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Buchwalter A. Intermediate, but not average: The unusual lives of the nuclear lamin proteins. Curr Opin Cell Biol 2023; 84:102220. [PMID: 37619289 DOI: 10.1016/j.ceb.2023.102220] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/26/2023]
Abstract
The nuclear lamins are polymeric intermediate filament proteins that scaffold the nucleus and organize the genome in nearly all eukaryotic cells. This review focuses on the dynamic regulation of lamin filaments through their biogenesis, assembly, disassembly, and degradation. The lamins are unusually long-lived proteins under homeostatic conditions, but their turnover can be induced in select contexts that are highlighted in this review. Finally, we discuss recent investigations into the influence of laminopathy-linked mutations on the assembly, folding, and stability of the nuclear lamins.
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Affiliation(s)
- Abigail Buchwalter
- Cardiovascular Research Institute and Department of Physiology, University of California, San Francisco, San Francisco, CA, USA; Chan Zuckerberg Biohub, San Francisco, CA, USA.
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2
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Li X, Feng C, Peng S. Epigenetics alternation in lung fibrosis and lung cancer. Front Cell Dev Biol 2022; 10:1060201. [PMID: 36420141 PMCID: PMC9676258 DOI: 10.3389/fcell.2022.1060201] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 10/20/2022] [Indexed: 09/10/2023] Open
Abstract
Respiratory disease including interstitial lung diseases (ILDs) and lung cancer is a group of devastating diseases that linked with increased morbidity and healthcare burden. However, respiratory diseases cannot be fully explained by the alternation of genetic information. Genetic studies described that epigenetic mechanisms also participate to transmit genetic information. Recently, many studies demonstrated the role of altered epigenetic modification in the pathogenesis of lung cancer and pulmonary fibrosis. Due to lacking effective medication, the underlying pathophysiological processes and causal relationships of lung diseases with epigenetic mechanisms still need to be better understood. Our present review provided a systematic revision of current knowledge concerning diverse epigenetic aberrations in major lung diseases, with special emphasis on DNA methylation, histone modifications, lncRNAs profiles, telomere patterns, as well as chromatin-remodelling complexes. We believed that a new target therapy for lung disease based on findings of the involved epigenetic pathway is a promising future direction.
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Affiliation(s)
- Xueren Li
- Department of Respiratory Medicine, Tianjin Haihe Hospital, Tianjin, China
- Tianjin Institute of Respiratory Diseases, Tianjin, China
| | - Chunjing Feng
- The Institute Includes H&B(Tianjin) Stem Cell Research Institute, Tianjin, China
| | - Shouchun Peng
- Department of Respiratory Medicine, Tianjin Haihe Hospital, Tianjin, China
- Tianjin Institute of Respiratory Diseases, Tianjin, China
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3
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Kim SY, McGraw MD. Post-translational modifications to hemidesmosomes in human airway epithelial cells following diacetyl exposure. Sci Rep 2022; 12:9738. [PMID: 35697719 PMCID: PMC9192738 DOI: 10.1038/s41598-022-14019-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 05/31/2022] [Indexed: 11/17/2022] Open
Abstract
Diacetyl (DA; 2,3-butanedione) is a highly reactive alpha (α)-diketone. Inhalation exposure to DA can cause significant airway epithelial cell injury, however, the mechanisms of toxicity remain poorly understood. The purpose of these experiments was to assess for changes in abundance and distribution of hemidesmosome-associated proteins following DA exposure that contribute to DA-induced epithelial toxicity. Human bronchial epithelial cells were grown in submerged cultures and exposed to three occupationally-relevant concentrations of DA (5.7, 8.6, or 11.4 mM) for 1 h. Following DA exposure, epithelial cells were cultured for 4 days to monitor for cell viability by MTT and WST-1 assays as well as for changes in cellular distribution and relative abundance of multiple hemidesmosome-associated proteins, including keratin 5 (KRT5), plectin (PLEC), integrin alpha 6 (ITGα6) and integrin beta 4 (ITGβ4). Significant toxicity developed in airway epithelial cells exposed to DA at concentrations ≥ 8.6 mM. DA exposure resulted in post-translational modifications to hemidesmosome-associated proteins with KRT5 crosslinking and ITGβ4 cleavage. Following DA exposure at 5.7 mM, these post-translational modifications to KRT5 resolved with time. Conversely, at DA concentrations ≥ 8.6 mM, modifications to KRT5 persisted in culture with decreased total abundance and perinuclear aggregation of hemidesmosome-associated proteins. Significant post-translational modifications to hemidesmosome-associated proteins develop in airway epithelial cells exposed to DA. At DA concentrations ≥ 8.6 mM, these hemidesmosome modifications persist in culture. Future work targeting hemidesmosome-associated protein modifications may prevent the development of lung disease following DA exposure.
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Affiliation(s)
- So-Young Kim
- Division of Pulmonary Medicine, Department of Pediatrics, University of Rochester Medical Center, 601 Elmwood Avenue, Box 850, Rochester, NY, 14642, USA
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Matthew D McGraw
- Division of Pulmonary Medicine, Department of Pediatrics, University of Rochester Medical Center, 601 Elmwood Avenue, Box 850, Rochester, NY, 14642, USA.
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, NY, 14642, USA.
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4
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Yu B, Kong D, Cheng C, Xiang D, Cao L, Liu Y, He Y. Assembly and recognition of keratins: A structural perspective. Semin Cell Dev Biol 2021; 128:80-89. [PMID: 34654627 DOI: 10.1016/j.semcdb.2021.09.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 09/22/2021] [Accepted: 09/29/2021] [Indexed: 12/21/2022]
Abstract
Keratins are one of the major components of cytoskeletal network and assemble into fibrous structures named intermediate filaments (IFs), which are important for maintaining the mechanical properties of cells and tissues. Over the past decades, evidence has shown that the functions of keratins go beyond providing mechanical support for cells, they interact with multiple cellular components and are widely involved in the pathways of cell proliferation, differentiation, motility and death. However, the structural details of keratins and IFs are largely missing and many questions remain regarding the mechanisms of keratin assembly and recognition. Here we briefly review the current structural models and assembly of keratins as well as the interactions of keratins with the binding partners, which may provide a structural view for understanding the mechanisms of keratins in the biological activities and the related diseases.
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Affiliation(s)
- Bowen Yu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Immunology, School of Basic Medical Sciences, Weifang Medical University, Weifang, China
| | - Dandan Kong
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chen Cheng
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Dongxi Xiang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Biliary-Pancreatic Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Longxing Cao
- School of Life Science, Westlake University, Hangzhou, Zhejiang, China
| | - Yingbin Liu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Biliary-Pancreatic Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yongning He
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Biliary-Pancreatic Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.
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5
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Speer J, Barcellona M, Jing L, Liu B, Lu M, Kelly M, Buchowski J, Zebala L, Luhmann S, Gupta M, Setton L. Integrin-mediated interactions with a laminin-presenting substrate modulate biosynthesis and phenotypic expression for cells of the human nucleus pulposus. Eur Cell Mater 2021; 41:793-810. [PMID: 34160056 PMCID: PMC8378851 DOI: 10.22203/ecm.v041a50] [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] [Indexed: 01/31/2023] Open
Abstract
With aging and pathology, cells of the nucleus pulposus (NP) de-differentiate towards a fibroblast-like phenotype, a change that contributes to degeneration of the intervertebral disc (IVD). Laminin isoforms are a component of the NP extracellular matrix during development but largely disappear in the adult NP tissue. Exposing human adult NP cells to hydrogels made from PEGylated-laminin-111 (PEGLM) has been shown to regulate NP cell behaviors and promote cells to assume a biosynthetically active state with gene/protein expression and morphology consistent with those observed in juvenile NP cells. However, the mechanism regulating this effect has remained unknown. In the present study, the integrin subunits that promote adult degenerative NP cell interactions with laminin-111 are identified by performing integrin blocking studies along with assays of intracellular signaling and cell phenotype. The findings indicate that integrin α3 is a primary regulator of cell attachment to laminin and is associated with phosphorylation of signaling molecules downstream of integrin engagement (ERK 1/2 and GSK3β). Sustained effects of blocking integrin α3 were also demonstrated including decreased expression of phenotypic markers, reduced biosynthesis, and altered cytoskeletal organization. Furthermore, blocking both integrin α3 and additional integrin subunits elicited changes in cell clustering, but did not alter the phenotype of single cells. These findings reveal that integrin- mediated interactions through integrin α3 are critical in the process by which NP cells sense and alter phenotype in response to culture upon laminin and further suggest that targeting integrin α3 has potential for reversing or slowing degenerative changes to the NP cell.
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Affiliation(s)
- J. Speer
- Department of Biomedical Engineering, Washington University in St. Louis; St. Louis, MO, USA
| | - M. Barcellona
- Department of Biomedical Engineering, Washington University in St. Louis; St. Louis, MO, USA
| | - L. Jing
- Department of Biomedical Engineering, Washington University in St. Louis; St. Louis, MO, USA
| | - B. Liu
- Department of Biomedical Engineering, Washington University in St. Louis; St. Louis, MO, USA
| | - M. Lu
- Department of Biomedical Engineering, Washington University in St. Louis; St. Louis, MO, USA
| | - M. Kelly
- Department of Orthopedic Surgery, Washington University School of Medicine; St. Louis, MO, USA
| | - J. Buchowski
- Department of Orthopedic Surgery, Washington University School of Medicine; St. Louis, MO, USA
| | - L. Zebala
- Department of Orthopedic Surgery, Washington University School of Medicine; St. Louis, MO, USA
| | - S. Luhmann
- Department of Orthopedic Surgery, Washington University School of Medicine; St. Louis, MO, USA
| | - M. Gupta
- Department of Orthopedic Surgery, Washington University School of Medicine; St. Louis, MO, USA
| | - L. Setton
- Department of Biomedical Engineering, Washington University in St. Louis; St. Louis, MO, USA,Department of Orthopedic Surgery, Washington University School of Medicine; St. Louis, MO, USA,Address for correspondence: Dr. Lori A. Setton, Department of Biomedical Engineering, Washington University in St. Louis, 1 Brookings Drive, Campus Box 1097, St. Louis, MO 63130, USA. Telephone number: +1 3149356164,
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6
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Watanabe A, Iida N, Enomoto K. Basal cell carcinoma with signet ring cell morphology accumulating the ubiquitinated cytokeratin 5/6. BMJ Case Rep 2021; 14:14/4/e241993. [PMID: 33893132 PMCID: PMC8074559 DOI: 10.1136/bcr-2021-241993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Basal cell carcinoma (BCC) showing signet ring (SR) cell morphology is a very rare variant of BCC. Here, we report BCC with SR cell morphology developed in the right cheek skin of a 79-year-old man. Histopathologic examination showed irregularly shaped islands of basaloid cells with characteristic peripheral palisading. Inside of the cancer islands, many tumour cells showed an enlarged fine granular cytoplasm with the peripherally compressed nuclei, being similar to the SR cell. Immunohistochemical examination revealed dense accumulation of cytokeratin (CK) 5/6 and a faint signal of 34βE12 in SR cells. The reported myoepithelial markers were not detected. Interestingly, ubiquitin, a component of the ubiquitin-proteasome protein degradation system, was co-localised in the SR cells. These suggest, for the first time, that accumulation of the undegraded CK5/6 with ubiquitination results in the SR cell morphology. Our report showed that the aberrant keratin turnover is associated with the SR cell BCC.
