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Kempmann A, Gensch T, Offenhäusser A, Tihaa I, Maybeck V, Balfanz S, Baumann A. The Functional Characterization of GCaMP3.0 Variants Specifically Targeted to Subcellular Domains. Int J Mol Sci 2022; 23:ijms23126593. [PMID: 35743038 PMCID: PMC9223625 DOI: 10.3390/ijms23126593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 05/31/2022] [Accepted: 06/06/2022] [Indexed: 11/16/2022] Open
Abstract
Calcium (Ca2+) ions play a pivotal role in physiology and cellular signaling. The intracellular Ca2+ concentration ([Ca2+]i) is about three orders of magnitude lower than the extracellular concentration, resulting in a steep transmembrane concentration gradient. Thus, the spatial and the temporal dynamics of [Ca2+]i are ideally suited to modulate Ca2+-mediated cellular responses to external signals. A variety of highly sophisticated methods have been developed to gain insight into cellular Ca2+ dynamics. In addition to electrophysiological measurements and the application of synthetic dyes that change their fluorescent properties upon interaction with Ca2+, the introduction and the ongoing development of genetically encoded Ca2+ indicators (GECI) opened a new era to study Ca2+-driven processes in living cells and organisms. Here, we have focused on one well-established GECI, i.e., GCaMP3.0. We have systematically modified the protein with sequence motifs, allowing localization of the sensor in the nucleus, in the mitochondrial matrix, at the mitochondrial outer membrane, and at the plasma membrane. The individual variants and a cytosolic version of GCaMP3.0 were overexpressed and purified from E. coli cells to study their biophysical properties in solution. All versions were examined to monitor Ca2+ signaling in stably transfected cell lines and in primary cortical neurons transduced with recombinant Adeno-associated viruses (rAAV). In this comparative study, we provide evidence for a robust approach to reliably trace Ca2+ signals at the (sub)-cellular level with pronounced temporal resolution.
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Affiliation(s)
- Annika Kempmann
- Institute of Biological Information Processing, IBI-1, Research Center Jülich, 52428 Jülich, Germany; (A.K.); (T.G.); (S.B.)
| | - Thomas Gensch
- Institute of Biological Information Processing, IBI-1, Research Center Jülich, 52428 Jülich, Germany; (A.K.); (T.G.); (S.B.)
| | - Andreas Offenhäusser
- Institute of Biological Information Processing, IBI-3, Research Center Jülich, 52428 Jülich, Germany; (A.O.); (I.T.); (V.M.)
| | - Irina Tihaa
- Institute of Biological Information Processing, IBI-3, Research Center Jülich, 52428 Jülich, Germany; (A.O.); (I.T.); (V.M.)
| | - Vanessa Maybeck
- Institute of Biological Information Processing, IBI-3, Research Center Jülich, 52428 Jülich, Germany; (A.O.); (I.T.); (V.M.)
| | - Sabine Balfanz
- Institute of Biological Information Processing, IBI-1, Research Center Jülich, 52428 Jülich, Germany; (A.K.); (T.G.); (S.B.)
| | - Arnd Baumann
- Institute of Biological Information Processing, IBI-1, Research Center Jülich, 52428 Jülich, Germany; (A.K.); (T.G.); (S.B.)
