a calcium-release bioassay and identified SI-9 as a partial agonist. SI-9 competed with [(3) H]IP3 binding, and reduced histamine-induced calcium signalling in HeLa cells. SI-9 has a novel 2D scaffold that represents a tractable lead for designing improved IP3 receptor modulators.
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Affiliation(s)
- Sridhar R Vasudevan
- Department of Pharmacology, University of Oxford, Mansfield Road, OX1 3QT (UK).
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37
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Transmembrane adaptor protein PAG/CBP is involved in both positive and negative regulation of mast cell signaling. Mol Cell Biol 2014; 34:4285-300. [PMID: 25246632 DOI: 10.1128/mcb.00983-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The transmembrane adaptor protein PAG/CBP (here, PAG) is expressed in multiple cell types. Tyrosine-phosphorylated PAG serves as an anchor for C-terminal SRC kinase, an inhibitor of SRC-family kinases. The role of PAG as a negative regulator of immunoreceptor signaling has been examined in several model systems, but no functions in vivo have been determined. Here, we examined the activation of bone marrow-derived mast cells (BMMCs) with PAG knockout and PAG knockdown and the corresponding controls. Our data show that PAG-deficient BMMCs exhibit impaired antigen-induced degranulation, extracellular calcium uptake, tyrosine phosphorylation of several key signaling proteins (including the high-affinity IgE receptor subunits, spleen tyrosine kinase, and phospholipase C), production of several cytokines and chemokines, and chemotaxis. The enzymatic activities of the LYN and FYN kinases were increased in nonactivated cells, suggesting the involvement of a LYN- and/or a FYN-dependent negative regulatory loop. When BMMCs from PAG-knockout mice were activated via the KIT receptor, enhanced degranulation and tyrosine phosphorylation of the receptor were observed. In vivo experiments showed that PAG is a positive regulator of passive systemic anaphylaxis. The combined data indicate that PAG can function as both a positive and a negative regulator of mast cell signaling, depending upon the signaling pathway involved.
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Chabosseau P, Tuncay E, Meur G, Bellomo EA, Hessels A, Hughes S, Johnson PRV, Bugliani M, Marchetti P, Turan B, Lyon AR, Merkx M, Rutter GA. Mitochondrial and ER-targeted eCALWY probes reveal high levels of free Zn2+. ACS Chem Biol 2014; 9:2111-20. [PMID: 25011072 PMCID: PMC6101202 DOI: 10.1021/cb5004064] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Zinc (Zn2+) ions are increasingly recognized as playing an important role in cellular physiology. Whereas the free Zn2+ concentration in the cytosol has been established to be 0.1-1 nM, the free Zn2+ concentration in subcellular organelles is not well-established. Here, we extend the eCALWY family of genetically encoded Förster Resonance Energy Transfer (FRET) Zn2+ probes to permit measurements in the endo(sarco)plasmic reticulum (ER) and mitochondrial matrix. Deployed in a variety of mammalian cell types, these probes reveal resting mitochondrial free [Zn2+] values of ∼300 pM, somewhat lower than in the cytosol but 3 orders of magnitude higher than recently reported using an alternative FRET-based sensor. By contrast, free ER [Zn2+] was found to be ≥5 nM, which is >5000-fold higher than recently reported but consistent with the proposed role of the ER as a mobilizable Zn2+ store. Treatment of β-cells or cardiomyocytes with sarco(endo)plasmic reticulum Ca2+-ATPase inhibitors, mobilization of ER Ca2+ after purinergic stimulation with ATP, or manipulation of ER redox, exerted no detectable effects on [Zn2+]ER. These findings question the previously proposed role of Ca2+ in Zn2+ mobilization from the ER and suggest that high ER Zn2+ levels may be an important aspect of cellular homeostasis.
