Journal: Frontiers in Cell and Developmental Biology

Article Title: LPS–TLR4 signaling attenuates CHOP-mediated apoptosis under endoplasmic reticulum stress conditions during porcine embryonic development

doi: 10.3389/fcell.2026.1750233

Figure Lengend Snippet: LPS suppresses CHOP expression during ER stress. (A) Relative mRNA expression levels of UPR sensors IRE1 , PERK , and ATF6 in Con, TM, and TM + LPS groups. (B) Representative immunofluorescence staining images of p-PERK and DNA in Con, TM, and TM + LPS. (C) Quantification of p-PERK fluorescence intensity in Con ( n = 31), TM ( n = 30), and TM + LPS ( n = 33). (D) Representative immunofluorescence staining images of ATF4 and DNA in Con, TM, and TM + LPS. (E) Quantification of ATF4 fluorescence intensity in Con ( n = 31), TM ( n = 35), and TM + LPS ( n = 33). (F) Representative immunofluorescence staining images of CHOP and DNA in Con, TM, and TM + LPS. (G) Quantification of CHOP fluorescence intensity in Con ( n = 30), TM ( n = 36), and TM + LPS ( n = 31). (H) Western blot images of p-eIF2α, eIF2α, ATF4, CHOP, and GAPDH protein from the 2C to BL stages. GAPDH was used as the internal reference protein. (I) Quantification of p-eIF2α protein levels normalized to eIF2α. (J) Quantification of ATF4 protein levels normalized to GAPDH. (K) Quantification of CHOP protein levels normalized to GAPDH. Scale bar: 20 μm, *: p < 0.05, **: p < 0.01, ***: p < 0.001, ****: p < 0.0001, #: p < 0.05, ##: p < 0.01, ####: p < 0.0001.

Article Snippet: Primary antibodies such as phospho-PERK (1:100, 3179S, Cell signaling), rabbit anti- ATF4 (1:100, 10835-1-AP, Proteintech), rabbit anti-CHOP (1:100, SC-166682; Santa Cruz Biotechnology), rabbit anti-phospho-eIF2α (1:100, AP0341; ABclonal), rabbit anti-eIF2α (1:100, A16205; ABclonal), rabbit anti-LC3 (1:100, ab58610; Abcam), and rabbit anti-cleaved caspase-3 (1:100,9664S, Cell signaling) were applied overnight at 4 °C.

Techniques: Expressing, Immunofluorescence, Staining, Fluorescence, Western Blot

Journal: Frontiers in Cell and Developmental Biology

Article Title: LPS–TLR4 signaling attenuates CHOP-mediated apoptosis under endoplasmic reticulum stress conditions during porcine embryonic development

doi: 10.3389/fcell.2026.1750233

Figure Lengend Snippet: Schematic diagram illustrating the role of TLR4 in signaling CHOP-mediated apoptosis and autophagy during porcine embryonic development under ER stress conditions. During embryonic development, tunicamycin-induced ER stress activates the PERK–eIF2α–ATF4–CHOP signaling axis, which upregulates pro-apoptotic factors ( BAX , cleaved Caspase-3) and autophagy-related genes ( LC3 , ATG7 ), while downregulating anti-apoptotic BCL-XL , ultimately leading to impaired development. Activation of TLR4 by LPS attenuates ER stress signaling by reducing eIF2α phosphorylation and CHOP expression. This suppression shifts the balance toward cell survival by decreasing apoptosis and autophagy, thereby improving embryonic developmental competence under persistent ER stress. Figure created with BioRender.com .

Article Snippet: Primary antibodies such as phospho-PERK (1:100, 3179S, Cell signaling), rabbit anti- ATF4 (1:100, 10835-1-AP, Proteintech), rabbit anti-CHOP (1:100, SC-166682; Santa Cruz Biotechnology), rabbit anti-phospho-eIF2α (1:100, AP0341; ABclonal), rabbit anti-eIF2α (1:100, A16205; ABclonal), rabbit anti-LC3 (1:100, ab58610; Abcam), and rabbit anti-cleaved caspase-3 (1:100,9664S, Cell signaling) were applied overnight at 4 °C.

Techniques: Activation Assay, Phospho-proteomics, Expressing