1
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Masato A, Andolfo A, Favetta G, Bellini EN, Cogo S, Dalla Valle L, Boassa D, Greggio E, Plotegher N, Bubacco L. Sequestosome-1 (SQSTM1/p62) as a target in dopamine catabolite-mediated cellular dyshomeostasis. Cell Death Dis 2024; 15:424. [PMID: 38890356 PMCID: PMC11189528 DOI: 10.1038/s41419-024-06763-x] [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: 04/07/2023] [Revised: 05/20/2024] [Accepted: 05/21/2024] [Indexed: 06/20/2024]
Abstract
Alterations in the dopamine catabolic pathway are known to contribute to the degeneration of nigrostriatal neurons in Parkinson's disease (PD). The progressive cellular buildup of the highly reactive intermediate 3,4-dihydroxyphenylacetaldehye (DOPAL) generates protein cross-linking, oligomerization of the PD-linked αSynuclein (αSyn) and imbalance in protein quality control. In this scenario, the autophagic cargo sequestome-1 (SQSTM1/p62) emerges as a target of DOPAL-dependent oligomerization and accumulation in cytosolic clusters. Although DOPAL-induced oxidative stress and activation of the Nrf2 pathway promote p62 expression, p62 oligomerization rather seems to be a consequence of direct DOPAL modification. DOPAL-induced p62 clusters are positive for ubiquitin and accumulate within lysosomal-related structures, likely affecting the autophagy-lysosomal functionality. Finally, p62 oligomerization and clustering is synergistically augmented by DOPAL-induced αSyn buildup. Hence, the substantial impact on p62 proteostasis caused by DOPAL appears of relevance for dopaminergic neurodegeneration, in which the progressive failure of degradative pathways and the deposition of proteins like αSyn, ubiquitin and p62 in inclusion bodies represent a major trait of PD pathology.
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Affiliation(s)
- Anna Masato
- Department of Biology, University of Padova, Padova, Italy
- UK Dementia Research Institute at University College London, London, UK
| | - Annapaola Andolfo
- Proteomics and Metabolomics Facility (ProMeFa), Center for Omics Sciences (COSR), IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Giulia Favetta
- Department of Biology, University of Padova, Padova, Italy
| | - Edoardo Niccolò Bellini
- Proteomics and Metabolomics Facility (ProMeFa), Center for Omics Sciences (COSR), IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Susanna Cogo
- Department of Biology, University of Padova, Padova, Italy
- School of Biological Sciences, University of Reading, Reading, UK
| | | | - Daniela Boassa
- Department of Neurosciences and National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA, USA
| | - Elisa Greggio
- Department of Biology, University of Padova, Padova, Italy
- Centro Studi per la Neurodegenerazione (CESNE), University of Padova, Padova, Italy
| | - Nicoletta Plotegher
- Department of Biology, University of Padova, Padova, Italy
- Centro Studi per la Neurodegenerazione (CESNE), University of Padova, Padova, Italy
| | - Luigi Bubacco
- Department of Biology, University of Padova, Padova, Italy.
- Centro Studi per la Neurodegenerazione (CESNE), University of Padova, Padova, Italy.
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2
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Consequences of Autophagy Deletion on the Age-Related Changes in the Epidermal Lipidome of Mice. Int J Mol Sci 2022; 23:ijms231911110. [PMID: 36232414 PMCID: PMC9569666 DOI: 10.3390/ijms231911110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/03/2022] [Accepted: 09/18/2022] [Indexed: 12/02/2022] Open
Abstract
Autophagy is a controlled mechanism of intracellular self-digestion with functions in metabolic adaptation to stress, in development, in proteostasis and in maintaining cellular homeostasis in ageing. Deletion of autophagy in epidermal keratinocytes does not prevent the formation of a functional epidermis and the permeability barrier but causes increased susceptibility to damage stress and metabolic alterations and accelerated ageing phenotypes. We here investigated how epidermal autophagy deficiency using Keratin 14 driven Atg7 deletion would affect the lipid composition of the epidermis of young and old mice. Using mass spectrometric lipidomics we found a reduction of age-related accumulation of storage lipids in the epidermis of autophagy-deficient mice, and specific changes in chain length and saturation of fatty acids in several lipid classes. Transcriptomics and immunostaining suggest that these changes are accompanied by changes in expression and localisation of lipid and fatty acid transporter proteins, most notably fatty acid binding protein 5 (FABP5) in autophagy knockouts. Thus, maintaining autophagic activity at an advanced age may be necessary to maintain epidermal lipid homeostasis in mammals.