- Correspondence: ; Tel.: +49-2461-614014
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Silva CA, Yalnizyan-Carson A, Fernández Busch MV, van Zwieten M, Verhage M, Lohmann C. Activity-dependent regulation of mitochondrial motility in developing cortical dendrites. eLife 2021; 10:62091. [PMID: 34491202 PMCID: PMC8423438 DOI: 10.7554/elife.62091] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 08/24/2021] [Indexed: 11/13/2022] Open
Abstract
Developing neurons form synapses at a high rate. Synaptic transmission is very energy-demanding and likely requires ATP production by mitochondria nearby. Mitochondria might be targeted to active synapses in young dendrites, but whether such motility regulation mechanisms exist is unclear. We investigated the relationship between mitochondrial motility and neuronal activity in the primary visual cortex of young mice in vivo and in slice cultures. During the first 2 postnatal weeks, mitochondrial motility decreases while the frequency of neuronal activity increases. Global calcium transients do not affect mitochondrial motility. However, individual synaptic transmission events precede local mitochondrial arrest. Pharmacological stimulation of synaptic vesicle release, but not focal glutamate application alone, stops mitochondria, suggesting that an unidentified factor co-released with glutamate is required for mitochondrial arrest. A computational model of synaptic transmission-mediated mitochondrial arrest shows that the developmental increase in synapse number and transmission frequency can contribute substantially to the age-dependent decrease of mitochondrial motility.
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Affiliation(s)
- Catia Ap Silva
- Department of Synapse and Network Development, Netherlands Institute for Neuroscience, Amsterdam, Netherlands
| | | | - M Victoria Fernández Busch
- Department of Synapse and Network Development, Netherlands Institute for Neuroscience, Amsterdam, Netherlands
| | - Mike van Zwieten
- Department of Synapse and Network Development, Netherlands Institute for Neuroscience, Amsterdam, Netherlands
| | - Matthijs Verhage
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, University Amsterdam, Amsterdam, Netherlands
| | - Christian Lohmann
- Department of Synapse and Network Development, Netherlands Institute for Neuroscience, Amsterdam, Netherlands.,Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, University Amsterdam, Amsterdam, Netherlands
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Chen Y, Gong K, Xu Q, Meng J, Long T, Chang C, Wang Z, Liu W. Phosphoglycerate Mutase 5 Knockdown Alleviates Neuronal Injury After Traumatic Brain Injury Through Drp1-Mediated Mitochondrial Dysfunction. Antioxid Redox Signal 2021; 34:154-170. [PMID: 32253918 DOI: 10.1089/ars.2019.7982] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Aims: Traumatic brain injury (TBI) is a major cause of disability and death, and a better understanding of the underlying mechanisms of mitochondrial dysfunction will provide important targets for preventing damage from neuronal insults. Phosphoglycerate mutase 5 (PGAM5) is localized to the mitochondrial outer-inner membrane contact sites, and the PGAM5-Drp1 pathway is involved in mitochondrial dysfunction and cell death. The purpose of this project was to evaluate the effects of PGAM5 on neuronal injury and mitochondrial dysfunction. Results: PGAM5 was overexpressed in mice subjected to TBI and in primary cortical neurons injured by mechanical equiaxial stretching. PGAM5 deficiency alleviated neuroinflammation, blocked Parkin, PINK1, and Drp1 translocation to mitochondria and abnormal phosphorylation of Drp1, mitochondrial ultrastructural changes, and nerve malfunction in TBI mouse model. PGAM5-shRNA (short hairpin RNA) reduced Drp1 translocation and activation, including dephosphorylation of p-Drp1 on Ser622 (human Drp1 Ser616) and phosphorylation of Drp1 on Ser643 (human Drp1 Ser637). The levels of inflammatory cytokines, the degree of mitochondrial impairment (mitochondrial membrane potential, ADP/ATP, AMP/ADP, antioxidant capacity), and neuronal injury in stretch-induced primary cortical neurons were reduced by blocking expression of PGAM5. The inhibition of PGAM5 is neuroprotective via attenuation of Drp1 activation, similar to that achieved by mitochondrial division inhibitor-1 (Mdivi1)-mediated Drp1 inhibition. Innovation and Conclusion: Our findings demonstrate the critical role of PGAM5 in progression of neuronal injury from TBI via Drp1 activation (dephosphorylation of p-Drp1 on Ser622 and phosphorylation of Drp1 on Ser643)-mediated mitochondrial dysfunction. The data may open a window for developing new drugs to prevent the neuropathology of TBI.
