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Zhao D, Zhang J, Zhang L, Wu Q, Wang Y, Zhang W, Xiao Y, Chen J, Zhan Q. PAFR/Stat3 axis maintains the symbiotic ecosystem between tumor and stroma to facilitate tumor malignancy. Acta Pharm Sin B 2023; 13:694-708. [PMID: 36873192 PMCID: PMC9978919 DOI: 10.1016/j.apsb.2022.08.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 06/17/2022] [Accepted: 08/07/2022] [Indexed: 11/18/2022] Open
Abstract
Stroma surrounding the tumor cells plays crucial roles for tumor progression. However, little is known about the factors that maintain the symbiosis between stroma and tumor cells. In this study, we found that the transcriptional regulator-signal transducer and activator of transcription 3 (Stat3) was frequently activated in cancer-associated fibroblasts (CAFs), which was a potent facilitator of tumor malignancy, and formed forward feedback loop with platelet-activating factor receptor (PAFR) both in CAFs and tumor cells. Importantly, PAFR/Stat3 axis connected intercellular signaling crosstalk between CAFs and cancer cells and drove mutual transcriptional programming of these two types of cells. Two central Stat3-related cytokine signaling molecules-interleukin 6 (IL-6) and IL-11 played the critical role in the process of PAFR/Stat3 axis-mediated communication between tumor and CAFs. Pharmacological inhibition of PAFR and Stat3 activities effectively reduced tumor progression using CAFs/tumor co-culture xenograft model. Our study reveals that PAFR/Stat3 axis enhances the interaction between tumor and its associated stroma and suggests that targeting this axis can be an effective therapeutic strategy against tumor malignancy.
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Affiliation(s)
- Di Zhao
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Laboratory of Molecular Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China
- Research Unit of Molecular Cancer Research, Chinese Academy of Medical Sciences, Beijing 100021, China
| | - Jing Zhang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Laboratory of Molecular Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China
| | - Lingyuan Zhang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Laboratory of Molecular Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China
| | - Qingnan Wu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Laboratory of Molecular Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China
- Research Unit of Molecular Cancer Research, Chinese Academy of Medical Sciences, Beijing 100021, China
- Peking University International Cancer Institute, Beijing 100191, China
| | - Yan Wang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Laboratory of Molecular Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China
- Research Unit of Molecular Cancer Research, Chinese Academy of Medical Sciences, Beijing 100021, China
- Peking University International Cancer Institute, Beijing 100191, China
| | - Weimin Zhang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Laboratory of Molecular Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China
- Research Unit of Molecular Cancer Research, Chinese Academy of Medical Sciences, Beijing 100021, China
- Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Yuanfan Xiao
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Laboratory of Molecular Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China
| | - Jie Chen
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Laboratory of Molecular Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China
- Research Unit of Molecular Cancer Research, Chinese Academy of Medical Sciences, Beijing 100021, China
- Peking University International Cancer Institute, Beijing 100191, China
- Corresponding authors.
| | - Qimin Zhan
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Laboratory of Molecular Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China
- Research Unit of Molecular Cancer Research, Chinese Academy of Medical Sciences, Beijing 100021, China
- Peking University International Cancer Institute, Beijing 100191, China
- Shenzhen Bay Laboratory, Shenzhen 518132, China
- Corresponding authors.
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2
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The Important Role of Ion Transport System in Cervical Cancer. Int J Mol Sci 2021; 23:ijms23010333. [PMID: 35008759 PMCID: PMC8745646 DOI: 10.3390/ijms23010333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 12/26/2021] [Accepted: 12/27/2021] [Indexed: 12/15/2022] Open
Abstract
Cervical cancer is a significant gynecological cancer and causes cancer-related deaths worldwide. Human papillomavirus (HPV) is implicated in the etiology of cervical malignancy. However, much evidence indicates that HPV infection is a necessary but not sufficient cause in cervical carcinogenesis. Therefore, the cellular pathophysiology of cervical cancer is worthy of study. This review summarizes the recent findings concerning the ion transport processes involved in cell volume regulation and intracellular Ca2+ homeostasis of epithelial cells and how these transport systems are themselves regulated by the tumor microenvironment. For cell volume regulation, we focused on the volume-sensitive Cl− channels and K+-Cl− cotransporter (KCC) family, important regulators for ionic and osmotic homeostasis of epithelial cells. Regarding intracellular Ca2+ homeostasis, the Ca2+ store sensor STIM molecules and plasma membrane Ca2+ channel Orai proteins, the predominant Ca2+ entry mechanism in epithelial cells, are discussed. Furthermore, we evaluate the potential of these membrane ion transport systems as diagnostic biomarkers and pharmacological interventions and highlight the challenges.