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3
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Narzt MS, Kremslehner C, Golabi B, Nagelreiter IM, Malikovic J, Hussein AM, Plasenzotti R, Korz V, Lubec G, Gruber F, Lubec J. Molecular species of oxidized phospholipids in brain differentiate between learning- and memory impaired and unimpaired aged rats. Amino Acids 2022; 54:1311-1326. [PMID: 35817992 PMCID: PMC9372013 DOI: 10.1007/s00726-022-03183-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 06/17/2022] [Indexed: 02/08/2023]
Abstract
Loss of cognitive function is a typical consequence of aging in humans and rodents. The extent of decline in spatial memory performance of rats, assessed by a hole-board test, reaches from unimpaired and comparable to young individuals to severely memory impaired. Recently, proteomics identified peroxiredoxin 6, an enzyme important for detoxification of oxidized phospholipids, as one of several synaptosomal proteins discriminating between aged impaired and aged unimpaired rats. In this study, we investigated several components of the epilipidome (modifications of phospholipids) of the prefrontal cortex of young, aged memory impaired (AI) and aged unimpaired (AU) rats. We observed an age-related increase in phospholipid hydroperoxides and products of phospholipid peroxidation, including reactive aldehydophospholipids. This increase went in hand with cortical lipofuscin autofluorescence. The memory impairment, however, was paralleled by additional specific changes in the aged rat brain epilipidome. There was a profound increase in phosphocholine hydroxides, and a significant decrease in phosphocholine-esterified azelaic acid. As phospholipid-esterified fatty acid hydroxides, and especially those deriving from arachidonic acid are both markers and effectors of inflammation, the findings suggest that in addition to age-related reactive oxygen species (ROS) accumulation, age-related impairment of spatial memory performance has an additional and distinct (neuro-) inflammatory component.
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Affiliation(s)
- Marie-Sophie Narzt
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Center, Linz/Vienna, Austria
| | | | - Bahar Golabi
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Ionela-Mariana Nagelreiter
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
- Center for Brain Research, Department of Molecular Neurosciences, Medical University of Vienna, Vienna, Austria
| | - Jovana Malikovic
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Ahmed M Hussein
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
- Programme for Proteomics, Paracelsus Private Medical University, Salzburg, Austria
- Department of Zoology, Faculty of Science, Al-Azhar University, Assiut, Egypt
| | - Roberto Plasenzotti
- Center for Biomedical Research, Division of Laboratory Animal Science and Genetics, Medical University of Vienna, Himberg, Austria
| | - Volker Korz
- Programme for Proteomics, Paracelsus Private Medical University, Salzburg, Austria
| | - Gert Lubec
- Programme for Proteomics, Paracelsus Private Medical University, Salzburg, Austria
| | - Florian Gruber
- Department of Dermatology, Medical University of Vienna, Vienna, Austria.
| | - Jana Lubec
- Programme for Proteomics, Paracelsus Private Medical University, Salzburg, Austria.
