BECN1 Knockout Cell Line (A549)

The quadrilateral reassortant IAV A/(H1N1) pdm09 is the pathogen responsible for the first influenza pandemic of the 21st century. The virus spread rapidly among hosts causing high mortality within human population. Efficient accumulation of virions is known to be important for the rapid transmission of virus. However, the mechanism by which A/(H1N1) pdm09 promotes its rapid replication has not been fully studied. Here, we found the NS1 of A/(H1N1) pdm09 mediated complete macroautophagy/autophagy, and then facilitated self-replication, which may be associated with the more rapid spread of this virus compared with H1N1 and H3N8. We found that the promotion of self-replication could be mainly attributed to NS1 strongly antagonizing the inhibitory effect of LRPPRC on autophagy. The interaction between NS1 and LRPPRC competitively blocked the interaction of LRPPRC with BECN1/Beclin1, resulting in increased recruitment of BECN1 for PIK3C3 (phosphatidylinositol 3-kinase catalytic subunit type 3) and induction of the initiation of autophagy. In conclusion, we uncover the unique molecular mechanism by which A/(H1N1) pdm09 utilizes autophagy to promote self-replication, and we provide theoretical basics for the analysis of the etiological characteristics of the A/(H1N1) pdm09 pandemic and the development of anti-influenza drugs and vaccines. 293T: human embryonic kidney 293 cells; 293T_LRPPRC: stable LRPPRC expression 293T cells; 3-MA: 3-methyladenine; A549 cells: human non-small cell lung cancer cells; AA: amino acid; ACTB: actin beta; BECN1: beclin 1; KO: knockout 293T cells; Cal: calyculin A; Co-IP: co-immunoprecipitation; CQ: chloroquine; DC: dendritic cell; Eug: eugenol; GFP: green fluorescent protein; HA: hemagglutinin; HIV: human immunodeficiency virus; IAVs: Influenza A viruses; IFN: interferon; JL89: A/equine/Jilin/1/1989 (H3N8); LAMP2: lysosomal associated membrane protein 2; LRPPRC: leucine rich pentatriicopeptide repeat containing; KO: knockout 293T cells; M2: matrix 2; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MDCK: Madin-Darby canine kidney cells; MOI: multiplicity of infection; MS: mass spectrometry; NP: nucleoprotein; NS1: non-structural protein 1; NS1: non-structural protein 1 of A/equine/Jilin/1/1989 (H3N8); NS1: non-structural protein 1 of A/(H1N1) pdm09; NS1: non-structural protein 1 of A/Sichuan/2009 (H1N1); NS1: non-structural protein 1 of A/WSN/1933 (H1N1); PB1: polymerase basic protein 1; PB1-F2: alternate reading frame discovered in PB1 gene segment; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; PR8: A/PR/8/34 (H1N1); Rapa: rapamycin; RFP: red fluorescent protein; SC09: A/Sichuan/2009 (H1N1); SQSTM1/p62: sequestosome 1; STK4/MST1: serine/threonine kinase 4; TEM: transmission electron microscopy; TOMM20: translocase of outer mitochondrial membrane 20; WHO: World Health Organization; WSN: A/WSN/1933 (H1N1); WSN-NS1: WSN recombinant strain in which NS1 was replaced with that of JL89; WSN-NS1: WSN recombinant strain in which NS1 was replaced with that of SC09.

() represents a major human bacterial pathogen leading to high morbidity and mortality in children and the elderly. Recent research emphasizes the role of extracellular vesicles (EVs) in bacterial pathogenicity. However, the contribution of EVs (pEVs) to host-microbe interactions has remained unclear. Here, we observed that infections in mice led to severe lung injuries and alveolar epithelial barrier (AEB) dysfunction. Infections of reduced the protein expression of tight junction protein OCLN (occludin) and activated macroautophagy/autophagy in lung tissues of mice and A549 cells. Mechanically, induced autophagosomal degradation of OCLN leading to AEB impairment in the A549 monolayer. released the pEVs that could be internalized by alveolar epithelial cells. Through proteomics, we profiled the cargo proteins inside pEVs and found that these pEVs contained many virulence factors, among which we identified a eukaryotic-like serine-threonine kinase protein StkP. The internalized StkP could induce the phosphorylation of BECN1 (beclin 1) at Ser93 and Ser96 sites, initiating autophagy and resulting in autophagy-dependent OCLN degradation and AEB dysfunction. Finally, the deletion of in completely protected infected mice from death, significantly alleviated OCLN degradation , and largely abolished the AEB disruption caused by pEVs . Overall, our results suggested that pEVs played a crucial role in the spread of virulence factors. The cargo protein StkP in pEVs could communicate with host target proteins and even hijack the BECN1 autophagy initiation pathway, contributing to AEB disruption and bacterial pathogenicity.: AEB: alveolarepithelial barrier; AECs: alveolar epithelial cells; ATG16L1: autophagy related 16 like 1; ATP:adenosine 5'-triphosphate; BafA: bafilomycin A; BBB: blood-brain barrier; CFU: colony-forming unit; co-IP: co-immunoprecipitation; CQ:chloroquine; CTRL: control; DiO: 3,3'-dioctadecylox-acarbocyanineperchlorate; DOX: doxycycline; DTT: dithiothreitol; ECIS: electricalcell-substrate impedance sensing; eGFP: enhanced green fluorescentprotein; erm: erythromycin-resistance expression cassette; Ery: erythromycin; eSTKs: eukaryotic-like serine-threoninekinases; EVs: extracellular vesicles; HA: hemagglutinin; H&E: hematoxylin and eosin; HsLC3B: human LC3B; hpi: hours post-infection; IP: immunoprecipitation; KD: knockdown; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LC/MS: liquid chromatography-mass spectrometry; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MVs: membranevesicles; NC:negative control; NETs:neutrophil extracellular traps; OD: optical density; OMVs: outer membrane vesicles; PBS: phosphate-buffered saline; pEVs: extracellular vesicles; protK: proteinase K; Rapa: rapamycin; RNAi: RNA interference; ; SNF:supernatant fluid; sgRNA: single guide RNA; ; TEER: trans-epithelium electrical resistance; moi: multiplicity ofinfection; TEM:transmission electron microscope; TJproteins: tight junction proteins; TJP1/ZO-1: tight junction protein1; TSA: tryptic soy agar; WB: western blot; WT: wild-type.

