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Dual-expression system for blue fluorescent protein optimization. Sci Rep 2022; 12:10190. [PMID: 35715437 PMCID: PMC9206027 DOI: 10.1038/s41598-022-13214-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 05/23/2022] [Indexed: 11/08/2022] Open
Abstract
Spectrally diverse fluorescent proteins (FPs) provide straightforward means for multiplexed imaging of biological systems. Among FPs fitting standard color channels, blue FPs (BFPs) are characterized by lower brightness compared to other spectral counterparts. Furthermore, available BFPs were not systematically characterized for imaging in cultured mammalian cells and common model organisms. Here we introduce a pair of new BFPs, named Electra1 and Electra2, developed through hierarchical screening in bacterial and mammalian cells using a novel dual-expression vector. We performed systematic benchmarking of Electras against state-of-art BFPs in cultured mammalian cells and demonstrated their utility as fluorescent tags for structural proteins. The Electras variants were validated for multicolor neuroimaging in Caenorhabditis elegans, zebrafish larvae, and mice in comparison with one of the best in the class BFP mTagBFP2 using one-photon and two-photon microscopy. The developed BFPs are suitable for multicolor imaging of cultured cells and model organisms in vivo. We believe that the described dual-expression vector has a great potential to be adopted by protein engineers for directed molecular evolution of FPs.
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Kedra J, Lin S, Pacheco A, Gallo G, Smith GM. Axotomy Induces Drp1-Dependent Fragmentation of Axonal Mitochondria. Front Mol Neurosci 2021; 14:668670. [PMID: 34149354 PMCID: PMC8209475 DOI: 10.3389/fnmol.2021.668670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 05/07/2021] [Indexed: 02/02/2023] Open
Abstract
It is well established that CNS axons fail to regenerate, undergo retrograde dieback, and form dystrophic growth cones due to both intrinsic and extrinsic factors. We sought to investigate the role of axonal mitochondria in the axonal response to injury. A viral vector (AAV) containing a mitochondrially targeted fluorescent protein (mitoDsRed) as well as fluorescently tagged LC3 (GFP-LC3), an autophagosomal marker, was injected into the primary motor cortex, to label the corticospinal tract (CST), of adult rats. The axons of the CST were then injured by dorsal column lesion at C4-C5. We found that mitochondria in injured CST axons near the injury site are fragmented and fragmentation of mitochondria persists for 2 weeks before returning to pre-injury lengths. Fragmented mitochondria have consistently been shown to be dysfunctional and detrimental to cellular health. Inhibition of Drp1, the GTPase responsible for mitochondrial fission, using a specific pharmacological inhibitor (mDivi-1) blocked fragmentation. Additionally, it was determined that there is increased mitophagy in CST axons following Spinal cord injury (SCI) based on increased colocalization of mitochondria and LC3. In vitro models revealed that mitochondrial divalent ion uptake is necessary for injury-induced mitochondrial fission, as inhibiting the mitochondrial calcium uniporter (MCU) using RU360 prevented injury-induced fission. This phenomenon was also observed in vivo. These studies indicate that following the injury, both in vivo and in vitro, axonal mitochondria undergo increased fission, which may contribute to the lack of regeneration seen in CNS neurons.
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Affiliation(s)
- Joseph Kedra
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Shen Lin
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Almudena Pacheco
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Gianluca Gallo
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States.,Department of Anatomy and Cell Biology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - George M Smith
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States.,Department of Neuroscience, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
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Aghanoori MR, Margulets V, Smith DR, Kirshenbaum LA, Gitler D, Fernyhough P. Sensory neurons derived from diabetic rats exhibit deficits in functional glycolysis and ATP that are ameliorated by IGF-1. Mol Metab 2021; 49:101191. [PMID: 33592336 PMCID: PMC7940986 DOI: 10.1016/j.molmet.2021.101191] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/04/2021] [Accepted: 02/09/2021] [Indexed: 11/29/2022] Open
Abstract
Objective The distal dying-back of the longest nerve fibres is a hallmark of diabetic neuropathy, and impaired provision of energy in the form of adenosine triphosphate (ATP) may contribute to this neurodegenerative process. We hypothesised that energy supplementation via glycolysis and/or mitochondrial oxidative phosphorylation is compromised in cultured dorsal root ganglion (DRG) sensory neurons from diabetic rodents, thus contributing to axonal degeneration. Functional analysis of glycolysis and mitochondrial respiration and real-time measurement of ATP levels in live cells were our specific means to test this hypothesis. Methods DRG neuron cultures from age-matched control or streptozotocin (STZ)-induced type 1 diabetic rats were used for in vitro studies. Three plasmids containing ATP biosensors of varying affinities were transfected into neurons to study endogenous ATP levels in real time. The Seahorse XF analyser was used for glycolysis and mitochondrial respiration measurements. Results Fluorescence resonance energy transfer (FRET) efficiency (YFP/CFP ratio) of the ATP biosensors AT1.03 (low affinity) and AT1.03YEMK (medium affinity) were significantly higher than that measured using the ATP-insensitive construct AT1.03R122/6K in both cell bodies and neurites of DRG neurons (p < 0.0001). The ATP level was homogenous along the axons but higher in cell bodies in cultured DRG neurons from both control and diabetic rats. Treatment with oligomycin (an ATP synthase inhibitor in mitochondria) decreased the ATP levels in cultured DRG neurons. Likewise, blockade of glycolysis using 2-deoxy-d-glucose (2-DG: a glucose analogue) reduced ATP levels (p < 0.001). Cultured DRG neurons derived from diabetic rats showed a diminishment of ATP levels (p < 0.01), glycolytic capacity, glycolytic reserve and non-glycolytic acidification. Application of insulin-like growth factor-1 (IGF-1) significantly elevated all the above parameters in DRG neurons from diabetic rats. Oligomycin pre-treatment of DRG neurons, to block oxidative phosphorylation, depleted the glycolytic reserve and lowered basal respiration in sensory neurons derived from control and diabetic rats. Depletion was much higher in sensory neurons from diabetic rats compared to control rats. In addition, an acute increase in glucose concentration, in the presence or absence of oligomycin, elevated parameters of glycolysis by 1.5- to 2-fold while having no impact on mitochondrial respiration. Conclusion We provide the first functional evidence for decreased glycolytic capacity in DRG neurons derived from type 1 diabetic rats. IGF-1 protected against the loss of ATP supplies in DRG cell bodies and axons in neurons derived from diabetic rats by augmenting various parameters of glycolysis and mitochondrial respiration. There is an energy deficit in the form of ATP in cell bodies and axons of sensory neurons derived from diabetic rats. Glycolytic capacity and reserve are depleted in sensory neurons from diabetic rats. IGF-1 treatment reverses the energy deficit and glycolysis defect in sensory neurons from diabetic rats. Glycolysis is a significant source of energy comprising up to 30% of ATP in adult rat sensory neurons.
