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Yang AJT, Mohammad A, Finch MS, Tsiani E, Spencer G, Necakov A, MacPherson REK. Influence of metabolic stress and metformin on synaptic protein profile in SH-SY5Y-derived neurons. Physiol Rep 2023; 11:10.14814/phy2.15852. [PMID: 38010200 PMCID: PMC10680579 DOI: 10.14814/phy2.15852] [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: 08/28/2023] [Revised: 10/02/2023] [Accepted: 10/02/2023] [Indexed: 11/29/2023] Open
Abstract
Insulin resistance (IR) is associated with reductions in neuronal proteins often observed with Alzheimer's disease (AD), however, the mechanisms through which IR promotes neurodegeneration/AD pathogenesis are poorly understood. Metformin (MET), a potent activator of the metabolic regulator AMPK is used to treat IR but its effectiveness for AD is unclear. We have previously shown that chronic AMPK activation impairs neurite growth and protein synthesis in SH-SY5Y neurons, however, AMPK activation in IR was not explored. Therefore, we examined the effects of MET-driven AMPK activation with and without IR. Retinoic acid-differentiated SH-SY5Y neurons were treated with: (1) Ctl: 24 h vehicle followed by 24 h Vehicle; (2) HI: 100 nM insulin (24 h HI followed by 24 h HI); or (3) MET: 24 h vehicle followed by 24 h 2 mM metformin; (4) HI/MET: 24 h 100 nM insulin followed by 24 h 100 nM INS+2 mM MET. INS and INS/MET groups saw impairments in markers of insulin signaling (Akt S473, mTOR S2448, p70s6k T389, and IRS-1S636) demonstrating IR was not recovered with MET treatment. All treatment groups showed reductions in neuronal markers (post-synaptic marker HOMER1 mRNA content and synapse marker synaptophysin protein content). INS and MET treatments showed a reduction in the content of the mature neuronal marker NeuN that was prevented by INS/MET. Similarly, increases in cell size/area, neurite length/area observed with INS and MET, were prevented with INS/MET. These findings indicate that IR and MET impair neuronal markers through distinct pathways and suggest that MET is ineffective in treating IR-driven impairments in neurons.
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Affiliation(s)
- Alex J. T. Yang
- Department of Health Sciences, Faculty of Applied Health SciencesBrock UniversitySt CatharinesOntarioCanada
| | - Ahmad Mohammad
- Department of Health Sciences, Faculty of Applied Health SciencesBrock UniversitySt CatharinesOntarioCanada
| | - Michael S. Finch
- Department of Health Sciences, Faculty of Applied Health SciencesBrock UniversitySt CatharinesOntarioCanada
| | - Evangelia Tsiani
- Department of Health Sciences, Faculty of Applied Health SciencesBrock UniversitySt CatharinesOntarioCanada
| | - Gaynor Spencer
- Department of Biological SciencesBrock UniversitySt CatharinesOntarioCanada
- Centre for NeuroscienceBrock UniversitySt. CatharinesOntarioCanada
| | - Aleksandar Necakov
- Department of Biological SciencesBrock UniversitySt CatharinesOntarioCanada
- Centre for NeuroscienceBrock UniversitySt. CatharinesOntarioCanada
| | - Rebecca E. K. MacPherson
- Department of Health Sciences, Faculty of Applied Health SciencesBrock UniversitySt CatharinesOntarioCanada
- Centre for NeuroscienceBrock UniversitySt. CatharinesOntarioCanada
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Chaiamarit T, Wu Y, Verhelle A, Encalada SE. Fluorescence Assays for Real-Time Tracking of Cell Surface Protein Internalization and Endosomal Sorting in Axons of Primary Mouse Hippocampal Neurons. Bio Protoc 2023; 13:e4651. [PMID: 37056248 PMCID: PMC10086550 DOI: 10.21769/bioprotoc.4651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/15/2022] [Accepted: 02/28/2023] [Indexed: 04/07/2023] Open
Abstract
The trafficking and sorting of proteins through the secretory-endolysosomal system is critical for the proper functioning of neurons. Defects in steps of these pathways are associated with neuronal toxicity in various neurodegenerative disorders. The prion protein (PrP) is a glycosylphosphatidylinositol (GPI)-anchored protein that follows the secretory pathway before reaching the cell surface. Following endocytosis from the cell surface, PrP sorts into endosomes and lysosomes for further recycling and degradation, respectively. A few detailed protocols using drug treatments and fluorescent dyes have previously allowed the tracking of PrP trafficking routes in real time in non-neuronal cells. Here, we present a protocol optimized for primary neurons that aims to monitor and/or manipulate the trafficking and sorting of PrP particles at several steps during their secretory-endolysosomal itineraries, including (a) ER export, (b) endocytosis, (c) lysosomal degradation, and (d) accumulation in axonal endolysosomes. These primary neuron live assays allow for the robust quantitation of accumulation and/or degradation of PrP or of other membrane-associated proteins that transition from the ER to the Golgi via the cell surface. Graphical abstract.
