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Jaeger K, Sukseree S, Zhong S, Phinney BS, Mlitz V, Buchberger M, Narzt MS, Gruber F, Tschachler E, Rice RH, Eckhart L. Cornification of nail keratinocytes requires autophagy for bulk degradation of intracellular proteins while sparing components of the cytoskeleton. Apoptosis 2020; 24:62-73. [PMID: 30552537 PMCID: PMC6373260 DOI: 10.1007/s10495-018-1505-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Epidermal keratinocytes undergo cornification to form the cellular building blocks of hard skin appendages such as nails and the protective layer on the surface of the skin. Cornification requires the cross-linking of structural proteins and the removal of other cellular components to form mechanically rigid and inert corneocytes. Autophagy has been proposed to contribute to this intracellular remodelling process, but its molecular targets in keratinocytes, if any, have remained elusive. Here, we deleted the essential autophagy factor Atg7 in K14-positive epithelia of mice and determined by proteomics the impact of this deletion on the abundance of individual proteins in cornified nails. The genetic suppression of autophagy in keratinocytes resulted in a significant increase in the number of proteins that survived cornification and in alterations of their abundance in the nail proteome. A broad range of enzymes and other non-structural proteins were elevated whereas the amounts of cytoskeletal proteins of the keratin and keratin-associated protein families, cytolinker proteins and desmosomal proteins were either unaltered or decreased in nails of mice lacking epithelial autophagy. Among the various types of non-cytoskeletal proteins, the subunits of the proteasome and of the TRiC/CCT chaperonin were most strongly elevated in mutant nails, indicating a particularly important role of autophagy in removing these large protein complexes during normal cornification. Taken together, the results of this study suggest that autophagy is active during nail keratinocyte cornification and its substrate specificity depends on the accessibility of proteins outside of the cytoskeleton and their presence in large complexes.
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Affiliation(s)
- Karin Jaeger
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Supawadee Sukseree
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Shaomin Zhong
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Brett S Phinney
- Proteomics Core Facility, UC Davis Genome Center, University of California, Davis, CA, USA
| | - Veronika Mlitz
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Maria Buchberger
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Marie Sophie Narzt
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria.,Christian Doppler Laboratory on Biotechnology of Skin Aging, Vienna, Austria
| | - Florian Gruber
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria.,Christian Doppler Laboratory on Biotechnology of Skin Aging, Vienna, Austria
| | - Erwin Tschachler
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Robert H Rice
- Department of Environmental Toxicology, University of California, One Shields Avenue, Davis, CA, 95616-8588, USA.
| | - Leopold Eckhart
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria.
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Sukseree S, László L, Gruber F, Bergmann S, Narzt MS, Nagelreiter IM, Höftberger R, Molnár K, Rauter G, Birngruber T, Larue L, Kovacs GG, Tschachler E, Eckhart L. Filamentous Aggregation of Sequestosome-1/p62 in Brain Neurons and Neuroepithelial Cells upon Tyr-Cre-Mediated Deletion of the Autophagy Gene Atg7. Mol Neurobiol 2018; 55:8425-8437. [PMID: 29550918 PMCID: PMC6153718 DOI: 10.1007/s12035-018-0996-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 03/07/2018] [Indexed: 12/21/2022]
Abstract
Defects in autophagy and the resulting deposition of protein aggregates have been implicated in aging and neurodegenerative diseases. While gene targeting in the mouse has facilitated the characterization of these processes in different types of neurons, potential roles of autophagy and accumulation of protein substrates in neuroepithelial cells have remained elusive. Here we report that Atg7f/fTyr-Cre mice, in which autophagy-related 7 (Atg7) is conditionally deleted under the control of the tyrosinase promoter, are a model for accumulations of the autophagy adapter and substrate sequestosome-1/p62 in both neuronal and neuroepithelial cells. In the brain of Atg7f/fTyr-Cre but not of fully autophagy competent control mice, p62 aggregates were present in sporadic neurons in the cortex and other brain regions as well in epithelial cells of the choroid plexus and the ependyma. Western blot analysis confirmed a dramatic increase of p62 abundance and formation of high-molecular weight species of p62 in the brain of Atg7f/fTyr-Cre mice relative to Atg7f/f controls. Immuno-electron microscopy showed that p62 formed filamentous aggregates in neurons and ependymal cells. p62 aggregates were also highly abundant in the ciliary body in the eye. Atg7f/fTyr-Cre mice reached an age of more than 2 years although neurological defects manifesting in abnormal hindlimb clasping reflexes were evident in old mice. These results show that p62 filaments form in response to impaired autophagy in vivo and suggest that Atg7f/fTyr-Cre mice are a model useful to study the long-term effects of autophagy deficiency on the homeostasis of different neuroectoderm-derived cells.
