XB-ART-56809Cell Rep March 17, 2020; 30 (11): 3875-3888.e3.
Mechanical Stress Regulates Epithelial Tissue Integrity and Stiffness through the FGFR/Erk2 Signaling Pathway during Embryogenesis.
Physical forces generated by tissue-tissue interactions are a critical component of embryogenesis, aiding the formation of organs in a coordinated manner. In this study, using Xenopus laevis embryos and phosphoproteome analyses, we uncover the rapid activation of the mitogen-activated protein (MAP) kinase Erk2 upon stimulation with centrifugal, compression, or stretching force. We demonstrate that Erk2 induces the remodeling of cytoskeletal proteins, including F-actin, an embryonic cadherin C-cadherin, and the tight junction protein ZO-1. We show these force-dependent changes to be prerequisites for the enhancement of cellular junctions and tissue stiffening during early embryogenesis. Furthermore, Erk2 activation is FGFR1 dependent while not requiring fibroblast growth factor (FGF) ligands, suggesting that cell/tissue deformation triggers receptor activation in the absence of ligands. These findings establish previously unrecognized functions for mechanical forces in embryogenesis and reveal its underlying force-induced signaling pathways.
PubMed ID: 32187556
Article link: Cell Rep
Genes referenced: cdh3 fgf4 fgfr1 grb2 mapk1 tjp1
Antibodies: Cdh3 Ab1 Fgfr1 Ab3 Mapk1 Ab 21 Mapk1 Ab20 Mapk1 Ab7 Tjp1 Ab2
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|Figure 1. Mechanical Stress by Centrifugation Activates Erk2 (A) Schematic diagram of the force applied to embryos by centrifugation. (B) Normal density curves of the ratio of phosphosites between centrifuged and control conditions from phosphoproteomic data. Blue and orange lines represent the density curve in the total phosphosites and that in Erk2 substrates, respectively. The p value represents statistical significance evaluated by the Mann-Whitney U test. (C) Heatmap of the Erk2 substrates (phosphosites) used in (B). (D) Phosphopeptides of Erk2 were quantified by phosphoproteomic analysis during the indicated times. Data are means ± SEM from three biological replicates. (E) Western blot using anti-pErk1/2 and anti-Erk1/2 antibodies. (F) The quantification of the pErk intensities examined as in (E). Three independent experiments were quantified. Error bar: standard deviation (SD). (G) Immunofluorescence using anti-pErk and anti-total Erk1/2 antibodies. Cells in the animal hemisphere were observed. Scale bar: 25 μm. (H) Embryos were treated with DMSO or the Mek inhibitor PD0325901 (25 μM). Scale bar: 25 μm. (I) Time course of Erk2 phosphorylation. (J) The quantification of the pErk intensities in the nuclei examined as in (I). Scale bar: 50 μm. (K) Western blot using anti-pErk1/2 and anti-Erk1/2 antibodies. (L) The quantification of the intensities of pErk and Erk examined as in (K). Data are mean from two independent experiments. Error bar: SD. See also Figure S1.|