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Wu J, Shindo Y, Hotta K, Vu CQ, Lu K, Wazawa T, Nagai T, Oka K. Calcium-induced upregulation of energy metabolism heats neurons during neural activity. Biochem Biophys Res Commun 2024; 708:149799. [PMID: 38522401 DOI: 10.1016/j.bbrc.2024.149799] [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: 02/06/2024] [Revised: 02/13/2024] [Accepted: 03/16/2024] [Indexed: 03/26/2024]
Abstract
Cellular temperature affects every biochemical reaction, underscoring its critical role in cellular functions. In neurons, temperature not only modulates neurotransmission but is also a key determinant of neurodegenerative diseases. Considering that the brain consumes a disproportionately high amount of energy relative to its weight, neural circuits likely generate a lot of heat, which can increase cytosolic temperature. However, the changes in temperature within neurons and the mechanisms of heat generation during neural excitation remain unclear. In this study, we achieved simultaneous imaging of Ca2+ and temperature using the genetically encoded indicators, B-GECO and B-gTEMP. We then compared the spatiotemporal distributions of Ca2+ responses and temperature. Following neural excitation induced by veratridine, an activator of the voltage-gated Na+ channel, we observed an approximately 2 °C increase in cytosolic temperature occurring 30 s after the Ca2+ response. The temperature elevation was observed in the non-nuclear region, while Ca2+ increased throughout the cell body. Moreover, this temperature increase was suppressed under Ca2+-free conditions and by inhibitors of ATP synthesis. These results indicate that Ca2+-induced upregulation of energy metabolism serves as the heat source during neural excitation.
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Affiliation(s)
- Jiayang Wu
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan
| | - Yutaka Shindo
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan; School of Frontier Engineering, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan
| | - Kohji Hotta
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan
| | - Cong Quang Vu
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
| | - Kai Lu
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
| | - Tetsuichi Wazawa
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
| | - Takeharu Nagai
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
| | - Kotaro Oka
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan; School of Frontier Engineering, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan; Waseda Research Institute for Science and Engineering, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo, 162-8480, Japan.
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He X, Zhou Z. Purinergic P2X 3 receptors in the carotid body as new therapeutic targets for controlling heart failure. Purinergic Signal 2024; 20:5-8. [PMID: 37211586 PMCID: PMC10828460 DOI: 10.1007/s11302-023-09945-y] [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] [Received: 04/27/2023] [Accepted: 05/11/2023] [Indexed: 05/23/2023] Open
Abstract
Heart failure is associated with multiple mechanisms, including sympatho-excitation, and is one of the leading causes of death worldwide. Enhanced carotid body chemoreflex function is strongly related to excessive sympathetic nerve activity and sleep-disordered breathing in heart failure. How to reduce the excitability of the carotid body is still scientifically challenging. Both clinical and experimental evidence have suggested that targeting purinergic receptors is of great potential to combat heart failure. In a recent study, Lataro et al. (Lataro et al. in Nat Commun 14:1725, 5) demonstrated that targeting purinergic P2X3 receptors in the carotid body attenuates the progression of heart failure. Using a series of molecular, biochemical, and functional assays, the authors observed that the carotid body generates spontaneous, episodic burst discharges coincident with the onset of disordered breathing in male rats with heart failure, which was generated by ligating the left anterior descending coronary artery. Moreover, P2X3 receptor expression was found to be upregulated in the petrosal ganglion chemoreceptive neurons of rats with heart failure. Of particular note, treatment with a P2X3 antagonist rescued pathological breathing disturbances, abolished episodic discharges, reinstated autonomic balance, attenuated cardiac dysfunction, and reduced the immune cell response and plasma cytokine levels in those rats.
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Affiliation(s)
- Ximeng He
- School of Acupuncture and Tuina/International Joint Research Centre On Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, 37 Shi-Er-Qiao Road, Chengdu, 610075, China
- Acupuncture & Chronobiology Key Laboratory of Sichuan Province, Chengdu, 610075, China
| | - Zhichao Zhou
- Division of Cardiology, Department of Medicine Solna, Karolinska University Hospital, Karolinska Institutet, 17176, Stockholm, Sweden.
