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Biology subjects

Xu, Y.

Publications and source records attributed to Xu, Y..

At least 361 records · Page 20Linked to original sources

RAS/PI3K pathway mutations sensitise epithelial ovarian cancer cells to a PARP/NAMPT inhibitor combination

The combination of PARP and NAMPT inhibitors (PARPi/NAMPTi) has been explored for the treatment of TNBC, Ewing Sarcoma and high grade serous carcinoma (HGSC). However, dose limiting toxicity has hampered NAMPTi in clinical trials. To maximise the therapeutic window, we set out to identify predictive genomic biomarkers. Bioinformatic analysis and screening of a panel of epithelial ovarian cancer (EOC) cell lines revealed that cells with RAS/PI3K pathway mutations were sensitive to the NAMPTi FK866. Activity of olaparib and FK866 was associated with a reduction in nicotinamide mononucleotide (NMN) and the PARP substrate nicotinamide adenine dinucleotide (NAD+), with coincident increases in ROS production, DNA damage and apoptosis induction. Caspase 3/7 activity was upregulated to a greater extent in RAS/PI3K mutant cell lines. Finally, the combination significantly reduced omental tumour weight and increased overall survival in mice injected with ID8 Trp53-/-;Pten-/- cells. This study highlights the potential of the PARPi/NAMPTi combination in RAS/PI3K pathway mutant EOC.

cancer biology↗

Advanced deep-tissue imaging and manipulation enabled by biliverdin reductase knockout.

We developed near-infrared (NIR) photoacoustic and fluorescence probes, as well as optogenetic tools from bacteriophytochromes, and enhanced their performance using biliverdin reductase-A knock-out model (Blvra-/-). Blvra-/- elevates endogenous heme-derived biliverdin chromophore for bacteriophytochrome-derived NIR constructs. Consequently, light-controlled transcription with IsPadC-based optogenetic tool improved up to 25-fold compared to wild-type cells, with 100-fold activation in Blvra-/- neurons. In vivo, light-induced insulin production in Blvra-/- reduced blood glucose in diabetes by [~]60%, indicating high potential for optogenetic therapy. Using 3D photoacoustic, ultrasound, and two-photon fluorescence imaging, we overcame depth limitations of recording NIR probes. We achieved simultaneous photoacoustic imaging of DrBphP in neurons and super-resolution ultrasound localization microscopy of blood vessels [~]7 mm deep in the brain, with intact scalp and skull. Two-photon microscopy provided cell-level resolution of miRFP720-expressing neurons [~]2.2 mm deep. Blvra-/- significantly enhances efficacy of biliverdin-dependent NIR systems, making it promising platform for interrogation and manipulation of biological processes.

cell biology↗

Multi-modal profiling identifies CD4+CXCR5+PD-1- Tfh cells as prognostic and predictive biomarkers for response to R-CHOP therapy in human DLBCL