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Affiliation(s)
- Ayako Watanabe
- Department of Plastic and Reconstructive Surgery, Japanese Red Cross Akita Hospital, Akita, Japan
| | - Naoshige Iida
- Department of Plastic and Reconstructive Surgery, Shonan Fujisawa Tokushukai Byoin, Fujisawa, Kanagawa, Japan
| | - Katsuhiko Enomoto
- Department of Pathology, Japanese Red Cross Akita Hospital, Akita, Japan
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7
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Kohl Y, Biehl M, Spring S, Hesler M, Ogourtsov V, Todorovic M, Owen J, Elje E, Kopecka K, Moriones OH, Bastús NG, Simon P, Dubaj T, Rundén-Pran E, Puntes V, William N, von Briesen H, Wagner S, Kapur N, Mariussen E, Nelson A, Gabelova A, Dusinska M, Velten T, Knoll T. Microfluidic In Vitro Platform for (Nano)Safety and (Nano)Drug Efficiency Screening. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2006012. [PMID: 33458959 DOI: 10.1002/smll.202006012] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 12/18/2020] [Indexed: 06/12/2023]
Abstract
Microfluidic technology is a valuable tool for realizing more in vitro models capturing cellular and organ level responses for rapid and animal-free risk assessment of new chemicals and drugs. Microfluidic cell-based devices allow high-throughput screening and flexible automation while lowering costs and reagent consumption due to their miniaturization. There is a growing need for faster and animal-free approaches for drug development and safety assessment of chemicals (Registration, Evaluation, Authorisation and Restriction of Chemical Substances, REACH). The work presented describes a microfluidic platform for in vivo-like in vitro cell cultivation. It is equipped with a wafer-based silicon chip including integrated electrodes and a microcavity. A proof-of-concept using different relevant cell models shows its suitability for label-free assessment of cytotoxic effects. A miniaturized microscope within each module monitors cell morphology and proliferation. Electrodes integrated in the microfluidic channels allow the noninvasive monitoring of barrier integrity followed by a label-free assessment of cytotoxic effects. Each microfluidic cell cultivation module can be operated individually or be interconnected in a flexible way. The interconnection of the different modules aims at simulation of the whole-body exposure and response and can contribute to the replacement of animal testing in risk assessment studies in compliance with the 3Rs to replace, reduce, and refine animal experiments.
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Affiliation(s)
- Yvonne Kohl
- Fraunhofer Institute for Biomedical Engineering IBMT, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., Joseph-von-Fraunhofer-Weg 1, Sulzbach, 66280, Germany
| | - Margit Biehl
- Fraunhofer Institute for Biomedical Engineering IBMT, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., Joseph-von-Fraunhofer-Weg 1, Sulzbach, 66280, Germany
| | - Sarah Spring
- Fraunhofer Institute for Biomedical Engineering IBMT, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., Joseph-von-Fraunhofer-Weg 1, Sulzbach, 66280, Germany
| | - Michelle Hesler
- Fraunhofer Institute for Biomedical Engineering IBMT, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., Joseph-von-Fraunhofer-Weg 1, Sulzbach, 66280, Germany
| | - Vladimir Ogourtsov
- Tyndall National Institute, University College Cork, Dyke Parade, Cork, T12 R5CP, Ireland
| | - Miomir Todorovic
- Tyndall National Institute, University College Cork, Dyke Parade, Cork, T12 R5CP, Ireland
| | - Joshua Owen
- Institute of Thermofluids, School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Elisabeth Elje
- NILU-Norwegian Institute for Air Research, Department for Environmental Chemistry, Health Effects Laboratory, Instituttveien 18, Kjeller, 2007, Norway
- Faculty of Medicine, Institute of Basic Medical Sciences, Department of Molecular Medicine, University of Oslo, Sognsvannsveien 9, Oslo, 0372, Norway
| | - Kristina Kopecka
- Department of Nanobiology, Cancer Research Institute, Biomedical Research Center of the Slovak Academy of Sciences, Dubravska cesta 9, Bratislava, 84505, Slovakia
| | - Oscar Hernando Moriones
- Institut Català de Nanociència i Nanotecnologia (ICN2), CSIC and BIST, Campus UAB, Bellaterra 08193, Barcelona, Spain
- Universitat Autònoma de Barcelona (UAB), Campus UAB, Bellaterra, 08193, Barcelona, Spain
| | - Neus G Bastús
- Institut Català de Nanociència i Nanotecnologia (ICN2), CSIC and BIST, Campus UAB, Bellaterra 08193, Barcelona, Spain
| | - Peter Simon
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology SUT, Radlinskeho 9, Bratislava, 812 37, Slovakia
| | - Tibor Dubaj
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology SUT, Radlinskeho 9, Bratislava, 812 37, Slovakia
| | - Elise Rundén-Pran
- NILU-Norwegian Institute for Air Research, Department for Environmental Chemistry, Health Effects Laboratory, Instituttveien 18, Kjeller, 2007, Norway
| | - Victor Puntes
- Institut Català de Nanociència i Nanotecnologia (ICN2), CSIC and BIST, Campus UAB, Bellaterra 08193, Barcelona, Spain
- Vall d'Hebron Institut de Recerca (VHIR), Barcelona, 08193, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, 08193, Spain
| | - Nicola William
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Hagen von Briesen
- Fraunhofer Institute for Biomedical Engineering IBMT, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., Joseph-von-Fraunhofer-Weg 1, Sulzbach, 66280, Germany
| | - Sylvia Wagner
- Fraunhofer Institute for Biomedical Engineering IBMT, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., Joseph-von-Fraunhofer-Weg 1, Sulzbach, 66280, Germany
| | - Nikil Kapur
- Institute of Thermofluids, School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Espen Mariussen
- NILU-Norwegian Institute for Air Research, Department for Environmental Chemistry, Health Effects Laboratory, Instituttveien 18, Kjeller, 2007, Norway
| | - Andrew Nelson
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Alena Gabelova
- Department of Nanobiology, Cancer Research Institute, Biomedical Research Center of the Slovak Academy of Sciences, Dubravska cesta 9, Bratislava, 84505, Slovakia
| | - Maria Dusinska
- NILU-Norwegian Institute for Air Research, Department for Environmental Chemistry, Health Effects Laboratory, Instituttveien 18, Kjeller, 2007, Norway
| | - Thomas Velten
- Fraunhofer Institute for Biomedical Engineering IBMT, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., Joseph-von-Fraunhofer-Weg 1, Sulzbach, 66280, Germany
| | - Thorsten Knoll
- Fraunhofer Institute for Biomedical Engineering IBMT, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., Joseph-von-Fraunhofer-Weg 1, Sulzbach, 66280, Germany
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8
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Lutz A, Jung D, Diem K, Fauler M, Port F, Gottschalk K, Felder E. Acute effects of cell stretch on keratin filaments in A549 lung cells. FASEB J 2020; 34:11227-11242. [PMID: 32632966 DOI: 10.1096/fj.201903160rr] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 05/29/2020] [Accepted: 06/18/2020] [Indexed: 12/31/2022]
Abstract
Keratin filaments (KFs) comprise the intermediate filaments of epithelial cells and are well known for their cytoprotective properties and their mechanical resilience. Although, several studies have demonstrated KFs' remarkable tensile properties relatively little is known about acute implications of mechanical stretch on KFs in living cells. This includes structural effects on the KFs and their higher level assembly structures as well as posttranslational response mechanisms to possibly modify KF's properties. We subjected simple epithelial A549 lung cells to 30% unidirectional stretch and already after 10 seconds we observed morphological changes of the KF-network as well as structural effects on their desmosomal anchor sites-both apparently caused by the tensile strain. Interestingly, the effect on the desmosomes was attenuated after 30 seconds of cell stretch with a concomitant increase in phosphorylation of keratin8-S432, keratin18-S53, and keratin18-S34 without an apparent increase in keratin solubility. When mimicking the phosphorylation of keratin18-S34 the stretch-induced effect on the desmosomes could be diminished and probing the cell surface with atomic force microscopy showed a lowered elastic modulus. We conclude that the stretch-induced KF phosphorylation affects KF's tensile properties, probably to lower the mechanical load on strained desmosomal cell-cell contacts, and hence, preserve epithelial integrity.
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Affiliation(s)
- Anngrit Lutz
- Department of General Physiology, Ulm University, Ulm, Germany
| | - Dominik Jung
- Department of General Physiology, Ulm University, Ulm, Germany
| | - Kathrin Diem
- Department of General Physiology, Ulm University, Ulm, Germany
| | - Michael Fauler
- Department of General Physiology, Ulm University, Ulm, Germany
| | - Fabian Port
- Department of Experimental Physics, Ulm University, Ulm, Germany
| | - Kay Gottschalk
- Department of Experimental Physics, Ulm University, Ulm, Germany
| | - Edward Felder
- Department of General Physiology, Ulm University, Ulm, Germany
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9
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Delon LC, Nilghaz A, Cheah E, Prestidge C, Thierry B. Unlocking the Potential of Organ-on-Chip Models through Pumpless and Tubeless Microfluidics. Adv Healthc Mater 2020; 9:e1901784. [PMID: 32342669 DOI: 10.1002/adhm.201901784] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/05/2020] [Indexed: 12/27/2022]
Abstract
Microfluidic organs-on-chips are rapidly being developed toward eliminating the shortcomings of static in vitro models and better addressing basic and translational research questions. A critical aspect is the dynamic culture environment they provide. However, the associated inherent requirement for controlled fluid shear stress (FSS) and therefore the need for precise pumps limits their implementation. To address this issue, here a novel approach to manufacture pumpless and tubeless organs-on-chips is reported. It relies on the use of a hydrophilic thread to provide a driving force for the perfusion of the cell culture medium through constant evaporation in the controlled conditions of a cell incubator. Well-defined and tuneable flow rates can be applied by adjusting the length and/or diameter of the thread. This approach for the preparation of an intestine-on-chip model based on the Caco-2 cell line is validated. Five days culture under 0.02 dyn·cm-2 shear conditions yield monolayers similar to those prepared using a high-precision peristaltic pump. A pumpless device can also be used to delineate the effect of FSS on the phenotype of adenocarcinomic human alveolar basal epithelial A549 cells. It is anticipated that the pumpless approach will facilitate and herefore increase the use of organs-on-chips models in the future.