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Affiliation(s)
- Pauline Chabosseau
- Section of Cell Biology, Division of Medicine, and ‡National Heart and Lung Institute, Imperial College London , London, United Kingdom
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Key role for store-operated Ca2+ channels in activating gene expression in human airway bronchial epithelial cells. PLoS One 2014; 9:e105586. [PMID: 25157492 PMCID: PMC4144895 DOI: 10.1371/journal.pone.0105586] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 07/21/2014] [Indexed: 01/17/2023] Open
Abstract
Ca2+ entry into airway epithelia is important for activation of the NFAT family of transcription factors and expression of genes including epidermal growth factor that help orchestrate local inflammatory responses. However, the identity of epithelial Ca2+ channel that activates these transcriptional responses is unclear. In many other non-excitable cells, store-operated Ca2+ entry is a major route for Ca2+ influx and is mediated by STIM1 and Orai1 proteins. This study was performed to determine if store-operated Ca2+ channels were expressed in human bronchial epithelial cells and, if so, whether they coupled Ca2+ entry to gene expression. Cytoplasmic Ca2+ measurements, patch clamp recordings, RNAi knockdown and functional assays were used to identify and then investigate the role of these Ca2+ channels in activating the NFAT and c-fos pathways and EGF expression. STIM1 and Orai1 mRNA transcripts as well as proteins were robustly in epithelial cells and formed functional Ca2+ channels. Ca2+ entry through the channels activated expression of c-fos and EGF as well as an NFAT-dependent reporter gene. Store-operated Ca2+ entry was also important for epithelial cell migration in a scrape wound assay. These findings indicate that store-operated Ca2+ channels play an important role in stimulating airway epithelial cell gene expression and therefore comprise a novel potential therapeutic target for the treatment of chronic asthma and related airway disorders.
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Rada B, Park JJ, Sil P, Geiszt M, Leto TL. NLRP3 inflammasome activation and interleukin-1β release in macrophages require calcium but are independent of calcium-activated NADPH oxidases. Inflamm Res 2014; 63:821-30. [PMID: 25048991 DOI: 10.1007/s00011-014-0756-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 06/18/2014] [Accepted: 07/02/2014] [Indexed: 12/18/2022] Open
Abstract
OBJECTIVE AND DESIGN We studied the involvement of calcium and calcium-activated NADPH oxidases in NLRP3 inflammasome activation and IL-1β release to better understand inflammasome signaling in macrophages. MATERIAL OR SUBJECTS Human volunteer blood donors were recruited to isolate monocytes to differentiate them into macrophages. Wild-type or DUOX1-deficient C57/B6 mice were used to prepare bone marrow-derived macrophages. TREATMENT Murine or human macrophages were treated in vitro with NLRP3 inflammasome agonists (ATP, silica crystals) or calcium agonists (thapsigargin, ionomycin) in calcium-containing or calcium-free medium. METHODS Intracellular calcium changes were followed by measuring FURA2-based fluorescence. Gene expression changes were measured by quantitative real-time PCR. Protein expression was assessed by western blotting. Enzymatic activity was measured by fluorescence caspase-1 activity assay. IL-1β release was determined by ELISA. ELISA data were analyzed by ANOVA and Tukey's post hoc test. RESULTS Our data show that calcium is essential for IL-1β release in human macrophages. Increases in cytosolic calcium alone lead to IL-1β secretion. Calcium removal blocks caspase-1 activation. Human macrophages express Duox1, a calcium-regulated NADPH oxidase that produces reactive oxygen species. However, Duox1-deficient murine macrophages show normal IL-1β release. CONCLUSIONS Human macrophage inflammasome activation and IL-1β secretion requires calcium but does not involve NADPH oxidases.