BACKGROUND:Programmed death-ligand 1 (PD-L1, CD274) is well known for its immunosuppressive function within the tumor microenvironment; however, its tumor cell-intrinsic roles remain incompletely characterized. Emerging evidence suggests that PD-L1 may regulate oncogenic processes beyond immune evasion. This study aimed to define the intrinsic functions of PD-L1 in non-small cell lung cancer (NSCLC), with a focus on autophagy and metastasis-related signaling pathways. METHODS:Integrated transcriptomic analyses of patient-derived NSCLC specimens were performed to evaluate associations between CD274 expression and oncogenic gene signatures. CRISPR-Cas9-mediated knockout and plasmid-driven overexpression of PD-L1 were conducted in H460 and A549 cell lines to assess proliferation, migration, clonogenicity, and 3D spheroid growth. Molecular interactions among PD-L1, TRAF6, and BECN1 were examined through immunoprecipitation and ubiquitination assays. Autophagy induction was evaluated by LC3 lipidation and autophagosome formation under Toll-like receptor (TLR) stimulation. The functional relevance of PD-L1 in metastasis was further assessed using xenograft models. RESULTS:Clinical transcriptomic analyses demonstrated that CD274 upregulation correlates with enrichment of cancer progression, proliferation, and autophagy-associated gene sets in NSCLC. PD-L1 knockout markedly reduced cell proliferation, migration, clonogenicity, and 3D spheroid formation, whereas its overexpression enhanced these oncogenic phenotypes. Mechanistically, PD-L1 physically interacted with TRAF6 and BECN1, promoting TRAF6-dependent BECN1 ubiquitination and TLR-induced autophagy. PD-L1 depletion suppressed TLR-driven LC3 lipidation, autophagosome formation, and epithelial-mesenchymal transition (EMT), while PD-L1 overexpression augmented autophagy and EMT responses. In vivo, PD-L1-deficient lung cancer cells displayed diminished tumor growth and reduced metastatic potential in xenograft models. CONCLUSIONS:This study identifies PD-L1 as a previously unrecognized intrinsic driver of NSCLC progression through activation of the TLR-TRAF6-BECN1 autophagy axis and promotion of EMT. Beyond its canonical role in immune evasion, PD-L1 functions as a dual-regulator of tumorigenesis by coordinating autophagy-dependent oncogenic processes. These findings provide novel mechanistic insight and support the therapeutic rationale for targeting PD-L1 not only as an immune checkpoint but also as a key modulator of cancer cell-intrinsic signaling in NSCLC.

TNF receptor-associated factor 6 (TRAF6)-BECN1 signaling axis plays a pivotal role in autophagy induction through ubiquitination of BECN1, thereby inducing lung cancer migration and invasion in response to toll-like receptor 4 (TLR4) stimulation. Herein, we provide novel molecular and cellular mechanisms involved in the negative effect of ubiquitin-specific peptidase 15 (USP15) on lung cancer progression. Clinical data of the TCGA and primary non-small cell lung cancer (NSCLC) patients (n = 41) revealed that the expression of USP15 was significantly downregulated in lung cancer patients. Importantly, USP15-knockout (USP15KO) A549 and USP15KO H1299 lung cancer cells generated with CRISPR-Cas9 gene-editing technology showed increases in cancer migration and invasion with enhanced autophagy induction in response to TLR4 stimulation. In addition, biochemical studies revealed that USP15 interacted with BECN1, but not with TRAF6, and induced deubiquitination of BECN1, thereby attenuating autophagy induction. Notably, in primary NSCLC patients (n = 4) with low expression of USP15, 10 genes (CCNE1, MMP9, SFN, UBE2C, CCR2, FAM83A, ETV4, MYO7A, MMP11, and GSDMB) known to promote lung cancer progression were significantly upregulated, whereas 10 tumor suppressor genes (FMO2, ZBTB16, FCN3, TCF21, SFTPA1B, HPGD, SOSTDC1, TMEM100, GDF10, and WIF1) were downregulated, providing clinical relevance of the functional role of USP15 in lung cancer progression. Taken together, our data demonstrate that USP15 can negatively regulate the TRAF6-BECN1 signaling axis for autophagy induction. Thus, USP15 is implicated in lung cancer progression.