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Affiliation(s)
- Ludivine C. Delon
- Future Industries Institute and ARC Centre of Excellence Convergent Bio‐Nano Science and Technology University of South Australia Mawson Lakes Campus Adelaide SA 5095 Australia
- School of Pharmacy and Medical Sciences and ARC Centre of Excellence Convergent Bio‐Nano Science and Technology University of South Australia City West Campus Adelaide SA 5000 Australia
| | - Azadeh Nilghaz
- Future Industries Institute and ARC Centre of Excellence Convergent Bio‐Nano Science and Technology University of South Australia Mawson Lakes Campus Adelaide SA 5095 Australia
| | - Edward Cheah
- Future Industries Institute and ARC Centre of Excellence Convergent Bio‐Nano Science and Technology University of South Australia Mawson Lakes Campus Adelaide SA 5095 Australia
| | - Clive Prestidge
- School of Pharmacy and Medical Sciences and ARC Centre of Excellence Convergent Bio‐Nano Science and Technology University of South Australia City West Campus Adelaide SA 5000 Australia
| | - Benjamin Thierry
- Future Industries Institute and ARC Centre of Excellence Convergent Bio‐Nano Science and Technology University of South Australia Mawson Lakes Campus Adelaide SA 5095 Australia
- School of Pharmacy and Medical Sciences and ARC Centre of Excellence Convergent Bio‐Nano Science and Technology University of South Australia City West Campus Adelaide SA 5000 Australia
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10
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McGraw MD, Kim SY, Reed C, Hernady E, Rahman I, Mariani TJ, Finkelstein JN. Airway basal cell injury after acute diacetyl (2,3-butanedione) vapor exposure. Toxicol Lett 2020; 325:25-33. [PMID: 32112875 DOI: 10.1016/j.toxlet.2020.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/15/2020] [Accepted: 02/25/2020] [Indexed: 01/22/2023]
Abstract
RATIONALE Diacetyl (DA; 2,3-butanedione) is a chemical found commonly in foods and e-cigarettes. When inhaled, DA causes epithelial injury, though the mechanism of repair remain poorly understood. The objective of this study was to evaluate airway basal cell repair after DA vapor exposure. METHODS Primary human bronchial epithelial cells were exposed to DA or PBS for 1 h. Lactate dehydrogenase, cleaved caspase 3/7 and trans-epithelial electrical resistance were measured prior to and following exposure. Exposed cultures were analyzed for the airway basal cell markers keratin 5 and p63 as well as ubiquitin and proteasome activity. Cultures were also treated with a proteasome inhibitor (MG132). RESULTS DA vapor exposure caused a transient decrease in trans-epithelial electrical resistance in all DA-exposed cultures. Supernatant lactate dehydrogenase and cleaved caspase 3/7 increased significantly at the highest DA concentration but not at lower DA concentrations. Increased keratin 5 ubiquitination occurred after DA exposure but resolved by day 3. Damage to airway basal cells persisted at day 3 in the presence of MG132. CONCLUSIONS Diacetyl exposure results in airway basal cell injury with keratin 5 ubiquitination and decreased p63 expression. The ubiquitin-proteasome-pathway partially mediates airway basal cell repair after acute DA exposure.
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Affiliation(s)
- Matthew D McGraw
- Department of Pediatrics, Division of Pulmonology, Rochester, NY, United States; Department of Environmental Medicine, Rochester, NY, United States.
| | - So-Young Kim
- Department of Pediatrics, Division of Pulmonology, Rochester, NY, United States
| | - Christina Reed
- Department of Environmental Medicine, Rochester, NY, United States; Department of Pediatrics, Division of Neonatology, Rochester, NY, United States
| | - Eric Hernady
- Department of Environmental Medicine, Rochester, NY, United States
| | - Irfan Rahman
- Department of Environmental Medicine, Rochester, NY, United States
| | - Thomas J Mariani
- Department of Pediatrics, Division of Pulmonology, Rochester, NY, United States; Department of Pediatrics, Division of Neonatology, Rochester, NY, United States; Department of Pediatrics, Program in Pediatric Molecular and Personalized Medicine, University of Rochester Medical Center, Rochester, NY, United States
| | - Jacob N Finkelstein
- Department of Environmental Medicine, Rochester, NY, United States; Department of Pediatrics, Division of Neonatology, Rochester, NY, United States
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11
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Dmello C, Srivastava SS, Tiwari R, Chaudhari PR, Sawant S, Vaidya MM. Multifaceted role of keratins in epithelial cell differentiation and transformation. J Biosci 2019; 44:33. [PMID: 31180046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Keratins, the epithelial-predominant members of the intermediate filament superfamily, are expressed in a pairwise, tissuespecific and differentiation-dependent manner. There are 28 type I and 26 type II keratins, which share a common structure comprising a central coiled coil α-helical rod domain flanked by two nonhelical head and tail domains. These domains harbor sites for major posttranslational modifications like phosphorylation and glycosylation, which govern keratin function and dynamics. Apart from providing structural support, keratins regulate various signaling machinery involved in cell growth, motility, apoptosis etc. However, tissue-specific functions of keratins in relation to cell proliferation and differentiation are still emerging. Altered keratin expression pattern during and after malignant transformation is reported to modulate different signaling pathways involved in tumor progression in a context-dependent fashion. The current review focuses on the literature related to the role of keratins in the regulation of cell proliferation, differentiation and transformation in different types of epithelia.
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Affiliation(s)
- Crismita Dmello
- Vaidya Laboratory, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre (TMC), Kharghar, Navi Mumbai 410210, India
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12
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Liao C, Ou Y, Wu Y, Zhou Y, Liang S, Wang Y. Sclerostin inhibits odontogenic differentiation of human pulp‐derived odontoblast‐like cells under mechanical stress. J Cell Physiol 2019; 234:20779-20789. [PMID: 31025337 DOI: 10.1002/jcp.28684] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 04/02/2019] [Accepted: 04/05/2019] [Indexed: 01/13/2023]
Affiliation(s)
- Chufang Liao
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) & Key Laboratory of Oral Biomedicine Ministry of Education School & Hospital of Stomatology, Wuhan University Wuhan China
| | - Yanjing Ou
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) & Key Laboratory of Oral Biomedicine Ministry of Education School & Hospital of Stomatology, Wuhan University Wuhan China
| | - Yun Wu
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) & Key Laboratory of Oral Biomedicine Ministry of Education School & Hospital of Stomatology, Wuhan University Wuhan China
| | - Yi Zhou
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) & Key Laboratory of Oral Biomedicine Ministry of Education School & Hospital of Stomatology, Wuhan University Wuhan China
- Department of Prosthodontics Hospital of Stomatology, Wuhan University Wuhan China
| | - Shanshan Liang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) & Key Laboratory of Oral Biomedicine Ministry of Education School & Hospital of Stomatology, Wuhan University Wuhan China
- Department of Prosthodontics Hospital of Stomatology, Wuhan University Wuhan China
| | - Yining Wang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) & Key Laboratory of Oral Biomedicine Ministry of Education School & Hospital of Stomatology, Wuhan University Wuhan China
- Department of Prosthodontics Hospital of Stomatology, Wuhan University Wuhan China
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13
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Dmello C, Srivastava SS, Tiwari R, Chaudhari PR, Sawant S, Vaidya MM. Multifaceted role of keratins in epithelial cell differentiation and transformation. J Biosci 2019. [DOI: 10.1007/s12038-019-9864-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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14
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FAK is Required for Tumor Metastasis-Related Fluid Microenvironment in Triple-Negative Breast Cancer. J Clin Med 2019; 8:jcm8010038. [PMID: 30609732 PMCID: PMC6352244 DOI: 10.3390/jcm8010038] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/20/2018] [Accepted: 12/26/2018] [Indexed: 01/08/2023] Open
Abstract
Cancer cell metastasis is the main cause of death in patients with cancer. Many studies have investigated the biochemical factors that affect metastasis; however, the role of physical factors such as fluid shear stress (FSS) in tumorigenesis and metastasis have been less investigated. Triple-negative breast cancer (TNBC) has a higher incidence of lymph node invasion and distant metastasis than other subtypes of breast cancer. In this study, we investigated the influence of FSS in regulating the malignant behavior of TNBC cells. Our data demonstrate that low FSS promotes cell migration, invasion, and drug resistance, while high FSS has the opposite results; additionally, we found that these phenomena were regulated through focal adhesion kinase (FAK). Using immunohistochemistry staining, we show that FAK levels correlate with the nodal stage and that FAK is a significant independent predictor of overall survival in patients. Altogether, these data implicate FAK as a fluid mechano-sensor that regulates the cell motility induced by FSS and provide a strong rationale for cancer treatments that combine the use of anti-cancer drugs and strategies to modulate tumor interstitial fluid flow.
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15
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Cheng X, Zheng J, Li G, Göbel V, Zhang H. Degradation for better survival? Role of ubiquitination in epithelial morphogenesis. Biol Rev Camb Philos Soc 2018; 93:1438-1460. [PMID: 29493067 DOI: 10.1111/brv.12404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 01/31/2018] [Accepted: 02/05/2018] [Indexed: 02/06/2023]
Abstract
As a prevalent post-translational modification, ubiquitination is essential for many developmental processes. Once covalently attached to the small and conserved polypeptide ubiquitin (Ub), a substrate protein can be directed to perform specific biological functions via its Ub-modified form. Three sequential catalytic reactions contribute to this process, among which E3 ligases serve to identify target substrates and promote the activated Ub to conjugate to substrate proteins. Ubiquitination has great plasticity, with diverse numbers, topologies and modifications of Ub chains conjugated at different substrate residues adding a layer of complexity that facilitates a huge range of cellular functions. Herein, we highlight key advances in the understanding of ubiquitination in epithelial morphogenesis, with an emphasis on the latest insights into its roles in cellular events involved in polarized epithelial tissue, including cell adhesion, asymmetric localization of polarity determinants and cytoskeletal organization. In addition, the physiological roles of ubiquitination are discussed for typical examples of epithelial morphogenesis, such as lung branching, vascular development and synaptic formation and plasticity. Our increased understanding of ubiquitination in epithelial morphogenesis may provide novel insights into the molecular mechanisms underlying epithelial regeneration and maintenance.
