Open AccessCortical stiffness of keratinocytes measured by lateral indentation with optical tweezers
Author(s) -
Špela Zemljič Jokhadar,
Biljana Stojković,
Marko Vidak,
Tjaša Sorčan,
Mirjana Liović,
Marcos Gouveia,
Rui D. M. Travasso,
Jure Derganc
Publication year - 2020
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0231606
Subject(s) - keratin , stiffness , cell cortex , cytochalasin d , cell culture , optical tweezers , cell type , biophysics , wild type , immortalised cell line , indentation , materials science , cytoskeleton , cell , mutant , chemistry , microbiology and biotechnology , biology , optics , physics , biochemistry , genetics , composite material , gene
Keratin intermediate filaments are the principal structural element of epithelial cells. Their importance in providing bulk cellular stiffness is well recognized, but their role in the mechanics of cell cortex is less understood. In this study, we therefore compared the cortical stiffness of three keratinocyte lines: primary wild type cells (NHEK2), immortalized wild type cells (NEB1) and immortalized mutant cells (KEB7). The cortical stiffness was measured by lateral indentation of cells with AOD-steered optical tweezers without employing any moving mechanical elements. The method was validated on fixed cells and Cytochalasin-D treated cells to ensure that the observed variations in stiffness within a single cell line were not a consequence of low measurement precision. The measurements of the cortical stiffness showed that primary wild type cells were significantly stiffer than immortalized wild type cells, which was also detected in previous studies of bulk elasticity. In addition, a small difference between the mutant and the wild type cells was detected, showing that mutation of keratin impacts also the cell cortex. Thus, our results indicate that the role of keratins in cortical stiffness is not negligible and call for further investigation of the mechanical interactions between keratins and elements of the cell cortex.