1
|
Karsch S, Büchau F, Magin TM, Janshoff A. An intact keratin network is crucial for mechanical integrity and barrier function in keratinocyte cell sheets. Cell Mol Life Sci 2020; 77:4397-4411. [PMID: 31912195 PMCID: PMC11104923 DOI: 10.1007/s00018-019-03424-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 11/25/2019] [Accepted: 12/11/2019] [Indexed: 12/20/2022]
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.
Collapse
Affiliation(s)
- Susanne Karsch
- Institute of Physical Chemistry, University of Göttingen, Göttingen, Germany
| | - Fanny Büchau
- Institute of Biology, University of Leipzig, Leipzig, Germany
| | - Thomas M Magin
- Institute of Biology, University of Leipzig, Leipzig, Germany.
| | - Andreas Janshoff
- Institute of Physical Chemistry, University of Göttingen, Göttingen, Germany.
| |
Collapse
|
2
|
Teo JL, Tomatis VM, Coburn L, Lagendijk AK, Schouwenaar IM, Budnar S, Hall TE, Verma S, McLachlan RW, Hogan BM, Parton RG, Yap AS, Gomez GA. Src kinases relax adherens junctions between the neighbors of apoptotic cells to permit apical extrusion. Mol Biol Cell 2020; 31:2557-2569. [PMID: 32903148 PMCID: PMC7851871 DOI: 10.1091/mbc.e20-01-0084] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 08/12/2020] [Accepted: 08/31/2020] [Indexed: 12/17/2022] Open
Abstract
Epithelia can eliminate apoptotic cells by apical extrusion. This is a complex morphogenetic event where expulsion of the apoptotic cell is accompanied by rearrangement of its immediate neighbors to form a rosette. A key mechanism for extrusion is constriction of an actomyosin network that neighbor cells form at their interface with the apoptotic cell. Here we report a complementary process of cytoskeletal relaxation that occurs when cortical contractility is down-regulated at the junctions between those neighbor cells themselves. This reflects a mechanosensitive Src family kinase (SFK) signaling pathway that is activated in neighbor cells when the apoptotic cell relaxes shortly after injury. Inhibiting SFK signaling blocks both the expulsion of apoptotic cells and the rosette formation among their neighbor cells. This reveals the complex pattern of spatially distinct contraction and relaxation that must be established in the neighboring epithelium for apoptotic cells to be extruded.
Collapse
Affiliation(s)
- Jessica L. Teo
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Vanesa M. Tomatis
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Luke Coburn
- Institute of Complex Systems and Mathematical Biology, University of Aberdeen, Aberdeen, United Kingdom, AB24 3UE
| | - Anne K. Lagendijk
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Irin-Maya Schouwenaar
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Srikanth Budnar
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Thomas E. Hall
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Suzie Verma
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Robert W. McLachlan
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Benjamin M. Hogan
- Division of Genomics of Development and Disease, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Robert G. Parton
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
- Centre for Microscopy and Microanalysis, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Alpha S. Yap
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
| | - Guillermo A. Gomez
- Division of Cell and Developmental Biology, The University of Queensland, St Lucia, Queensland, Australia, 4072
- Centre for Cancer Biology, SA Pathology and the University of South Australia, Adelaide, South Australia, Australia, 5000
| |
Collapse
|
3
|
Mathur J, Sarker B, Pathak A. Predicting Collective Migration of Cell Populations Defined by Varying Repolarization Dynamics. Biophys J 2018; 115:2474-2485. [PMID: 30527449 PMCID: PMC6302036 DOI: 10.1016/j.bpj.2018.11.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 11/06/2018] [Accepted: 11/12/2018] [Indexed: 01/23/2023] Open
Abstract
Collective migration of heterogeneous cell populations is an essential aspect of fundamental biological processes, including morphogenesis, wound healing, and tumor invasion. Through experiments and modeling, it has been shown that cells attain front-rear polarity, generate forces, and form adhesions to migrate. However, it remains unclear how the ability of individual cells in a population to dynamically repolarize themselves into new directions could regulate the collective response. We present a vertex-based model in which each deformable cell randomly chooses a new polarization direction after every defined time interval, elongates, proportionally generates forces, and causes collective migration. Our simulations predict that cell types that repolarize at longer time intervals attain more elongated shapes, migrate faster, deform the cell sheet, and roughen the leading edge. By imaging collectively migrating epithelial cell monolayers at high temporal resolution, we found longer repolarization intervals and elongated shapes of cells at the leading edge compared to those within the monolayer. Based on these experimental measurements and simulations, we defined aggressive mutant leader cells by long repolarization interval and minimal intercellular contact. The cells with frequent and random repolarization were defined as normal cells. In simulations with uniformly dispersed leader cells in a normal cell population at a 1:10 ratio, the resulting migration and deformation of the heterogeneous cell sheet remained low. However, when the 10% mutant leaders were placed only at the leading edge, we predicted a rise in the migration of an otherwise normal cell sheet. Our model predicts that a repolarization-based definition of leader cells and their placement within a healthy population can generate myriad modes of collective cell migration, which can enhance our understanding of collective cell migration in disease and development.
Collapse
Affiliation(s)
- Jairaj Mathur
- Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, Missouri
| | - Bapi Sarker
- Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, Missouri
| | - Amit Pathak
- Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, Missouri.
| |
Collapse
|