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Affiliation(s)
- Xiaoxiang Cheng
- Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, Macau 999078, China
| | - Jun Zheng
- Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, Macau 999078, China
| | - Gang Li
- Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, Macau 999078, China
| | - Verena Göbel
- Department of Pediatrics, Mucosal Immunology and Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114,, U.S.A
| | - Hongjie Zhang
- Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, Macau 999078, China
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16
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Chan JKL, Yuen D, Too PHM, Sun Y, Willard B, Man D, Tam C. Keratin 6a reorganization for ubiquitin-proteasomal processing is a direct antimicrobial response. J Cell Biol 2018; 217:731-744. [PMID: 29191848 PMCID: PMC5800800 DOI: 10.1083/jcb.201704186] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 10/01/2017] [Accepted: 11/08/2017] [Indexed: 01/09/2023] Open
Abstract
Skin and mucosal epithelia deploy antimicrobial peptides (AMPs) to eliminate harmful microbes. We reported that the intermediate filament keratin 6a (K6a) is constitutively processed into antimicrobial fragments in corneal epithelial cells. In this study, we show that K6a network remodeling is a host defense response that directly up-regulates production of keratin-derived AMPs (KAMPs) by the ubiquitin-proteasome system (UPS). Bacterial ligands trigger K6a phosphorylation at S19, S22, S37, and S60, leading to network disassembly. Mutagenic analysis of K6a confirmed that the site-specific phosphorylation augmented its solubility. K6a in the cytosol is ubiquitinated by cullin-RING E3 ligases for subsequent proteasomal processing. Without an appreciable increase in K6a gene expression and proteasome activity, a higher level of cytosolic K6a results in enhanced KAMP production. Although proteasome-mediated proteolysis is known to produce antigenic peptides in adaptive immunity, our findings demonstrate its new role in producing AMPs for innate immune defense. Manipulating K6a phosphorylation or UPS activity may provide opportunities to harness the innate immunity of epithelia against infection.
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Affiliation(s)
- Jonathan K L Chan
- Department of Ophthalmic Research, Cole Eye Institute and Lerner Research Institute, Cleveland Clinic, Cleveland, OH
- Department of Ophthalmology, Lerner College of Medicine of Case Western Reserve University, Cleveland Clinic, Cleveland, OH
| | - Don Yuen
- Department of Ophthalmic Research, Cole Eye Institute and Lerner Research Institute, Cleveland Clinic, Cleveland, OH
| | - Priscilla Hiu-Mei Too
- Department of Ophthalmic Research, Cole Eye Institute and Lerner Research Institute, Cleveland Clinic, Cleveland, OH
| | - Yan Sun
- Department of Ophthalmic Research, Cole Eye Institute and Lerner Research Institute, Cleveland Clinic, Cleveland, OH
| | - Belinda Willard
- Proteomics Core, Lerner Research Institute, Cleveland Clinic, Cleveland, OH
| | - David Man
- Department of Ophthalmic Research, Cole Eye Institute and Lerner Research Institute, Cleveland Clinic, Cleveland, OH
| | - Connie Tam
- Department of Ophthalmic Research, Cole Eye Institute and Lerner Research Institute, Cleveland Clinic, Cleveland, OH
- Department of Ophthalmology, Lerner College of Medicine of Case Western Reserve University, Cleveland Clinic, Cleveland, OH
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17
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He Y, Maier K, Leppert J, Hausser I, Schwieger-Briel A, Weibel L, Theiler M, Kiritsi D, Busch H, Boerries M, Hannula-Jouppi K, Heikkilä H, Tasanen K, Castiglia D, Zambruno G, Has C. Monoallelic Mutations in the Translation Initiation Codon of KLHL24 Cause Skin Fragility. Am J Hum Genet 2016; 99:1395-1404. [PMID: 27889062 DOI: 10.1016/j.ajhg.2016.11.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 11/07/2016] [Indexed: 11/28/2022] Open
Abstract
The genetic basis of epidermolysis bullosa, a group of genetic disorders characterized by the mechanically induced formation of skin blisters, is largely known, but a number of cases still remain genetically unsolved. Here, we used whole-exome and targeted sequencing to identify monoallelic mutations, c.1A>G and c.2T>C, in the translation initiation codon of the gene encoding kelch-like protein 24 (KLHL24) in 14 individuals with a distinct skin-fragility phenotype and skin cleavage within basal keratinocytes. Remarkably, mutation c.1A>G occurred de novo and was recurrent in families originating from different countries. The striking similarities of the clinical features of the affected individuals point to a unique and very specific pathomechanism. We showed that mutations in the translation initiation codon of KLHL24 lead to the usage of a downstream translation initiation site with the same reading frame and formation of a truncated polypeptide. The pathobiology was examined in keratinocytes and fibroblasts of the affected individuals and via expression of mutant KLHL24, and we found mutant KLHL24 to be associated with abnormalities of intermediate filaments in keratinocytes and fibroblasts. In particular, KLHL24 mutations were associated with irregular and fragmented keratin 14. Recombinant overexpression of normal KLHL24 promoted keratin 14 degradation, whereas mutant KLHL24 showed less activity than the normal molecule. These findings identify KLHL24 mutations as a cause of skin fragility and identify a role for KLHL24 in maintaining the balance between intermediate filament stability and degradation required for skin integrity.
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Affiliation(s)
- Yinghong He
- Department of Dermatology, University Medical Center Freiburg, Freiburg 79104, Germany
| | - Kristin Maier
- Department of Dermatology, University Medical Center Freiburg, Freiburg 79104, Germany
| | - Juna Leppert
- Department of Dermatology, University Medical Center Freiburg, Freiburg 79104, Germany
| | - Ingrid Hausser
- Department of Pathology, University of Heidelberg, Heidelberg 69120, Germany
| | - Agnes Schwieger-Briel
- Department of Paediatric Dermatology, University Children's Hospital Zurich, Zurich 8091, Switzerland; Department of Dermatology, University Hospital Zurich, Zurich 8091, Switzerland
| | - Lisa Weibel
- Department of Paediatric Dermatology, University Children's Hospital Zurich, Zurich 8091, Switzerland; Department of Dermatology, University Hospital Zurich, Zurich 8091, Switzerland
| | - Martin Theiler
- Department of Paediatric Dermatology, University Children's Hospital Zurich, Zurich 8091, Switzerland; Department of Dermatology, University Hospital Zurich, Zurich 8091, Switzerland
| | - Dimitra Kiritsi
- Department of Dermatology, University Medical Center Freiburg, Freiburg 79104, Germany
| | - Hauke Busch
- Systems Biology of the Cellular Microenvironment Group, Institute of Molecular Medicine and Cell Research, Albert-Ludwigs-University Freiburg, Freiburg 79104, Germany; German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg 69120, Germany; Comprehensive Cancer Center Freiburg, Freiburg 79106, Germany
| | - Melanie Boerries
- Systems Biology of the Cellular Microenvironment Group, Institute of Molecular Medicine and Cell Research, Albert-Ludwigs-University Freiburg, Freiburg 79104, Germany; German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg 69120, Germany; Comprehensive Cancer Center Freiburg, Freiburg 79106, Germany
| | - Katariina Hannula-Jouppi
- Department of Dermatology and Allergology, University of Helsinki and Helsinki University Hospital, Helsinki 00014, Finland; Folkhälsan Institute of Genetics, University of Helsinki, Helsinki 00014, Finland
| | - Hannele Heikkilä
- Department of Dermatology and Allergology, University of Helsinki and Helsinki University Hospital, Helsinki 00014, Finland
| | - Kaisa Tasanen
- Department of Dermatology, PEDEGO Research Unit, Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu 90014, Finland
| | - Daniele Castiglia
- Laboratory of Molecular and Cell Biology, Istituto Dermopatico dell'Immacolata, Istituto di Ricovero e Cura a Carattere Scientifico, Rome 00167, Italy
| | - Giovanna Zambruno
- Genetic and Rare Diseases Research Area, Bambino Gesù Children's Hospital, Istituto di Ricovero e Cura a Carattere Scientifico, Rome 00165, Italy
| | - Cristina Has
- Department of Dermatology, University Medical Center Freiburg, Freiburg 79104, Germany.
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18
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Keratins Are Altered in Intestinal Disease-Related Stress Responses. Cells 2016; 5:cells5030035. [PMID: 27626448 PMCID: PMC5040977 DOI: 10.3390/cells5030035] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 08/18/2016] [Accepted: 08/25/2016] [Indexed: 12/17/2022] Open
Abstract
Keratin (K) intermediate filaments can be divided into type I/type II proteins, which form obligate heteropolymers. Epithelial cells express type I-type II keratin pairs, and K7, K8 (type II) and K18, K19 and K20 (type I) are the primary keratins found in the single-layered intestinal epithelium. Keratins are upregulated during stress in liver, pancreas, lung, kidney and skin, however, little is known about their dynamics in the intestinal stress response. Here, keratin mRNA, protein and phosphorylation levels were studied in response to murine colonic stresses modeling human conditions, and in colorectal cancer HT29 cells. Dextran sulphate sodium (DSS)-colitis was used as a model for intestinal inflammatory stress, which elicited a strong upregulation and widened crypt distribution of K7 and K20. K8 levels were slightly downregulated in acute DSS, while stress-responsive K8 serine-74 phosphorylation (K8 pS74) was increased. By eliminating colonic microflora using antibiotics, K8 pS74 in proliferating cells was significantly increased, together with an upregulation of K8 and K19. In the aging mouse colon, most colonic keratins were upregulated. In vitro, K8, K19 and K8 pS74 levels were increased in response to lipopolysaccharide (LPS)-induced inflammation in HT29 cells. In conclusion, intestinal keratins are differentially and dynamically upregulated and post-translationally modified during stress and recovery.