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Barvitenko N, Aslam M, Lawen A, Saldanha C, Skverchinskaya E, Uras G, Manca A, Pantaleo A. Two Motors and One Spring: Hypothetic Roles of Non-Muscle Myosin II and Submembrane Actin-Based Cytoskeleton in Cell Volume Sensing. Int J Mol Sci 2021; 22:7967. [PMID: 34360739 PMCID: PMC8347689 DOI: 10.3390/ijms22157967] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/16/2021] [Accepted: 07/23/2021] [Indexed: 12/12/2022] Open
Abstract
Changes in plasma membrane curvature and intracellular ionic strength are two key features of cell volume perturbations. In this hypothesis we present a model of the responsible molecular apparatus which is assembled of two molecular motors [non-muscle myosin II (NMMII) and protrusive actin polymerization], a spring [a complex between the plasma membrane (PM) and the submembrane actin-based cytoskeleton (smACSK) which behaves like a viscoelastic solid] and the associated signaling proteins. We hypothesize that this apparatus senses changes in both the plasma membrane curvature and the ionic strength and in turn activates signaling pathways responsible for regulatory volume increase (RVI) and regulatory volume decrease (RVD). During cell volume changes hydrostatic pressure (HP) changes drive alterations in the cell membrane curvature. HP difference has opposite directions in swelling versus shrinkage, thus allowing distinction between them. By analogy with actomyosin contractility that appears to sense stiffness of the extracellular matrix we propose that NMMII and actin polymerization can actively probe the transmembrane gradient in HP. Furthermore, NMMII and protein-protein interactions in the actin cortex are sensitive to ionic strength. Emerging data on direct binding to and regulating activities of transmembrane mechanosensors by NMMII and actin cortex provide routes for signal transduction from transmembrane mechanosensors to cell volume regulatory mechanisms.
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Affiliation(s)
| | - Muhammad Aslam
- Department of Internal Medicine I, Experimental Cardiology, Justus Liebig University, 35392 Giessen, Germany;
| | - Alfons Lawen
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, VIC 3800, Australia;
| | - Carlota Saldanha
- Institute of Biochemistry, Institute of Molecular Medicine, Faculty of Medicine University of Lisbon, 1649-028 Lisboa, Portugal;
| | | | - Giuseppe Uras
- Department of Clinical and Movement Neurosciences, Institute of Neurology, University College London, London NW3 2PF, UK;
| | - Alessia Manca
- Department of Biomedical Science, University of Sassari, Viale San Pietro 43/B, 07100 Sassari, Italy;
| | - Antonella Pantaleo
- Department of Biomedical Science, University of Sassari, Viale San Pietro 43/B, 07100 Sassari, Italy;
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Netti V, Fernández J, Kalstein M, Pizzoni A, Di Giusto G, Rivarola V, Ford P, Capurro C. TRPV4 Contributes to Resting Membrane Potential in Retinal Müller Cells: Implications in Cell Volume Regulation. J Cell Biochem 2017; 118:2302-2313. [PMID: 28098409 DOI: 10.1002/jcb.25884] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/13/2017] [Indexed: 11/10/2022]
Abstract
Neural activity alters osmotic gradients favoring cell swelling in retinal Müller cells. This swelling is followed by a regulatory volume decrease (RVD), partially mediated by an efflux of KCl and water. The transient receptor potential channel 4 (TRPV4), a nonselective calcium channel, has been proposed as a candidate for mediating intracellular Ca2+ elevation induced by swelling. We previously demonstrated in a human Müller cell line (MIO-M1) that RVD strongly depends on ion channel activation and, consequently, on membrane potential (Vm ). The aim of this study was to investigate if Ca2+ influx via TRPV4 contributes to RVD by modifying intracellular Ca2+ concentration and/or modulating Vm in MIO-M1 cells. Cell volume, intracellular Ca2+ levels, and Vm changes were evaluated using fluorescent probes. Results showed that MIO-M1 cells express functional TRPV4 which determines the resting Vm associated with K+ channels. Swelling-induced increases in Ca2+ levels was due to both Ca2+ release from intracellular stores and Ca2+ influx by a pathway alternative to TRPV4. TRPV4 blockage affected swelling-induced biphasic response (depolarization-repolarization), suggesting its participation in modulating Vm changes during RVD. Agonist stimulation of Ca2+ influx via TRPV4 activated K+ channels hyperpolarizing Vm and accelerating RVD. We propose that TRPV4 forms a signaling complex with Ca2+ and/or voltage-dependent K+ channels to define resting Vm and Vm changes during RVD. TRPV4 involvement in RVD depends on the type of stimuli and/or degree of channel activation, leading to a maximum RVD response when Ca2+ influx overcomes a threshold and activates further signaling pathways in cell volume regulation. J. Cell. Biochem. 118: 2302-2313, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Vanina Netti