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4
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Chen TT, Zhou X, Xu YN, Li Y, Wu XY, Xiang Q, Fu LY, Hu XX, Tao L, Shen XC. Gastrodin ameliorates learning and memory impairment in rats with vascular dementia by promoting autophagy flux via inhibition of the Ca 2+/CaMKII signal pathway. Aging (Albany NY) 2021; 13:9542-9565. [PMID: 33714957 PMCID: PMC8064221 DOI: 10.18632/aging.202667] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 11/30/2020] [Indexed: 12/12/2022]
Abstract
Vascular dementia (VD) is a common disease that occurs during human aging. Gastrodin (GAS) has potential benefits for the prevention and treatment of VD. In the present study, we investigated the effects of GAS on cognitive dysfunction in rats with VD induced by permanent middle cerebral artery occlusion (pMCAO) and explored the underlying mechanism. Immunohistochemical and western blot analyses revealed that GAS attenuated hippocampal levels of LC3 (microtubule-associated protein 1 light chain 3), p62, and phosphorylated CaMKII (Ca2+-calmodulin stimulated protein kinase II) in VD rats. Additionally, our results revealed that cobalt chloride blocked autophagic flux in HT22 cells, which was confirmed by increased levels of LC3 and p62 when combined with chloroquine. Notably, GAS ameliorated the impaired autophagic flux. Furthermore, we confirmed that GAS combined with KN93 (a CaMKII inhibitor) or CaMKII knockdown did not impact the reduced p62 levels when compared with GAS treatment alone. Furthermore, a co-immunoprecipitation assay demonstrated that endogenous p62 bound to CaMKII, as confirmed by mass spectrometric analysis after the immunoprecipitation of p62 from HT22 cells. These findings revealed that GAS attenuated autophagic flux dysfunction by inhibiting the Ca2+/CaMKII signaling pathway to ameliorate cognitive impairment in VD.
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Affiliation(s)
- Ting-Ting Chen
- The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, P.R. China.,Guiyang Maternal and Child Health-Care Hospital, Guiyang 550000, P.R. China.,The Key Laboratory of Optimal Utilization of Natural Medicine Resources and The Union Key Laboratory of Guiyang City, Guizhou Medical University, School of Pharmaceutical Sciences, Guiyang 550025, P.R. China
| | - Xue Zhou
- The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, P.R. China
| | - Yi-Ni Xu
- The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, P.R. China
| | - Yue Li
- Guiyang Maternal and Child Health-Care Hospital, Guiyang 550000, P.R. China
| | - Xiao-Ying Wu
- The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, P.R. China.,The Key Laboratory of Optimal Utilization of Natural Medicine Resources and The Union Key Laboratory of Guiyang City, Guizhou Medical University, School of Pharmaceutical Sciences, Guiyang 550025, P.R. China
| | - Quan Xiang
- The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, P.R. China.,The Key Laboratory of Endemic and Ethnic Diseases of Ministry of Education, Guizhou Medical University, Guiyang 550025, P.R. China
| | - Ling-Yun Fu
- The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, P.R. China.,The Key Laboratory of Endemic and Ethnic Diseases of Ministry of Education, Guizhou Medical University, Guiyang 550025, P.R. China
| | - Xiao-Xia Hu
- The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, P.R. China.,The Key Laboratory of Endemic and Ethnic Diseases of Ministry of Education, Guizhou Medical University, Guiyang 550025, P.R. China
| | - Ling Tao
- The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, P.R. China
| | - Xiang-Chun Shen
- The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, P.R. China.,The Key Laboratory of Optimal Utilization of Natural Medicine Resources and The Union Key Laboratory of Guiyang City, Guizhou Medical University, School of Pharmaceutical Sciences, Guiyang 550025, P.R. China.,The Key Laboratory of Endemic and Ethnic Diseases of Ministry of Education, Guizhou Medical University, Guiyang 550025, P.R. China
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5
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Berkamp S, Mostafavi S, Sachse C. Structure and function of p62/SQSTM1 in the emerging framework of phase separation. FEBS J 2020; 288:6927-6941. [PMID: 33332721 DOI: 10.1111/febs.15672] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/27/2020] [Accepted: 12/15/2020] [Indexed: 12/28/2022]
Abstract
p62/SQSTM1 is a multiprotein interaction hub forming cellular punctate structures known as p62 bodies. p62 is centrally involved in the degradation of ubiquitinated cargo through autophagy, as well as in a wide range of signaling activities as part of the cellular response to nutrient sensing, oxidative stress, infection, immunity, and inflammation. Structural work has shown that p62 forms flexible filamentous assemblies composed of an N-terminal PB1-domain scaffold and a C-terminal binding platform, including folded recognition domains and structurally disordered binding motifs. In the cell, these filaments are part of cellular p62 bodies that display properties of liquid-liquid-phase separation. Here, we review the accumulated structural and functional work of p62 and integrate them with the emerging framework of filamentous biomolecular condensates.
