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Tan TS, Common JEA, Lim JSY, Badowski C, Firdaus MJ, Leonardi SS, Lane EB. A cell-based drug discovery assay identifies inhibition of cell stress responses as a new approach to treatment of epidermolysis bullosa simplex. J Cell Sci 2021; 134:272475. [PMID: 34643242 PMCID: PMC8542385 DOI: 10.1242/jcs.258409] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 09/07/2021] [Indexed: 11/20/2022] Open
Abstract
In the skin fragility disorder epidermolysis bullosa simplex (EBS), mutations in keratin 14 (K14, also known as KRT14) or keratin 5 (K5, also known as KRT5) lead to keratinocyte rupture and skin blistering. Severe forms of EBS are associated with cytoplasmic protein aggregates, with elevated kinase activation of ERK1 and ERK2 (ERK1/2; also known as MAPK3 and MAPK1, respectively), suggesting intrinsic stress caused by misfolded keratin protein. Human keratinocyte EBS reporter cells stably expressing GFP-tagged EBS-mimetic mutant K14 were used to optimize a semi-automated system to quantify the effects of test compounds on keratin aggregates. Screening of a protein kinase inhibitor library identified several candidates that reduced aggregates and impacted on epidermal growth factor receptor (EGFR) signalling. EGF ligand exposure induced keratin aggregates in EBS reporter keratinocytes, which was reversible by EGFR inhibition. EBS keratinocytes treated with a known EGFR inhibitor, afatinib, were driven out of activation and towards quiescence with minimal cell death. Aggregate reduction was accompanied by denser keratin filament networks with enhanced intercellular cohesion and resilience, which when extrapolated to a whole tissue context would predict reduced epidermal fragility in EBS patients. This assay system provides a powerful tool for discovery and development of new pathway intervention therapeutic avenues for EBS.
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Affiliation(s)
- Tong San Tan
- Skin Research Institute of Singapore, A*STAR, Immunos Building, 8A Biomedical Grove, Singapore138648.,Institute of Medical Biology, A*STAR, Immunos Building, 8A Biomedical Grove, Singapore138648
| | - John E A Common
- Skin Research Institute of Singapore, A*STAR, Immunos Building, 8A Biomedical Grove, Singapore138648.,Institute of Medical Biology, A*STAR, Immunos Building, 8A Biomedical Grove, Singapore138648
| | - John S Y Lim
- A*STAR Microscopy Platform, Immunos Building, 8A Biomedical Grove, Singapore138648
| | - Cedric Badowski
- Institute of Medical Biology, A*STAR, Immunos Building, 8A Biomedical Grove, Singapore138648
| | - Muhammad Jasrie Firdaus
- Skin Research Institute of Singapore, A*STAR, Immunos Building, 8A Biomedical Grove, Singapore138648.,Institute of Medical Biology, A*STAR, Immunos Building, 8A Biomedical Grove, Singapore138648
| | - Steven S Leonardi
- Skin Research Institute of Singapore, A*STAR, Immunos Building, 8A Biomedical Grove, Singapore138648
| | - E Birgitte Lane
- Skin Research Institute of Singapore, A*STAR, Immunos Building, 8A Biomedical Grove, Singapore138648.,Institute of Medical Biology, A*STAR, Immunos Building, 8A Biomedical Grove, Singapore138648
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Keratin gene mutations influence the keratinocyte response to DNA damage and cytokine induced apoptosis. Arch Dermatol Res 2017. [DOI: 10.1007/s00403-017-1757-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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