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Juan Fernández
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Maia Kalstein
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Alejandro Pizzoni
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gisela Di Giusto
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Valeria Rivarola
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Paula Ford
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Claudia Capurro
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
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5
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Huang J, Wang L, Xiong C, Yuan F. Elastic hydrogel as a sensor for detection of mechanical stress generated by single cells grown in three-dimensional environment. Biomaterials 2016; 98:103-12. [DOI: 10.1016/j.biomaterials.2016.04.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 04/20/2016] [Accepted: 04/22/2016] [Indexed: 12/12/2022]
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Thrombin-Facilitated Efflux of d-[3H]-Aspartate from Cultured Astrocytes and Neurons Under Hyponatremia and Chemical Ischemia. Neurochem Res 2014; 39:1219-31. [DOI: 10.1007/s11064-014-1300-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 03/26/2014] [Accepted: 03/28/2014] [Indexed: 01/17/2023]
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7
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Fedan JS, Thompson JA, Ismailoglu UB, Jing Y. Tracheal epithelium cell volume responses to hyperosmolar, isosmolar and hypoosmolar solutions: relation to epithelium-derived relaxing factor (EpDRF) effects. Front Physiol 2013; 4:287. [PMID: 24130533 PMCID: PMC3795350 DOI: 10.3389/fphys.2013.00287] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 09/21/2013] [Indexed: 11/16/2022] Open
Abstract
In asthmatic patients, inhalation of hyperosmolar saline or D-mannitol (D-M) elicits bronchoconstriction, but in healthy subjects exercise causes bronchodilation. Hyperventilation causes drying of airway surface liquid (ASL) and increases its osmolarity. Hyperosmolar challenge of airway epithelium releases epithelium-derived relaxing factor (EpDRF), which relaxes the airway smooth muscle. This pathway could be involved in exercise-induced bronchodilation. Little is known of ASL hyperosmolarity effects on epithelial function. We investigated the effects of osmolar challenge maneuvers on dispersed and adherent guinea-pig tracheal epithelial cells to examine the hypothesis that EpDRF-mediated relaxation is associated with epithelial cell shrinkage. Enzymatically-dispersed cells shrank when challenged with ≥10 mOsM added D-M, urea or NaCl with a concentration-dependence that mimics relaxation of the of isolated perfused tracheas (IPT). Cells shrank when incubated in isosmolar N-methyl-D-glucamine (NMDG) chloride, Na gluconate (Glu), NMDG-Glu, K-Glu and K2SO4, and swelled in isosmolar KBr and KCl. However, isosmolar challenge is not a strong stimulus of relaxation in IPTs. In previous studies amiloride and 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) inhibited relaxation of IPT to hyperosmolar challenge, but had little effect on shrinkage of dispersed cells. Confocal microscopy in tracheal segments showed that adherent epithelium is refractory to low hyperosmolar concentrations that induce dispersed cell shrinkage and relaxation of IPT. Except for gadolinium and erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), actin and microtubule inhibitors and membrane permeabilizing agents did not affect on ion transport by adherent epithelium or shrinkage responses of dispersed cells. Our studies dissociate relaxation of IPT from cell shrinkage after hyperosmolar challenge of airway epithelium.
