Search Results (1,808)

Arsenic exposure increases lung cancer risk, yet its molecular mechanisms remain unclear but are linked to peroxisome proliferator-activated receptor gamma (PPARγ). We investigated PPARγ-related molecules affected by sodium arsenite (NaAR) in non-small cell lung cancer (NSCLC) cells using immunochemical, gene knockdown, and immunoprecipitation approaches. PPARγ was critical for NSCLC growth, as high PPARγ-expressing A549 cells proliferated more than low-expressing H1299 cells after NaAR treatment. In A549 cells, NaAR upregulated polyubiquitinated PPARγ, activating cell cycle arrest and DNA damage response pathways. Rather than inducing significant caspase-dependent apoptosis, NaAR activated nuclear factor-kappa B and downregulated mixed lineage kinase domain-like (MLKL) via K63-linked polyubiquitinated receptor-interacting protein kinase 1, thereby inhibiting apoptosis and necroptosis. PPARγ knockdown or NAD⁺ supplementation induced PARP-1 hyperactivation and MLKL upregulation, leading to DNA damage and necroptosis. PARP-1 inhibition by 3-aminobenzamide induced apoptosis, indicating that PPARγ regulates apoptosis and necroptosis through PARP-1 activation. Proteasome inhibition increased polyubiquitinated PPARγ but not p53. Leptomycin B induced PPARγ degradation and p53 accumulation, promoting necroptosis and apoptosis, suggesting cytoplasmic p53 contributes to cell death. p62 interacted with PPARγ and p53, and its knockdown suppressed their NaAR-induced upregulation. In conclusion, NaAR-induced PPARγ promotes A549 cell survival by enhancing DNA repair and inhibiting apoptosis and necroptosis via cooperation with p53 and p62, highlighting PPARγ as a potential therapeutic target. Full article

Vascular remodeling driven by the phenotypic switching of vascular smooth muscle cells (VSMCs) poses a significant health risk to astronauts during long-duration spaceflight. While the morphological and molecular changes are well recognized, the underlying metabolic drivers and potential translational countermeasures remain elusive. To investigate the metabolic determinants of VSMCs phenotypic switching, human aortic smooth muscle cells (HASMCs) were subjected to cyclic mechanical stretch, an in vitro model offering indirect mechanistic insights into mechanical loading conditions relevant to spaceflight-associated hemodynamic alterations. An integrated approach combining quantitative proteomics, flux analysis (Seahorse), and functional assays (cell cycle, wound healing, transwell) was used to characterize the accompanying metabolic and phenotypic alterations. Molecular mechanisms were assessed using immunoprecipitation, protein crosslinking, and immunofluorescence. Mechanical stretch triggered a contractile-to-synthetic phenotypic switch in HASMCs, accompanied by a shift from oxidative phosphorylation to aerobic glycolysis. Pyruvate kinase M2 (PKM2) was identified as a central metabolic regulator of this process, its silencing reversed the pro-synthetic phenotype. Notably, lactate, a glycolytic product, was found to exert a self-limiting feedback signal. Exogenous lactate suppressed the synthetic switch in associated with increased PKM2 lactylation. Further analysis indicated that PKM2 lactylation was associated with enhanced stability of its active tetrameric conformation, which was associated with a metabolic shift toward oxidative phosphorylation and restored expression of contractile markers. Although specific lactylation sites on PKM2 were not identified in this study, and direct causality between lactylation and tetramerization remains to be established, these findings identify a previously unrecognized association. This study reveals a novel metabolic regulatory mechanism in which lactate correlates with the suppression of synthetic switching of VSMCs, linked to PKM2 lactylation and tetramer stabilization. The observed lactate-PKM2 axis represents a candidate metabolic node associated with VSMCs phenotype regulation and offers a potential therapeutic target for modulating vascular remodeling. Upon direct validation under relevant conditions in future studies, this mechanism may inform the development of novel therapeutic strategies for managing vascular adaptation during long-duration spaceflight and other aerospace-related physiological challenges. Full article