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Affiliation(s)
- Balázs Rada
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12441 Parklawn Drive, Rockville, MD, 20852, USA,
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Nitoiu D, Etheridge SL, Kelsell DP. Insights into Desmosome Biology from Inherited Human Skin Disease and Cardiocutaneous Syndromes. ACTA ACUST UNITED AC 2014; 21:129-40. [DOI: 10.3109/15419061.2014.908854] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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SERCA2 dysfunction in Darier disease causes endoplasmic reticulum stress and impaired cell-to-cell adhesion strength: rescue by Miglustat. J Invest Dermatol 2014; 134:1961-1970. [PMID: 24390139 DOI: 10.1038/jid.2014.8] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 10/31/2013] [Accepted: 12/09/2013] [Indexed: 12/17/2022]
Abstract
Darier disease (DD) is a severe dominant genetic skin disorder characterized by the loss of cell-to-cell adhesion and abnormal keratinization. The defective gene, ATP2A2, encodes sarco/endoplasmic reticulum (ER) Ca2+ -ATPase isoform 2 (SERCA2), a Ca2+ -ATPase pump of the ER. Here we show that Darier keratinocytes (DKs) display biochemical and morphological hallmarks of constitutive ER stress with increased sensitivity to ER stressors. Desmosome and adherens junctions (AJs) displayed features of immature adhesion complexes: expression of desmosomal cadherins (desmoglein 3 (Dsg3) and desmocollin 3 (Dsc3)) and desmoplakin was impaired at the plasma membrane, as well as E-cadherin, β-, α-, and p120-catenin staining. Dsg3, Dsc3, and E-cadherin showed perinuclear staining and co-immunostaining with ER markers, indicative of ER retention. Consistent with these abnormalities, intercellular adhesion strength was reduced as shown by a dispase mechanical dissociation assay. Exposure of normal keratinocytes to the SERCA2 inhibitor thapsigargin recapitulated these abnormalities, supporting the role of loss of SERCA2 function in impaired desmosome and AJ formation. Remarkably, treatment of DKs with the orphan drug Miglustat, a pharmacological chaperone, restored mature AJ and desmosome formation, and improved adhesion strength. These results point to an important contribution of ER stress in DD pathogenesis and provide the basis for future clinical evaluation of Miglustat in Darier patients.
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Abou-Saleh H, Pathan AR, Daalis A, Hubrack S, Abou-Jassoum H, Al-Naeimi H, Rusch NJ, Machaca K. Inositol 1,4,5-trisphosphate (IP3) receptor up-regulation in hypertension is associated with sensitization of Ca2+ release and vascular smooth muscle contractility. J Biol Chem 2013; 288:32941-51. [PMID: 24097979 PMCID: PMC3829145 DOI: 10.1074/jbc.m113.496802] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 09/20/2013] [Indexed: 12/22/2022] Open
Abstract
Resistance arteries show accentuated responsiveness to vasoconstrictor agonists in hypertension, and this abnormality relies partly on enhanced Ca(2+) signaling in vascular smooth muscle (VSM). Although inositol 1,4,5-triphosphate receptors (IP3Rs) are abundant in VSM, their role in the molecular remodeling of the Ca(2+) signaling machinery during hypertension has not been addressed. Therefore, we compared IP3R expression and function between mesenteric arteries of normotensive and hypertensive animals. Levels of IP3R transcript and protein were significantly increased in mesenteric arteries of hypertensive animals, and pharmacological inhibition of the IP3R revealed a higher contribution of IP3-dependent Ca(2+) release to vascular contraction in these arteries. Subsequently, we established cultured aortic VSM A7r5 cells as a cellular model that replicates IP3R up-regulation during hypertension by depolarizing the VSM cell membrane. IP3R up-regulation requires Ca(2+) influx through L-type Ca(2+) channels, followed by activation of the calcineurin-NFAT axis, resulting in IP3R transcription. Functionally, IP3R up-regulation in VSM is associated with enhancement and sensitization of IP3-dependent Ca(2+) release, resulting in increased VSM contraction in response to agonist stimulation.
