Panel A shows fluorescence microscopy images and zoomed insets illustrating endogenous Col1A1 condensates positioned near Sec31-positive endoplasmic reticulum exit sites. Panel B shows fluorescence intensity profile graphs comparing Col1A1 and Sec31 localization across measured distances from condensates. The horizontal axis represents distance in micrometers, while the vertical axes represent normalized Sec31 and Col1A1 fluorescence intensity values. Panel C shows fluorescence microscopy images and enlarged insets displaying TANGO1 and Hsp47 localization surrounding intracellular condensate regions. Panel D shows fluorescence microscopy images and zoomed insets illustrating Col1A1 and Sec31 localization after non-targeting small interfering RNA treatment. Panel E shows fluorescence microscopy images and enlarged insets comparing Col1A1 and Sec31 localization after TANGO1 knockdown treatment. Panel F shows a scatter plot quantifying reduced PC1 condensate and Sec31 coupling after TANGO1 knockdown conditions. The vertical axis represents PC1-Sec31 coupling index values, while the horizontal axis represents experimental conditions. Panel G shows a box-and-scatter plot comparing distances between PC1 condensates and Sec31 puncta after TANGO1 knockdown treatment. The vertical axis represents PC1-Sec31 distance in nanometers, while the horizontal axis represents experimental conditions. Panel H shows dot blot and western blot images comparing secreted Col1A1, intracellular TANGO1, beta-tubulin, and alpha-smooth muscle actin levels under different treatments. Panel I shows a bar graph quantifying secreted Col1A1 levels across experimental conditions. The vertical axis represents secreted Col1A1 intensity in arbitrary units, while the horizontal axis represents treatment categories. Panel J shows a bar graph quantifying intracellular TANGO1 levels across experimental conditions. The vertical axis represents TANGO1L levels, while the horizontal axis represents treatment categories.
PC1 condensates are captured by TANGO1 at ERES. (A) Fluorescence images of fixed LX-2 cells activated with TGF-β and stained for antibodies against endogenous Col1A1 (green) and Sec31 (magenta) (top), and zoomed insets (bottom) (scale bars: 5 µm; inset: 2 µm). (B) Fluorescence intensity profiles corresponding to lines similar to the dashed white line in the zoomed inset in A for anti-Col1A1 (green) and anti-Sec31 (magenta) showing the proximity of ERES to PC1 condensates. The black lines represent the mean, and the shaded region within the dotted lines represents the SD of intensity profiles from 14 different PC1 condensates. (C) Fluorescence images of fixed LX-2 cells activated with TGF-β and stained for antibodies against endogenous TANGO1 (green) and Hsp47 (magenta) (top), and zoomed insets (bottom) (scale bars: 5 µm; inset: 2 µm). (D) Fluorescence images of fixed LX-2 cells activated with TGF-β and treated with NT siRNAs and stained using antibodies against endogenous Col1A1 (green) and Sec31 (magenta) (top), and zoomed insets (bottom) (scale bars: 5 µm; inset: 2 µm). (E) Fluorescence images of fixed LX-2 cells activated with TGF-β and treated with siRNAs against TANGO1 (TANGO1 KD) and stained using antibodies against endogenous Col1A1 (green) and Sec31 (magenta) (top), and zoomed insets (bottom) (scale bars: 5 µm; inset: 2 µm). (F) Plot showing decreased PCI condensate–Sec31 coupling upon TANGO1 KD. Data show values representing the mean and SD from six cells in NT and eight cells in TANGO1 KD from two independent experiments (****P < 0.0001). (G) Plot showing increased distances between PC1 condensates and Sec31 puncta upon TANGO1 KD. A total of 2,407 and 1,940 condensates were analyzed from 6 cells in NT and eight cells in TANGO1 KD, respectively, from two independent experiments (*P = 0.0193). (H) Dot blot probed with anti-Col1A1 antibody showing levels of secreted Col1A1 from 4-h-old medium of cells (medium) grown in the absence of TGF-β and with TGF-β, and treated with NT siRNAs or grown with TGF-β and treated with siRNAs against TANGO1 (TANGO1 KD), and western blot showing intracellular levels (lysate) of TANGO1, β-tubulin, and ⍺-SMA in cells grown in the same conditions corresponding to cells used for the dot blot. (I) Levels of secreted Col1A1 in 4-h-old culture medium of cells grown under conditions specified in H (***P = 0.0003, ****P < 0.0001, ****P < 0.0001; top to bottom). (J) Intracellular levels of TANGO1 in cells grown under conditions specified in H (****P < 0.0001, **P = 0.0097, **P = 0.0073; top to bottom). NT, nontargeting. Source data are available for this figure: SourceData F4.