Background/Objectives: Head and neck squamous cell carcinoma (HNSCC) often exhibits limited clinical response to targeted therapies, such as Cetuximab. Identifying key drivers of tumor progression and elucidating the factors that modulate therapeutic sensitivity are essential for improving clinical outcomes. In this study, we aimed to investigate the role of CAV2 in HNSCC proliferation and its impact on Cetuximab sensitivity. Methods: Prognosis-associated genes in HNSCC were screened using the The Cancer Genome Atlas (TCGA) database. The functional role of Caveolin-2 (CAV2) in cell proliferation and apoptosis was assessed via Cell Counting Kit-8 (CCK-8), colony formation, and flow cytometry assays. Mechanistic insights were obtained through co-immunoprecipitation, ubiquitination assays, and proteomic analysis. The impact of CAV2 on Cetuximab sensitivity was evaluated both in vitro and in a xenograft mouse model. Results: Clinical analysis of 43 pairs of HNSCC tumor and adjacent normal tissues revealed that elevated CAV2 expression was significantly associated with poor prognosis in HNSCC patients (95%CI: 1.197–1.7518, p = 1.33 × 10⁻¹³). In vitro, knockdown of CAV2 suppressed cell proliferation and significantly increased apoptosis rates (from 5.1% to 10.8%, p = 0.004). Mechanistically, CAV2 interacted with the PACT protein and disrupted the PACT-PKR axis via the ubiquitin–proteasome pathway. Notably, CAV2 deficiency synergized with Cetuximab treatment, reducing the the half maximal inhibitory concentration (IC₅₀) value by 6-fold compared with control cells and suppressing tumor growth by 48.41% in xenograft models compared to Cetuximab monotherapy (p < 0.0001). Conclusions: In conclusion, these findings establish CAV2 as a critical regulator of HNSCC progression and Cetuximab sensitivity via post-translational modulation of the PACT–PKR axis. Targeting the CAV2/PACT/PKR axis may therefore represent a promising therapeutic strategy to potentiate the efficacy of EGFR-targeted therapy in patients with HNSCC. Full article

Transcription factors that control stem cell programs are central drivers of cancer progression, metastasis, and therapy resistance. ARID3B, a DNA-binding protein overexpressed across multiple tumor types, expands the cancer stem cell population by regulating these pathways. Yet, how ARID3B is regulated remains largely unknown. Here, we uncover phosphorylation at Serine 89 as a critical switch controlling ARID3B localization and function. We used site-directed mutagenesis to generate phospho-dead (S89A) and phospho-mimetic (S89D) ARID3B constructs, and we generated a phospho-specific antibody for S89. With these tools, we showed that phosphorylation confines ARID3B to the nucleus in ovarian cancer and glioblastoma cells, as well as in human tissues, while unphosphorylated ARID3B can localize to the nucleus, cytoplasm, and membrane. Functionally, S89D mirrors wild-type ARID3B in regulating key transcriptional programs, whereas S89A diverges, consistent with altered subcellular localization. Chromatin immunoprecipitation confirms that direct gene regulation is enhanced in WT ARID3B and S89D compared to cells expressing S89A. Collectively, these findings reveal phosphorylation as a previously unrecognized molecular switch that dictates ARID3B’s localization and transcriptional activity, providing novel insights into cancer stem cell regulation and identifying a potential targetable vulnerability in aggressive tumors. Full article

