Keratocytes Generate High Integrin Tension at the Trailing Edge to Mediate Rear De-adhesion during Rapid Cell Migration

Abstract

SummaryRapid cell migration requires efficient rear de-adhesion. It remains undetermined whether cells mechanically detach or biochemically disassemble integrin-mediated rear adhesion sites in highly motile cells such as keratocytes. Using molecular tension sensor, we calibrated and mapped integrin tension in migrating keratocytes. Our experiments revealed that high-level integrin tension abbreviated as HIT, in the range of 50–100 pN (piconewton) and capable of rupturing integrin-ligand bonds, is exclusively and narrowly generated at cell rear margin during cell migration. Co-imaging of HIT and focal adhesions (FAs) shows that HIT is produced to mechanically peel off FAs that lag behind, and HIT intensity is correlated with the local cell retraction rate. High-level molecular tension was also consistently generated at the cell margin during artificially induced cell front retraction and during keratocyte migration mediated by biotin-streptavidin bonds. Collectively, these experiments provide direct evidence showing that migrating keratocytes concentrate force at the cell rear margin to mediate rear de-adhesion.

Mechanical Regulation of Nuclear Translocation in Migratory Neurons

“…A possible mechanism for detachment at the rear of the cell could be the mechanical disruption of integrin-ECM bonds by the actomyosin force behind the nucleus. Previous studies using keratocytes and cancer cell lines have demonstrated that actomyosin generates a traction force on focal adhesions which readily break integrin-ECM bonds (Jurchenko et al, 2014;Zhao et al, 2018). However, adhesions and stress fibers are less prominent in migrating neurons than in fibroblasts, seemingly downplaying the importance of de-adhesion at the cell posterior for neuronal migration (Jiang et al, 2015).…”

Recent Advances in Cell Adhesive Force Microscopy

“…However, real-time force mapping can still be achieved by recording the force map in a time-series manner and obtaining the newly produced force signal with the frame subtraction method. Figure 2 E demonstrates the real-time force in a migrating keratocyte [ 50 ]. ITSs have been applied to study cell adhesive force in keratocytes and platelets.…”

“…ITSs have been applied to study cell adhesive force in keratocytes and platelets. It was shown that high-level integrin tension (>54 pN) was generated at the cell rear margin to detach integrins off from the substrate, therefore facilitating cell rear retraction during fast cell migration [ 50 ]. ITSs also revealed the polarized force distribution in adherent platelets [ 49 ].…”

“…The resolution is in the range of 1–5 µm. ( D – F ) Force maps of a fibroblast obtained by molecular tension sensor (MTS) [ 43 ], a keratocyte obtained by integrative tension sensor (ITS) [ 50 ] and a platelet obtained by molecular tension fluorescence microscopy (MTFM) [ 60 ], respectively. The resolutions are at the diffraction limit: 0.3–0.4 µm.…”

DNA Nanotechnology as an Emerging Tool to Study Mechanotransduction in Living Systems

“…Importantly, Wang and co‐workers showed that actomyosin contraction was responsible for generating >54 pN integrin forces but not the weaker forces. In a subsequent report, Wang and co‐workers used ITS to study the magnitude and spatiotemporal dynamic of the integrin forces in migrating cells . Using keratocytes as a model system, the authors revealed that these cells generated forces >54 but <100−150 pN during rapid migration.…”