Biology Direct最新文献

Background: SARS-CoV-2 papain-like protease (PLpro) is essential for viral replication and immune evasion. It contains an N-terminal ubiquitin-like (Ubl) domain, whose involvement in enzymatic function remains poorly understood.

Results: In this study, we investigated the role of the Ubl domain in modulating the structural dynamics and catalytic efficiency of PLpro. Using molecular dynamics (MD) simulations, inhibitor binding assays, and steady-state kinetic analyses, we found that the Ubl domain stabilizes critical structural elements, notably the ridge helix in the thumb subdomain. Removal of the Ubl domain altered substrate processing, reducing catalytic efficiency of the enzyme. Interestingly, free ubiquitin enhanced enzymatic activity, likely via non-canonical binding sites distinct from the SUb1 and SUb2 sites.

Conclusion: These findings uncover a regulatory role for the Ubl domain in allosteric modulation of PLpro activity and reveal additional layers of enzymatic plasticity. Understanding these mechanisms could guide the design of future antiviral therapeutics targeting PLpro's regulatory or allosteric sites.

Background: Advancements in precision oncology have generated increased interest in the prognostic and therapeutic capabilities of transcription factors, among which HMGA1 is significantly correlated with LUAD prognosis. However, our understanding of HMGA1 remains insufficient. This study seeks to elucidate the biological functions of HMGA1 and to investigate the underlying mechanisms.

Methods: The prognostic value of HMGA1 was validated across multiple independent patient cohorts with LUAD, and its impact on tumor proliferation was verified by both in vitro and in vivo models. A series of experiments were performed to investigate the underlying molecular mechanism, including RNA sequencing, co-immunoprecipitation and chromatin immunoprecipitation.

Results: HMGA1 plays a crucial role in promoting the proliferation of LUAD. The underlying mechanism involves the recruitment of STAT1 to the promoter region of DDAH1, which synergistically increases its transcription and subsequently activates the ADMA/NO signaling pathway. Notably, the STAT1 inhibitor fludarabine has been shown to effectively impede the progression of LUAD models characterized by high levels of HMGA1.

Conclusion: Our research reveals a previously unrecognized mechanism through which the HMGA1/STAT1 complex facilitates LUAD proliferation by transcriptionally activating DDAH1. Moreover, we propose that fludarabine could serve as a promising therapeutic option for LUAD patients exhibiting elevated levels of HMGA1.

Background: Hepatocellular carcinoma (HCC) is significantly influenced by hepatitis B virus (HBV) infection. However, the roles of ferroptosis and ubiquitination modifications in this context remain poorly understood.

Methods: In this study, we utilized immunoprecipitation, immunofluorescence, and analysis of ubiquitin modifications to explore the regulatory mechanisms of MINPP1 in ferroptosis and its effects on tumor progression. Further mechanistic studies revealed that ZRANB1 regulates the K33-linked ubiquitination of CTSB. Ultimately, the contribution of the MINPP1-CTSB axis to tumor progression was validated using in vivo experiments.

Results: Our study demonstrates that MINPP1 regulates ferroptosis in HBV-positive HCC cells via a glycolytic bypass mechanism. Bioinformatics analysis indicates that MINPP1 stabilizes CTSB, thereby participating in the regulation of ferroptosis. Specifically, MINPP1 modulates K33-linked deubiquitination of CTSB through ZRANB1, which stabilizes CTSB expression and identifies its deubiquitination site. In contrast, the MINPP1-ZRANB1-CTSB axis does not regulate ferroptosis in HBV-negative HCC cells. However, upon the introduction of HBV into these cells, the MINPP1-ZRANB1-CTSB axis becomes active and promotes ferroptosis. Finally, in vivo assays showed that MINPP1 regulates tumor progression by regulating K33-linked ubiquitination of CTSB, thereby affecting ferroptosis levels.

Conclusion: Our research showed outcomes suggest that the MINPP1-ZRANB1-CTSB axis promotes ferroptosis in HBV-positive HCC cells through glycolysis, emphasizing the function of MINPP1 in mediating ferroptosis in HBV-related HCC cells via CTSB deubiquitination modification. This provides valuable insights and a foundation for the treatment of HBV-associated HCC.

Pseudomonas aeruginosa, one of the most prevalent pathogens, is notorious for its multidrug resistance, necessitating novel therapeutic strategies. Phage therapy has emerged as a promising alternative treatment strategy, which offers a dual advantage by directly killing bacteria and modulating host-pathogen interactions. Here, we identify PavP (PaoP5_160), a small protein encoded by bacteriophage PaoP5, which exhibits bacteriostatic activity on P. aeruginosa while altering virulence pathways at sub-inhibitory concentrations. Specifically, PavP impairs bacterial motility, enhances biofilm formation, and upregulates type 3 secretion system expression. The global transcriptome analysis shows that PavP modulates multiple pathways which participate in the pathogenicity and cell vitality of host bacteria. Crucially, in vivo virulence assays confirm that PavP attenuates P. aeruginosa pathogenicity. Our results reveal PavP as a multifunctional virulence modulator in P. aeruginosa, which highlights its potential as a dual-target antimicrobial agent capable of simultaneously restricting bacterial proliferation and disrupting virulence networks.