Background: Lipoprotein(a) [Lp(a)] is a genetically determined risk factor for atherosclerotic cardiovascular disease (ASCVD). Proteomic studies suggest that Lp(a)-associated proteins mediate inflammation, thrombosis, and vascular calcification, but methodological variability may influence proteome definition. Methods: Lp(a) was immunoprecipitated from human plasma using an apo(a)-specific monoclonal antibody and analyzed by mass spectrometry following either in-gel digestion or automated in-solution proteolysis. Proteins identified by ≥3 unique peptides and consistently detected across all samples by both methods were considered high confidence. Functional enrichment and interaction networks were assessed using STRING. Results: In-solution proteolysis identified 92 proteins and in-gel digestion identified 55 proteins, with 34 proteins shared between methods. These high-confidence proteins were enriched for pathways involved in lipoprotein remodeling, coagulation regulation, vesicle-mediated transport, lipid binding, and extracellular matrix organization, providing biological insight into mechanisms linking Lp(a) to inflammation, thrombosis, and calcification. Conclusions: Proteome composition of Lp(a) is method-dependent; however, a rigorously defined core proteome of 34 proteins was consistently identified across analytical approaches, highlighting biologically relevant pathways that may underlie Lp(a)-mediated ASCVD risk. Full article

Background: Excessive abdominal fat deposition is a major challenge in the chicken farming industry, making it essential to elucidate the molecular mechanisms underlying chicken adipogenesis. Nuclear Respiratory Factor 1 (NRF1) has been reported to suppress chicken adipogenesis by downregulating peroxisome proliferator-activated receptor gamma (PPARγ) expression. Protein Phosphatase 1 Catalytic Subunit Gamma (PPP1CC) is a multifunctional phosphatase involved in various biological processes; however, its role in chicken adipogenesis remains unclear. Objective: This study aimed to investigate the functional role and underlying mechanism of PPP1CC in chicken preadipocyte differentiation. Methods: Co-immunoprecipitation (Co-IP) and immunofluorescence assays were performed to determine the interaction between PPP1CC and NRF1 in DF1 cells. Bioinformatic analysis predicted potential NRF1 dephosphorylation sites targeted by PPP1CC, based on which NRF1 mutants mimicking dephosphorylation were constructed. Phos-tag SDS-PAGE combined with Western blot analysis were used to verify PPP1CC-mediated dephosphorylation of wild-type NRF1. Dual-luciferase reporter assays were used to evaluate the effect of PPP1CC-mediated dephosphorylation on NRF1-regulated PPARγ P1 promoter transcriptional activity. ChIP-qPCR was employed to assess the occupancy of NRF1 to the PPARγ P1 promoter upon PPP1CC overexpression. The effect of PPP1CC overexpression was assessed on preadipocyte differentiation using Oil Red O staining and marker gene expression analysis. Results: PPP1CC interacted with NRF1 in both the cytoplasm and nucleus of DF1 cells. Overexpression of PPP1CC significantly promoted NRF1 dephosphorylation during oleic acid-induced preadipocyte differentiation and increased endogenous NRF1 expression. Moreover, dual-luciferase assays showed that while PPP1CC strengthened the inhibitory effect of wild-type NRF1 on PPARγ P1 promoter transcriptional activity, it exerted no additional suppression on the already low activity mediated by the dephosphorylation-mimicking NRF1 mutants. Consistently, ChIP-qPCR results demonstrated that PPP1CC overexpression enhanced the occupancy of NRF1 to the PPARγ P1 promoter. Functional assays revealed that PPP1CC overexpression significantly inhibited chicken preadipocyte differentiation. Conclusions: PPP1CC interacts with NRF1 and promotes its dephosphorylation, enhancing NRF1-mediated suppression of PPARγ transcription and ultimately inhibiting chicken preadipocyte differentiation. These results identify the PPP1CC–NRF1–PPARγ regulatory axis and provide a potential molecular target for controlling fat deposition in broiler chickens. Full article

