Journal: bioRxiv
Article Title: Bclaf1 biomolecular condensates protect nuclear PTK2 from ubiquitin-proteasome system promoting cardiomyocyte survival during oxidative stress
doi: 10.1101/2025.02.04.636487
Figure Lengend Snippet: A. Triple-label SR-SIM image showing PTK2 and Bclaf1 concentrated on biomolecular condensates on the nucleus of H9c2 cardiomyocytes treated with dox. Scale bar = 10 µm. 1. Fluorescence line profile plot showing PTK2 colocalizing with ubiquitin outside the Bclaf1 condensate. Scale bar = 0.5 µm. 2. Fluorescence line profile plot showing low ubiquitin level inside the Bclaf1 condensate, where PTK2 is enriched. Scale bar = 0.5 µm B. Pearson correlation coefficient between Bclaf1 and PTK2, ubiquitin and PTK2, and ubiquitin and Bclaf1. C. PTK2 immunoblots of extracts from control (CT) and dox-treated (DOX) H9c2 cells and bar graph showing a decrease in PTK2 levels after dox treatment. D. RT-qPCR assay shows no difference in PTK2 mRNA levels in cardiomyocytes on basal conditions or after dox treatment. GAPDH was used as endogenous control. E. Western-blot of PTK2 and ubiquitin comparing soluble (S) and insoluble (P) fractions of H9c2 cardiomyocytes. F. Super-resolution images of PTK2, Bclaf1, and ubiquitin staining after 36 hours of recovery from dox treatment. Scale bar = 5 µm. 1. Fluorescence line profile plot showing low PTK2 ubiquitination inside Bclaf1 condensate. Scale bar = 0.5 µm. 2. Fluorescence line profile plot showing PTK2 ubiquitinated and agglomerated outside Bclaf1 condensate. G. Graphical representation of PTK2-Bclaf1 undergoing LLPT to avoid PTK2 ubiquitination and aggregation. H. Western-blot showing ubiquitin accumulation on cardiomyocytes treated with dox and co-treated with dox and MG132. I. SR-SIM image showing the accumulation of ubiquitinated PTK2 on the nucleus of cardiomyocytes co-treated with dox and MG132. Scale bar of nuclear image = 5 µm. (1) Orthogonal Z projection showing yz planes and xz planes of a PTK2 agglomerate, which colocalize with ubiquitin. Scale bar = 0.5 µm. J. Cell number count after dox combined with MG132 treatment, as indicated. Green: PTK2; Red: Bclaf1; Grey: Ubiquitin. Asterisks demonstrates statistical significance, while ns means P > 0.05; * means P ≤ 0.05; ** means P ≤ 0.01; *** means P ≤ 0.001 and **** means P ≤ 0.0001.
Article Snippet: Then, primary antibodies against PTK2 (Thermo Fisher, ZF002, mouse) and Bclaf1 (Thermo Fisher, PA5-78299, rabbit) were added to a 1:200 concentration and incubated in a humidity chamber at 4°C for 1 hour.
Techniques: Fluorescence, Ubiquitin Proteomics, Western Blot, Control, Quantitative RT-PCR, Staining