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Aoki Y, Raquel M, Lee Y, Douglas A, Aoki M, Varela M, Sathyaprakash C, Mutihac R, Talbot K, Wood M. Development of LNA gapmer oligonucleotide based therapy for FTD/ALS caused by the C9orf72 repeat expansion. Neuromuscul Disord 2015. [DOI: 10.1016/j.nmd.2015.06.459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Mutihac R, Alegre-Abarrategui J, Gordon D, Farrimond L, Yamasaki-Mann M, Talbot K, Wade-Martins R. TARDBP pathogenic mutations increase cytoplasmic translocation of TDP-43 and cause reduction of endoplasmic reticulum Ca²⁺ signaling in motor neurons. Neurobiol Dis 2014; 75:64-77. [PMID: 25526708 DOI: 10.1016/j.nbd.2014.12.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 11/24/2014] [Accepted: 12/10/2014] [Indexed: 12/12/2022] Open
Abstract
The transactive response DNA binding protein (TDP-43) is a major component of the characteristic neuronal cytoplasmic inclusions seen in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Furthermore, pathogenic mutations in the gene encoding TDP-43, TARDBP, are found in sporadic and familial ALS cases. To study the molecular mechanisms of cellular toxicity due to TDP-43 mutations we generated a novel in vitro cellular model using a fluorescently tagged human genomic TARDBP locus carrying one of two ALS-associated mutations, A382T or M337V, which were used to generate site-specific bacterial artificial chromosome (BAC) human stable cell lines and BAC transgenic mice. In cell lines and primary motor neurons in culture, TDP-M337V mislocalized to the cytoplasm more frequently than wild-type TDP (wt-TDP) and TDP-A382T, an effect potentiated by oxidative stress. Expression of mutant TDP-M337V correlated with increased apoptosis detected by cleaved caspase-3 staining. Cells expressing mislocalized TDP-M337V spontaneously developed cytoplasmic aggregates, while for TDP-A382T aggregates were only revealed after endoplasmic reticulum (ER) stress induced by the calcium-modifying drug thapsigargin. Lowering Ca(2+) concentration in the ER of wt-TDP cells partially recapitulated the effect of pathogenic mutations by increasing TDP-43 cytoplasmic mislocalization, suggesting Ca(2+) dysregulation as a potential mediator of pathology through alterations in Bcl-2 protein levels. Ca(2+) signaling from the ER was impaired in immortalized cells and primary neurons carrying TDP-43 mutations, with a 50% reduction in the levels of luminal ER Ca(2+) stores content and delayed Ca(2+) release compared with cells carrying wt-TDP. The deficits in Ca(2+) release in human cells correlated with the upregulation of Bcl-2 and siRNA-mediated knockdown of Bcl-2 restored the amplitude of Ca(2+) oscillations in TDP-M337V cells. These results suggest that TDP-43 pathogenic mutations elicit cytoplasmic mislocalization of TDP-43 and Bcl-2 mediated ER Ca(2+) signaling dysregulation.
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Affiliation(s)
- R Mutihac
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford OX3 9DU, UK.
| | - J Alegre-Abarrategui
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK.
| | - D Gordon
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford OX3 9DU, UK.
| | - L Farrimond
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford OX3 9DU, UK.
| | - M Yamasaki-Mann
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK; Oxford Stem Cell Institute, University of Oxford, Oxford OX1 3QX, UK.
| | - K Talbot
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford OX3 9DU, UK.
| | - R Wade-Martins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK.
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Posse S, Ackley E, Mutihac R, Zhang T, Hummatov R, Akhtari M, Chohan M, Fisch B, Yonas H. High-speed real-time resting-state FMRI using multi-slab echo-volumar imaging. Front Hum Neurosci 2013; 7:479. [PMID: 23986677 PMCID: PMC3752525 DOI: 10.3389/fnhum.2013.00479] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 07/29/2013] [Indexed: 11/21/2022] Open
Abstract
We recently demonstrated that ultra-high-speed real-time fMRI using multi-slab echo-volumar imaging (MEVI) significantly increases sensitivity for mapping task-related activation and resting-state networks (RSNs) compared to echo-planar imaging (Posse et al., 2012). In the present study we characterize the sensitivity of MEVI for mapping RSN connectivity dynamics, comparing independent component analysis (ICA) and a novel seed-based connectivity analysis (SBCA) that combines sliding-window correlation analysis with meta-statistics. This SBCA approach is shown to minimize the effects of confounds, such as movement, and CSF and white matter signal changes, and enables real-time monitoring of RSN dynamics at time scales of tens of seconds. We demonstrate highly sensitive mapping of eloquent cortex in the vicinity of brain tumors and arterio-venous malformations, and detection of abnormal resting-state connectivity in epilepsy. In patients with motor impairment, resting-state fMRI provided focal localization of sensorimotor cortex compared with more diffuse activation in task-based fMRI. The fast acquisition speed of MEVI enabled segregation of cardiac-related signal pulsation using ICA, which revealed distinct regional differences in pulsation amplitude and waveform, elevated signal pulsation in patients with arterio-venous malformations and a trend toward reduced pulsatility in gray matter of patients compared with healthy controls. Mapping cardiac pulsation in cortical gray matter may carry important functional information that distinguishes healthy from diseased tissue vasculature. This novel fMRI methodology is particularly promising for mapping eloquent cortex in patients with neurological disease, having variable degree of cooperation in task-based fMRI. In conclusion, ultra-high-real-time speed fMRI enhances the sensitivity of mapping the dynamics of resting-state connectivity and cerebro-vascular pulsatility for clinical and neuroscience research applications.