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19
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Kakade PS, Budnar S, Kalraiya RD, Vaidya MM. Functional Implications of O-GlcNAcylation-dependent Phosphorylation at a Proximal Site on Keratin 18. J Biol Chem 2016; 291:12003-13. [PMID: 27059955 DOI: 10.1074/jbc.m116.728717] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Indexed: 01/16/2023] Open
Abstract
Keratins 8/18 (K8/18) are phosphoglycoproteins and form the major intermediate filament network of simple epithelia. The three O-GlcNAcylation (Ser(29), Ser(30), and Ser(48)) and two phosphorylation (Ser(33) and Ser(52)) serine sites on K18 are well characterized. Both of these modifications have been reported to increase K18 solubility and regulate its filament organization. In this report, we investigated the site-specific interplay between these two modifications in regulating the functional properties of K18, like solubility, stability, and filament organization. An immortalized hepatocyte cell line (HHL-17) stably expressing site-specific single, double, and triple O-GlcNAc and phosphomutants of K18 were used to identify the site(s) critical for regulating these functions. Keratin 18 mutants where O-GlcNAcylation at Ser(30) was abolished (K18-S30A) exhibited reduced phosphorylation induced solubility, increased stability, defective filament architecture, and slower migration. Interestingly, K18-S30A mutants also showed loss of phosphorylation at Ser(33), a modification known to regulate the solubility of K18. Further to this, the K18 phosphomutant (K18-S33A) mimicked K18-S30A in its stability, filament organization, and cell migration. These results indicate that O-GlcNAcylation at Ser(30) promotes phosphorylation at Ser(33) to regulate the functional properties of K18 and also impact cellular processes like migration. O-GlcNAcylation and phosphorylation on the same or adjacent sites on most proteins antagonize each other in regulating protein functions. Here we report a novel, positive interplay between O-GlcNAcylation and phosphorylation at adjacent sites on K18 to regulate its fundamental properties.
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Affiliation(s)
- Poonam S Kakade
- From the Advanced Centre for Treatment, Research, and Education in Cancer (ACTREC), Tata Memorial Centre, Sector 22, Kharghar, Navi Mumbai 410210, India
| | - Srikanth Budnar
- From the Advanced Centre for Treatment, Research, and Education in Cancer (ACTREC), Tata Memorial Centre, Sector 22, Kharghar, Navi Mumbai 410210, India
| | - Rajiv D Kalraiya
- From the Advanced Centre for Treatment, Research, and Education in Cancer (ACTREC), Tata Memorial Centre, Sector 22, Kharghar, Navi Mumbai 410210, India
| | - Milind M Vaidya
- From the Advanced Centre for Treatment, Research, and Education in Cancer (ACTREC), Tata Memorial Centre, Sector 22, Kharghar, Navi Mumbai 410210, India
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20
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Lee EJ, Park MK, Kim HJ, Kim EJ, Kang GJ, Byun HJ, Lee CH. Epithelial membrane protein 2 regulates sphingosylphosphorylcholine-induced keratin 8 phosphorylation and reorganization: Changes of PP2A expression by interaction with alpha4 and caveolin-1 in lung cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1157-69. [PMID: 26876307 DOI: 10.1016/j.bbamcr.2016.02.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 02/06/2016] [Accepted: 02/09/2016] [Indexed: 12/13/2022]
Abstract
Sphingosylphosphorylcholine (SPC) is found at increased in the malignant ascites of tumor patients and induces perinuclear reorganization of keratin 8 (K8) filaments that contribute to the viscoelasticity of metastatic cancer cells. However, the detailed mechanism of SPC-induced K8 phosphorylation and reorganization is not clear. We observed that SPC dose-dependently reduced the expression of epithelial membrane protein 2 (EMP2) in lung cancer cells. Then, we examined the role of EMP2 in SPC-induced phosphorylation and reorganization of K8 in lung cancer cells. We found that SPC concentration-dependently reduced EMP2 in A549, H1299, and other lung cancer cells. This was verified at the mRNA level by RT-PCR and real-time PCR (qPCR), and intracellular variation through confocal microscopy. EMP2 gene silencing and stable lung cancer cell lines established using EMP2 lentiviral shRNA induced K8 phosphorylation and reorganization. EMP2 overexpression reduced K8 phosphorylation and reorganization. We also observed that SPC-induced loss of EMP2 induces phosphorylation of JNK and ERK via reduced expression of protein phosphatase 2A (PP2A). Loss of EMP2 induces ubiquitination of protein phosphatase 2A (PP2A). SPC induced caveolin-1 (cav-1) expression and EEA1 endosome marker protein but not cav-2. SPC treatment enhanced the binding of cav-1 and PP2A and lowered binding of PP2A and alpha4. Gene silencing of EMP2 increased and gene silencing of cav-1 reduced migration of A549 lung cancer cells. Overall, these results suggest that SPC induces EMP2 down-regulation which reduces the PP2A via ubiquitination induced by cav-1, which sequestered alpha4, leading to the activation of ERK and JNK.
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Affiliation(s)
- Eun Ji Lee
- BK21PLUS R-FIND team, College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Mi Kyung Park
- BK21PLUS R-FIND team, College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Hyun Ji Kim
- BK21PLUS R-FIND team, College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Eun Ji Kim
- BK21PLUS R-FIND team, College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Gyeoung-Jin Kang
- BK21PLUS R-FIND team, College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Hyun Jung Byun
- BK21PLUS R-FIND team, College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Chang Hoon Lee
- BK21PLUS R-FIND team, College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea.
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21
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Leube RE, Moch M, Kölsch A, Windoffer R. "Panta rhei": Perpetual cycling of the keratin cytoskeleton. BIOARCHITECTURE 2014; 1:39-44. [PMID: 21866261 DOI: 10.4161/bioa.1.1.14815] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 01/12/2011] [Accepted: 01/12/2011] [Indexed: 01/13/2023]
Abstract
The filamentous cytoskeletal systems fulfil seemingly incompatible functions by maintaining a stable scaffolding to ensure tissue integrity and simultaneously facilitating rapid adaptation to intracellular processes and environmental stimuli. This paradox is particularly obvious for the abundant keratin intermediate filaments in epithelial tissues. The epidermal keratin cytoskeleton, for example, supports the protective and selective barrier function of the skin while enabling rapid growth and remodelling in response to physical, chemical and microbial challenges. We propose that these dynamic properties are linked to the perpetual re-cycling of keratin intermediate filaments that we observe in cultured cells. This cycle of assembly and disassembly is independent of protein biosynthesis and consists of distinct, temporally and spatially defined steps. In this way, the keratin cytoskeleton remains in constant motion but stays intact and is also able to restructure rapidly in response to specific regulatory cues as is needed, e.g., during division, differentiation and wound healing.
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Affiliation(s)
- Rudolf E Leube
- Institute of Molecular and Cellular Anatomy; RWTH Aachen University; Aachen, Germany
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22
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Piwil2 inhibits keratin 8 degradation through promoting p38-induced phosphorylation to resist Fas-mediated apoptosis. Mol Cell Biol 2014; 34:3928-38. [PMID: 25113562 DOI: 10.1128/mcb.00745-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The piwi-like 2 (piwil2) gene is widely expressed in tumors and protects cells from apoptosis induced by a variety of stress stimuli. However, the role of Piwil2 in Fas-mediated apoptosis remains unknown. Here, we present evidence that Piwil2 inhibits Fas-mediated apoptosis. By a bacterial two-hybrid screening, we identify a new Piwil2-interacting partner, keratin 8 (K8), a major intermediate filament protein protecting the cell from Fas-mediated apoptosis. Our results show that Piwil2 binds to K8 and p38 through its PIWI domain and forms a Piwil2/K8/P38 triple protein-protein complex. Thus, Piwil2 increases the phosphorylation level of K8 Ser-73 and then inhibits ubiquitin-mediated degradation of K8. As a result, the knockdown of Piwil2 increases the Fas protein level at the membrane. In addition to our previous finding that Piwil2 inhibits the expression of p53 through the Src/STAT3 pathway, here we demonstrate that Piwil2 represses p53 phosphorylation through p38. Our present study indicates that Piwil2 plays a role in Fas-mediated apoptosis for the first time and also can affect p53 phosphorylation in tumor cells, revealing a novel mechanism of Piwil2 in apoptosis, and supports that Piwil2 plays an active role in tumorigenesis.
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23
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24
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Cai W, Chen Z, Jiang B, Yu F, Xu P, Wang M, Wan R, Liu J, Xue Z, Yang J, Liu S, Wang X. Keratin 13 mutations associated with oral white sponge nevus in two Chinese families. Meta Gene 2014; 2:374-83. [PMID: 25606422 PMCID: PMC4287858 DOI: 10.1016/j.mgene.2014.04.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 04/25/2014] [Accepted: 04/25/2014] [Indexed: 01/11/2023] Open
Abstract
White sponge nevus (WSN) is an autosomal dominant hereditary disease. Keratin 4 (KRT4) and Keratin 13 (KRT13) gene mutations were involved in the WSN. We recruited two WSN Chinese families, and oral lesion biopsy with hematoxylin and eosin staining showed that patients had significant pathological characteristics. The mutations of KRT4 and KRT13 gene were detected by PCR and direct sequencing. The multiple alignments of KRT13 from 23 diverse species homology analyses were performed by the ClustalW program. The KRT13 expression was measured by Real-Time RT-PCR and Western blot analysis. Sequencing analysis revealed two mutations of KRT13 gene: one mutation was 332T>C and amino acid change was Leu111Pro. Another mutation was 340C>T and amino acid change was Arg114Cys. The sequence of KRT13 was highly conserved. Real-Time RT-PCR and Western blot analysis results show that KRT13 expression level is lower in patient but keep almost no change in mRNA level. When cells were treated with MG132, KRT13 protein level was increased and kept almost the same in normal and patient cells. We identified two heritable mutations in the KRT13 gene, which were associated with the development of WSN. The abnormal degradation of KRT13 protein of WSN may probably associate with the abnormal ubiquitination process.