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Affiliation(s)
- Jeffrey S. Fedan
- Pathology and Physiology Research Branch, National Institute for Occupational Safety and HealthMorgantown, WV, USA
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8
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G protein modulation of K2P potassium channel TASK-2 : a role of basic residues in the C terminus domain. Pflugers Arch 2013; 465:1715-26. [PMID: 23812165 DOI: 10.1007/s00424-013-1314-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 06/12/2013] [Accepted: 06/13/2013] [Indexed: 12/24/2022]
Abstract
TASK-2 (K2P5.1) is a background K(+) channel opened by extra- or intracellular alkalinisation that plays a role in renal bicarbonate handling, central chemoreception and cell volume regulation. Here, we present results that suggest that TASK-2 is also modulated by Gβγ subunits of heterotrimeric G protein. TASK-2 was strongly inhibited when GTP-γ-S was used as a replacement for intracellular GTP. No inhibition was present using GDP-β-S instead. Purified Gβγ introduced intracellularly also inhibited TASK-2 independently of whether GTP or GDP-β-S was present. The effects of GTP-γ-S and Gβγ subunits were abolished by neutralisation of TASK-2 C terminus double lysine residues K257-K258 or K296-K297. Use of membrane yeast two hybrid (MYTH) experiments and immunoprecipitation assays using tagged proteins gave evidence for a physical interaction between Gβ1 and Gβ2 subunits and TASK-2, in agreement with expression of these subunits in proximal tubule cells. Co-immunoprecipitation was impeded by mutating C terminus K257-K258 (but not K296-K297) to alanines. Gating by extra- or intracellular pH was unaltered in GTP-γ-S-insensitive TASK-2-K257A-K258A mutant. Shrinking TASK-2-expressing cells in hypertonic solution decreased the current to 36 % of its initial value. The same manoeuvre had a significantly diminished effect on TASK-2-K257A-K258A- or TASK-2-K296-K297-expressing cells, or in cells containing intracellular GDP-β-S. Our data are compatible with the concept that TASK-2 channels are modulated by Gβγ subunits of heterotrimeric G protein. We propose that this modulation is a novel way in which TASK-2 can be tuned to its physiological functions.
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9
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Tang C, Zelenak C, Völkl J, Eichenmüller M, Regel I, Fröhlich H, Kempe D, Jimenez L, Le Bellego L, Vergne S, Lang F. Hydration-sensitive gene expression in brain. Cell Physiol Biochem 2011; 27:757-68. [PMID: 21691093 DOI: 10.1159/000330084] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2011] [Indexed: 12/16/2022] Open
Abstract
Dehydration has a profound influence on neuroexcitability. The mechanisms remained, however, incompletely understood. The present study addressed the effect of water deprivation on gene expression in the brain. To this end, animals were exposed to a 24 hours deprivation of drinking water and neuronal gene expression was determined by microarray technology with subsequent confirmation by RT-PCR. As a result, water deprivation was followed by significant upregulation of clathrin (light polypeptide Lcb), serum/glucocorticoid-regulated kinase (SGK) 1, and protein kinase A (PRKA) anchor protein 8-like. Water deprivation led to downregulation of janus kinase and microtubule interacting protein 1, neuronal PAS domain protein 4, thrombomodulin, purinergic receptor P2Y - G-protein coupled 13 gene, gap junction protein beta 1, neurotrophin 3, hyaluronan and proteoglycan link protein 1, G protein-coupled receptor 19, CD93 antigen, forkhead box P1, suppressor of cytokine signaling 3, apelin, immunity-related GTPase family M, serine (or cysteine) peptidase inhibitor clade B member 1a, serine (or cysteine) peptidase inhibitor clade H member 1, glutathion peroxidase 8 (putative), discs large (Drosophila) homolog-associated protein 1, zinc finger and BTB domain containing 3, and H2A histone family member V. Western blotting revealed the downregulation of forkhead box P1, serine (or cysteine) peptidase inhibitor clade H member 1, and gap junction protein beta 1 protein abundance paralleling the respective alterations of transcript levels. In conclusion, water deprivation influences the transcription of a wide variety of genes in the brain, which may participate in the orchestration of brain responses to water deprivation.