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Affiliation(s)
- Tai Chaiamarit
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
- Neurodegeneration New Medicines Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Yin Wu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
- Neurodegeneration New Medicines Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Adriaan Verhelle
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
- Neurodegeneration New Medicines Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Sandra E. Encalada
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
- Neurodegeneration New Medicines Center, The Scripps Research Institute, La Jolla, CA 92037, USA
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Chaiamarit T, Verhelle A, Chassefeyre R, Shukla N, Novak SW, Andrade LR, Manor U, Encalada SE. Mutant Prion Protein Endoggresomes are Hubs for Local Axonal Organelle-Cytoskeletal Remodeling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.19.533383. [PMID: 36993610 PMCID: PMC10055262 DOI: 10.1101/2023.03.19.533383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Dystrophic axons comprising misfolded mutant prion protein (PrP) aggregates are a characteristic pathological feature in the prionopathies. These aggregates form inside endolysosomes -called endoggresomes-, within swellings that line up the length of axons of degenerating neurons. The pathways impaired by endoggresomes that result in failed axonal and consequently neuronal health, remain undefined. Here, we dissect the local subcellular impairments that occur within individual mutant PrP endoggresome swelling sites in axons. Quantitative high-resolution light and electron microscopy revealed the selective impairment of the acetylated vs tyrosinated microtubule cytoskeleton, while micro-domain image analysis of live organelle dynamics within swelling sites revealed deficits uniquely to the MT-based active transport system that translocates mitochondria and endosomes toward the synapse. Cytoskeletal and defective transport results in the retention of mitochondria, endosomes, and molecular motors at swelling sites, enhancing mitochondria-Rab7 late endosome contacts that induce mitochondrial fission via the activity of Rab7, and render mitochondria dysfunctional. Our findings point to mutant Pr Pendoggresome swelling sites as selective hubs of cytoskeletal deficits and organelle retention that drive the remodeling of organelles along axons. We propose that the dysfunction imparted locally within these axonal micro-domains spreads throughout the axon over time, leading to axonal dysfunction in prionopathies.
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Lin S, Leitão ADG, Fang S, Gu Y, Barber S, Gilliard-Telefoni R, Castro A, Sung K, Shen R, Florio JB, Mante ML, Ding J, Spencer B, Masliah E, Rissman RA, Wu C. Overexpression of alpha synuclein disrupts APP and Endolysosomal axonal trafficking in a mouse model of synucleinopathy. Neurobiol Dis 2023; 178:106010. [PMID: 36702318 PMCID: PMC10754494 DOI: 10.1016/j.nbd.2023.106010] [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: 08/11/2022] [Revised: 01/18/2023] [Accepted: 01/20/2023] [Indexed: 01/24/2023] Open
Abstract
Mutations or triplication of the alpha synuclein (ASYN) gene contribute to synucleinopathies including Parkinson's disease (PD), Dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). Recent evidence suggests that ASYN also plays an important role in amyloid-induced neurotoxicity, although the mechanism(s) remains unknown. One hypothesis is that accumulation of ASYN alters endolysosomal pathways to impact axonal trafficking and processing of the amyloid precursor protein (APP). To define an axonal function for ASYN, we used a transgenic mouse model of synucleinopathy that expresses a GFP-human ASYN (GFP-hASYN) transgene and an ASYN knockout (ASYN-/-) mouse model. Our results demonstrate that expression of GFP-hASYN in primary neurons derived from a transgenic mouse impaired axonal trafficking and processing of APP. In addition, axonal transport of BACE1, Rab5, Rab7, lysosomes and mitochondria were also reduced in these neurons. Interestingly, axonal transport of these organelles was also affected in ASYN-/- neurons, suggesting that ASYN plays an important role in maintaining normal axonal transport function. Therefore, selective impairment of trafficking and processing of APP by ASYN may act as a potential mechanism to induce pathological features of Alzheimer's disease (AD) in PD patients.
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Affiliation(s)
- Suzhen Lin
- Institute of Neurology, Ruijing Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China; Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - André D G Leitão
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Savannah Fang
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Yingli Gu
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Sophia Barber
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | | | - Alfredo Castro
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Kijung Sung
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Ruinan Shen
- Institute of Neurology, Ruijing Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China; Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Jazmin B Florio
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Michael L Mante
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Jianqing Ding
- Institute of Neurology, Ruijing Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Brian Spencer
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Eliezer Masliah
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Robert A Rissman
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA; VA San Diego Health System, La Jolla, CA, USA.
| | - Chengbiao Wu
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA.
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Pathophysiology of neurodegenerative diseases: An interplay among axonal transport failure, oxidative stress, and inflammation? Semin Immunol 2022; 59:101628. [PMID: 35779975 PMCID: PMC9807734 DOI: 10.1016/j.smim.2022.101628] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 04/09/2022] [Accepted: 06/13/2022] [Indexed: 01/15/2023]
Abstract
Neurodegenerative diseases (NDs) are heterogeneous neurological disorders characterized by a progressive loss of selected neuronal populations. A significant risk factor for most NDs is aging. Considering the constant increase in life expectancy, NDs represent a global public health burden. Axonal transport (AT) is a central cellular process underlying the generation and maintenance of neuronal architecture and connectivity. Deficits in AT appear to be a common thread for most, if not all, NDs. Neuroinflammation has been notoriously difficult to define in relation to NDs. Inflammation is a complex multifactorial process in the CNS, which varies depending on the disease stage. Several lines of evidence suggest that AT defect, axonopathy and neuroinflammation are tightly interlaced. However, whether these impairments play a causative role in NDs or are merely a downstream effect of neuronal degeneration remains unsettled. We still lack reliable information on the temporal relationship between these pathogenic mechanisms, although several findings suggest that they may occur early during ND pathophysiology. This article will review the latest evidence emerging on whether the interplay between AT perturbations and some aspects of CNS inflammation can participate in ND etiology, analyze their potential as therapeutic targets, and the urge to identify early surrogate biomarkers.
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