Despite the improvements in clinical outcomes for patients with Diffuse Large B-Cell Lymphoma (DLBCL), a significant proportion of those patients still face challenges with refractory/relapsed (R/R) disease after receiving first-line R-CHOP treatment. Characterizing the heterogeneity of the tumor microenvironment (TME) in diffuse large B cell lymphoma (DLBCL) is crucial for understanding relapsed/refractory disease. However, the complex and diverse nature of the TME has impeded progress. Here, using single-cell RNA sequencing(scRNA-seq), we explored the DLBCL landscape at single-cell resolution, profiling 77,344 cells from both primary and relapsed DLBCL patients. We further investigated the shared and distinct molecular and cellular features of tumor microenvironment in both primary and relapsed DLBCL tumors by integrating next-generation DNA sequencing data and multiple scRNA-seq datasets from total 72,351 cells. Our results demonstrated that there was a significant decrease of CD4+CXCR5+PD-1- Tfh cells, along with excessive activation of the TNF-NF{kappa}B signaling pathways in malignant B cells in R/R disease. Furthermore, by using multiplex IHC, we confirmed that CD4+CXCR5+PD-1- Tfh cells are prognostic and predictive biomarkers for response to R-CHOP treatment. As a proof of concept, we successfully generated mutilplexed images of CD4+CXCR5+PD-1- Tfh cells from a single DAPI staining in human DLBCL tissues through using generative artificial intelligence. Our study offers critical insights into the heterogeneity and molecular features of DLBCL, shedding light on the crucial role of CD4+CXCR5+PD-1- Tfh cells in the recurrent process. HighlightsO_LIShared and distinct molecular and cellular features of tumor microenvironment in both primary and relapsed DLBCL tumors; C_LIO_LIThe characteristic of relapsed DLBCL TME is a dysfunctional immune microenvironment with a significant decrease of CD4+CXCR5+PD-1- Tfh cells. C_LIO_LICD4+CXCR5+PD-1- Tfh cells are prognostic and predictive biomarkers for response to R-CHOP treatment C_LIO_LIDetermination of CD4+CXCR5+PD-1- Tfh cells in human DLBCL tissues through using generative artificial intelligence. C_LI

immunology↗

Modeling Thoracic Aortic Dissection Using Patient-Specific iPSCs Reveals VSMC Dysfunction and Extracellular Matrix Dysregulation

Thoracic aortic dissection (TAD) is a life-threatening condition characterized by medial degeneration and vascular smooth muscle cell (VSMC) dysfunction, with no effective medical therapy currently available. The underlying pathological mechanisms of TAD remain incompletely understood. In this study, we used a non-integrated episomal vector-based reprogramming system to generate induced pluripotent stem cells (iPSCs) from TAD patients and healthy controls. Both TAD and normal iPSCs expressed key pluripotency markers and were capable of differentiating into the three germ layers in vitro. These iPSCs were differentiated into VSMCs through a mesodermal intermediate for disease modeling. VSMCs derived from both TAD and normal iPSCs expressed smooth muscle -actin (-SMA), calponin, and SM22. However, TAD-iPSC-derived VSMCs exhibited significantly reduced contraction in response to carbachol stimulation compared to their normal counterparts. Whole-exome sequencing identified a mutation in the COL4A2 gene (c.392G>T, p. R131M) in TAD-iPSCs. This mutation was associated with reduced collagen IV expression and increased expression of collagen I and III in TAD-VSMCs, both with and without TGF-{beta} stimulation. Furthermore, noncanonical TGF-{beta} signaling was hyperactivated in TAD-VSMCs, accompanied by elevated MMP9 expression. This patient-specific iPSC model reveals key dysfunctions in VSMC contractility, extracellular matrix protein expression, and dysregulated TGF-{beta} signaling, which may contribute to TAD pathogenesis. Our findings provide new insights into the molecular mechanisms driving TAD and offer a platform for future therapeutic development.

pathology↗

Quantitative proteomic mass spectrometry of protein kinases to determine dynamic heterogeneity of the human kinome

The kinome is a dynamic system of kinases regulating signaling networks in cells and dysfunction of protein kinases contributes to many diseases. Regulation of the protein expression of kinases alters cellular responses to environmental changes and perturbations. We configured a library of 672 proteotypic peptides to quantify >300 kinases in a single LC-MS experiment using ten micrograms protein from human tissues including biopsies. This enables absolute quantitation of kinase protein abundance at attomole-femtomole expression levels, requiring no kinase enrichment and less than ten micrograms of starting protein from flash-frozen and formalin fixed paraffin embedded tissues. Breast cancer biopsies, organoids, and cell lines were analyzed using the SureQuant method, demonstrating the heterogeneity of kinase protein expression across and within breast cancer clinical subtypes. Kinome quantitation was coupled with nanoscale phosphoproteomics, providing a feasible method for novel clinical diagnosis and understanding of patient kinome responses to treatment.

biochemistry↗

Proteolysis-targeting vaccines (PROTAVs) for robust tumor combination immunotherapy