Background: Cholangiocarcinoma (CCA) is an aggressive malignancy with limited treatment options. Despite the approval of chemotherapy and immune checkpoint inhibitors (ICIs) in clinical practice, treatment outcomes remain poor, largely due to the poorly immunogenic tumor microenvironment associated with this type of carcinoma. Necroptosis, an inflammatory form of programmed cell death, has emerged as a promising therapeutic target for stimulating antitumor immunity. Our previous study linked necroptosis to increased CD8 + T cell infiltration and T cell-induced PD-L1 expression in CCA cells, suggesting its role in enhancing ICI efficacy. However, the underlying mechanisms by which necroptosis-activated T cells induce PD-L1 expression remain unclear. Here, we investigate how necroptosis in CCA cells influences T cell response, which subsequently promotes PD-L1 expression, thus providing insights for optimizing necroptosis-based therapies in combination with ICIs.

Results: Conditioned medium from gemcitabine-induced necroptotic CCA cells triggers PBMC-derived T cell activation by upregulating the surface activation marker CD69 and promoting cytokine release, primarily IL-6 and IL-1β. This cytokine release subsequently induces PD-L1 expression in CCA cells via IL-6, as confirmed by IL-6 neutralizing antibodies. Furthermore, T cell killing assays demonstrated that pembrolizumab, an anti-PD-1 inhibitor, enhances T cell cytotoxicity against PD-L1-upregulated CCA cells. Additionally, bioinformatics analysis identified an IL-6 signaling-related gene signature associated with ICI responsiveness, suggesting potential biomarkers for personalized treatment strategies.

Conclusion: This study highlights that necroptosis shapes the tumor immune microenvironment by promoting T cell activation and IL-6-mediated PD-L1 upregulation in CCA cells. These findings support the integration of necroptosis-based therapies with ICIs as a sequential chemo-immunotherapy strategy. Additionally, the identified IL-6 signaling-related gene signature may serve as a biomarker for patient stratification and personalized treatment in CCA.

Background: Despite therapeutic advances, metastatic melanoma, and particularly brain metastasis (MBM), remains a lethal burden for patients. Existing single-cell studies offer a more detailed view of melanoma and its microenvironment, which is crucial to improve diagnosis and treatment.

Results: We here present a computational reanalysis of single-nucleus data comparing 15 MBM and 10 extracranial melanoma metastases (ECM), considering recent best practice recommendations. We used cell type-specific pseudobulking and omit imputation during patient integration to gain complementary insights. Interestingly, our analysis revealed high homogeneity in tumor cell expression profiles within and between MBM and ECM. However, MBM displayed even higher homogeneity but a more flexible energy metabolism, suggesting a specific metastatic adaptation to the putatively more restricted brain microenvironment. While tumor cells were homogeneous, the metastasis microenvironment, especially lymphocytes and related immune-tumor interaction pathways, exhibited greater divergence between MBM and ECM. Overall, this suggests that major differences between MBM and ECM are potentially driven by variations in their microenvironment. Finally, a comparison of single-cell data to previous bulk studies, including their deconvoluted putative cell types, showed significant differences, potentially causing divergent conclusions.

Conclusion: Our study contributed to refine the understanding of differences between MBM and ECM, suggesting these are potentially more influenced by their local microenvironments. Future research and therapies could possibly focus on the metabolic flexibility of melanoma brain metastases and patient-specific immune pathway alterations.

Background: Psoriasis is an immune-mediated chronic inflammatory condition characterized by significant neutrophil infiltration in the skin. Given that the spleen is the largest peripheral immune organ in the body, it is important to investigate whether it has any impact on skin inflammation in psoriasis.

Methods: To investigate this mechanism, a psoriatic mouse model was established by IMQ application. Flow cytometry and immunohistochemistry analyses were performed to determine the percentage of various immune cells in the spleen. The role of neutrophils was specifically assessed using the anti-Gr-1 antibody. Splenic granulopoiesis was evaluated using EdU labeling. To understand the spleen's role in skin inflammation, splenectomy was performed on the experimental mice. IL-6 levels were measured by ELISA, and P-STAT3 in neutrophils was detected via immunofluorescence. Further examination of IL-6's effects on neutrophil formation involved treating mice with IL-6 antibody. The severity of psoriasis was evaluated through histological staining and PASI scoring.

Results: Our study revealed that the spleens of psoriatic mice were enlarged compared to those of vehicle mice. Among immune cell populations, neutrophils showed the most significant changes, with marked increases in both spleen and skin of psoriatic mice and patients, contributing to disease progression. Post-splenectomy, neutrophil infiltration in the skin was reduced by approximately 60% in psoriatic mice. This indicates that the neutrophils in the skin were primarily derived from the spleen. Additionally, the spleen showed a notable capacity for granulopoiesis with elevated neutrophils. Moreover, we found elevated IL-6 levels in the skin, blood, and spleen in the model, which was decreased after splenectomy. Treatment with an IL-6 antibody reduced neutrophil formation in both the spleen and skin, which alleviated skin inflammation in psoriatic mice. Additionally, P-STAT3 signaling was decreased following IL-6 antibody treatment. The neutrophil infiltration in spleen and skin was decreased after injection with the inhibitor of P-STAT3, which also alleviated the inflammation of psoriatic model. Thus, IL-6 served as the dominant regulator of spleen granulopoiesis, a process potentially mediated by P-STAT3 signaling.

Conclusions: The spleen plays a crucial role in the immune microenvironment of psoriasis as a major site of granulopoiesis, influencing neutrophil infiltration in the skin of psoriatic mice. Additionally, IL-6 is a key regulator of neutrophil formation in the spleen of psoriatic mice, likely through P-STAT3-dependent mechanisms.