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3
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Wang Q, Yuan W, Yang X, Wang Y, Li Y, Qiao H. Role of Cofilin in Alzheimer's Disease. Front Cell Dev Biol 2020; 8:584898. [PMID: 33324642 PMCID: PMC7726191 DOI: 10.3389/fcell.2020.584898] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/26/2020] [Indexed: 01/14/2023] Open
Abstract
Alzheimer's disease (AD) is a degenerative neurological disease and has an inconspicuous onset and progressive development. Clinically, it is characterized by severe dementia manifestations, including memory impairment, aphasia, apraxia, loss of recognition, impairment of visual-spatial skills, executive dysfunction, and changes in personality and behavior. Its etiology is unknown to date. However, several cellular biological signatures of AD have been identified such as synaptic dysfunction, β-amyloid plaques, hyperphosphorylated tau, cofilin-actin rods, and Hirano bodies which are related to the actin cytoskeleton. Cofilin is one of the most affluent and common actin-binding proteins and plays a role in cell motility, migration, shape, and metabolism. They also play an important role in severing actin filament, nucleating, depolymerizing, and bundling activities. In this review, we summarize the structure of cofilins and their functional and regulating roles, focusing on the synaptic dysfunction, β-amyloid plaques, hyperphosphorylated tau, cofilin-actin rods, and Hirano bodies of AD.
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Affiliation(s)
- Qiang Wang
- College of Acupuncture and Massage, Shaanxi University of Chinese Medicine, Xianyang, China
- Shaanxi Key Laboratory of Acupuncture and Medicine, Xianyang, China
| | - Wei Yuan
- College of Acupuncture and Massage, Shaanxi University of Chinese Medicine, Xianyang, China
- Shaanxi Key Laboratory of Acupuncture and Medicine, Xianyang, China
| | - Xiaohang Yang
- College of Acupuncture and Massage, Shaanxi University of Chinese Medicine, Xianyang, China
- College of Medical Technology, Shaanxi University of Chinese Medicine, Xi’an, China
| | - Yuan Wang
- College of Acupuncture and Massage, Shaanxi University of Chinese Medicine, Xianyang, China
- Shaanxi Key Laboratory of Acupuncture and Medicine, Xianyang, China
| | - Yongfeng Li
- College of Acupuncture and Massage, Shaanxi University of Chinese Medicine, Xianyang, China
- Shaanxi Key Laboratory of Acupuncture and Medicine, Xianyang, China
| | - Haifa Qiao
- College of Acupuncture and Massage, Shaanxi University of Chinese Medicine, Xianyang, China
- Shaanxi Key Laboratory of Acupuncture and Medicine, Xianyang, China
- Xianyang Key Laboratory of Neurobiology and Acupuncture, Xi’an, China
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The Purinergic Receptor P2rx3 is Required for Spiral Ganglion Neuron Branch Refinement during Development. eNeuro 2020; 7:ENEURO.0179-20.2020. [PMID: 32675174 PMCID: PMC7418533 DOI: 10.1523/eneuro.0179-20.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/03/2020] [Accepted: 07/08/2020] [Indexed: 12/18/2022] Open
Abstract
The mammalian cochlea undergoes a highly dynamic process of growth and innervation during development. This process includes spiral ganglion neuron (SGN) branch refinement, a process whereby Type I SGNs undergo a phase of “debranching” before forming unramified synaptic contacts with inner hair cells. Using Sox2CreERT2 and R26RtdTomato as a strategy to genetically label individual SGNs in mice of both sexes, we report on both a time course of SGN branch refinement and a role for P2rx3 in this process. P2rx3 is an ionotropic ATP receptor that was recently implicated in outer hair cell spontaneous activity and Type II SGN synapse development (Ceriani et al., 2019), but its function in Type I SGN development is unknown. Here, we demonstrate that P2rx3 is expressed by Type I SGNs and hair cells during developmental periods that coincide with SGN branching refinement. P2rx3 null mice show SGNs with more complex branching patterns on their peripheral synaptic terminals and near their cell bodies around the time of birth. Loss of P2rx3 does not appear to confer general changes in axon outgrowth or hair cell formation, and alterations in branching complexity appear to mostly recover by postnatal day (P)6. However, when we examined the distribution of Type I SGN subtypes using antibodies that bind Calb2, Calb1, and Pou4f1, we found that P2rx3 null mice showed an increased proportion of SGNs that express Calb2. These data suggest P2rx3 may be necessary for normal Type I SGN differentiation in addition to serving a role in branch refinement.