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Affiliation(s)
- Supawadee Sukseree
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Lajos László
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Florian Gruber
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria.,Christian Doppler Laboratory on Biotechnology of Skin Aging, Vienna, Austria
| | - Sophie Bergmann
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Marie Sophie Narzt
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria.,Christian Doppler Laboratory on Biotechnology of Skin Aging, Vienna, Austria
| | - Ionela Mariana Nagelreiter
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria.,Christian Doppler Laboratory on Biotechnology of Skin Aging, Vienna, Austria
| | - Romana Höftberger
- Institute of Neurology, Medical University of Vienna, Vienna, Austria
| | - Kinga Molnár
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Günther Rauter
- Division of Biomedical Research, Medical University of Graz, Graz, Austria
| | - Thomas Birngruber
- Joanneum Research, Health - Institute for Biomedicine and Health Sciences, Graz, Austria
| | - Lionel Larue
- Institut Curie, INSERM U1021, CNRS UMR3347, Normal and Pathological Development of Melanocytes, PSL Research University, Orsay, France.,INSERM, Orsay, France.,Equipe labellisée - Ligue Nationale contre le Cancer, Université Paris 11, Orsay, France
| | - Gabor G Kovacs
- Institute of Neurology, Medical University of Vienna, Vienna, Austria
| | - Erwin Tschachler
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria
| | - Leopold Eckhart
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria.
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Song X, Narzt MS, Nagelreiter IM, Hohensinner P, Terlecki-Zaniewicz L, Tschachler E, Grillari J, Gruber F. Autophagy deficient keratinocytes display increased DNA damage, senescence and aberrant lipid composition after oxidative stress in vitro and in vivo. Redox Biol 2017; 11:219-230. [PMID: 28012437 PMCID: PMC5192251 DOI: 10.1016/j.redox.2016.12.015] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/15/2016] [Accepted: 12/16/2016] [Indexed: 01/05/2023] Open
Abstract
Autophagy allows cells fundamental adaptations to metabolic needs and to stress. Using autophagic bulk degradation cells can clear crosslinked macromolecules and damaged organelles that arise under redox stress. Accumulation of such debris results in cellular dysfunction and is observed in aged tissue and senescent cells. Conversely, promising anti-aging strategies aim at inhibiting the mTOR pathway and thereby activating autophagy, to counteract aging associated damage. We have inactivated autophagy related 7 (Atg7), an essential autophagy gene, in murine keratinocytes (KC) and have found in an earlier study that this resulted in increased baseline oxidative stress and reduced capacity to degrade crosslinked proteins after oxidative ultraviolet stress. To investigate whether autophagy deficiency would promote cellular aging, we studied how Atg7 deficient (KO) and Atg7 bearing cells (WT) would respond to stress induced by paraquat (PQ), an oxidant drug commonly used to induce cellular senescence. Atg7 deficient KC displayed increased prostanoid signaling and a pro- mitotic gene expression signature as compared to the WT. After exposure to PQ, both WT and KO cells showed an inflammatory and stress-related transcriptomic response. However, the Atg7 deficient cells additionally showed drastic DNA damage- and cell cycle arrest signaling. Indeed, DNA fragmentation and -oxidation were strongly increased in the stressed Atg7 deficient cells upon PQ stress but also after oxidizing ultraviolet A irradiation. Damage associated phosphorylated histone H2AX (γH2AX) foci were increased in the nuclei, whereas expression of the nuclear lamina protein lamin B1 was strongly decreased. Similarly, in both, PQ treated mouse tail skin explants and in UVA irradiated mouse tail skin, we found a strong increase in γH2AX positive nuclei within the basal layer of Atg7 deficient epidermis. Atg7 deficiency significantly affected expression of lipid metabolic genes. Therefore we performed lipid profiling of keratinocytes which demonstrated a major dysregulation of cellular lipid metabolism. We found accumulation of autophagy agonisitic free fatty acids, whereas triglyceride levels were strongly decreased. Together, our data show that in absence of Atg7/autophagy the resistance of keratinocytes to intrinsic and environmental oxidative stress was severely impaired and resulted in DNA damage, cell cycle arrest and a disturbed lipid phenotype, all typical for premature cell aging.
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Affiliation(s)
- Xiuzu Song
- Department of Dermatology, Medical University of Vienna, Währinger Gürtel 18-20, Leitstelle 7J, A-1090 Vienna, Austria; Department of Dermatology, The Third Hospital of Hangzhou, 38 Xihu Road, Hangzhou, Zhejiang, 310009, PR China
| | - Marie Sophie Narzt
- Department of Dermatology, Medical University of Vienna, Währinger Gürtel 18-20, Leitstelle 7J, A-1090 Vienna, Austria
| | - Ionela Mariana Nagelreiter
- Department of Dermatology, Medical University of Vienna, Währinger Gürtel 18-20, Leitstelle 7J, A-1090 Vienna, Austria
| | - Philipp Hohensinner
- Department of Internal Medicine II - Cardiology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria
| | - Lucia Terlecki-Zaniewicz
- Department of Biotechnology, BOKU - University of Natural Resources and Life Sciences Vienna, Muthgasse 18, 1190 Vienna, Austria; Christian Doppler Laboratory for Biotechnology of Skin Aging, Austria
| | - Erwin Tschachler
- Department of Dermatology, Medical University of Vienna, Währinger Gürtel 18-20, Leitstelle 7J, A-1090 Vienna, Austria
| | - Johannes Grillari
- Department of Biotechnology, BOKU - University of Natural Resources and Life Sciences Vienna, Muthgasse 18, 1190 Vienna, Austria; Austrian Cluster for Tissue Regeneration, Muthgasse 18, 1190 Vienna, Austria; Christian Doppler Laboratory for Biotechnology of Skin Aging, Austria
| | - Florian Gruber
- Department of Dermatology, Medical University of Vienna, Währinger Gürtel 18-20, Leitstelle 7J, A-1090 Vienna, Austria; Christian Doppler Laboratory for Biotechnology of Skin Aging, Austria.
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