An intact keratin network is crucial for mechanical integrity and barrier function in keratinocyte cell sheets
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Cellular and Molecular Life Sciences
ORIGINAL ARTICLE
An intact keratin network is crucial for mechanical integrity and barrier function in keratinocyte cell sheets Susanne Karsch1 · Fanny Büchau2 · Thomas M. Magin2 · Andreas Janshoff1 Received: 20 June 2019 / Revised: 25 November 2019 / Accepted: 11 December 2019 © Springer Nature Switzerland AG 2020
Abstract The isotype-specific composition of the keratin cytoskeleton is important for strong adhesion, force resilience, and barrier function of the epidermis. However, the mechanisms by which keratins regulate these functions are still incompletely understood. In this study, the role and significance of the keratin network for mechanical integrity, force transmission, and barrier formation were analyzed in murine keratinocytes. Following the time-course of single-cell wound closure, wild-type (WT) cells slowly closed the gap in a collective fashion involving tightly connected neighboring cells. In contrast, the mechanical response of neighboring cells was compromised in keratin-deficient cells, causing an increased wound area initially and an inefficient overall wound closure. Furthermore, the loss of the keratin network led to impaired, fragmented cell–cell junctions, and triggered a profound change in the overall cellular actomyosin architecture. Electric cell-substrate impedance sensing of cell junctions revealed a dysfunctional barrier in knockout ( Kty−/−) cells compared to WT cells. These findings demonstrate that Kty−/− cells display a novel phenotype characterized by loss of mechanocoupling and failure to form a functional barrier. Re-expression of K5/K14 rescued the barrier defect to a significant extent and reestablished the mechanocoupling with remaining discrepancies likely due to the low abundance of keratins in that setting. Our study reveals the major role of the keratin network for mechanical homeostasis and barrier functionality in keratinocyte layers. Keywords Keratin cytoskeleton · Mechanical homeostasis · Barrier functionality · Wound closure
Introduction The mammalian epidermis is a multilayered barrier-forming epithelium that protects the body against physical and chemical insults and against dehydration. Its physico-chemical properties depend on the presence of adherens junctions, desmosomes, and tight junctions, which couple to Susanne Karsch and Fanny Büchau both authors contributed equally. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00018-019-03424-7) contains supplementary material, which is available to authorized users. * Thomas M. Magin thomas.magin@uni‑leipzig.de * Andreas Janshoff [email protected] 1
Institute of Physical Chemistry, University of Göttingen, Göttingen, Germany
Institute of Biology, University of Leipzig, Leipzig, Germany
2
the actin and keratin cytoskeletons through cadherin and zonula occludens family members, respectively [1]. Studies in model organisms and cultured mammalian cells have established an instructive role of E-cadherin in the formati
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