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Affiliation(s)
- Wenping Cai
- Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, P. R. China
| | - Zhenghu Chen
- Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, P. R. China
| | - Beizhan Jiang
- Laboratory of Oral Biomedical Science and Translational Medicine, School of Stomatology, Tongji University, Shanghai 200072, P. R. China
| | - Fang Yu
- Laboratory of Oral Biomedical Science and Translational Medicine, School of Stomatology, Tongji University, Shanghai 200072, P. R. China
| | - Ping Xu
- Laboratory of Oral Biomedical Science and Translational Medicine, School of Stomatology, Tongji University, Shanghai 200072, P. R. China
| | - Mu Wang
- School of Stomatology, Central South University, Xiangya Road, Changsha 410078, P. R. China
| | - Rui Wan
- Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, P. R. China
| | - Junjun Liu
- Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, P. R. China
| | - Zhigang Xue
- Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, P. R. China
| | - Jianhua Yang
- Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, P. R. China
| | - Shangfeng Liu
- Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, P. R. China
| | - Xiaoping Wang
- Laboratory of Oral Biomedical Science and Translational Medicine, School of Stomatology, Tongji University, Shanghai 200072, P. R. China
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25
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Ge C, Song J, Chen L, Wang L, Chen Y, Liu X, Zhang Y, Zhang L, Zhang M. Atheroprotective pulsatile flow induces ubiquitin-proteasome-mediated degradation of programmed cell death 4 in endothelial cells. PLoS One 2014; 9:e91564. [PMID: 24626527 PMCID: PMC3953479 DOI: 10.1371/journal.pone.0091564] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 02/12/2014] [Indexed: 01/18/2023] Open
Abstract
Objectives We recently found low level of tumor suppressor programmed cell death 4 (PDCD4) associated with reduced atherosclerotic plaque area (unpublished). We investigated whether atheroprotective unidirectional pulsatile shear stress affects the expression of PDCD4 in endothelial cells. Methods and Results En face co-immunostaining of the mouse aortic arch revealed a low level of PDCD4 in endothelial cells undergoing pulsatile shear stress. Application of unidirectional pulsatile shear stress to human umbilical vein endothelial cells (HUVECs) decreased PDCD4 protein but not mRNA level. Immunoprecipitation revealed that pulsatile shear stress induced the coupling of ubiquitin with PDCD4 expression. The phosphatidyl inositol 3-kinase (PI3K)/Akt pathway was involved in this ubiquitin-proteasome–mediated degradation of PDCD4. Gain of function and loss of function experiments showed that PDCD4 induced turnover (proliferation and apoptosis) of HUVECs. Low PDCD4 level was associated with reduced proliferation but not apoptosis or phosphorylation of endothelial nitric oxide synthase caused by pulsatile shear stress to help maintain the homeostasis of endothelial cells. Conclusions Pulsatile shear stress induces ubiquitin-proteasome–mediated degradation of PDCD4 via a PI3K/Akt pathway in HUVECs. PDCD4 induces turnover (proliferation and apoptosis) of HUVECs. Low PDCD4 level is associated with reduced proliferation for maintenance of HUVEC homeostasis under pulsatile shear stress.
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Affiliation(s)
- Cheng Ge
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Department of Cardiology, Shandong University Qilu Hospital, Jinan, Shandong, People’s Republic of China
| | - Jiantao Song
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Department of Cardiology, Shandong University Qilu Hospital, Jinan, Shandong, People’s Republic of China
| | - Liang Chen
- Department of Emergency, Shandong University Qilu Hospital, Jinan, Shandong, People’s Republic of China
| | - Lin Wang
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Department of Cardiology, Shandong University Qilu Hospital, Jinan, Shandong, People’s Republic of China
| | - Yifei Chen
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Department of Cardiology, Shandong University Qilu Hospital, Jinan, Shandong, People’s Republic of China
| | - Xinxin Liu
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Department of Cardiology, Shandong University Qilu Hospital, Jinan, Shandong, People’s Republic of China
| | - Yu Zhang
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Department of Cardiology, Shandong University Qilu Hospital, Jinan, Shandong, People’s Republic of China
| | - Lining Zhang
- Department of Immunology, School of Medicine, Shandong University, Jinan, Shandong, People’s Republic of China
| | - Mei Zhang
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Department of Cardiology, Shandong University Qilu Hospital, Jinan, Shandong, People’s Republic of China
- * E-mail:
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26
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Snider NT, Omary MB. Post-translational modifications of intermediate filament proteins: mechanisms and functions. Nat Rev Mol Cell Biol 2014; 15:163-77. [PMID: 24556839 PMCID: PMC4079540 DOI: 10.1038/nrm3753] [Citation(s) in RCA: 374] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Intermediate filaments (IFs) are cytoskeletal and nucleoskeletal structures that provide mechanical and stress-coping resilience to cells, contribute to subcellular and tissue-specific biological functions, and facilitate intracellular communication. IFs, including nuclear lamins and those in the cytoplasm (keratins, vimentin, desmin, neurofilaments and glial fibrillary acidic protein, among others), are functionally regulated by post-translational modifications (PTMs). Proteomic advances highlight the enormous complexity and regulatory potential of IF protein PTMs, which include phosphorylation, glycosylation, sumoylation, acetylation and prenylation, with novel modifications becoming increasingly appreciated. Future studies will need to characterize their on-off mechanisms, crosstalk and utility as biomarkers and targets for diseases involving the IF cytoskeleton.
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Affiliation(s)
- Natasha T. Snider
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan
| | - M. Bishr Omary
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
- VA Ann Arbor Healthcare System, Ann Arbor, Michigan
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27
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CK8 phosphorylation induced by compressive loads underlies the downregulation of CK8 in human disc degeneration by activating protein kinase C. J Transl Med 2013; 93:1323-30. [PMID: 24166186 DOI: 10.1038/labinvest.2013.122] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 08/21/2013] [Accepted: 09/23/2013] [Indexed: 12/23/2022] Open
Abstract
Cytokeratin 8 (CK8) is a member of the cytokeratins family with multiple functions on the basis of its unique structural hallmark. The aberrant expression of CK8 and its phosphorylation are pertinent with various diseases. We have previously shown that CK8 exists in normal human nucleus pulposus (NP) cells and decreases as the intervertebral disc degenerates. However, the underlying molecular regulatory machinery of CK8 in intervertebral disc degeneration (IDD) has not been clarified. Here, we collected NP samples from patients with idiopathic scoliosis as control and IDD as degenerate groups. We found that CK8 expression decreased in IDD with an increased phosphorylation in degenerate NP cells. Moreover, NP cells were cultured under different compressive load schemes for diverse time duration. We found that compressive loads resulted in phosphorylation and disassembly of CK8 in a time-dependent and degree-dependent manner in vitro. The activation of protein kinase C was a significant molecular factor contributing to this phenomenon. Taken together, this study is the first to address the molecular mechanisms of CK8 downregulation in NP cells. Importantly, our findings provide clues regarding a molecular link between compressive loads and CK8 alterations, which shed a novel light on the etiology of IDD.
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28
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Affiliation(s)
- Rebecca L Haines
- Epithelial Biology Group, Institute of Medical Biology, Immunos, Singapore
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29
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Tam C, Mun JJ, Evans DJ, Fleiszig SMJ. Cytokeratins mediate epithelial innate defense through their antimicrobial properties. J Clin Invest 2012; 122:3665-77. [PMID: 23006328 DOI: 10.1172/jci64416] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 07/26/2012] [Indexed: 02/06/2023] Open
Abstract
Epithelial cells express antimicrobial proteins in response to invading pathogens, although little is known regarding epithelial defense mechanisms during healthy conditions. Here we report that epithelial cytokeratins have innate defense properties because they constitutively produce cytoprotective antimicrobial peptides. Glycine-rich C-terminal fragments derived from human cytokeratin 6A were identified in bactericidal lysate fractions of human corneal epithelial cells. Structural analysis revealed that these keratin-derived antimicrobial peptides (KDAMPs) exhibited coil structures with low α-helical content. Synthetic analogs of these KDAMPS showed rapid bactericidal activity against multiple pathogens and protected epithelial cells against bacterial virulence mechanisms, while a scrambled peptide showed no bactericidal activity. However, the bactericidal activity of a specific KDAMP was somewhat reduced by glycine-alanine substitutions. KDAMP activity involved bacterial binding and permeabilization, but the activity was unaffected by peptide charge or physiological salt concentration. Knockdown of cytokeratin 6A markedly reduced the bactericidal activity of epithelial cell lysates in vitro and increased the susceptibility of murine corneas to bacterial adherence in vivo. These data suggest that epithelial cytokeratins function as endogenous antimicrobial peptides in the host defense against infection and that keratin-derived antimicrobials may serve as effective therapeutic agents.
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Affiliation(s)
- Connie Tam
- School of Optometry, University of California, Berkeley, Berkeley, CA 94720-2020, USA
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30
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Khapare N, Kundu ST, Sehgal L, Sawant M, Priya R, Gosavi P, Gupta N, Alam H, Karkhanis M, Naik N, Vaidya MM, Dalal SN. Plakophilin3 loss leads to an increase in PRL3 levels promoting K8 dephosphorylation, which is required for transformation and metastasis. PLoS One 2012; 7:e38561. [PMID: 22701666 PMCID: PMC3368841 DOI: 10.1371/journal.pone.0038561] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 05/08/2012] [Indexed: 12/13/2022] Open
Abstract
The desmosome anchors keratin filaments in epithelial cells leading to the formation of a tissue wide IF network. Loss of the desmosomal plaque protein plakophilin3 (PKP3) in HCT116 cells, leads to an increase in neoplastic progression and metastasis, which was accompanied by an increase in K8 levels. The increase in levels was due to an increase in the protein levels of the Phosphatase of Regenerating Liver 3 (PRL3), which results in a decrease in phosphorylation on K8. The increase in PRL3 and K8 protein levels could be reversed by introduction of an shRNA resistant PKP3 cDNA. Inhibition of K8 expression in the PKP3 knockdown clone S10, led to a decrease in cell migration and lamellipodia formation. Further, the K8 PKP3 double knockdown clones showed a decrease in colony formation in soft agar and decreased tumorigenesis and metastasis in nude mice. These results suggest that a stabilisation of K8 filaments leading to an increase in migration and transformation may be one mechanism by which PKP3 loss leads to tumor progression and metastasis.
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Affiliation(s)
- Nileema Khapare
- KS215, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar Node, Navi Mumbai, Maharashtra, India
| | - Samrat T. Kundu
- KS215, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar Node, Navi Mumbai, Maharashtra, India
| | - Lalit Sehgal
- KS215, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar Node, Navi Mumbai, Maharashtra, India
| | - Mugdha Sawant
- KS215, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar Node, Navi Mumbai, Maharashtra, India
| | - Rashmi Priya
- KS215, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar Node, Navi Mumbai, Maharashtra, India
| | - Prajakta Gosavi
- KS215, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar Node, Navi Mumbai, Maharashtra, India
| | - Neha Gupta
- KS215, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar Node, Navi Mumbai, Maharashtra, India
| | - Hunain Alam
- KS215, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar Node, Navi Mumbai, Maharashtra, India
| | - Madhura Karkhanis
- Pharmacology Department, Piramal Life Sciences Ltd., Mumbai, Maharashtra, India
| | - Nishigandha Naik
- Pharmacology Department, Piramal Life Sciences Ltd., Mumbai, Maharashtra, India
| | - Milind M. Vaidya
- KS215, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar Node, Navi Mumbai, Maharashtra, India
| | - Sorab N. Dalal
- KS215, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar Node, Navi Mumbai, Maharashtra, India
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Vadász I, Weiss CH, Sznajder JI. Ubiquitination and proteolysis in acute lung injury. Chest 2012; 141:763-771. [PMID: 22396561 DOI: 10.1378/chest.11-1660] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ubiquitination is a posttranslational modification that regulates a variety of cellular functions depending on timing, subcellular localization, and type of tagging, as well as modulators of ubiquitin binding leading to proteasomal or lysosomal degradation or nonproteolytic modifications. Ubiquitination plays an important role in the pathogenesis of acute lung injury (ALI) and other lung diseases with pathologies secondary to inflammation, mechanical ventilation, and decreased physical mobility. Particularly, ubiquitination has been shown to affect alveolar epithelial barrier function and alveolar edema clearance by targeting the Na,K-ATPase and epithelial Na(+) channels upon lung injury. Notably, the proteasomal system also exhibits distinct functions in the extracellular space, which may contribute to the pathogenesis of ALI and other pulmonary diseases. Better understanding of these mechanisms may ultimately lead to novel therapeutic modalities by targeting elements of the ubiquitination pathway.