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Affiliation(s)
- Yuhua Chen
- Department of Central Laboratory, Xi'an Peihua University, Xi'an, China
| | - Kai Gong
- Department of Neurosurgery, First Affiliated Hospital of Xia'men University, Xia'men, China
| | - Quanhua Xu
- Department of Neurosurgery, Bijie First People's Hospital, Bijie, China
| | - Jiao Meng
- Department of Central Laboratory, Xi'an Peihua University, Xi'an, China
| | - Tianlin Long
- Department of Neurosurgery, Bijie First People's Hospital, Bijie, China
| | - Cuicui Chang
- Department of Central Laboratory, Xi'an Peihua University, Xi'an, China
| | - Zhanxiang Wang
- Department of Neurosurgery, First Affiliated Hospital of Xia'men University, Xia'men, China
| | - Wei Liu
- Department of Neurosurgery, Bijie First People's Hospital, Bijie, China
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Newman LE, Zhou CJ, Mudigonda S, Mattheyses AL, Paradies E, Marobbio CMT, Kahn RA. The ARL2 GTPase is required for mitochondrial morphology, motility, and maintenance of ATP levels. PLoS One 2014; 9:e99270. [PMID: 24911211 PMCID: PMC4050054 DOI: 10.1371/journal.pone.0099270] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/13/2014] [Indexed: 02/06/2023] Open
Abstract
ARF-like 2 (ARL2) is a member of the ARF family and RAS superfamily of regulatory GTPases, predicted to be present in the last eukaryotic common ancestor, and essential in a number of model genetic systems. Though best studied as a regulator of tubulin folding, we previously demonstrated that ARL2 partially localizes to mitochondria. Here, we show that ARL2 is essential to a number of mitochondrial functions, including mitochondrial morphology, motility, and maintenance of ATP levels. We compare phenotypes resulting from ARL2 depletion and expression of dominant negative mutants and use these to demonstrate that the mitochondrial roles of ARL2 are distinct from its roles in tubulin folding. Testing of current models for ARL2 actions at mitochondria failed to support them. Rather, we found that knockdown of the ARL2 GTPase activating protein (GAP) ELMOD2 phenocopies two of three phenotypes of ARL2 siRNA, making it a likely effector for these actions. These results add new layers of complexity to ARL2 signaling, highlighting the need to deconvolve these different cell functions. We hypothesize that ARL2 plays essential roles inside mitochondria along with other cellular functions, at least in part to provide coupling of regulation between these essential cell processes.
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Affiliation(s)
- Laura E. Newman
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Cheng-jing Zhou
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Samatha Mudigonda
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Alexa L. Mattheyses
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Eleonora Paradies
- Consiglio Nazionale delle Ricerche Institute of Biomembranes and Bioenergetics, Bari, Italy
| | | | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
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Brennan KC, Bates EA, Shapiro RE, Zyuzin J, Hallows WC, Huang Y, Lee HY, Jones CR, Fu YH, Charles AC, Ptáček LJ. Casein kinase iδ mutations in familial migraine and advanced sleep phase. Sci Transl Med 2014; 5:183ra56, 1-11. [PMID: 23636092 DOI: 10.1126/scitranslmed.3005784] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Migraine is a common disabling disorder with a significant genetic component, characterized by severe headache and often accompanied by nausea, vomiting, and light sensitivity. We identified two families, each with a distinct missense mutation in the gene encoding casein kinase Iδ (CKIδ), in which the mutation cosegregated with both the presence of migraine and advanced sleep phase. The resulting alterations (T44A and H46R) occurred in the conserved catalytic domain of CKIδ, where they caused reduced enzyme activity. Mice engineered to carry the CKIδ-T44A allele were more sensitive to pain after treatment with the migraine trigger nitroglycerin. CKIδ-T44A mice also exhibited a reduced threshold for cortical spreading depression (believed to be the physiological analog of migraine aura) and greater arterial dilation during cortical spreading depression. Astrocytes from CKIδ-T44A mice showed increased spontaneous and evoked calcium signaling. These genetic, cellular, physiological, and behavioral analyses suggest that decreases in CKIδ activity can contribute to the pathogenesis of migraine.