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Köles L, Szepesy J, Berekméri E, Zelles T. Purinergic Signaling and Cochlear Injury-Targeting the Immune System? Int J Mol Sci 2019; 20:ijms20122979. [PMID: 31216722 PMCID: PMC6627352 DOI: 10.3390/ijms20122979] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 06/14/2019] [Accepted: 06/14/2019] [Indexed: 02/06/2023] Open
Abstract
Hearing impairment is the most common sensory deficit, affecting more than 400 million people worldwide. Sensorineural hearing losses currently lack any specific or efficient pharmacotherapy largely due to the insufficient knowledge of the pathomechanism. Purinergic signaling plays a substantial role in cochlear (patho)physiology. P2 (ionotropic P2X and the metabotropic P2Y) as well as adenosine receptors expressed on cochlear sensory and non-sensory cells are involved mostly in protective mechanisms of the cochlea. They are implicated in the sensitivity adjustment of the receptor cells by a K+ shunt and can attenuate the cochlear amplification by modifying cochlear micromechanics. Cochlear blood flow is also regulated by purines. Here, we propose to comprehend this field with the purine-immune interactions in the cochlea. The role of harmful immune mechanisms in sensorineural hearing losses has been emerging in the horizon of cochlear pathologies. In addition to decreasing hearing sensitivity and increasing cochlear blood supply, influencing the immune system can be the additional avenue for pharmacological targeting of purinergic signaling in the cochlea. Elucidating this complexity of purinergic effects on cochlear functions is necessary and it can result in development of new therapeutic approaches in hearing disabilities, especially in the noise-induced ones.
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Affiliation(s)
- László Köles
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, H-1089 Budapest, Hungary.
| | - Judit Szepesy
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, H-1089 Budapest, Hungary.
| | - Eszter Berekméri
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, H-1089 Budapest, Hungary.
- Department of Ecology, University of Veterinary Medicine, H-1078 Budapest, Hungary.
| | - Tibor Zelles
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, H-1089 Budapest, Hungary.
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary.
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6
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Berekméri E, Szepesy J, Köles L, Zelles T. Purinergic signaling in the organ of Corti: Potential therapeutic targets of sensorineural hearing losses. Brain Res Bull 2019; 151:109-118. [PMID: 30721767 DOI: 10.1016/j.brainresbull.2019.01.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 01/10/2019] [Accepted: 01/25/2019] [Indexed: 01/04/2023]
Abstract
Purinergic signaling is deeply involved in the development, functions and protective mechanisms of the cochlea. Release of ATP and activation of purinergic receptors on sensory and supporting/epithelial cells play a substantial role in cochlear (patho)physiology. Both the ionotropic P2X and the metabotropic P2Y receptors are widely distributed on the inner and outer hair cells as well as on the different supporting cells in the organ of Corti and on other epithelial cells in the scala media. Among others, they are implicated in the sensitivity adjustment of the receptor cells by a K+ shunt and can attenuate the cochlear amplification by modifying cochlear micromechanics acting on outer hair cells and supporting cells. Cochlear blood flow is also regulated by purines. Sensorineural hearing losses currently lack any specific or efficient pharmacotherapy. Decreasing hearing sensitivity and increasing cochlear blood supply by pharmacological targeting of purinergic signaling in the cochlea are potential new therapeutic approaches in these hearing disabilities, especially in the noise-induced ones.
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Affiliation(s)
- Eszter Berekméri
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - Judit Szepesy
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - László Köles
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - Tibor Zelles
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary; Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
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7
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Ferreira-Neto HC, Antunes VR, Stern JE. ATP stimulates rat hypothalamic sympathetic neurons by enhancing AMPA receptor-mediated currents. J Neurophysiol 2015; 114:159-69. [PMID: 25904713 PMCID: PMC4507951 DOI: 10.1152/jn.01011.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 04/19/2015] [Indexed: 01/12/2023] Open
Abstract
We have previously shown that ATP within the paraventricular nucleus (PVN) induces an increase in sympathetic activity, an effect attenuated by the antagonism of P2 and/or glutamatergic receptors. Here, we evaluated precise cellular mechanisms underlying the ATP-glutamate interaction in the PVN and assessed whether this receptor coupling contributed to osmotically driven sympathetic PVN neuronal activity. Whole-cell patch-clamp recordings obtained from PVN-rostral ventrolateral medulla neurons showed that ATP (100 μM, 1 min, bath applied) induced an increase in firing rate (89%), an effect blocked by kynurenic acid (1 mM) or 4-[[4-Formyl-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl]-2-pyridinyl]azo]-1,3-benzenedisulfonic acid tetrasodium salt (PPADS) (10 μM). Whereas ATP did not affect glutamate synaptic function, α-amino-3-hydroxy-5-methylisoxazole propionic acid (AMPA) receptor-mediated currents evoked by focal application of AMPA (50 μM, n = 13) were increased in magnitude by ATP (AMPA amplitude: 33%, AMPA area: 52%). ATP potentiation of AMPA currents was blocked by PPADS (n = 12) and by chelation of intracellular Ca(2+) (BAPTA, n = 10). Finally, a hyperosmotic stimulus (mannitol 1%, +55 mosM, n = 8) potentiated evoked AMPA currents (53%), an effect blocked by PPADS (n = 6). Taken together, our data support a functional stimulatory coupling between P2 and AMPA receptors (likely of extrasynaptic location) in PVN sympathetic neurons, which is engaged in response to an acute hyperosmotic stimulus, which might contribute in turn to osmotically driven sympathoexcitatory responses by the PVN.