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Affiliation(s)
- Stefan Posse
- Department of Neurology, School of Medicine, The University of New Mexico, Albuquerque, NM, USA
- Department of Electrical and Computer Engineering, The University of New Mexico, Albuquerque, NM, USA
- Department of Physics and Astronomy, The University of New Mexico, Albuquerque, NM, USA
| | - Elena Ackley
- Department of Neurology, School of Medicine, The University of New Mexico, Albuquerque, NM, USA
| | - Radu Mutihac
- Department of Physics, University of Bucharest, Bucharest, Romania
- Division of Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Tongsheng Zhang
- Department of Neurology, School of Medicine, The University of New Mexico, Albuquerque, NM, USA
| | - Ruslan Hummatov
- Department of Physics and Astronomy, The University of New Mexico, Albuquerque, NM, USA
| | - Massoud Akhtari
- Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, CA, USA
| | - Muhammad Chohan
- Department of Neurosurgery, School of Medicine, The University of New Mexico, Albuquerque, NM, USA
| | - Bruce Fisch
- Department of Neurology, School of Medicine, The University of New Mexico, Albuquerque, NM, USA
| | - Howard Yonas
- Department of Neurosurgery, School of Medicine, The University of New Mexico, Albuquerque, NM, USA
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Posse S, Ackley E, Mutihac R, Rick J, Shane M, Murray-Krezan C, Zaitsev M, Speck O. Enhancement of temporal resolution and BOLD sensitivity in real-time fMRI using multi-slab echo-volumar imaging. Neuroimage 2012; 61:115-30. [PMID: 22398395 DOI: 10.1016/j.neuroimage.2012.02.059] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Revised: 02/06/2012] [Accepted: 02/20/2012] [Indexed: 11/25/2022] Open
Abstract
In this study, a new approach to high-speed fMRI using multi-slab echo-volumar imaging (EVI) is developed that minimizes geometrical image distortion and spatial blurring, and enables nonaliased sampling of physiological signal fluctuation to increase BOLD sensitivity compared to conventional echo-planar imaging (EPI). Real-time fMRI using whole brain 4-slab EVI with 286 ms temporal resolution (4mm isotropic voxel size) and partial brain 2-slab EVI with 136 ms temporal resolution (4×4×6 mm(3) voxel size) was performed on a clinical 3 Tesla MRI scanner equipped with 12-channel head coil. Four-slab EVI of visual and motor tasks significantly increased mean (visual: 96%, motor: 66%) and maximum t-score (visual: 263%, motor: 124%) and mean (visual: 59%, motor: 131%) and maximum (visual: 29%, motor: 67%) BOLD signal amplitude compared with EPI. Time domain moving average filtering (2s width) to suppress physiological noise from cardiac and respiratory fluctuations further improved mean (visual: 196%, motor: 140%) and maximum (visual: 384%, motor: 200%) t-scores and increased extents of activation (visual: 73%, motor: 70%) compared to EPI. Similar sensitivity enhancement, which is attributed to high sampling rate at only moderately reduced temporal signal-to-noise ratio (mean: -52%) and longer sampling of the BOLD effect in the echo-time domain compared to EPI, was measured in auditory cortex. Two-slab EVI further improved temporal resolution for measuring task-related activation and enabled mapping of five major resting state networks (RSNs) in individual subjects in 5 min scans. The bilateral sensorimotor, the default mode and the occipital RSNs were detectable in time frames as short as 75 s. In conclusion, the high sampling rate of real-time multi-slab EVI significantly improves sensitivity for studying the temporal dynamics of hemodynamic responses and for characterizing functional networks at high field strength in short measurement times.
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Affiliation(s)
- Stefan Posse
- Department of Neurology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
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