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Affiliation(s)
- K C Brennan
- Department of Neurology, University of California, Los Angeles, Los Angeles, CA 90095, USA
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6
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Rodríguez J, Luria-Pérez R, López-Valdés HE, Casero D, Daniels TR, Patel S, Avila D, Leuchter R, So S, ánchez EOS, Bonavida B, Martínez-Maza O, Charles A.C, Pellegrini M, Helguera G, Penichet ML. Lethal iron deprivation induced by non-neutralizing antibodies targeting transferrin receptor 1 in malignant B cells. Leuk Lymphoma 2011; 52:2169-78. [PMID: 21870996 PMCID: PMC3732792 DOI: 10.3109/10428194.2011.596964] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A number of antibodies have been developed that induce lethal iron deprivation (LID) by targeting the transferrin receptor 1 (TfR1/CD71) and either neutralizing transferrin (Tf) binding, blocking internalization of the receptor and/or inducing its degradation. We have developed recombinant antibodies targeting human TfR1 (ch128.1 and ch128.1Av), which induce receptor degradation and are cytotoxic to certain malignant B-cells. We now show that internalization of TfR1 bound to these antibodies can lead to its sequestration and degradation, as well as reduced Tf uptake, and the induction of a transcriptional response consistent with iron deprivation, which is mediated in part by downstream targets of p53. Cells resistant to these antibodies do not sequester and degrade TfR1 after internalization of the antibody/receptor complex, and accordingly maintain their ability to internalize Tf. These findings are expected to facilitate the rational design and clinical use of therapeutic agents targeting iron import via TfR1 in hematopoietic malignancies.
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Affiliation(s)
- JoséA. Rodríguez
- Molecular Biology Institute, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Rosendo Luria-Pérez
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Unit of Investigative Research on Oncological Disease, Children’s Hospital of Mexico “Federico Gómez”, Mexico City, Mexico
| | - Héctor E. López-Valdés
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - David Casero
- Department of Molecular Cell and Developmental Biology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Tracy R. Daniels
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Shabnum Patel
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - David Avila
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Richard Leuchter
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Sokuntheavy So
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Elizabeth Ortiz-S ánchez
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Benjamin Bonavida
- Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Otoniel Martínez-Maza
- Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Department of Obstetrics and Gynecology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Department of Epidemiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Andrew .C Charles
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Matteo Pellegrini
- Department of Molecular Cell and Developmental Biology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Gustavo Helguera
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Manuel L. Penichet
- Molecular Biology Institute, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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7
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Tan AR, Cai AY, Deheshi S, Rintoul GL. Elevated intracellular calcium causes distinct mitochondrial remodelling and calcineurin-dependent fission in astrocytes. Cell Calcium 2011; 49:108-14. [DOI: 10.1016/j.ceca.2010.12.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Revised: 12/01/2010] [Accepted: 12/02/2010] [Indexed: 11/26/2022]
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8
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López-Valdés HE, Beltran-Parrazal L, Brennan KC, Charles AC. Bradykinin increases resensitization of purinergic receptor signaling in glioma cells. Cancer Cell Int 2010; 10:35. [PMID: 20875097 PMCID: PMC2955562 DOI: 10.1186/1475-2867-10-35] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 09/27/2010] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Purinergic receptor-mediated signaling plays an important role in the function of glial cells, including glial tumor cells. Bradykinin is also an important paracrine mediator which is highly expressed in brain tumors and may correlate with their pathological grade. Interaction between bradykinin and purinergic signaling may therefore be involved in the regulation of glial tumor cells. RESULTS We examined the effect of bradykinin on glial purinergic signaling in an immortalized glioma cell line. Confocal calcium imaging revealed that ATP evokes an increase in [Ca2+]i in the U87 human astrocytoma cell line. This response was reduced with repetitive application of ATP, likely due to receptor desensitization. However exposure to bradykinin increased the Ca2+ response to a second application of ATP, consistent with increased resensitization. The bradykinin effect on resensitization was similar in the absence of extracellular Ca2+ or in the presence of the PKC activator PMA, but was inhibited by the protein phosphatase inhibitor okadaic acid and the PI3K inhibitor LY294002. CONCLUSIONS Modulation of protein phosphatases and the PI3K pathway may represent a mechanism by which bradykinin potentiates purinergic signaling in glial cells.