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Affiliation(s)
- Cai Tang
- Department of Physiology, University of Tübingen, Gmelinstr. 5, D-72076 Tübingen
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Koltsova SV, Platonova A, Maksimov GV, Mongin AA, Grygorczyk R, Orlov SN. Activation of P2Y receptors causes strong and persistent shrinkage of C11-MDCK renal epithelial cells. Am J Physiol Cell Physiol 2011; 301:C403-12. [PMID: 21562307 DOI: 10.1152/ajpcell.00018.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Purinergic receptors activate diverse signaling cascades and regulate the activity of cell volume-sensitive ion transporters. However, the effects of ATP and other agonists of P2 receptors on cell volume dynamics are only scarcely studied. In the present work, we used the recently developed dual-image surface reconstruction technique to explore the influence of purinergic agonists on cell volume in the C11-Madin-Darby canine kidney cell line resembling intercalated cells from kidney collecting ducts. Unexpectedly, we found that ATP and UTP triggered very robust (55-60%) cell shrinkage that lasted up to 2 h after agonist washout. Purinergic regulation of cell volume required increases in intracellular Ca(2+) and could be partially mimicked by the Ca(2+)-ionophore ionomycin or activation of protein kinase C by 4β-phorbol 12-myristate 13-acetate. Cell shrinkage was accompanied by strong reductions in intracellular K(+) and Cl(-) content measured using steady-state (86)Rb(+) and (36)Cl(-) distribution. Both shrinkage and ion efflux in ATP-treated cells were prevented by the anion channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) and by the BK(Ca) channel inhibitors charybdotoxin, iberiotoxin, and paxilline. To evaluate the significance of cell-volume changes in purinergic signaling, we measured the impact of ATP on the expression of the immediate-early gene c-Fos. Thirty-minute treatment with ATP increased c-Fos immunoreactivity by approximately fivefold, an effect that was strongly inhibited by charybdotoxin and completely prevented by NPPB. Overall, our findings suggest that ATP-induced cell-volume changes are partially responsible for the physiological actions of purinergic agonists.
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Affiliation(s)
- Svetlana V Koltsova
- Research Centre, Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
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11
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Cai L, Du T, Song D, Li B, Hertz L, Peng L. Astrocyte ERK phosphorylation precedes K+-induced swelling but follows hypotonicity-induced swelling. Neuropathology 2010; 31:250-64. [DOI: 10.1111/j.1440-1789.2010.01172.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Goldsmith AD, Sarin S, Lockery S, Hobert O. Developmental control of lateralized neuron size in the nematode Caenorhabditis elegans. Neural Dev 2010; 5:33. [PMID: 21122110 PMCID: PMC3014911 DOI: 10.1186/1749-8104-5-33] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 12/01/2010] [Indexed: 01/11/2023] Open
Abstract
Background Nervous systems are generally bilaterally symmetric on a gross structural and organizational level but are strongly lateralized (left/right asymmetric) on a functional level. It has been previously noted that in vertebrate nervous systems, symmetrically positioned, bilateral groups of neurons in functionally lateralized brain regions differ in the size of their soma. The genetic mechanisms that control these left/right asymmetric soma size differences are unknown. The nematode Caenorhabditis elegans offers the opportunity to study this question with single neuron resolution. A pair of chemosensory neurons (ASEL and ASER), which are bilaterally symmetric on several levels (projections, synaptic connectivity, gene expression patterns), are functionally lateralized in that they express distinct chemoreceptors and sense distinct chemosensory cues. Results We describe here that ASEL and ASER also differ substantially in size (soma volume, axonal and dendritic diameter), a feature that is predicted to change the voltage conduction properties of the two sensory neurons. This difference in size is not dependent on sensory input or neuronal activity but developmentally programmed by a pathway of gene regulatory factors that also control left/right asymmetric chemoreceptor expression of the two ASE neurons. This regulatory pathway funnels via the DIE-1 Zn finger transcription factor into the left/right asymmetric distribution of nucleoli that contain the rRNA regulator Fibrillarin/FIB-1, a RNA methyltransferase implicated in the non-hereditary immune disease scleroderma, which we find to be essential to establish the size differences between ASEL and ASER. Conclusions Taken together, our findings reveal a remarkable conservation of the linkage of functional lateralization with size differences across phylogeny and provide the first insights into the developmentally programmed regulatory mechanisms that control neuron size lateralities.