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MESH Headings
- Animals
- Calcineurin/metabolism
- Calcium/metabolism
- Calcium Channels, L-Type/metabolism
- Calcium Signaling
- Cell Line
- Hypertension/metabolism
- Hypertension/pathology
- Inositol 1,4,5-Trisphosphate Receptors/biosynthesis
- Membrane Potentials
- Mesenteric Arteries/metabolism
- Mesenteric Arteries/pathology
- Mice
- Muscle Contraction
- Muscle Proteins/biosynthesis
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/pathology
- NFATC Transcription Factors/metabolism
- Rats
- Transcription, Genetic
- Up-Regulation
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Affiliation(s)
- Haissam Abou-Saleh
- From the Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Qatar Foundation, Education City, Doha 24144, Qatar
| | - Asif R. Pathan
- the Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, and
| | - Arwa Daalis
- From the Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Qatar Foundation, Education City, Doha 24144, Qatar
| | - Satanay Hubrack
- From the Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Qatar Foundation, Education City, Doha 24144, Qatar
| | - Hamda Abou-Jassoum
- the Department of Biological and Environmental Sciences, Qatar University, Doha 2713, Qatar
| | - Hamda Al-Naeimi
- the Department of Biological and Environmental Sciences, Qatar University, Doha 2713, Qatar
| | - Nancy J. Rusch
- the Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, and
| | - Khaled Machaca
- From the Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Qatar Foundation, Education City, Doha 24144, Qatar
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Tovey SC, Taylor CW. High-throughput functional assays of IP3-evoked Ca2+ release. Cold Spring Harb Protoc 2013; 2013:930-7. [PMID: 24086049 DOI: 10.1101/pdb.prot073072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
This protocol describes procedures for high-throughput functional analyses of inositol 1,4,5-trisphosphate receptors (IP3Rs) in permeabilized cells. The methods are applicable to native IP3Rs in a variety of cells and to recombinant IP3Rs stably expressed in DT40 cells in which gene disruption has abolished expression of endogenous IP3Rs. A low-affinity Ca(2+)-indicator (Mag-Fluo-4) trapped within the endoplasmic reticulum (ER) of permeabilized cells is used to report changes in luminal free Ca(2+) concentration. A fluorescence plate-reader equipped to allow automated additions permits rapid measurements of the Ca(2+) release evoked by IP3R. The procedure can be completed in 2-3 h.
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Affiliation(s)
- Stephen C Tovey
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom
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Brickley DR, Agyeman AS, Kopp RF, Hall BA, Harbeck MC, Belova L, Volden PA, Wu W, Roe MW, Conzen SD. Serum- and glucocorticoid-induced protein kinase 1 (SGK1) is regulated by store-operated Ca2+ entry and mediates cytoprotection against necrotic cell death. J Biol Chem 2013; 288:32708-32719. [PMID: 24043625 DOI: 10.1074/jbc.m113.507210] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Serum and glucocorticoid-regulated kinase 1 (SGK1) encodes a phosphatidylinositol 3-kinase-dependent serine/threonine kinase that is rapidly induced in response to cellular stressors and is an important cell survival signal. Previous studies have suggested that an increase in cytoplasmic Ca(2+) concentration ([Ca(2+)]c) is required for increased SGK1 expression, but the subcellular source of Ca(2+) regulating SGK1 transcription remains uncertain. Activation of endoplasmic reticulum stress (ERS) with thapsigargin (TG) increased SGK1 mRNA and protein expression in MDA-MB-231 cells. Intracellular Ca(2+) imaging revealed that store-operated Ca(2+) entry played a prominent role in SGK1 induction by TG. Neither ERS nor release of Ca(2+) from the ER was sufficient to activate SGK1. Prolonged elevation of intracellular Ca(2+) levels, however, triggered cell death with a much greater proportion of the cells undergoing necrosis rather than apoptosis. A relative increase in the percentage of cells undergoing necrosis was observed in cells expressing a short hairpin RNA targeted to the SGK1 gene. Necrotic cell death evoked by cytoplasmic Ca(2+) overloading was associated with persistent hyperpolarization of the inner mitochondrial membrane and a modest increase in calpain activation, but did not involve detectable caspase 3 or caspase 7 activation. The effects of cytoplasmic Ca(2+) overloading on mitochondrial membrane potential were significantly reduced in cells expressing SGK1 compared with SGK1-depleted cells. Our findings indicate that store-operated Ca(2+) entry regulates SGK1 expression in epithelial cells and suggest that SGK1-dependent cytoprotective signaling involves effects on maintaining mitochondrial function.