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Affiliation(s)
- Héctor E López-Valdés
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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9
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Control of mitochondrial transport and localization in neurons. Trends Cell Biol 2009; 20:102-12. [PMID: 20006503 DOI: 10.1016/j.tcb.2009.11.002] [Citation(s) in RCA: 268] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 11/17/2009] [Accepted: 11/17/2009] [Indexed: 12/18/2022]
Abstract
Mitochondria play an essential role in ATP generation, calcium buffering and apoptotic signalling. In neurons, the transport of mitochondria to specific locations where they are needed has emerged as an important process for correct nerve cell function. Recent studies have shed light on the mechanisms that control mitochondrial transport and localization in neurons. We describe the machinery that is important for constitutive transport of mitochondria throughout the cell, and highlight recent advances in our understanding of how signalling pathways can converge on this machinery and allow for rapid activity-dependent control of mitochondrial trafficking and localization. Regulation of mitochondrial trafficking might work in concert with mitochondrial tethering systems to give precise control of mitochondrial delivery and localization to regions of high energy and calcium buffering requirements within neurons.
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10
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Rintoul GL, Reynolds IJ. Mitochondrial trafficking and morphology in neuronal injury. Biochim Biophys Acta Mol Basis Dis 2009; 1802:143-50. [PMID: 19747973 DOI: 10.1016/j.bbadis.2009.09.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Revised: 09/05/2009] [Accepted: 09/08/2009] [Indexed: 01/05/2023]
Abstract
Alterations in mitochondrial function may have a central role in the pathogenesis of many neurodegenerative diseases. The study of mitochondrial dysfunction has typically focused on ATP generation, calcium homeostasis and the production of reactive oxygen species. However, there is a growing appreciation of the dynamic nature of mitochondria within cells. Mitochondria are highly motile organelles, and also constantly undergo fission and fusion. This raises the possibility that impairment of mitochondrial dynamics could contribute to the pathogenesis of neuronal injury. In this review we describe the mechanisms that govern mitochondrial movement, fission and fusion. The key proteins that are involved in mitochondrial fission and fusion have also been linked to some inherited neurological diseases, including autosomal dominant optic atrophy and Charcot-Marie-Tooth disease 2A. We will discuss the evidence that altered movement, fission and fusion are associated with impaired neuronal viability. There is a growing collection of literature that links impaired mitochondrial dynamics to a number of disease models. Additionally, the concept that the failure to deliver a functional mitochondrion to the appropriate site within a neuron could contribute to neuronal dysfunction provides an attractive framework for understanding the mechanisms underlying neurologic disease. However, it remains difficult to clearly establish that altered mitochondrial dynamics clearly represent a cause of neuronal dysfunction.
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Affiliation(s)
- Gordon L Rintoul
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A1S6
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11
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Mironov SL. Complexity of mitochondrial dynamics in neurons and its control by ADP produced during synaptic activity. Int J Biochem Cell Biol 2009; 41:2005-14. [PMID: 19379829 DOI: 10.1016/j.biocel.2009.04.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 04/07/2009] [Accepted: 04/09/2009] [Indexed: 12/20/2022]
Abstract
This review focuses on different aspects of dynamics of mitochondria in neuronal cytoplasm which play an important role in the life and fate of neurons. It starts with description of the energy supply in the brain; considers the typical patterns of mitochondrial movements; relates them to the neuronal activity and in particular at the synapses; extends to the analysis of the origin of local ATP changes in the cytoplasm; considers main features of motor-assisted movements of mitochondria and their role in determining a transport velocity; describes the measurements of ATP gradients in neuronal processes and relates them to spatial variations in the mobility of mitochondria that occur in the vicinity of synapses due to the local ADP increases; considers the influence of hypoxia and intracellular signalling pathways on mitochondria movements. Finally, the recent views on the mechanisms and possible functional role of mitochondrial network as a whole in neurons are discussed and unresolved issues and future perspectives in this field of research are delineated.
