Journal: Science Advances
Article Title: External strain on the plasma membrane is relayed to the endoplasmic reticulum by membrane contact sites and alters cellular energetics
doi: 10.1126/sciadv.ads6132
Figure Lengend Snippet: ( A ) RT-qPCR analysis of PM-ER tether proteins in mouse tendon cells (three biological replicates from three independent experiments). ( B ) Schematic diagram illustrating the experimental approach used to test membrane tension of tendon cells transfected with scrambled siRNA or Stim1 -siRNA. ( C and D ) Immunoblot analysis (C) and quantification (D) of STIM1 expression in cells 3 days post-siRNA transfection (three biological replicates from three independent experiments). ( E and F ) Representative FLIM images (E) of ER Flipper-TR in cells transfected with siRNA (top). Bottom panels show enlarged views of ER tubules (purple dashed rectangles) and ER sheets (white dashed rectangles) from the top panels, alongside confocal images displaying intensity, and quantification (F) selecting the overall ER, ER tubules, or ER sheets ( n = 25 to 30), as the ROI. ( G and H ) Representative FLIM images (G) of Flipper-TR in cells transfected with siRNA and quantification (H) selecting the PM as the ROI ( n = 30). ( I ) Schematic illustrating 2D mechanical stimulation to tendon cells transfected with siRNA. ( J and K ) Representative FLIM images of ER Flipper-TR in cells transfected with siRNA after 2D 6% cyclic strain (J) and quantification (K) ( n = 30). ( L and M ) Representative FLIM images of ER Flipper-TR in tendon cells transfected with siRNA after 2D 0, 3, or 9% cyclic strain (L) and quantification (M) ( n = 21 to 24). ( N ) Interaction plot from two-way ANOVA indicating the interactive effect of partial Stim1 knockdown and cyclic strain on ER tension. ( O ) Schematic illustrating that detethering the ER from the PM disrupts mechanical force propagation, reducing adaptive ER tension. Scale bars, 1 μm. n , cells per group, each with at least two ROIs, from three independent experiments. * P < 0.05; ** P < 0.01; *** P < 0.001; n.s., not significant by Student’s t test (D, F, H, and K) or two-way ANOVA with Sidak’s post hoc (M and N). Error bars stand for SEM. (B), (I), and (O) created with BioRender.com .
Article Snippet: Tendon cells were transfected with Stim1 siRNA (s13563, Thermo Fisher Scientific) and negative control scrambled siRNA (4390843, Thermo Fisher Scientific) at 10 nM unless stated otherwise, using Lipofectamine RNAiMAX Transfection Reagent (Invitrogen) for a 6-hour incubation according to the manufacturer’s protocol.
Techniques: Quantitative RT-PCR, Membrane, Transfection, Western Blot, Expressing, Knockdown