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Affiliation(s)
- Andrew D Goldsmith
- Howard Hughes Medical Institute, Department of Biochemistry and Molecular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
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13
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Brain volume regulation: osmolytes and aquaporin perspectives. Neuroscience 2010; 168:871-84. [DOI: 10.1016/j.neuroscience.2009.11.074] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 11/13/2009] [Accepted: 11/25/2009] [Indexed: 02/08/2023]
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14
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Fisher SK, Heacock AM, Keep RF, Foster DJ. Receptor regulation of osmolyte homeostasis in neural cells. J Physiol 2010; 588:3355-64. [PMID: 20498228 DOI: 10.1113/jphysiol.2010.190777] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The capacity of cells to correct their volume in response to hyposmotic stress via the efflux of inorganic and organic osmolytes is well documented. However, the ability of cell-surface receptors, in particular G-protein-coupled receptors (GPCRs), to regulate this homeostatic mechanism has received much less attention. Mechanisms that underlie the regulation of cell volume are of particular importance to cells in the central nervous system because of the physical restrictions of the skull and the adverse impact that even small increases in cell volume can have on their function. Increases in brain volume are seen in hyponatraemia, which can arise from a variety of aetiologies and is the most frequently diagnosed electrolyte disorder in clinical practice. In this review we summarize recent evidence that the activation of GPCRs facilitates the volume-dependent efflux of osmolytes from neural cells and permits them to more efficiently respond to small, physiologically relevant, reductions in osmolarity. The characteristics of receptor-regulated osmolyte efflux, the signalling pathways involved and the physiological significance of receptor activation are discussed. In addition, we propose that GPCRs may also regulate the re-uptake of osmolytes into neural cells, but that the influx of organic and inorganic osmolytes is differentially regulated. The ability of neural cells to closely regulate osmolyte homeostasis through receptor-mediated alterations in both efflux and influx mechanisms may explain, in part at least, why the brain selectively retains its complement of inorganic osmolytes during chronic hyponatraemia, whereas its organic osmolytes are depleted.
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Affiliation(s)
- Stephen K Fisher
- Molecular and Behavioral Neuroscience Institute, University of Michigan, 5039 Biomedical Sciences Research Building, 109 Zina Pitcher, Ann Arbor, MI 48109-2200, USA.
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15
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Foster DJ, Heacock AM, Fisher SK. Muscarinic receptor stimulation of D-aspartate uptake into human SH-SY5Y neuroblastoma cells is attenuated by hypoosmolarity. J Pharmacol Exp Ther 2010; 333:297-309. [PMID: 20080957 DOI: 10.1124/jpet.109.164277] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In addition to its function as an excitatory neurotransmitter, glutamate plays a major role as an osmolyte within the central nervous system (CNS). Accordingly, mechanisms that regulate glutamate release and uptake are of physiological importance not only during conditions in which cell volume remains constant but also when cells are subjected to hypoosmotic stress. In the present study, the ability of muscarinic cholinergic receptors (mAChRs) to regulate the uptake of glutamate (monitored as D-aspartate) into human SH-SY5Y neuroblastoma cells under isotonic or hypotonic conditions has been examined. In isotonic media, agonist activation of mAChRs resulted in a significant increase (250-300% of control) in the uptake of D-aspartate and, concurrently, a cellular redistribution of the excitatory amino acid transporter 3 (EAAT3) to the plasma membrane. mAChR-mediated increases in d-aspartate uptake were potently blocked by the EAAT3 inhibitor l-beta-threo-benzyl-aspartate. In hypotonic media, the ability of mAChR activation to facilitate D-aspartate uptake was significantly attenuated (40-50%), and the cellular distribution of EAAT3 was disrupted. Reduction of mAChR-stimulated D-aspartate uptake under hypoosmotic conditions could be fully reversed upon re-exposure of the cells to isotonic media. Under both isotonic and hypotonic conditions, mAChR-mediated increases in D-aspartate uptake depended on cytoskeletal integrity, protein kinase C and phosphatidylinositol 3-kinase activities, and the availability of intracellular Ca2+. In contrast, dependence on extracellular Ca2+ was observed only under isotonic conditions. The results suggest that, although the uptake of D-aspartate into SH-SY5Y cells is enhanced after mAChR activation, this process is markedly attenuated by hypoosmolarity.