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Affiliation(s)
- Sergei L Mironov
- DFG-Center of Molecular Physiology of the Brain, Georg-August-University, Department of Neuro- and Sensory Physiology, Humboldtallee 23, Göttingen, 37075, Germany.
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12
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Mellen NM, Tuong CM. Semi-automated region of interest generation for the analysis of optically recorded neuronal activity. Neuroimage 2009; 47:1331-40. [PMID: 19362155 DOI: 10.1016/j.neuroimage.2009.04.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 03/27/2009] [Accepted: 04/01/2009] [Indexed: 10/20/2022] Open
Abstract
Bath-applied membrane-permeant Ca(2+) indicators offer access to network function with single-cell resolution. A barrier to wider and more efficient use of this technique is the difficulty of extracting fluorescence signals from the active constituents of the network under study. Here we present a method for semi-automatic region of interest (ROI) detection that exploits the spatially compact, slowly time-varying character of the somatic signals that these indicators typically produce. First, the image series is differenced to eliminate static and very slowly varying fluorescence values, and then the differenced image series undergoes low-pass filtering in the spatial domain, to eliminate temporally isolated fluctuations in brightness. This processed image series is then thresholded so that pixel regions of fluctuating brightness are set to white, while all other regions are set to black. Binary images are averaged, and then subjected to iterative thresholding to extract ROIs associated with both dim and bright cells. The original image series is then analyzed using the generated ROIs, after which the end-user rejects spurious signals. These methods are applied to respiratory networks in the neonate rat tilted sagittal slab preparation, and to simulations with signal-to-noise ratios ranging between 1.0-0.2. Simulations established that algorithm performance degraded gracefully with increasing noise. Because signal extraction is the necessary first step in the analysis of time-varying Ca(2+) signals, semi-automated ROI detection frees the researcher to focus on the next step: selecting traces of interest from the relatively complete set generated using these methods.
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Affiliation(s)
- Nicholas M Mellen
- Kosair Children's Hospital Research Institute, University of Louisville, Louisville, KY 40202, USA.
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13
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Karumbayaram S, Kelly TK, Paucar AA, Roe AJT, Umbach JA, Charles A, Goldman SA, Kornblum HI, Wiedau-Pazos M. Human embryonic stem cell-derived motor neurons expressing SOD1 mutants exhibit typical signs of motor neuron degeneration linked to ALS. Dis Model Mech 2009; 2:189-95. [PMID: 19259395 DOI: 10.1242/dmm.002113] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Accepted: 12/18/2008] [Indexed: 11/20/2022] Open
Abstract
Human embryonic stem cell (hESC)-derived neurons have the potential to model neurodegenerative disorders. Here, we demonstrate the expression of a mutant gene, superoxide dismutase 1(SOD1), linked to familial amyotrophic lateral sclerosis (ALS) in hESC-derived motor neurons. Green fluorescent protein (GFP) expression under the control of the HB9 enhancer was used to identify SOD1-transfected motor neurons that express human wild-type SOD1 or one of three different mutants (G93A, A4V and I113T) of SOD1. Neurons transfected with mutant SOD1 exhibited reduced cell survival and shortened axonal processes as compared with control-transfected cells, which could survive for 3 weeks or more. The results indicate that hESC-derived cell populations can be directed to express disease-relevant genes and to display characteristics of the disease-specific cell type. These genetically manipulated hESC-derived motor neurons can facilitate and advance the study of disease-specific cellular pathways, and serve as a model system to test new therapeutic approaches.
