Caspase 3

Protein concentrations were measured using BCA kit (Beyotime). Equal amounts of proteins were subjected to 10-15% SDS-PAGE and transferred to NC membrane. Antibodies against ST6Gal-I (Abcam, 1:500), p38, pp38, caspase-3 or GAPDH (Bioworld, 1:300, 1:300, 1:400, 1:10,000), Bcl-2, Bax, Bad or PARP (Sangon, 1:500), ctochrome c or caspase-9 (Proteintech, 1:500) were used as the primary antibodies. The detection was performed using ECL kit. Densitometry of proteins was analyzed with Gel-Pro software.

Cells, exosomes, and tissues were lysed in RIPA buffer. Protein concentration was determined using the BCA assay kit (Pierce, USA). Sources and dilution factors of primary antibodies were: rabbit polyclonal CD63 (1:1000; Bioworld, USA), CD9 (1:1000; Bioworld), CD81 (1:1000; Epitomics, USA), PCNA (1:1000; Bioworld), BCL-XL (1:100; SAB, USA), BCL-2 (1:1000; Bioworld), Bax (1:1000; Bioworld), Cytochrome C (1:500; Abcam, USA), caspase-3 (1:500; Bioworld), IL-1β (1:500; Bioworld,), LC3B (1:500; Abcam), Beclin-1 (1:600; Proteintech, USA), mTOR (1:500; SAB), p-mTOR (1:500; SAB), 4EBP1 (1:200; SAB), p70S6K (1:200; SAB), and mouse monoclonal GAPDH (1:3000; Kang Chen, China). The nucleoprotein and plasma protein was separated by the nuclear and plasma protein isolation kit (Vazyme, China), with the primary antibody NF-kB-P65 in the nucleus (1:500; SAB), primary antibody nucleoprotein Histone (1:1000; SAB). After incubation with the primary antibodies overnight at 4 °C, membranes were washed three times with Tris-buffered saline with 0.05% Tween-20 and challenged with HRP-conjugated goat anti-rabbit or goat anti-mouse antibody (1:2000; Bioworld). Western blot was performed by Luminata™ crescendo western HRP substrate (Millipore, USA) and analyzed using MD Image Quant Software.

Antibodies used in this study were anti PERK (Cell Signaling, D11A8), IRE1α (Cell Signaling, 14C10), Bcl-2 (Cell Signaling, D55G8), Bip (Cell Signaling, C50B12), CHOP (Cell Signaling, L63F7), Bax (Cell Signaling, D2E11), caspase3 (Bioworld, BS6428), caspase9 (Bioworld, BS1731), β-Actin (Signaling, 8H10D10), Anti-GAPDH (Genomics, 5A12), and anti-Alexa Fluor 488 Labeled Goat Anti-Rabbit IgG (H+L) (Biyuntian, A0423). All these antibodies were purchased from Shanghai Biyuntian Biological Company. PG was isolated from Serratia marcescens, strain WA12-1-18, in the intestinal tract of cockroaches. The metabolite was extracted using 3.0 g/L of PBS from previously described [10 (link)]. Flou3-AM fluorescent probe, PVDF membrane, (2-(4-Amidinophenyl)-6-indolecarbamidine dihydrochloride) DAPI, TUNEL apoptosis kit, and ECL kits were purchased from Shanghai Biyuntian Biological Company (Shanghai, China), whereas 4-PBA was purchased from Sigma Aldrich Company (St. Louis, MI, USA). A fluorescent quantitative PCR kit was purchased from Thermo Fisher Scientific (Waltham, MA, USA). Cell cycle and apoptosis kits were purchased from Beijing Sizhengbai Biotechnology Company (Beijing, China).