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Affiliation(s)
| | | | | | - Ben A Hall
- From the Sections of Hematology/Oncology
| | | | | | | | - Wei Wu
- From the Sections of Hematology/Oncology
| | - Michael W Roe
- the Departments of Medicine; Cell and Developmental Biology, The State University of New York Upstate Medical University, Syracuse, New York 13210.
| | - Suzanne D Conzen
- From the Sections of Hematology/Oncology; Ben May Department for Cancer Biology, The University of Chicago, Chicago, Illinois 60637.
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Tobío A, Fernández-Araujo A, Alfonso A, Botana LM. Role of yessotoxin in calcium and cAMP-crosstalks in primary and K-562 human lymphocytes: the effect is mediated by anchor kinase A mitochondrial proteins. J Cell Biochem 2013; 113:3752-61. [PMID: 22807343 DOI: 10.1002/jcb.24249] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Yessotoxin (YTX) is a marine polyether toxin previously described as a phosphodiesterase (PDE) activator in fresh human lymphocytes. This toxin induces a decrease of adenosine 3',5'-cyclic monophosphate (cAMP) levels in fresh human lymphocytes in a medium with calcium (Ca(2+) ), whereas the contrary effect has been observed in a Ca(2+) -free medium. In the present article, the effect of YTX in K-562 lymphocytes cell line has been analysed. Surprisingly, results obtained in K-562 cell line are completely opposite than in fresh human lymphocytes, since in K-562 cells YTX induces an increase of cAMP levels. YTX cytotoxicity was also studied in both K-562 cell line and fresh human lymphocytes. Results demonstrate that YTX does not modify fresh human lymphocytes viability, whereas in K-562 cells, YTX has a highly cytotoxic effect. It has been described in a previous study that YTX induces a small cytosolic Ca(2+) increase in fresh human lymphocytes but no effect was observed on Ca(2+) pools depletion in these cells. However, our results show that, in K-562 cells, YTX has no effect on cytosolic Ca(2+) levels in a medium with Ca(2+) and induces an increase on Ca(2+) pools depletion followed by a Ca(2+) influx. As far as Ca(2+) modulation is concerned these results demonstrate that YTX has a clear opposite effect in tumoural and fresh human lymphocytes. In addition, intracellular Ca(2+) reservoirs affected by YTX are different than thapsigargin-sensible pools. Furthermore, YTX-dependent Ca(2+) pools depletion was abolished by cAMP analogue (dibutyryl cAMP), phosphodiesterase-4 (PDE4) inhibitor (rolipram), protein kinase A inhibitor (H89) and oxidative phosphorylation uncoupler carbonyl cyanide p-(trifluoromethoxy) (FCCP) treatments. This evidences the crosstalks between Ca(2+) , YTX and cAMP pathways. Also, results obtain demonstrate that YTX-dependent Ca(2+) influx was only abolished by FCCP pre-treatment, which indicates a link between YTX and mitochondria in K-562 cell line. Cytosolic expression of A-kinase anchor proteins (AKAPs), the proteins which integrates phosphodiesterases (PDEs) and PKA to the mitochondria, was determined in both cell models. On the one hand, in human fresh lymphocytes, YTX increases AKAP149 cytosolic expression. This fact is accompanied with a decrease in cAMP levels, and therefore PDEs activation, which finally leads to cell survival. On the other hand, in tumoural lymphocytes, YTX has an opposite effect since decreases AKAP149 cytosolic expression and increase cAMP levels which leads to cell death. This is the first time that YTX and mitochondrial AKAPs proteins relationship is characterised.