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Affiliation(s)
- Saravanan Karumbayaram
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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14
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Abstract
Mitochondrial dynamics and transport have emerged as key factors in the regulation of neuronal differentiation and survival. Mitochondria are dynamically transported in and out of axons and dendrites to maintain neuronal and synaptic function. Transport proceeds through a controlled series of plus- and minus-end directed movements along microtubule tracks (MTs) that are often interrupted by short stops. This bidirectional motility of mitochondria is facilitated by plus end-directed kinesin and minus end-directed dynein motors, and may be coordinated and controlled by a number of mechanisms that integrate intracellular signals to ensure efficient transport and targeting of mitochondria. In this chapter, we discuss our understanding of mechanisms that facilitate mitochondrial transport and delivery to specific target sites in dendrites and axons.
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15
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Bidirectional Ca2+-dependent control of mitochondrial dynamics by the Miro GTPase. Proc Natl Acad Sci U S A 2008; 105:20728-33. [PMID: 19098100 DOI: 10.1073/pnas.0808953105] [Citation(s) in RCA: 413] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Calcium oscillations suppress mitochondrial movements along the microtubules to support on-demand distribution of mitochondria. To activate this mechanism, Ca(2+) targets a yet unidentified cytoplasmic factor that does not seem to be a microtubular motor or a kinase/phosphatase. Here, we have studied the dependence of mitochondrial dynamics on the Miro GTPases that reside in the mitochondria and contain two EF-hand Ca(2+)-binding domains, in H9c2 cells and primary neurons. At resting cytoplasmic [Ca(2+)] ([Ca(2+)](c)), movements of the mitochondria were enhanced by Miro overexpression irrespective of the presence of the EF-hands. The Ca(2+)-induced arrest of mitochondrial motility was also promoted by Miro overexpression and was suppressed when either the Miro were depleted or their EF-hand was mutated. Miro also enhanced the fusion state of the mitochondria at resting [Ca(2+)](c) but promoted mitochondrial fragmentation at high [Ca(2+)](c). These effects of Miro on mitochondrial morphology seem to involve Drp1 suppression and activation, respectively. In primary neurons, Miro also caused an increase in dendritic mitochondrial mass and enhanced mitochondrial calcium signaling. Thus, Miro proteins serve as a [Ca(2+)](c)-sensitive switch and bifunctional regulator for both the motility and fusion-fission dynamics of the mitochondria.
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Ramirez DMO, Andersson S, Russell DW. Neuronal expression and subcellular localization of cholesterol 24-hydroxylase in the mouse brain. J Comp Neurol 2008; 507:1676-93. [PMID: 18241055 DOI: 10.1002/cne.21605] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Cholesterol 24-hydroxylase is a cytochrome P450 (CYP46A1) that is selectively expressed in the brain and is responsible for the majority of cholesterol turnover in the central nervous system. Mice deficient in 24-hydroxylase exhibit impaired learning and defective hippocampal long-term potentiation, suggesting that the metabolism of cholesterol by this enzyme is required for learning and memory formation. To determine where in the neuron cholesterol turnover was taking place, monoclonal antibodies directed against 24-hydroxylase were generated by immunization of mice with recombinant protein and used to detect the enzyme in brain homogenates, cultured neurons, and histological sections. 24-Hydroxylase was localized to the endoplasmic reticulum and was distributed throughout the cell bodies and dendrites of multiple types of neurons; the enzyme was not detected in axon terminals or in the cells of 24-hydroxylase knockout mice. 24-Hydroxylase was highly expressed in pyramidal neurons of the hippocampus and cortex, in Purkinje cells of the cerebellum, and in hippocampal and cerebellar interneurons. Within the retina, 24-hydroxylase was detected in ganglion cells and some but not all cells of the inner nuclear layer. These findings reveal the microsomal localization of 24-hydroxylase and provide subcellular insight into cholesterol turnover in the brain.