Pyruvate kinase M2 (PKM2) influences meat quality through glycolysis and also exhibits its moonlighting function as a protein kinase that catalyzes protein phosphorylation. However, it remains unclear whether PKM2 phosphorylates myofibrillar proteins, thereby affecting postmortem myofibrillar protein stability. This study investigates PKM2’s non-canonical kinase function using quantitative phosphoproteomics and an in vitro myofibrillar protein incubation model to identify its phosphorylation substrates and functional impacts. The quantitative phosphoproteomics identified 441 phosphoproteins, 881 phosphopeptides, and 1040 phosphorylation sites. Notably, the myosin regulatory light chain (MRLC) was identified as a likely candidate phosphorylation substrate of PKM2 in vitro. The interaction between PKM2 and MRLC was confirmed using co-immunoprecipitation (Co-IP) and Western blotting. Furthermore, MRLC phosphorylation by PKM2 significantly inhibited its degradation and enhanced its stability. This work establishes an in vitro biochemical framework for the moonlighting role of glycolytic enzymes, suggesting a potential mechanistic pathway that might influence myofibrillar protein stability during meat aging. Full article

Acyl-CoA carboxylase (YCC) complexes generate essential starter and extender units for fatty acid and polyketide biosynthesis in Actinobacteria. In Streptomyces coelicolor, two tri-subunit YCC complexes, acetyl-CoA carboxylase (ACC) and propionyl-CoA carboxylase (PCC), have been characterized. However, comparative genomic analyses indicate that β/ε subunits are more diversified than currently appreciated. Here, we identify a previously unrecognized β/ε pair, AccB2 and AccE2, and demonstrate that they assemble with the canonical α subunit to form a functional YCC complex. Both genes are transcribed in vivo, and co-immunoprecipitation (Co-IP) reveals association with AccA1 and AccA2, with AccE2 showing stronger relative association with AccA1-containing pull-downs. In vitro reconstitution confirms carboxylation activity toward acetyl-CoA, propionyl-CoA, and butyryl-CoA, which is strongly dependent on AccE2. These findings expand the YCC repertoire in S. coelicolor and support a modular assembly model in which alternative β/ε combinations contribute to functional diversification of YCC complexes. Full article

Background: While neutrophil extracellular traps (NETs) have been shown to contribute to cancer progression, including that of lung adenocarcinoma, the mechanisms underlying NET formation within the tumor immune microenvironment (TIME) remain incompletely understood. Notably, neutrophil infiltration has been strongly linked to tumor necrosis factor alpha-inducible protein 6 (TNFAIP6) expression. Methods: In vitro and in vivo experiments were performed. DNA pulldown coupled with mass spectrometry, bioinformatics analyses, immunohistochemistry, and dual-luciferase reporter assays were conducted. DNA pulldown Western blotting, chromatin immunoprecipitation–quantitative PCR, and dual-luciferase reporter assays using truncated promoter constructs were also employed. Results: TNFAIP6 expressed by lung adenocarcinoma cells was shown to induce NET formation (a form of programmed cell death called NETosis). Mechanistically, TNFAIP6 interacted with CD44 in lung adenocarcinoma cells, leading to increased extracellular availability of secreted phosphoprotein 1 (SPP1) within the TIME and the subsequent promotion of NETosis. Additionally, nucleophosmin 1 (NPM1) significantly enhances the transcriptional activation of TNFAIP6 and associates with the −2000 to −1700 bp region of its promoter. Conclusions: These findings delineate a regulatory model in which lung adenocarcinoma cells directly stimulate NETosis through the NPM1–TNFAIP6–CD44–SPP1 axis, suggesting that therapeutic targeting of this pathway may attenuate tumor progression. Full article