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Affiliation(s)
- Araceli Tobío
- Departamento de Farmacología, Facultad de Veterinaria, 27002 Lugo, Spain
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Identification and characterization of a kunzeaol synthase from Thapsia garganica: implications for the biosynthesis of the pharmaceutical thapsigargin. Biochem J 2012; 448:261-71. [DOI: 10.1042/bj20120654] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Thapsigargin is a major terpenoid constituent of Thapsia garganica root. Owing to its potent antagonistic effect on the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase, thapsigargin has been widely used to study Ca2+ signalling and is also a potential drug for prostate cancer. Despite its importance, thapsigargin biosynthesis in T. garganica remains unknown. In order to decipher thapsigargin biosynthesis, deep transcript sequencing (454 and Illumina) of the T. garganica root was performed, and two terpene synthases (TgTPS1/2) were identified. Functional characterization of their encoded enzymes in a metabolically engineered yeast revealed that TgTPS1 synthesized δ-cadinene, whereas TgTPS2 produced ten distinct terpenoids. However, cultivation of the TgTPS2-expressing yeast in pH-maintained conditions (pH 6–7) yielded one major oxygenated sesquiterpenoid, suggesting that formation of multiple terpenoids was caused by acidity. The major terpene product from TgTPS2 was identified as 6β-hydroxygermacra-1(10),4-diene (kunzeaol) by mass-fragmentation pattern, retention index, the nature of its acid-induced degradation and NMR. Also, recombinant TgTPS2 efficiently catalysed the synthesis of kunzeaol in vitro from farnesyl diphosphate with a Km of 2.6 μM and a kcat of 0.03 s−1. The present paper is the first report of a kunzeaol synthase, and a mechanism for the transformation of kunzeaol into the thapsigargin backbone is proposed.
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Maddalo D, Neeb A, Jehle K, Schmitz K, Muhle-Goll C, Shatkina L, Walther TV, Bruchmann A, Gopal SM, Wenzel W, Ulrich AS, Cato ACB. A peptidic unconjugated GRP78/BiP ligand modulates the unfolded protein response and induces prostate cancer cell death. PLoS One 2012; 7:e45690. [PMID: 23049684 PMCID: PMC3462190 DOI: 10.1371/journal.pone.0045690] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 08/23/2012] [Indexed: 02/07/2023] Open
Abstract
The molecular chaperone GRP78/BiP is a key regulator of protein folding in the endoplasmic reticulum, and it plays a pivotal role in cancer cell survival and chemoresistance. Inhibition of its function has therefore been an important strategy for inhibiting tumor cell growth in cancer therapy. Previous efforts to achieve this goal have used peptides that bind to GRP78/BiP conjugated to pro-drugs or cell-death-inducing sequences. Here, we describe a peptide that induces prostate tumor cell death without the need of any conjugating sequences. This peptide is a sequence derived from the cochaperone Bag-1. We have shown that this sequence interacts with and inhibits the refolding activity of GRP78/BiP. Furthermore, we have demonstrated that it modulates the unfolded protein response in ER stress resulting in PARP and caspase-4 cleavage. Prostate cancer cells stably expressing this peptide showed reduced growth and increased apoptosis in in vivo xenograft tumor models. Amino acid substitutions that destroyed binding of the Bag-1 peptide to GRP78/BiP or downregulation of the expression of GRP78 compromised the inhibitory effect of this peptide. This sequence therefore represents a candidate lead peptide for anti-tumor therapy.
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Affiliation(s)
- Danilo Maddalo
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Antje Neeb
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Katja Jehle
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Katja Schmitz
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Claudia Muhle-Goll
- Institute of Biological Interfaces 2, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Liubov Shatkina
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Tamara Vanessa Walther
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Anja Bruchmann
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Srinivasa M. Gopal
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Wolfgang Wenzel
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Anne S. Ulrich
- Institute of Biological Interfaces 2, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Andrew C. B. Cato
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