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Affiliation(s)
- Hildebrando Candido Ferreira-Neto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil; Department of Physiology, Georgia Regents University, Augusta, Georgia
| | - Vagner R Antunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Javier E Stern
- Department of Physiology, Georgia Regents University, Augusta, Georgia
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Du HQ, Chen L, Wang Y, Wang LJ, Yan H, Liu HY, Xiao H. Increasing radiosensitivity with the downregulation of cofilin-1 in U251 human glioma cells. Mol Med Rep 2014; 11:3354-60. [PMID: 25529407 PMCID: PMC4368146 DOI: 10.3892/mmr.2014.3125] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 11/19/2014] [Indexed: 11/06/2022] Open
Abstract
The aim of the present study was to examine the association between cofilin-1 (CFL1) and radioresistance in human glioma U251 cells. CFL1 expression was downregulated and upregulated in U251 cells through the transfection of CFL1-small interfering (si)RNA and pcDNA3.1-CFL1, respectively. The radiosensitivity of U251 cells and established radioresistant U251 cells (RR-U251) was evaluated using cell viability, migration and invasion ability assays. Cell cycle distribution was also examined. The results showed that CFL1 expression was significantly increased in RR-U251 cells; in addition, the cell viability, migration and invasion ability of RR-U251 cells were significantly enhanced compared to those of the normal U251 cells, whereas the number of cells arrested in G2 phase was markedly decreased. In CFL1-silenced RR-U251 and CFL1-silenced U251 cells, the cell viability, migration and invasion abilities were significantly downregulated and the number of cells arrested in G2 phase was increased compared to that of the untransfected cells. In U251 cells overexpressing CFL1, cell viability, migration and invasion abilities were markedly upregulated and the number of cells arrested in G2 phase was decreased. In conclusion, the results of the present study suggested that downregulation of CFL1 may increase radiosensitivity in U251 cells.
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Affiliation(s)
- Hua-Qing Du
- Neuro‑Psychiatric Institute, Nanjing Medical University, Affiliated Nanjing Brain Hospital, Nanjing, Jiangsu 210029, P.R. China
| | - Ling Chen
- Neuro‑Psychiatric Institute, Nanjing Medical University, Affiliated Nanjing Brain Hospital, Nanjing, Jiangsu 210029, P.R. China
| | - Ying Wang
- Neuro‑Psychiatric Institute, Nanjing Medical University, Affiliated Nanjing Brain Hospital, Nanjing, Jiangsu 210029, P.R. China
| | - Li-Jun Wang
- Neuro‑Psychiatric Institute, Nanjing Medical University, Affiliated Nanjing Brain Hospital, Nanjing, Jiangsu 210029, P.R. China
| | - Hua Yan
- Department of Neurosurgery, Nanjing Medical University, Affiliated Nanjing Brain Hospital, Nanjing, Jiangsu 210029, P.R. China
| | - Hong-Yi Liu
- Department of Neurosurgery, Nanjing Medical University, Affiliated Nanjing Brain Hospital, Nanjing, Jiangsu 210029, P.R. China
| | - Hong Xiao
- Neuro‑Psychiatric Institute, Nanjing Medical University, Affiliated Nanjing Brain Hospital, Nanjing, Jiangsu 210029, P.R. China
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Burnstock G, Di Virgilio F. Purinergic signalling and cancer. Purinergic Signal 2014; 9:491-540. [PMID: 23797685 DOI: 10.1007/s11302-013-9372-5] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 06/06/2013] [Indexed: 01/24/2023] Open
Abstract
Receptors for extracellular nucleotides are widely expressed by mammalian cells. They mediate a large array of responses ranging from growth stimulation to apoptosis, from chemotaxis to cell differentiation and from nociception to cytokine release, as well as neurotransmission. Pharma industry is involved in the development and clinical testing of drugs selectively targeting the different P1 nucleoside and P2 nucleotide receptor subtypes. As described in detail in the present review, P2 receptors are expressed by all tumours, in some cases to a very high level. Activation or inhibition of selected P2 receptor subtypes brings about cancer cell death or growth inhibition. The field has been largely neglected by current research in oncology, yet the evidence presented in this review, most of which is based on in vitro studies, although with a limited amount from in vivo experiments and human studies, warrants further efforts to explore the therapeutic potential of purinoceptor targeting in cancer.
