Fig. 1.
Desmoplakin (DP) tension sensors localize to desmosomes (DSMs). a DSM adhesion is mediated by the desmosomal cadherins desmocollin (Dsc) and desmoglein (Dsg), which engage the adapter proteins plakophilin (Pkp) and plakoglobin (Pg); DP forms the connection to intermediate filaments (IFs). The tension sensor module (TSM) was inserted into DP after the rod domain. b DP tension sensors (DPI-TS, DPII-TS) were generated along with controls lacking the IF-binding C-terminal region (DPI-ctrl, DPII-ctrl). The TSM comprises the F40 linker peptide (GPGGA)8 flanked by mTFP1/mEYFP in DPI, and YPet/mCherry in DPII. Tension reduces FRET in DP-TS but not in DP-ctrl constructs. c Live-cell imaging reveals normal subcellular localization of DPI-TS (expressed in MDCK cells) and DPII-TS (expressed in MEK-wt one day after DSM induction by Ca2+). Scale bar: 20 μm; in zoom: 4 μm. d DPII constructs localize to intercellular junctions in MEK-KO one day after DSM induction, similar to endogenous DP in MEK-wt. Immunostainings show that DPII constructs co-localize with Dsg1/2, and that full-length constructs but not DPII-ctrl mediate the recruitment of a coherent keratin 5 (K5) network. Images are summed projections of nine optical slices covering 3.1 μm. Scale bars: 10 μm; in zoom: 4 μm. e Ultrastructural analysis of MEKs one day after DSM induction reveals that the expression of DPII-wt and DPII-TS but not DPII-ctrl rescue both the DSM formation (arrows) and IF attachment (arrow heads) defects of MEK-KO. Electron microscopy images are contrast adjusted. Scale bars: 2 μm; zoom: 0.5 μm