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Affiliation(s)
- István Vadász
- Department of Internal Medicine, University of Giessen Lung Center, Justus Liebig University, Giessen, Germany.
| | - Curtis H Weiss
- Division of Pulmonary and Critical Care Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL
| | - Jacob I Sznajder
- Division of Pulmonary and Critical Care Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL
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32
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Windoffer R, Beil M, Magin TM, Leube RE. Cytoskeleton in motion: the dynamics of keratin intermediate filaments in epithelia. ACTA ACUST UNITED AC 2012; 194:669-78. [PMID: 21893596 PMCID: PMC3171125 DOI: 10.1083/jcb.201008095] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Epithelia are exposed to multiple forms of stress. Keratin intermediate filaments are abundant in epithelia and form cytoskeletal networks that contribute to cell type–specific functions, such as adhesion, migration, and metabolism. A perpetual keratin filament turnover cycle supports these functions. This multistep process keeps the cytoskeleton in motion, facilitating rapid and protein biosynthesis–independent network remodeling while maintaining an intact network. The current challenge is to unravel the molecular mechanisms underlying the regulation of the keratin cycle in relation to actin and microtubule networks and in the context of epithelial tissue function.
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Affiliation(s)
- Reinhard Windoffer
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52057 Aachen, Germany
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33
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Colas J, Faure G, Saussereau E, Trudel S, Rabeh WM, Bitam S, Guerrera IC, Fritsch J, Sermet-Gaudelus I, Davezac N, Brouillard F, Lukacs GL, Herrmann H, Ollero M, Edelman A. Disruption of cytokeratin-8 interaction with F508del-CFTR corrects its functional defect. Hum Mol Genet 2011; 21:623-34. [PMID: 22038833 DOI: 10.1093/hmg/ddr496] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have previously reported an increased expression of cytokeratins 8/18 (K8/K18) in cells expressing the F508del mutation of cystic fibrosis transmembrane conductance regulator (CFTR). This is associated with increased colocalization of CFTR and K18 in the vicinity of the endoplasmic reticulum, although this is reversed by treating cells with curcumin, resulting in the rescue of F508del-CFTR. In the present work, we hypothesized that (i) the K8/K18 network may interact physically with CFTR, and that (ii) this interaction may modify CFTR function. CFTR was immunoprecipitated from HeLa cells transfected with either wild-type (WT) CFTR or F508del-CFTR. Precipitates were subjected to 2D-gel electrophoresis and differential spots identified by mass spectrometry. K8 and K18 were found significantly increased in F508del-CFTR precipitates. Using surface plasmon resonance, we demonstrate that K8, but not K18, binds directly and preferentially to the F508del over the WT human NBD1 (nucleotide-binding domain-1). In vivo K8 interaction with F508del-CFTR was confirmed by proximity ligation assay in HeLa cells and in primary cultures of human respiratory epithelial cells. Ablation of K8 expression by siRNA in F508del-expressing HeLa cells led to the recovery of CFTR-dependent iodide efflux. Moreover, F508del-expressing mice topically treated with K8-siRNA showed restored nasal potential difference, equivalent to that of WT mice. These results show that disruption of F508del-CFTR and K8 interaction leads to the correction of the F508del-CFTR processing defect, suggesting a novel potential therapeutic target in CF.
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Affiliation(s)
- Julien Colas
- Faculté de Médecine Paris-Descartes, INSERM, U845, Paris, France
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34
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Abstract
Keratins are the intermediate filament (IF)-forming proteins of epithelial cells. Since their initial characterization almost 30 years ago, the total number of mammalian keratins has increased to 54, including 28 type I and 26 type II keratins. Keratins are obligate heteropolymers and, similarly to other IFs, they contain a dimeric central α-helical rod domain that is flanked by non-helical head and tail domains. The 10-nm keratin filaments participate in the formation of a proteinaceous structural framework within the cellular cytoplasm and, as such, serve an important role in epithelial cell protection from mechanical and non-mechanical stressors, a property extensively substantiated by the discovery of human keratin mutations predisposing to tissue-specific injury and by studies in keratin knockout and transgenic mice. More recently, keratins have also been recognized as regulators of other cellular properties and functions, including apico-basal polarization, motility, cell size, protein synthesis and membrane traffic and signaling. In cancer, keratins are extensively used as diagnostic tumor markers, as epithelial malignancies largely maintain the specific keratin patterns associated with their respective cells of origin, and, in many occasions, full-length or cleaved keratin expression (or lack there of) in tumors and/or peripheral blood carries prognostic significance for cancer patients. Quite intriguingly, several studies have provided evidence for active keratin involvement in cancer cell invasion and metastasis, as well as in treatment responsiveness, and have set the foundation for further exploration of the role of keratins as multifunctional regulators of epithelial tumorigenesis.
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Affiliation(s)
- V Karantza
- Department of Medicine, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ, USA.
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35
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Srikanth B, Vaidya MM, Kalraiya RD. O-GlcNAcylation determines the solubility, filament organization, and stability of keratins 8 and 18. J Biol Chem 2010; 285:34062-71. [PMID: 20729549 DOI: 10.1074/jbc.m109.098996] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Keratins 8 and 18 (K8/18) are intermediate filament proteins expressed specifically in simple epithelial tissues. Dynamic equilibrium of these phosphoglycoproteins in the soluble and filament pool is an important determinant of their cellular functions, and it is known to be regulated by site-specific phosphorylation. However, little is known about the role of dynamic O-GlcNAcylation on this keratin pair. Here, by comparing immortalized (Chang) and transformed hepatocyte (HepG2) cell lines, we have demonstrated that O-GlcNAcylation of K8/18 exhibits a positive correlation with their solubility (Nonidet P-40 extractability). Heat stress, which increases K8/18 solubility, resulted in a simultaneous increase in O-GlcNAc on these proteins. Conversely, increasing O-GlcNAc levels were associated with a concurrent increase in their solubility. This was also associated with a notable decrease in total cellular levels of K8/18. Unaltered levels of transcripts and the reduced half-life of K8 and K18 indicated their decreased stability on increasing O-GlcNAcylation. On the contrary, the K18 glycosylation mutant (K18 S29A/S30A/S48A) was notably more stable than the wild type K18 in Chang cells. The K18-O-GlcNAc mutant accumulated as aggregates upon stable expression, which possibly altered endogenous filament architecture. These results strongly indicate the involvement of O-GlcNAc on K8/18 in regulating their solubility and stability, which may have a bearing on the functions of these keratins.
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Affiliation(s)
- Budnar Srikanth
- Advanced Centre for Treatment Research and Education in Cancer, Tata Memorial Centre, Kharghar, Navi Mumbai 410210, India
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36
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McIntosh PB, Laskey P, Sullivan K, Davy C, Wang Q, Jackson DJ, Griffin HM, Doorbar J. E1--E4-mediated keratin phosphorylation and ubiquitylation: a mechanism for keratin depletion in HPV16-infected epithelium. J Cell Sci 2010; 123:2810-22. [PMID: 20663917 DOI: 10.1242/jcs.061978] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The keratin IF network of epidermal keratinocytes provides a protective barrier against mechanical insult, it is also a major player in absorbing stress in these cells. The human papilloma virus (HPV) type 16 E1--E4 protein accumulates in the upper layers of HPV16-infected epithelium and is known to associate with and reorganise the keratin IF network in cells in culture. Here, we show that this function is conserved amongst a number of HPV alpha-group E1--E4 proteins and that the differentiation-dependent keratins are also targeted. Using time-lapse microscopy, HPV16 E1--E4 was found to effect a dramatic cessation of keratin IF network dynamics by associating with both soluble and insoluble keratin. Network disruption was accompanied by keratin hyperphosphorylation at several sites, including K8 S73, which is typically phosphorylated in response to stress stimuli. Keratin immunoprecipitated from E1--E4-expressing cells was also found to be ubiquitylated, indicating that it is targeted for proteasomal degradation. Interestingly, the accumulation of hyperphosphorylated, ubiquitylated E1--E4-keratin structures was found to result in an impairment of proteasomal function. These observations shed new light on the mechanism of keratin IF network reorganisation mediated by HPV16 E1--E4 and provide an insight into the depletion of keratin co-incident with E1--E4 accumulation observed in HPV-infected epithelium.
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Affiliation(s)
- Pauline B McIntosh
- MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, N10 3UE, UK
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37
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Kölsch A, Windoffer R, Würflinger T, Aach T, Leube RE. The keratin-filament cycle of assembly and disassembly. J Cell Sci 2010; 123:2266-72. [DOI: 10.1242/jcs.068080] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Continuous and regulated remodelling of the cytoskeleton is crucial for many basic cell functions. In contrast to actin filaments and microtubules, it is not understood how this is accomplished for the third major cytoskeletal filament system, which consists of intermediate-filament polypeptides. Using time-lapse fluorescence microscopy of living interphase cells, in combination with photobleaching, photoactivation and quantitative fluorescence measurements, we observed that epithelial keratin intermediate filaments constantly release non-filamentous subunits, which are reused in the cell periphery for filament assembly. This cycle is independent of protein biosynthesis. The different stages of the cycle occur in defined cellular subdomains: assembly takes place in the cell periphery and newly formed filaments are constantly transported toward the perinuclear region while disassembly occurs, giving rise to diffusible subunits for another round of peripheral assembly. Remaining juxtanuclear filaments stabilize and encage the nucleus. Our data suggest that the keratin-filament cycle of assembly and disassembly is a major mechanism of intermediate-filament network plasticity, allowing rapid adaptation to specific requirements, notably in migrating cells.