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Affiliation(s)
- Mohamad-Reza Aghanoori
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | - Vicky Margulets
- Department of Physiology & Pathophysiology, University of Manitoba, Winnipeg, MB, Canada
| | - Darrell R Smith
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - Lorrie A Kirshenbaum
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada; Department of Physiology & Pathophysiology, University of Manitoba, Winnipeg, MB, Canada; Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Paul Fernyhough
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada.
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Spillane M, Ketschek A, Merianda TT, Twiss JL, Gallo G. Mitochondria coordinate sites of axon branching through localized intra-axonal protein synthesis. Cell Rep 2013; 5:1564-75. [PMID: 24332852 DOI: 10.1016/j.celrep.2013.11.022] [Citation(s) in RCA: 193] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 09/30/2013] [Accepted: 11/12/2013] [Indexed: 11/16/2022] Open
Abstract
The branching of axons is a fundamental aspect of nervous system development and neuroplasticity. We report that branching of sensory axons in the presence of nerve growth factor (NGF) occurs at sites populated by stalled mitochondria. Translational machinery targets to presumptive branching sites, followed by recruitment of mitochondria to these sites. The mitochondria promote branching through ATP generation and the determination of localized hot spots of active axonal mRNA translation, which contribute to actin-dependent aspects of branching. In contrast, mitochondria do not have a role in the regulation of the microtubule cytoskeleton during NGF-induced branching. Collectively, these observations indicate that sensory axons exhibit multiple potential sites of translation, defined by presence of translational machinery, but active translation occurs following the stalling and respiration of mitochondria at these potential sites of translation. This study reveals a local role for axonal mitochondria in the regulation of the actin cytoskeleton and axonal mRNA translation underlying branching.
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Affiliation(s)
- Mirela Spillane
- Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - Andrea Ketschek
- Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - Tanuja T Merianda
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19210, USA
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208, USA
| | - Gianluca Gallo
- Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA.
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Reeves BN, Dakhil SR, Sloan JA, Wolf SL, Burger KN, Kamal A, Le-Lindqwister NA, Soori GS, Jaslowski AJ, Kelaghan J, Novotny PJ, Lachance DH, Loprinzi CL. Further data supporting that paclitaxel-associated acute pain syndrome is associated with development of peripheral neuropathy: North Central Cancer Treatment Group trial N08C1. Cancer 2012; 118:5171-8. [PMID: 22415454 DOI: 10.1002/cncr.27489] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 11/21/2011] [Accepted: 11/29/2011] [Indexed: 11/10/2022]
Abstract
BACKGROUND Paclitaxel causes an acute pain syndrome (P-APS), occurring within days after each dose and usually abating within days. Paclitaxel also causes a more classic peripheral neuropathy, which steadily increases in severity with increasing paclitaxel total doses. Little detail is available regarding the natural history of these 2 syndromes, or any relationship between them, although a recent publication does provide natural history data about weekly paclitaxel, supporting an association between the severity of P-APS and eventual peripheral neuropathy symptoms. METHODS Patients entering this study were about to receive paclitaxel and carboplatin every 3 weeks. Daily questionnaires were completed for the first week after every chemotherapy dose, and European Organization for Research and Treatment of Cancer, Quality of Life Questionnaire, Chemotherapy-Induced Peripheral Neuropathy 20-item instruments were completed weekly. RESULTS The P-APS severity peaked on day 4 after the initial chemotherapy dose, with 12%, 29%, 23%, and 36% of patients having maximal pain scores of 0, 1 to 4, 5 or 6, or 7 to 10 during the first week after the first dose of therapy, respectively. Patients with P-APS scores of 0 to 4 with the first dose of chemotherapy had less eventual sensory neuropathy than did patients with P-APS scores of 5 to 10 (P = 0.001). With regard to the more peripheral neuropathy, sensory neuropathy was more problematic than was either motor or autonomic neuropathy. Numbness and tingling were more common components of the sensory neuropathy than was pain. CONCLUSIONS Patients with worse P-APS severities appear to have more eventual chemotherapy-induced peripheral neuropathy. This provides support for the concept that P-APS is a form of nerve pathology.
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