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Affiliation(s)
- Denise M O Ramirez
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Louie K, Russo GJ, Salkoff DB, Wellington A, Zinsmaier KE. Effects of imaging conditions on mitochondrial transport and length in larval motor axons of Drosophila. Comp Biochem Physiol A Mol Integr Physiol 2008; 151:159-72. [PMID: 18639643 DOI: 10.1016/j.cbpa.2008.06.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 06/17/2008] [Accepted: 06/18/2008] [Indexed: 10/21/2022]
Abstract
The distribution of mitochondria is sensitive to physiological stresses and changes in metabolic demands. Consequently, it is important to carefully define the conditions facilitating live imaging of mitochondrial transport in dissected animal preparations. In this study, we examined Schneider's and the haemolymph-like solutions HL3 and HL6 for their suitability to image mitochondrial transport in motor axons of dissected Drosophila melanogaster larvae. Overall, mitochondrial transport kinetics in larval motor axons appeared similar among all three solutions. Unexpectedly, HL3 solution selectively increased the length of mitochondria in the context of the net-direction of transport. We also found that mitochondrial transport is sensitive to the extracellular Ca(2+) but not glutamate concentration. High concentrations of extracellular glutamate affected only the ratio between motile and stationary mitochondria. Our study offers a valuable overview of mitochondrial transport kinetics in larval motor axons of Drosophila under various conditions, guiding future studies genetically dissecting mechanisms of mitochondrial transport.
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Affiliation(s)
- Kathryn Louie
- Arizona Research Laboratories Division of Neurobiology, University of Arizona, Tucson, AZ 85721, USA
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Zorov DB, Isaev NK, Plotnikov EY, Zorova LD, Stelmashook EV, Vasileva AK, Arkhangelskaya AA, Khrjapenkova TG. The mitochondrion as janus bifrons. BIOCHEMISTRY (MOSCOW) 2008; 72:1115-26. [PMID: 18021069 DOI: 10.1134/s0006297907100094] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The signaling function of mitochondria is considered with a special emphasis on their role in the regulation of redox status of the cell, possibly determining a number of pathologies including cancer and aging. The review summarizes the transport role of mitochondria in energy supply to all cellular compartments (mitochondria as an electric cable in the cell), the role of mitochondria in plastic metabolism of the cell including synthesis of heme, steroids, iron-sulfur clusters, and reactive oxygen and nitrogen species. Mitochondria also play an important role in the Ca(2+)-signaling and the regulation of apoptotic cell death. Knowledge of mechanisms responsible for apoptotic cell death is important for the strategy for prevention of unwanted degradation of postmitotic cells such as cardiomyocytes and neurons.
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Affiliation(s)
- D B Zorov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia.
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Abstract
Mitochondria form a dynamic network responsible for energy production, calcium homeostasis and cell signaling. Appropriate distribution of the mitochondrial network contributes to organelle function and is essential for cell survival. Highly polarized cells, including neurons and budding yeast, are particularly sensitive to defects in mitochondrial movement and have emerged as model systems for studying mechanisms that regulate organelle distribution. Mitochondria in multicellular eukaryotes move along microtubule tracks. Actin, the primary cytoskeletal component used for transport in yeast, has more subtle functions in other organisms. Kinesin, dynein and myosin isoforms drive motor-based movement along cytoskeletal tracks. Milton and syntabulin have recently been identified as potential organelle-specific adaptor molecules for microtubule-based motors. Miro, a conserved GTPase, may function with Milton to regulate transport. In yeast, Mmr1p and Ypt11p, a Rab GTPase, are implicated in myosin V-based mitochondrial movement. These potential adaptors could regulate motor activity and therefore determine individual organelle movements. Anchoring of stationary mitochondria also contributes to organelle retention at specific sites in the cell. Together, movement and anchoring ultimately determine mitochondrial distribution throughout the cell.
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Affiliation(s)
- Rebecca L Frederick
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112, USA
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