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Affiliation(s)
- Anne Kölsch
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Reinhard Windoffer
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Thomas Würflinger
- Institute of Imaging and Computer Vision, RWTH Aachen University, 52056 Aachen, Germany
| | - Til Aach
- Institute of Imaging and Computer Vision, RWTH Aachen University, 52056 Aachen, Germany
| | - Rudolf E. Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
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38
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The role of the ubiquitin proteasome pathway in keratin intermediate filament protein degradation. Ann Am Thorac Soc 2010; 7:71-6. [PMID: 20160151 DOI: 10.1513/pats.200908-089js] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Lung injury, whether caused by hypoxic or mechanical stresses, elicits a variety of responses at the cellular level. Alveolar epithelial cells respond and adapt to such injurious stimuli by reorganizing the cellular cytoskeleton, mainly accomplished through modification of the intermediate filament (IF) network. The structural and mechanical integrity in epithelial cells is maintained through this adaptive reorganization response. Keratin, the predominant IF expressed in epithelial cells, displays highly dynamic properties in response to injury, sometimes in the form of degradation of the keratin IF network. Post-translational modification, such as phosphorylation, targets keratin proteins for degradation in these circumstances. As with other structural and regulatory proteins, turnover of keratin is regulated by the ubiquitin (Ub)-proteasome pathway. The degradation process begins with activation of Ub by the Ub-activating enzyme (E1), followed by the exchange of Ub to the Ub-conjugating enzyme (E2). E2 shuttles the Ub molecule to the substrate-specific Ub ligase (E3), which then delivers the Ub to the substrate protein, thereby targeting it for degradation. In some cases of injury and IF-related disease, aggresomes form in epithelial cells. The mechanisms that regulate aggresome formation are currently unknown, although proteasome overload may play a role. Therefore, a more complete understanding of keratin degradation--causes, mechanisms, and consequences--will allow for a greater understanding of epithelial cell biology and lung pathology alike.
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Kongara S, Kravchuk O, Teplova I, Lozy F, Schulte J, Moore D, Barnard N, Neumann CA, White E, Karantza V. Autophagy regulates keratin 8 homeostasis in mammary epithelial cells and in breast tumors. Mol Cancer Res 2010; 8:873-84. [PMID: 20530580 DOI: 10.1158/1541-7786.mcr-09-0494] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Autophagy is activated in response to cellular stressors and mediates lysosomal degradation and recycling of cytoplasmic material and organelles as a temporary cell survival mechanism. Defective autophagy is implicated in human pathology, as disruption of protein and organelle homeostasis enables disease-promoting mechanisms such as toxic protein aggregation, oxidative stress, genomic damage, and inflammation. We previously showed that autophagy-defective immortalized mouse mammary epithelial cells are susceptible to metabolic stress, DNA damage, and genomic instability. We now report that autophagy deficiency is associated with endoplasmic reticulum (ER) and oxidative stress, and with deregulation of p62-mediated keratin homeostasis in mammary cells, allograft tumors, and mammary tissues from genetically engineered mice. In human breast tumors, high phospho(Ser73)-K8 levels are inversely correlated with Beclin 1 expression. Thus, autophagy preserves cellular fitness by limiting ER and oxidative stress, a function potentially important in autophagy-mediated suppression of mammary tumorigenesis. Furthermore, autophagy regulates keratin homeostasis in the mammary gland via a p62-dependent mechanism. High phospho(Ser73)-K8 expression may be a marker of autophagy functional status in breast tumors and, as such, could have therapeutic implications for breast cancer patients.
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Affiliation(s)
- Sameera Kongara
- Cancer Institute of New Jersey, 195 Little Albany Street, New Brunswick, NJ 08903, USA
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40
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Laminar high shear stress up-regulates type IV collagen synthesis and down-regulates MMP-2 secretion in endothelium. A quantitative analysis. Cell Tissue Res 2010; 340:471-9. [DOI: 10.1007/s00441-010-0968-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 03/19/2010] [Indexed: 10/19/2022]
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Löffek S, Wöll S, Höhfeld J, Leube RE, Has C, Bruckner-Tuderman L, Magin TM. The ubiquitin ligase CHIP/STUB1 targets mutant keratins for degradation. Hum Mutat 2010; 31:466-76. [DOI: 10.1002/humu.21222] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Intermediate filaments take the heat as stress proteins. Trends Cell Biol 2010; 20:79-91. [PMID: 20045331 DOI: 10.1016/j.tcb.2009.11.004] [Citation(s) in RCA: 193] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Revised: 11/13/2009] [Accepted: 11/17/2009] [Indexed: 11/18/2022]
Abstract
Intermediate filament (IF) proteins and heat shock proteins (HSPs) are large multimember families that share several features, including protein abundance, significant upregulation in response to a variety of stresses, cytoprotective functions, and the phenocopying of several human diseases after IF protein or HSP mutation. We are now coming to understand that these common elements point to IFs as important cellular stress proteins with some roles akin to those already well-characterized for HSPs. Unique functional roles for IFs include protection from mechanical stress, whereas HSPs are characteristically involved in protein folding and as chaperones. Shared IF and HSP cytoprotective roles include inhibition of apoptosis, organelle homeostasis, and scaffolding. In this report, we review data that corroborate the view that IFs function as highly specialized cytoskeletal stress proteins that promote cellular organization and homeostasis.
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SUMO regulates the assembly and function of a cytoplasmic intermediate filament protein in C. elegans. Dev Cell 2009; 17:724-35. [PMID: 19922876 DOI: 10.1016/j.devcel.2009.10.005] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Revised: 08/03/2009] [Accepted: 10/08/2009] [Indexed: 11/21/2022]
Abstract
Sumoylation is a reversible posttranslational modification that plays roles in many processes, including transcriptional regulation, cell division, chromosome integrity, and DNA damage response. Using a proteomics approach, we identified approximately 250 candidate targets of sumoylation in C. elegans. One such target is the cytoplasmic intermediate filament (cIF) protein named IFB-1, which is expressed in hemidesmosome-like structures in the worm epidermis and is essential for embryonic elongation and maintenance of muscle attachment to the cuticle. In the absence of SUMO, IFB-1 formed ectopic filaments and protein aggregates in the lateral epidermis. Moreover, depletion of SUMO or mutation of the SUMO acceptor site on IFB-1 resulted in a reduction of its cytoplasmic soluble pool, leading to a decrease in its exchange rate within epidermal attachment structures. These observations indicate that SUMO regulates cIF assembly by maintaining a cytoplasmic pool of nonpolymerized IFB-1, and that this is necessary for normal IFB-1 function.
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Na N, Chandel NS, Litvan J, Ridge KM. Mitochondrial reactive oxygen species are required for hypoxia-induced degradation of keratin intermediate filaments. FASEB J 2009; 24:799-809. [PMID: 19897662 DOI: 10.1096/fj.08-128967] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Hypoxia can cause stress and structural changes to the epithelial cytoskeleton. The intermediate filament (IF) network is known to reorganize in response to stress. We examined whether rats exposed to hypoxia had altered keratin IF expression in their alveolar epithelial type II (ATII) cells. There was a significant decrease in keratin protein levels in hypoxic ATII cells compared with those in ATII cells isolated from normoxic rats. To define the mechanisms regulating this process we studied changes to the keratin IF network in A549 cells (an alveolar epithelial cell line) exposed to 1.5% oxygen. We observed a time-dependent disassembly-degradation of keratin 8 and 18 proteins, which was associated with an increase in reactive oxygen species (ROS). Hypoxia-treated A549 cells deficient in mitochondrial DNA or A549 cells treated with a small interfering RNA against the Rieske iron-sulfur protein of mitochondrial complex III did not have increased levels of ROS nor was the keratin IF network disassembled and degraded. The superoxide dismutase (SOD)/catalase mimetic (EUK-134) prevented the hypoxia-mediated keratin IF degradation as did the overexpression of SOD1 but not of SOD2. Accordingly, we provide evidence that hypoxia promotes the disassembly and degradation of the keratin IF network via mitochondrial complex III-generated reactive oxygen species.-Na, N., Chandel, N. S., Litvan, J., Ridge, K. M. Mitochondrial reactive oxygen species are required for hypoxia-induced degradation of keratin intermediate filaments.
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Affiliation(s)
- Ni Na
- Northwestern University Medical School, Pulmonary and Critical Care Medicine, 240 East Huron, McGaw 2328, Chicago, IL 60611, USA
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Omary MB, Ku NO, Strnad P, Hanada S. Toward unraveling the complexity of simple epithelial keratins in human disease. J Clin Invest 2009; 119:1794-805. [PMID: 19587454 DOI: 10.1172/jci37762] [Citation(s) in RCA: 204] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Simple epithelial keratins (SEKs) are found primarily in single-layered simple epithelia and include keratin 7 (K7), K8, K18-K20, and K23. Genetically engineered mice that lack SEKs or overexpress mutant SEKs have helped illuminate several keratin functions and served as important disease models. Insight into the contribution of SEKs to human disease has indicated that K8 and K18 are the major constituents of Mallory-Denk bodies, hepatic inclusions associated with several liver diseases, and are essential for inclusion formation. Furthermore, mutations in the genes encoding K8, K18, and K19 predispose individuals to a variety of liver diseases. Hence, as we discuss here, the SEK cytoskeleton is involved in the orchestration of several important cellular functions and contributes to the pathogenesis of human liver disease.
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Affiliation(s)
- M Bishr Omary
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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Sivaramakrishnan S, Schneider JL, Sitikov A, Goldman RD, Ridge KM. Shear stress induced reorganization of the keratin intermediate filament network requires phosphorylation by protein kinase C zeta. Mol Biol Cell 2009; 20:2755-65. [PMID: 19357195 DOI: 10.1091/mbc.e08-10-1028] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Keratin intermediate filaments (KIFs) form a fibrous polymer network that helps epithelial cells withstand external mechanical forces. Recently, we established a correlation between the structure of the KIF network and its local mechanical properties in alveolar epithelial cells. Shear stress applied across the cell surface resulted in the structural remodeling of KIF and a substantial increase in the elastic modulus of the network. This study examines the mechanosignaling that regulates the structural remodeling of the KIF network. We report that the shear stress-mediated remodeling of the KIF network is facilitated by a twofold increase in the dynamic exchange rate of KIF subunits, which is regulated in a PKC zeta and 14-3-3-dependent manner. PKC zeta phosphorylates K18pSer33, and this is required for the structural reorganization because the KIF network in A549 cells transfected with a dominant negative PKC zeta, or expressing the K18Ser33Ala mutation, is unchanged. Blocking the shear stress-mediated reorganization results in reduced cellular viability and increased apoptotic levels. These data suggest that shear stress mediates the phosphorylation of K18pSer33, which is required for the reorganization of the KIF network, resulting in changes in mechanical properties of the cell that help maintain the integrity of alveolar epithelial cells.
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