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Affiliation(s)
- Sabrina Berkamp
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, Germany.,JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, Germany
| | - Siavash Mostafavi
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, Germany.,JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, Germany
| | - Carsten Sachse
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, Germany.,JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, Germany.,Department of Biology, Heinrich Heine University, Düsseldorf, Germany
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6
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Cao Y, Pan L, Zhang X, Guo W, Huang D. LncRNA SNHG3 promotes autophagy-induced neuronal cell apoptosis by acting as a ceRNA for miR-485 to up-regulate ATG7 expression. Metab Brain Dis 2020; 35:1361-1369. [PMID: 32860611 DOI: 10.1007/s11011-020-00607-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 08/11/2020] [Indexed: 01/16/2023]
Abstract
Long non-coding RNAs (lncRNAs) are bound up with various human diseases. However, their roles in brain ischemia-reperfusion (I/R) injury remain largely unknown. This study aimed to reveal the potential mechanism of LncRNA SNHG3 on autophagy-induced neuronal cell apoptosis in the brain I/R injury. LncRNA SNHG3 and miR-485 or autophagy markers LC3II/I and Beclin-1 expressions were detected by qRT-PCR or Western blot and the apoptosis of N2a cells was analyzed by flow cytometry. Besides, the interactions between LncRNA SNHG3 and miR-485, miR-485 and ATG7 were validated by RNA pull-down and dual-luciferase reporter system assays. After the Oxygen and Glucose Deprivation (OGD) treatment of N2a cells transfected with pcDNA-SNHG3, pcDNA-SNHG3 + miR-485 mimic for 6 h, 1 mM autophagy inhibitor 3-MA was added and reoxygenated for 24 h, the effect of LncRNA SNHG3 on the autophagy-induced neuronal cell apoptosis was measured by Western blot and flow cytometry. LncRNA SNHG3 was highly expressed in the mouse model of transient middle cerebral artery occlusion and cell model of Oxygen and Glucose Deprivation/Reperfusion, while miR-485 was lowly expressed. Furthermore, miR-485 negatively regulated the luciferase activities of LncRNA SNHG3 and ATG7. After the OGD treatment of N2a cells transfected with pcDNA-SNHG3, pcDNA-SNHG3 + miR-485 mimic for 6 h, 1 mM 3-MA was added and reoxygenated for 24 h, the overexpression of LncRNA SNHG3 raised the ratio of LC3-II/LC3-I and Beclin-1 expression and boosted the apoptosis of N2a cells, while these effects were reversed after the transfection of miR-485 mimic. In general, our data expounded that the interference with LncRNA SNHG3 improved brain I/R injury by up-regulating miR-485 and down-regulating ATG7 to restrain autophagy and neuronal cell apoptosis.
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Affiliation(s)
- Yanbin Cao
- Department of Neurosurgery, Weihai municipal hospital, Weihai, Shandong, China
| | - Lihua Pan
- Department of Neurosurgery, Weihai municipal hospital, Weihai, Shandong, China
| | - Xuejun Zhang
- Department of Neurosurgery, Weihai municipal hospital, Weihai, Shandong, China
| | - Wenbin Guo
- Department of Neurosurgery, Weihai municipal hospital, Weihai, Shandong, China
| | - Dezhang Huang
- Department of Neurosurgery, Qilu Hospital (Qingdao), Cheeloo college of Medicine, Shandong University, No.758 Hefei Road, Qingdao, 266035, Shandong Province, China.