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Affiliation(s)
- Daniel J Foster
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
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Vázquez-Juárez E, Hernández-BenÃtez R, López-DomÃnguez A, Pasantes-Morales H. Thrombin potentiates d-aspartate efflux from cultured astrocytes under conditions of K+homeostasis disruption. J Neurochem 2009; 111:1398-408. [DOI: 10.1111/j.1471-4159.2009.06418.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Zonia L, Munnik T. Uncovering hidden treasures in pollen tube growth mechanics. TRENDS IN PLANT SCIENCE 2009; 14:318-27. [PMID: 19446491 DOI: 10.1016/j.tplants.2009.03.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 02/22/2009] [Accepted: 03/03/2009] [Indexed: 05/08/2023]
Abstract
The long-standing model of tip growth in pollen tubes considers that exocytosis and growth occur at the apex and that the pool of very small vesicles in the apical dome contains secretory (exocytic) vesicles. However, recent work on vesicle trafficking dynamics in tobacco pollen tubes shows that exocytosis occurs in the subapical region. Taking these and other new results into account, we set out to resolve specific problems that are endemic in current models and present a two-part ACE (apical cap extension)-H (hydrodynamics) growth model. The ACE model involves delivery and recycling of materials required for new cell synthesis and the H model involves mechanisms that integrate and regulate key cellular pathways and drive cell elongation during growth.
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Affiliation(s)
- Laura Zonia
- Swammerdam Institute for Life Sciences, Plant Physiology Section, University of Amsterdam, Kruislaan 904, 1098 XH Amsterdam, The Netherlands.
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18
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Bondarava M, Li T, Endl E, Wehner F. alpha-ENaC is a functional element of the hypertonicity-induced cation channel in HepG2 cells and it mediates proliferation. Pflugers Arch 2009; 458:675-87. [PMID: 19241091 PMCID: PMC2704294 DOI: 10.1007/s00424-009-0649-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 02/04/2009] [Accepted: 02/08/2009] [Indexed: 11/25/2022]
Abstract
The molecular correlate of hypertonicity-induced cation channels (HICCs) and their role in proliferation vs. apoptosis is a matter of debate. We report in this paper that, in whole-cell patch-clamp recordings, hypertonic stress (340→450 mosM) reversibly increased the Na+ conductance of HepG2 cells from 0.8 to 5.8 nS. The effect was dose-dependently inhibited by flufenamate and amiloride, known blockers of HICCs, with some 50% efficiency at 300 μM. In parallel, both drugs decreased HepG2 cell proliferation [in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays and with automatic cell counting]. Small interfering RNA (siRNA) silencing of the α-subunit of the epithelial Na+ channel (ENaC) reduced hypertonicity-induced Na+ currents to 60%, whereas the rate of HepG2 cell proliferation was approximately half of that of the control. Moreover, α-ENaC siRNA inhibited the regulatory volume increase of HepG2 cells (measured with scanning acoustic microscopy) by 60%. In florescence-activated cell sorting measurements, silencing of α-ENaC led to a significant decrease in the G1 and an increase in the G2/M phase of the cell cycle, whereas the S phase was not changing. Finally (determined by a caspase 3/7 assay), HICC inhibition by flufenamate and silencing of α-ENaC increased the rate of apoptosis in HepG2 cells. It is concluded that α-ENaC is one functional element of the HICC in HepG2 cells and that the channel is an important mediator of cell proliferation; likewise, HICC blockage shifts the system from a proliferative into a rather apoptotic one. This is the first report of a role of α-ENaC in cell proliferation.
