Journal: The Journal of Biological Chemistry
Article Title: Brucella Omp25 activates the unfolded protein response to promote intracellular proliferation and inflammation
doi: 10.1016/j.jbc.2026.111333
Figure Lengend Snippet: Brucella abortus Omp25 activates UPR signaling. A , screening of Brucella proteins for UPR activation. HEK293T cells (5 × 10 5 ) were transfected with empty vector or Brucella protein expression plasmids for 24 h before RT–qPCR analysis. B , effects of B. abortus Omp25 on transcription of UPR downstream genes. HEK293T cells (5 × 10 5 ) were transfected with increasing amounts of Omp25-FLAG plasmid (0, 75, 150, or 300 ng) for 24 h before RT–qPCR analysis. C , effects of Omp25 on XBP1 mRNA splicing. Total RNA was analyzed by RT–PCR, and XBP1s band intensities were quantified relative to GAPDH. D , effects of Omp25 on activation of UPR reporters. HEK293T cells (1 × 10 5 ) were cotransfected with Omp25-FLAG (50 ng), pRL-TK (20 ng), and luciferase reporters for ATF6 (20 ng), ATF4 (20 ng), or XBP1s (10 ng). Luciferase activity was measured 24 h post-transfection. E and F , Omp25 activates PERK, IRE1α, and ATF6 pathways. HEK293T cells (5 × 10 5 ) were transfected with increasing doses of Omp25-FLAG (0, 0.3, 0.9, and 2.7 μg) for 24 h ( E ) or with 2 μg Omp25-FLAG for 24, 36, and 48 h ( F ) before Western blotting with the indicated antibodies. Band intensities were quantified relative to β-actin. Data are presented as mean ± SD from n = 3 to 4 independent samples. Statistical significance was determined using one-way ANOVA ( A , B ) or unpaired t test ( D ). ∗ p < 0.05, ∗∗ p < 0.01. ATF, activating transcription factor; HEK293T, human embryonic kidney 293T cell line; IRE1α, inositol-requiring enzyme 1 alpha; Omp, outer membrane protein; PERK, PKR-like ER kinase; qPCR, quantitative PCR; UPR, unfolded protein response; XBP1, X-box binding protein 1; XBP1s, the spliced form of XBP1.
Article Snippet: Mouse monoclonal antibodies against HA (66006, Proteintech); rabbit monoclonal antibodies against HA (H6908, Sigma); mouse monoclonal antibodies against FLAG (F3165, Sigma); horseradish peroxidase (HRP)-FLAG (ZB15939, Servicebio); rabbit polyclonal antibodies against Myc (16286-1-AP, Proteintech); HRP-His (HRP-66005, Proteintech); IgG (I5381 and I5006, Sigma); BiP (11587-1-AP, Proteintech); phosphorylated PERK (29546-1-AP, Proteintech); p-IRE1α ( Ab124945 , Abcam); IRE1α (3294S, Cell Signaling Technology); PERK (20582-1-AP, Proteintech); phosphorylated eIF2α (3398S, Cell Signaling Technology); eIF2α (11170-1-AP, Proteintech); ATF6 (ab122897, Abcam); XBP1s (24868-1-AP, Proteintech); CHOP (15204-1-AP, Proteintech); p-IκBα (9246S, Cell Signaling Technology); IκBα (9242S, Cell Signaling Technology); GST (66001-2-Ig, Proteintech); β-actin (A2228, Sigma–Aldrich); anti-mouse IgG (H+L), F(ab')2 fragment (Alexa Fluor 594 Conjugate) (8890, Cell Signaling Technology); Alexa Fluor 555 goat anti-rabbit IgG (H+L) (A-21428, Invitrogen), and Alexa Fluor 488 goat anti-rabbit IgG (H+L) (A11008, Invitrogen) were purchased from the indicated manufacturers.
Techniques: Activation Assay, Transfection, Plasmid Preparation, Expressing, Quantitative RT-PCR, Reverse Transcription Polymerase Chain Reaction, Luciferase, Activity Assay, Western Blot, Membrane, Real-time Polymerase Chain Reaction, Binding Assay