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Boyce AKJ, Wicki-Stordeur LE, Swayne LA. Powerful partnership: crosstalk between pannexin 1 and the cytoskeleton. Front Physiol 2014; 5:27. [PMID: 24523699 PMCID: PMC3906563 DOI: 10.3389/fphys.2014.00027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 01/13/2014] [Indexed: 12/26/2022] Open
Abstract
The roles of pannexin 1 (Panx1) large-pore ion and metabolite channels are becoming recognized in many physiological and pathophysiological scenarios. Recent evidence has tightly linked Panx1 trafficking and function to the cytoskeleton, a multi-component network that provides critical structural support, transportation, and scaffolding functions in all cell types. Here we review early work demonstrating the mechanosensitive activation of Panx1 channels, and expand on more recent evidence directly linking Panx1 to the cytoskeleton. Further, we examine the reciprocal regulation between Panx1 and the cytoskeleton, and discuss the involvement of Panx1 in cytoskeletal-regulated cell behaviors. Finally, we identify important gaps in the current knowledge surrounding this emerging Panx1-cytoskeleton relationship.
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Affiliation(s)
- Andrew K J Boyce
- Division of Medical Sciences, University of Victoria Victoria, BC, Canada
| | | | - Leigh Anne Swayne
- Division of Medical Sciences, University of Victoria Victoria, BC, Canada ; Department of Biology, University of Victoria Victoria, BC, Canada ; Department of Biochemistry and Microbiology, University of Victoria Victoria, BC, Canada ; Department of Cellular and Physiological Sciences and Island Medical Program, University of British Columbia Vancouver, BC, Canada
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11
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Mi J, Shaw AE, Pak CW, Walsh KP, Minamide LS, Bernstein BW, Kuhn TB, Bamburg JR. A genetically encoded reporter for real-time imaging of cofilin-actin rods in living neurons. PLoS One 2013; 8:e83609. [PMID: 24391794 PMCID: PMC3877059 DOI: 10.1371/journal.pone.0083609] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 11/05/2013] [Indexed: 01/18/2023] Open
Abstract
Filament bundles (rods) of cofilin and actin (1:1) form in neurites of stressed neurons where they inhibit synaptic function. Live-cell imaging of rod formation is hampered by the fact that overexpression of a chimera of wild type cofilin with a fluorescent protein causes formation of spontaneous and persistent rods, which is exacerbated by the photostress of imaging. The study of rod induction in living cells calls for a rod reporter that does not cause spontaneous rods. From a study in which single cofilin surface residues were mutated, we identified a mutant, cofilinR21Q, which when fused with monomeric Red Fluorescent Protein (mRFP) and expressed several fold above endogenous cofilin, does not induce spontaneous rods even during the photostress of imaging. CofilinR21Q-mRFP only incorporates into rods when they form from endogenous proteins in stressed cells. In neurons, cofilinR21Q-mRFP reports on rods formed from endogenous cofilin and induced by all modes tested thus far. Rods have a half-life of 30-60 min upon removal of the inducer. Vesicle transport in neurites is arrested upon treatments that form rods and recovers as rods disappear. CofilinR21Q-mRFP is a genetically encoded rod reporter that is useful in live cell imaging studies of induced rod formation, including rod dynamics, and kinetics of rod elimination.