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Affiliation(s)
- Maryna Bondarava
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Tongju Li
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
- Institute of Physiological Chemistry, University of Essen, Essen, Germany
| | - Elmar Endl
- Institute of Molecular Physiology and Experimental Immunology, University of Bonn, Bonn, Germany
| | - Frank Wehner
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
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Foster DJ, Vitvitsky VM, Banerjee R, Heacock AM, Fisher SK. Muscarinic receptor regulation of osmosensitive taurine transport in human SH-SY5Y neuroblastoma cells. J Neurochem 2008; 108:437-49. [PMID: 19012745 DOI: 10.1111/j.1471-4159.2008.05773.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The ability of G protein-coupled receptors to regulate osmosensitive uptake of the organic osmolyte, taurine, into human SH-SY5Y neuroblastoma cells has been examined. When monitored under isotonic conditions and in the presence of physiologically relevant taurine concentrations (1-100 microM), taurine influx was mediated exclusively by a Na(+)-dependent, high-affinity (K(m) = 2.5 microM) saturable transport mechanism (V(max) = 0.087 nmol/mg protein/min). Reductions in osmolarity of > 20% (attained under conditions of a constant NaCl concentration) resulted in an inhibition of taurine influx (> 30%) that could be attributed to a reduction in V(max), whereas the K(m) for uptake remained unchanged. Inclusion of the muscarinic cholinergic agonist, oxotremorine-M (Oxo-M), also resulted in an attenuation of taurine influx (EC(50) approximately 0.7 microM). Although Oxo-M-mediated inhibition of taurine uptake could be observed under isotonic conditions (approximately 25-30%), the magnitude of inhibition was significantly enhanced by hypotonicity (approximately 55-60%), a result that also reflected a reduction in the V(max), but not the K(m), for taurine transport. Oxo-M-mediated inhibition of taurine uptake was dependent upon the availability of extracellular Ca(2+) but was independent of protein kinase C activity. In addition to Oxo-M, inclusion of either thrombin or sphingosine 1-phosphate also attenuated volume-dependent taurine uptake. The ability of Oxo-M to inhibit the influx of taurine was attenuated by 4-[(2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]butanoic acid, an inhibitor of the volume-sensitive organic osmolyte and anion channel. 4-[(2-Butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]butanoic acid also prevented receptor-mediated changes in the efflux and influx of K(+) under hypoosmotic conditions. The results suggest that muscarinic receptor activation can regulate both the volume-dependent efflux and uptake of taurine and that these events may be functionally coupled.
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Affiliation(s)
- Daniel J Foster
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109-2200, USA
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Fisher SK, Cheema TA, Foster DJ, Heacock AM. Volume-dependent osmolyte efflux from neural tissues: regulation by G-protein-coupled receptors. J Neurochem 2008; 106:1998-2014. [PMID: 18518929 DOI: 10.1111/j.1471-4159.2008.05510.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The CNS is particularly vulnerable to reductions in plasma osmolarity, such as occur during hyponatremia, the most commonly encountered electrolyte disorder in clinical practice. In response to a lowered plasma osmolarity, neural cells initially swell but then are able to restore their original volume through the release of osmolytes, both inorganic and organic, and the exit of osmotically obligated water. Given the importance of the maintenance of cell volume within the CNS, mechanisms underlying the release of osmolytes assume major significance. In this context, we review recent evidence obtained from our laboratory and others that indicates that the activation of specific G-protein-coupled receptors can markedly enhance the volume-dependent release of osmolytes from neural cells. Of particular significance is the observation that receptor activation significantly lowers the osmotic threshold at which osmolyte release occurs, thereby facilitating the ability of the cells to respond to small, more physiologically relevant, reductions in osmolarity. The mechanisms underlying G-protein-coupled receptor-mediated osmolyte release and the possibility that this efflux can result in both physiologically beneficial and potentially harmful pathophysiological consequences are discussed.
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Affiliation(s)
- Stephen K Fisher
- Molecular and Behavioral Neuroscience Institute; and Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109-2200, USA.
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