N6-methyladenosine (m⁶A) is a reversible RNA modification that dynamically regulates gene expression by modulating RNA stability, splicing, nuclear export, translation, and maturation—thereby orchestrating organismal development. In birds, including geese, the liver is a multi-functional organ central to metabolic regulation. Studies on the dynamic patterns of RNA m⁶A modifications during healthy liver growth and development remain limited. Here, we performed integrative methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) on liver tissues from geese at three biologically defined stages: post-hatch day 0 (0 week, P), fast growth (10 weeks, F), and sexual maturation (30 weeks, S). The level of m⁶A modification in total RNA extracted from liver tissues was higher in P than in F samples. Compared with other groups, the S group recorded the lowest m⁶A modification. In addition, 1641, 668, and 558 m⁶A peaks were differentially modified in the P, F, and S groups, respectively. The m⁶A peaks in the liver of the three groups were mainly enriched in the coding sequence and 3′ untranslated region. Moreover, integrated multi-omics analysis (MeRIP-seq and RNA-seq), combined with protein–protein interaction networks analysis, identified CDK1 as a core cell cycle regulator and IGF2BP3—a well-established m⁶A reader—as a consistently differentially expressed gene across all developmental stages. The m⁶A-regulated cell cycle, p53 signaling pathway, and pyrimidine metabolism pathway were identified in liver tissue as novel potential targets for controlling geese growth and metabolism. Together, these findings shed light on the dynamic regulation of RNA methylation during distinct growth phases in geese and advance our understanding of epigenetic mechanisms underlying poultry liver development. Full article

Cellular therapy using human cardiac mesenchymal progenitor cells (hMPCs) for regenerative medicine is hindered by poor cell survival and senescence. Long non-coding RNAs (lncRNAs) are critical regulators of cellular processes, yet their role in cardiac aging remains underexplored. Here, lncRNA microarray profiling identified a novel lncRNA, XLOC_002543, upregulated in hMPCs preconditioned with cobalt protoporphyrin (CoPP), which was named CoPP-Induced and SFPQ-Associated RNA Transcript (CISAT) due to its interaction with splicing factor proline and glutamine rich (SFPQ), confirmed via RNA pull-down and immunoprecipitation. CISAT was the only highly expressed transcript among seven lnc-ANKMY1-5 variants in hMPCs, as shown by RT-PCR. Notably, CISAT expression decreased in aging/senescent hMPCs, correlating with elevated p16^INK4A, a senescence marker. Overexpression of CISAT reduced p16^INK4A levels; enhanced hMPC survival, proliferation, and migration; and increased antioxidant and anti-apoptotic protein expression, while CISAT knockdown reduced resistance to H₂O₂-induced oxidative stress. In vivo, intramyocardial transplantation of CISAT-overexpressed hMPCs in an immune-deficient murine myocardial infarction model reduced fibrosis, promoted angiogenesis, and preserved cardiac function. Mechanistically, CISAT interacts with SFPQ to regulate NRF2-mediated redox homeostasis and inhibits p38 MAPK phosphorylation, mitigating senescence and enhancing cell survival. These findings suggest that targeting CISAT to modulate redox signaling and p38 MAPK pathways in aging hMPCs could improve their therapeutic efficacy for myocardial repair in heart disease. Full article

The transcription factor c-Myc is known to regulate DNA replication via a non-transcriptional mechanism by interacting with proteins of the pre-replicative complex. In addition, c-Myc localizes to DNA replication foci, similarly to Proliferating Cell Nuclear Antigen (PCNA); however, the significance of this localization remains unclear. Here, we investigated whether c-Myc interacts with PCNA and analyzed the possible function of this association. We found a conserved interaction motif, the PCNA-interacting protein (PIP) box, in the N-terminal region of c-Myc. Confocal microscopy analysis showed co-localization with PCNA in early S-phase, but not in late S-phase cells. Co-immunoprecipitation from cell extracts and pull-down of recombinant proteins indicated a direct physical association between c-Myc and PCNA, which was confirmed in situ by the Proximity Ligation Assay (PLA). Further experiments demonstrated that c-Myc interacts with CUL4A and DDB1, components of the Cullin Ring E3 ubiquitin ligase 4 (CRL4) complex, in which PCNA functions as a cofactor. Mutations in the PIP box of c-Myc, as well as depletion of CUL4A by RNA interference, resulted in an increased stability of c-Myc protein. These results suggest that the interaction with PCNA functionally contributes to the regulation of c-Myc stability in early S phase via the CRL4 complex. Full article