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Affiliation(s)
- Jianjie Mi
- Department of Biochemistry and Molecular Biology, and Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, United States of America
| | - Alisa E. Shaw
- Department of Biochemistry and Molecular Biology, and Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, United States of America
| | - Chi W. Pak
- Department of Biochemistry and Molecular Biology, and Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, United States of America
| | - Keifer P. Walsh
- Department of Biochemistry and Molecular Biology, and Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, United States of America
| | - Laurie S. Minamide
- Department of Biochemistry and Molecular Biology, and Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, United States of America
| | - Barbara W. Bernstein
- Department of Biochemistry and Molecular Biology, and Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, United States of America
| | - Thomas B. Kuhn
- Department of Biochemistry and Molecular Biology, and Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, United States of America
- Department of Chemistry and Biochemistry, University of Alaska, Fairbanks, Alaska, United States of America
| | - James R. Bamburg
- Department of Biochemistry and Molecular Biology, and Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, United States of America
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12
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Ueda Y, Kwok S, Hayashi Y. Application of FRET probes in the analysis of neuronal plasticity. Front Neural Circuits 2013; 7:163. [PMID: 24133415 PMCID: PMC3794420 DOI: 10.3389/fncir.2013.00163] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 09/23/2013] [Indexed: 12/12/2022] Open
Abstract
Breakthroughs in imaging techniques and optical probes in recent years have revolutionized the field of life sciences in ways that traditional methods could never match. The spatial and temporal regulation of molecular events can now be studied with great precision. There have been several key discoveries that have made this possible. Since green fluorescent protein (GFP) was cloned in 1992, it has become the dominant tracer of proteins in living cells. Then the evolution of color variants of GFP opened the door to the application of Förster resonance energy transfer (FRET), which is now widely recognized as a powerful tool to study complicated signal transduction events and interactions between molecules. Employment of fluorescent lifetime imaging microscopy (FLIM) allows the precise detection of FRET in small subcellular structures such as dendritic spines. In this review, we provide an overview of the basic and practical aspects of FRET imaging and discuss how different FRET probes have revealed insights into the molecular mechanisms of synaptic plasticity and enabled visualization of neuronal network activity both in vitro and in vivo.
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13
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Descazeaud V, Mestre E, Marquet P, Essig M. Calcineurin regulation of cytoskeleton organization: a new paradigm to analyse the effects of calcineurin inhibitors on the kidney. J Cell Mol Med 2012; 16:218-27. [PMID: 21801302 PMCID: PMC3823286 DOI: 10.1111/j.1582-4934.2011.01398.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Calcineurin is a serine/threonine phosphatase originally involved in the immune response but is also known for its role as a central mediator in various non-immunological intracellular signals. The nuclear factor of activated T cell (NFAT) proteins are the most widely described substrates of calcineurin, but ongoing work has uncovered other substrates among which are the cytoskeleton organizing proteins (i.e. cofilin, synaptopodin, WAVE-1). Control over cytoskeletal proteins is of outmost interest because the phenotypic properties of cells are dependent on cytoskeleton architecture integrity, while rearrangements of the cytoskeleton are implicated in both physiological and pathological processes. Previous works investigating the role of calcineurin on the cytoskeleton have focused on neurite elongation, myocyte hypertrophic response and recently in kidney cells structure. Nuclear factor of activated T cell activation is expectedly identified in the signalling pathways for calcineurin-induced cytoskeleton organization, however new NFAT-independent pathways have also been uncovered. The aim of this review is to summarize the current knowledge on the effects of calcineurin on cytoskeletal proteins and related intracellular pathways. These newly described properties of calcineurin on cytoskeletal proteins may explain some of the beneficial or deleterious effects observed in kidney cells associated with the use of the calcineurin inhibitors, cyclosporine and tacrolimus.
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Prasai P, Stefos GC, Becker W. Extracellular ATP activates NFAT-dependent gene expression in neuronal PC12 cells via P2X receptors. BMC Neurosci 2011; 12:90. [PMID: 21943104 PMCID: PMC3189881 DOI: 10.1186/1471-2202-12-90] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2011] [Accepted: 09/23/2011] [Indexed: 02/04/2023] Open
Abstract
Background Treatment of neuronal PC12 cells with ATP induces depolarisation and increases intracellular calcium levels via purinergic receptors. In many cell types, sustained elevation of intracellular calcium levels cause changes in gene expression via activation of the transcription factor NFAT (nuclear factor of activated T cells). We have therefore characterised the signalling pathway by which ATP regulates NFAT-dependent gene expression in PC12 cells. Results The activation of NFAT transcriptional activity by extracellular ATP was characterised with the help of reporter gene assays. Treatment of PC12 cells with ATP elicited a dose-dependent increase in luciferase activity (EC50 = 78 μM). UTP, 4-benzoylbenzoyl ATP and α,β-methylene ATP did not mimic the effect of ATP, which was abolished by treatment with the P2X receptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (PPADS). This pharmacological characterisation provides evidence for a critical role of ionotropic P2X receptors. Blockade of L-type voltage-dependent calcium channels by nifedipine reduced the response of NFAT to ATP, indicating that a depolarisation-mediated calcium influx was required for maximal NFAT activation. Inhibition of store-operated calcium entry by the pyrazole derivative BTP2 also diminished ATP-dependent NFAT activation. Furthermore, ATP-induced NFAT activation was associated with the activation of the mitogen-activated protein kinases ERK1/2. Finally, treatment with ATP increased the levels of the NFAT target transcripts, RCAN1-4 (regulator of calcineurin) and BDNF (brain derived neurotrophic factor). Conclusion The present data show that ATP induces NFAT-dependent changes in gene expression in PC12 cells by acting on P2X receptors. Maximal NFAT activation depends on both depolarisation-induced calcium influx and store-operated calcium entry and requires the activity of the protein phosphatase calcineurin and the mitogen-activated protein kinase cascade.
