Journal: The Journal of Cell Biology

Article Title: Landscape expansion microscopy reveals interactions between membrane and phase-separated organelles

doi: 10.1083/jcb.202502035

Figure Lengend Snippet: land-ExM visualizes phase-separated and membrane organelles. (A–G) land-ExM protein images of membraneless phase separation structures. The proteins were labeled with NHS-biotin-MS and after gelation stained with streptavidin-Alexa Fluor 488. (A) land-ExM protein image of nucleoli in a U2OS cell. Red arrowheads indicate the fibrillar center (FC) or dense fibrillar component (DFC) of the nucleolus. Scale bar: 1 µm in pre-expansion unit. Linear expansion factor: 4.0. (B) land-ExM protein image of nuclear bodies of breast cancer cell, UCI082014. Red arrowheads indicate the nuclear bodies. Scale bar: 1 µm in pre-expansion unit. Linear expansion factor: 4.2. (C) land-ExM protein image of SGs of a U2OS cell treated with NaAsO 2 for 20 min. The red arrowhead indicates a SG. Scale bar: 1 µm in pre-expansion unit. Linear expansion factor: 4.0. (D) land-ExM protein image of chromatin of a breast cancer cell. Scale bar: 500 nm in pre-expansion unit. Linear expansion factor: 4.2. (E) land-ExM protein image of NPCs of a breast cancer cell. Scale bar: 1 µm in pre-expansion unit. Linear expansion factor: 4.2. (F and G) land-ExM protein images of mitochondria and cytoskeleton of a U2OS cell. Scale bar: 1 µm in pre-expansion unit. Linear expansion factor: 4.0. (H–P) land-ExM lipid images of membrane structures. The lipids were labeled with mCLING-Atto647N. (H) land-ExM lipid image of breast cancer cell. Scale bar: 5 µm in pre-expansion unit. Linear expansion factor: 4.0. (I–M) magnified images of H showing different membrane structures: lipid vesicles (I), mitochondria (J), filopodia (K), nuclear invagination (L), and Golgi apparatus (M). Scale bar: 1 µm (I–M) in pre-expansion unit. (N) 3D land-ExM lipid image of a breast cancer cell after maximum intensity projection, showing the cell membrane. Color-coded by the z-dimension slices from bottom to top. Color bar: purple to white: 0–6 µm in pre-expansion unit. Scale bar: 5 µm in pre-expansion unit. Linear expansion factor: 4.0. (O and P) magnified images of N showing detailed structures of the cell membrane. Scale bar: 1 µm in pre-expansion unit. All images were taken with an Airyscan microscope.

Article Snippet: The cell-gelation solution was then incubated at 37°C for 1–2 h. Gelled cells were immersed in heat denaturation buffer (200 mM sodium dodecyl sulfate, 200 mM NaCl, and 50 mM Tris, pH 6.8) for 1.5 h at 78°C and washed with excess of water for 30 min. To fluorescently label the whole proteins, immerse the gelled cells in poststaining buffer (10 mM HEPES and 150 mM NaCl, pH 7.5) twice, 30 min each time, then incubate the gelled cells with 4 μg/ml streptavidin dyes (included in cat#LD-P568-050/LD-P488-050; Cytoseen, or cat#016-540-084; Jackson ImmunoResearch) in poststaining buffer overnight.

Techniques: Membrane, Labeling, Staining, Microscopy