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7
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Structural basis of p62/SQSTM1 helical filaments and their role in cellular cargo uptake. Nat Commun 2020; 11:440. [PMID: 31974402 PMCID: PMC6978347 DOI: 10.1038/s41467-020-14343-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 01/02/2020] [Indexed: 12/21/2022] Open
Abstract
p62/SQSTM1 is an autophagy receptor and signaling adaptor with an N-terminal PB1 domain that forms the scaffold of phase-separated p62 bodies in the cell. The molecular determinants that govern PB1 domain filament formation in vitro remain to be determined and the role of p62 filaments inside the cell is currently unclear. We here determine four high-resolution cryo-EM structures of different human and Arabidopsis PB1 domain assemblies and observed a filamentous ultrastructure of p62/SQSTM1 bodies using correlative cellular EM. We show that oligomerization or polymerization, driven by a double arginine finger in the PB1 domain, is a general requirement for lysosomal targeting of p62. Furthermore, the filamentous assembly state of p62 is required for autophagosomal processing of the p62-specific cargo KEAP1. Our results show that using such mechanisms, p62 filaments can be critical for cargo uptake in autophagy and are an integral part of phase-separated p62 bodies. PB1-mediated oligomerization of p62/SQSTM1 is essential for its function as a selective autophagy receptor. Here the authors present the cryo-EM structures of human and Arabidopsis PB1 domain helical assemblies and find that a conserved double arginine finger in the PB1 domain is important for p62 polymerisation and lysosomal targeting of p62.
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8
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Eckhart L, Tschachler E, Gruber F. Autophagic Control of Skin Aging. Front Cell Dev Biol 2019; 7:143. [PMID: 31417903 PMCID: PMC6682604 DOI: 10.3389/fcell.2019.00143] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/11/2019] [Indexed: 12/13/2022] Open
Abstract
The skin forms the barrier to the environment. Maintenance of this barrier during aging requires orchestrated responses to variable types of stress, the continuous renewal of the epithelial compartment, and the homeostasis of long-lived cell types. Recent experimental evidence suggests that autophagy is critically involved in skin homeostasis and skin aging is associated with and partially caused by defects of autophagy. In the outer skin epithelium, autophagy is constitutively active during cornification of keratinocytes and increases the resistance to environmental stress. Experimental suppression of autophagy in the absence of stress is tolerated by the rapidly renewing epidermal epithelium, whereas long-lived skin cells such as melanocytes, Merkel cells and secretory cells of sweat glands depend on autophagy for cellular homeostasis and normal execution of their functions during aging. Yet other important roles of autophagy have been identified in the dermis where senescence of mesenchymal cells and alterations of the extracellular matrix (ECM) are hallmarks of aging. Here, we review the evidence for cell type-specific roles of autophagy in the skin and their differential contributions to aging.
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Affiliation(s)
- Leopold Eckhart
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Erwin Tschachler
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Florian Gruber
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Vienna, Austria.,Christian Doppler Laboratory for Biotechnology of Skin Aging, Vienna, Austria
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Hoem G, Bowitz Larsen K, Øvervatn A, Brech A, Lamark T, Sjøttem E, Johansen T. The FMRpolyGlycine Protein Mediates Aggregate Formation and Toxicity Independent of the CGG mRNA Hairpin in a Cellular Model for FXTAS. Front Genet 2019; 10:249. [PMID: 30984240 PMCID: PMC6447689 DOI: 10.3389/fgene.2019.00249] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 03/05/2019] [Indexed: 11/13/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by a CGG-repeat expansion in the 5' UTR of the FMR1 gene on the X-chromosome. Both elevated levels of the expanded FMR1 mRNA and aberrant expression of a polyglycine protein (FMRpolyG) from the CGG-repeat region are hypothesized to trigger the pathogenesis of FXTAS. While increased expression of FMRpolyG leads to higher toxicity in FXTAS models, the pathogenic effect of this protein has only been studied in the presence of CGG-containing mRNA. Here we present a model that allows measurement of the effect of FMRpolyG-expression without co-expression of the corresponding CGG mRNA hairpin. This allows direct comparison of the effect of the FMRpolyG protein per se, vs. that of the FMRpolyG protein together with the CGG mRNA hairpin. Our results show that expression of the FMRpolyG, in the absence of any CGG mRNA, is sufficient to cause reduced cell viability, lamin ring disruption and aggregate formation. Furthermore, we found FMRpolyG to be a long-lived protein degraded primarily by the ubiquitin-proteasome-system. Together, our data indicate that accumulation of FMRpolyG protein per se may play a major role in the development of FXTAS.
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Affiliation(s)
- Gry Hoem
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
| | - Kenneth Bowitz Larsen
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
| | - Aud Øvervatn
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
| | - Andreas Brech
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.,Faculty of Medicine, Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Trond Lamark
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
| | - Eva Sjøttem
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
| | - Terje Johansen
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
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