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Affiliation(s)
- Prabin Prasai
- Institute of Pharmacology and Toxicology, Medical Faculty of RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany
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Yang X, Liu X, Zhang X, Lu H, Zhang J, Zhang Y. Investigation of morphological and functional changes during neuronal differentiation of PC12 cells by combined Hopping Probe Ion Conductance Microscopy and patch-clamp technique. Ultramicroscopy 2011; 111:1417-22. [PMID: 21864785 DOI: 10.1016/j.ultramic.2011.05.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/09/2011] [Accepted: 05/22/2011] [Indexed: 12/12/2022]
Affiliation(s)
- Xi Yang
- Nanomedicine Laboratory, China National Academy of Nanotechnology and Engineering, Tianjin 300457, China
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Kang DE, Roh SE, Woo JA, Liu T, Bu JH, Jung AR, Lim Y. The Interface between Cytoskeletal Aberrations and Mitochondrial Dysfunction in Alzheimer's Disease and Related Disorders. Exp Neurobiol 2011; 20:67-80. [PMID: 22110363 PMCID: PMC3213703 DOI: 10.5607/en.2011.20.2.67] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 05/17/2011] [Indexed: 01/19/2023] Open
Abstract
The major defining pathological hallmarks of Alzheimer's disease (AD) are the accumulations of Aβ in senile plaques and hyperphosphorylated tau in neurofibrillary tangles and neuropil threads. Recent studies indicate that rather than these insoluble lesions, the soluble Aβ oligomers and hyperphosphorylated tau are the toxic agents of AD pathology. Such pathological protein species are accompanied by cytoskeletal changes, mitochondrial dysfunction, Ca2+ dysregulation, and oxidative stress. In this review, we discuss how the binding of Aβ to various integrins, defects in downstream focal adhesion signaling, and activation of cofilin can impact mitochondrial dysfunction, cytoskeletal changes, and tau pathology induced by Aβ oligomers. Such pathological consequences can also feedback to further activate cofilin to promote cofilin pathology. We also suggest that the mechanism of Aβ generation by the endocytosis of APP is mechanistically linked with perturbations in integrin-based focal adhesion signaling, as APP, LRP, and β-integrins are physically associated with each other.
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Affiliation(s)
- David E Kang
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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17
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Davis RC, Marsden IT, Maloney MT, Minamide LS, Podlisny M, Selkoe DJ, Bamburg JR. Amyloid beta dimers/trimers potently induce cofilin-actin rods that are inhibited by maintaining cofilin-phosphorylation. Mol Neurodegener 2011; 6:10. [PMID: 21261978 PMCID: PMC3037337 DOI: 10.1186/1750-1326-6-10] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 01/24/2011] [Indexed: 11/10/2022] Open
Abstract
Background Previously we reported 1 μM synthetic human amyloid beta1-42 oligomers induced cofilin dephosphorylation (activation) and formation of cofilin-actin rods within rat hippocampal neurons primarily localized to the dentate gyrus. Results Here we demonstrate that a gel filtration fraction of 7PA2 cell-secreted SDS-stable human Aβ dimers and trimers (Aβd/t) induces maximal neuronal rod response at ~250 pM. This is 4,000-fold more active than traditionally prepared human Aβ oligomers, which contain SDS-stable trimers and tetramers, but are devoid of dimers. When incubated under tyrosine oxidizing conditions, synthetic human but not rodent Aβ1-42, the latter lacking tyrosine, acquires a marked increase (620 fold for EC50) in rod-inducing activity. Gel filtration of this preparation yielded two fractions containing SDS-stable dimers, trimers and tetramers. One, eluting at a similar volume to 7PA2 Aβd/t, had maximum activity at ~5 nM, whereas the other, eluting at the void volume (high-n state), lacked rod inducing activity at the same concentration. Fractions from 7PA2 medium containing Aβ monomers are not active, suggesting oxidized SDS-stable Aβ1-42 dimers in a low-n state are the most active rod-inducing species. Aβd/t-induced rods are predominantly localized to the dentate gyrus and mossy fiber tract, reach significance over controls within 2 h of treatment, and are reversible, disappearing by 24 h after Aβd/t washout. Overexpression of cofilin phosphatases increase rod formation when expressed alone and exacerbate rod formation when coupled with Aβd/t, whereas overexpression of a cofilin kinase inhibits Aβd/t-induced rod formation. Conclusions Together these data support a mechanism by which Aβd/t alters the actin cytoskeleton via effects on cofilin in neurons critical to learning and memory.