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Beltran-Parrazal L, Fernandez-Ruiz J, Toledo R, Manzo J, Morgado-Valle C. Inhibition of endoplasmic reticulum Ca²⁺ ATPase in preBötzinger complex of neonatal rat does not affect respiratory rhythm generation. Neuroscience 2012; 224:116-24. [PMID: 22906476 DOI: 10.1016/j.neuroscience.2012.08.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 08/03/2012] [Accepted: 08/13/2012] [Indexed: 10/28/2022]
Abstract
PreBötzinger complex (preBötC) neurons in the brainstem underlie respiratory rhythm generation in vitro. As a result of network interactions, preBötC neurons burst synchronously to produce rhythmic premotor inspiratory activity. Each inspiratory neuron has a characteristic 10-20 mV, 0.3-0.8 s synchronous depolarization known as the inspiratory drive potential or inspiratory envelope, topped by action potentials (APs). Mechanisms involving Ca(2+) fluxes have been proposed to underlie the initiation of the inspiratory drive potential. An important source of intracellular Ca(2+) is the endoplasmic reticulum (ER) in which active Ca(2+) sequestration is mediated by a class of transporters termed sarco/endoplasmic reticulum Ca(2+) ATPases (SERCAs). We aim to test the hypothesis that disruption of Ca(2+) sequestration into the ER affects respiratory rhythm generation. We examined the effect of inhibiting SERCA on respiratory rhythm generation in an in vitro slice preparation. Bath application of the potent SERCA inhibitors thapsigargin or cyclopiazonic acid (CPA) for up to 90 min did not significantly affect the period or amplitude of respiratory-related motor output or integral and duration of inspiratory drive in preBötC neurons. We promoted the depletion of intracellular Ca(2+) stores by a transient bath application of 30 mM K(+) (high K(+)) in the continuous presence of thapsigargin or CPA. After washing out the high K(+), respiratory rhythm period and amplitude returned to baseline values. These results show that after inhibition of SERCA and depletion of intracellular Ca(2+) stores, respiratory rhythm remains substantially the same, suggesting that this source of Ca(2+) does not significantly contribute to rhythm generation in the preBötC in vitro.
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Affiliation(s)
- L Beltran-Parrazal
- Centro de Investigaciones Cerebrales, Direccion General de Investigaciones, Universidad Veracruzana, Mexico
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50
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Hall BA, Kim TY, Skor MN, Conzen SD. Serum and glucocorticoid-regulated kinase 1 (SGK1) activation in breast cancer: requirement for mTORC1 activity associates with ER-alpha expression. Breast Cancer Res Treat 2012; 135:469-79. [PMID: 22842983 DOI: 10.1007/s10549-012-2161-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Accepted: 07/03/2012] [Indexed: 12/21/2022]
Abstract
Mammalian target of rapamycin (mTOR) is an attractive target for cancer treatment. While rapamycin and its derivatives (e.g., everolimus) have been shown to inhibit mTOR signaling and cell proliferation in preclinical models of breast cancer, mTOR inhibition has demonstrated variable clinical efficacy with a trend toward better responses in estrogen receptor alpha positive (ERα+) compared to ERα negative (ERα-) tumors. Recently, serum- and glucocorticoid-regulated kinase 1 (SGK1) was identified as a substrate of mTOR kinase activity. Previous studies have alternatively suggested that either mTORC1 or mTORC2 is exclusively required for SGK1's Ser422 phosphorylation and activation in breast cancer cells. We investigated the effect of rapamycin on the growth of several ERα+ and ERα- breast cancer cell lines and examined differences in the phosphorylation of mTOR substrates (SGK1, p70S6K, and Akt) that might account for the differing sensitivity of these cell lines to rapamycin. We also examined which mTOR complex contributes to SGK1-Ser422 phosphorylation in ERα+ versus ERα- breast cell lines. We then assessed whether inhibiting SGK1 activity added to rapamycin-mediated cell growth inhibition by either using the SGK1 inhibitor GSK650394A or expressing an SGK1 shRNA. We observed sensitivity to rapamycin-mediated growth inhibition and inactivation of insulin-mediated SGK1-Ser422 phosphorylation in ERα+ MCF-7 and T47D cells, but not in ERα- MDA-MB-231 or MCF10A-Myc cells. In addition, either depleting SGK1 with shRNA or inhibiting SGK1 with GSK650394A preferentially sensitized MDA-MB-231 cells to rapamycin. Finally, we found that rapamycin-sensitive SGK1-Ser422 phosphorylation required ERα expression in MCF-7 derived cell lines. Therefore, targeting SGK1 activity may improve the efficacy of rapamycin and its analogs in the treatment of ERα- breast cancer.
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Affiliation(s)
- Ben A Hall
- Department of Medicine, The University of Chicago, Chicago, IL 60637, USA.
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