Context: S-phase kinase-associated protein 2 (SKP2) is an oncogene and cell cycle regulator that mediates the ubiquitination of cell cycle regulators. Curcumol, a sesquiterpene natural product, has been reported to regulate SKP2-mediated ubiquitination degradation to overcome drug resistance in cancer cells. However, whether the cell cycle arrest effect of curcumol is related to SKP2’s function in cancer cells and its mechanisms are still unclear. Objective: To investigate the role of SKP2 in curcumol-induced cell cycle arrest and its underlying mechanisms. Materials and Methods: Transcriptomic and proteomic analyses were used to screen the ubiquitination-related factors in curcumol treated hepatocellular carcinoma cells. Lentiviral overexpression, co-immunoprecipitation assays, ubiquitination analysis, and cell-line-derived xenograft (CDX) models were used to dissect the role and mechanisms of the identified ubiquitination-related factor in the cell cycle arrest effect of curcucmol. Results: Curcumol modulated the expression of CDK4, CDK6, Cyclin D1, p27 and SKP2. SKP2 was one candidate target of curcumol selected by multi-omics. Overexpressed SKP2 partially reversed curcumol-induced growth inhibition and G1-phase arrest. The increased expression of p27 induced by curcumol was attenuated by overexpressed SKP2. Curcumol impaired the interaction between SKP2 and p27, and led to the ubiquitination and degradation of p27. In vivo, curcumol effectively reduced tumor growth, and its antitumor effect was significantly mitigated by SKP2 overexpression. Discussion and Conclusions: Curcumol reduced SKP2 expression, weakened the interaction between SKP2 and p27, inhibited degradation of p27, and then induced G1 phase cell-cycle arrest in SK-Hep-1 cells. Full article

Brucella is a neglected foodborne pathogen, which contaminates milk, dairy products, meat, and meat products of infected animals. However, the role of the Brucella putative effector (BPE) protein family, which relies on the type IV secretion system (T4SS) in Brucella abortus, remains unclear. We demonstrated that BPE159 mediates the regulation of host nuclei in autophagy. The host-interacting protein Eci1 was screened using yeast two-hybridization, molecular docking, and immunoprecipitation, and BPE159-deleted (ΔBPE159) and complementary (ΔBPE159-C) strains were constructed by homologous recombination. We evaluated their growth, survival, and replication and measured the expression of autophagy-related cytokine mRNAs in macrophages. BPE159 was localized in the nucleus of host cells and interacted with Eci1 to downregulate the expression of macrophage autophagy factors, thereby inhibiting host autophagy and enabling the persistence of Brucella. These findings highlight the critical role of BPE159 in mediating autophagy through Eci1 in host cells to promote Brucella survival in host cells. Full article

Avian reovirus (ARV) is a major poultry pathogen recently recognized for its potential as an oncolytic virus that selectively infects and kills cancer cells without harming healthy human cells. However, the receptors mediating ARV entry into cancer cells remain unclear. Using mouse melanoma B16-F10 cells as a model, this study identified ARV-binding receptor candidates through viral overlay protein binding assay (VOPBA), SDS-PAGE, and LC-MS/MS analysis. Plaque-forming assays (PFAs) evaluated viral replication efficiency, while co-immunoprecipitation (Co-IP) and proximity ligation assay (PLA) confirmed direct interactions between viral σC and host receptor proteins. Functional assays using shRNA knockdown and antibody blocking demonstrated that inhibition of Plg-RKT expression markedly reduced ARV infection. Western blot analysis revealed that ARV binding to Plg-RKT activates Src and p38 MAPK signaling pathways, which promote caveolin-1 phosphorylation and caveolae-mediated endocytosis. These findings identify Plg-RKT as a crucial receptor mediating ARV σC binding and entry into B16-F10 melanoma cells. Furthermore, activation of Src-p38 MAPK signaling was shown to be essential for viral internalization. This study elucidates the molecular mechanism underlying ARV entry into melanoma cells and provides valuable insight for improving the selectivity and therapeutic potential of ARV as an oncolytic virus. Full article