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Affiliation(s)
- Richard C Davis
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA.
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Bjelobaba I, Lavrnja I, Parabucki A, Stojkov D, Stojiljkovic M, Pekovic S, Nedeljkovic N. The cortical stab injury induces beading of fibers expressing ecto-nucleoside triphosphate diphosphohydrolase 3. Neuroscience 2010; 170:107-16. [PMID: 20620196 DOI: 10.1016/j.neuroscience.2010.06.063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 06/24/2010] [Accepted: 06/24/2010] [Indexed: 01/03/2023]
Abstract
The ecto-nucleoside triphosphate diphosphohydrolase 3 (NTPDase3), an enzyme involved in degradation of extracellular adenosine triphosphate (ATP), is expressed on nerve fibers in different brain regions, including cortex. Here we studied the expression and role of this enzyme after unilateral cortical stab injury in rats. In cortical sections of control rats, NTPDase3 immunoreactivity was associated with two types of fibers: thin processes, occasionally with small mushroom-like protrusions and slightly thicker fibers with more pronounced and more frequent varicosities, whereas immunopositive neuronal perycaria were never observed. Although NTPDase3-positive thin processes and thicker fibers, by general appearance, size and shape, could be dendrites and axons, respectively, they were never immunopositive for microtubule associated protein-2 or neurofilament H subunit. Cortical stab injury induced rapid (within 4 hours) focal varicose swelling that evolved over time to prominent beading of NTPDase3-positive fibers. The NTPDase3-positive fibers in all experimental groups also abundantly express NTPDase1, ecto-5'-nucleotidase and P2X2 receptor channels. Because the brain injury causes a massive ATP release, it is reasonable to conclude that purinoreceptors and ectonucleotidases play an important role in the process of neuritic beading.
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Affiliation(s)
- I Bjelobaba
- Department for Neurobiology, Institute for Biological Research "Sinisa Stankovic", University of Belgrade, Bulevar Despota Stefana 142, 11000 Belgrade, Republic of Serbia.
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Díaz-Hernandez M, del Puerto A, Díaz-Hernandez JI, Diez-Zaera M, Lucas JJ, Garrido JJ, Miras-Portugal MT. Inhibition of the ATP-gated P2X7 receptor promotes axonal growth and branching in cultured hippocampal neurons. J Cell Sci 2009; 121:3717-28. [PMID: 18987356 DOI: 10.1242/jcs.034082] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
During the establishment of neural circuits, the axons of neurons grow towards their target regions in response to both positive and negative stimuli. Because recent reports show that Ca2+ transients in growth cones negatively regulate axonal growth, we studied how ionotropic ATP receptors (P2X) might participate in this process. Our results show that exposing cultured hippocampal neurons to ATP induces Ca2+ transients in the distal domain of the axon and the concomitant inhibition of axonal growth. This effect is mediated by the P2X7 receptor, which is present in the growth cone of the axon. Pharmacological inhibition of P2X7 or its silencing by shRNA interference induces longer and more-branched axons, coupled with morphological changes to the growth cone. Our data suggest that these morphological changes are induced by a signalling cascade in which CaMKII and FAK activity activates PI3-kinase and modifies the activity of its downstream targets. Thus, in the absence or inactivation of P2X7 receptor, axons grow more rapidly and form more branches in cultured hippocampal neurons, indicative that ATP exerts a negative influence on axonal growth. These data suggest that P2X7 antagonists have therapeutic potential to promote axonal regeneration.
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Affiliation(s)
- Miguel Díaz-Hernandez
- Departamento de Bioquímica y Biología Molecular IV, Facultad de Veterinaria, UCM, 28040-Madrid, Spain
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