Protein/peptide subunit vaccines are promising to promote the tumor therapeutic efficacy of immune checkpoint blockade (ICB). However, current protein/peptide vaccines elicit limited antitumor T cell responses, leading to suboptimal therapeutic efficacy. Here, we present proteolysis-targeting vaccines (PROTAVs) that facilitate antigen proteolytic processing and cross-presentation to potentiate T cell responses for robust ICB combination immunotherapy of melanoma. PROTAVs are modular conjugates of protein/peptide antigens, E3 ligase-binding ligands, and linkers. In antigen-presenting cells (APCs), PROTAVs bind to E3 ligases to rapidly ubiquitinate PROTAV antigens, facilitating antigen proteolytic processing by proteasome, and thereby promoting antigen cross-presentation to T cells and potentiating CD8+ T cell responses. We developed a melanoma PROTAV using a tandem peptide of trivalent melanoma-associated antigens. Co-delivered by lipid nanoparticles (LNPs) with bivalent immunostimulant adjuvants, this PROTAV promotes the quantity and quality of melanoma-specific CD8+ T cells in mice. Further, combining PROTAV and ICB ameliorates the immunosuppressive melanoma microenvironment. As a result, PROTAV and ICB combination enhances melanoma complete regression rates and eradicated 100% large BrafV600E melanoma without recurrence in syngeneic mice. PROTAVs hold the potential for robust tumor combination immunotherapy.

bioengineering↗

Mitigation of multi-scale biases in cell-type deconvolution for spatially resolved transcriptomics using HarmoDecon

The advent of spatially resolved transcriptomics (SRT) has revolutionized our understanding of tissue molecular microenvironments by enabling the study of gene expression in its spatial context. However, many SRT platforms lack single-cell resolution, necessitating cell-type deconvolution methods to estimate cell-type proportions in SRT spots. Despite advancements in existing tools, these methods have not addressed biases occurring at three scales: individual spots, entire tissue samples, and discrepancies between SRT and reference scRNA-seq datasets. These biases result in overbalanced cell-type proportions for each spot, mismatched cell-type fractions at the sample level, and data distribution shifts across platforms. To mitigate these biases, we introduce HarmoDecon, a novel semi-supervised deep learning model for spatial cell-type deconvolution. HarmoDecon leverages pseudo-spots derived from scRNA-seq data and employs Gaussian Mixture Graph Convolutional Networks to address the aforementioned issues. Through extensive simulations on multi-cell spots from STARmap and osmFISH, HarmoDecon outperformed 11 state-of-the-art methods. Additionally, when applied to legacy SRT platforms and 10x Visium datasets, HarmoDecon achieved the highest accuracy in spatial domain clustering and maintained strong correlations between cancer marker genes and cancer cells in human breast cancer samples. These results highlight the utility of HarmoDecon in advancing spatial transcriptomics analysis.

bioinformatics↗

TET2 contributes to gluconeogenesis and pathology of type 2 diabetes

The control of gluconeogenesis is critical for glucose homeostasis and the pathology of type 2 diabetes (T2D). Here, we uncover a novel function of TET2 in the regulation of gluconeogenesis. In mice, both fasting and a high-fat diet (HFD) stimulate the expression of TET2, and TET2 knockout impairs glucose production. Mechanistically, FBP1, a rate-limiting enzyme in gluconeogenesis, is positively regulated by TET2 in liver cells. TET2 is recruited by HNF4, contributing to the demethylation of FBP1 promoter and activating its expression in response to glucagon stimulation. Moreover, metformin treatment increases the phosphorylation of HNF4 on Ser313, which prevents its interaction with TET2, thereby decreasing the expression level of FBP1 and ameliorating the pathology of T2D. Collectively, we identify an HNF4-TET2-FBP1 axis in the control of gluconeogenesis, which contributes to the therapeutic effect of metformin on T2D and provides a potential target for the clinical treatment of T2D.

cell biology↗

PRESSED FLOWER works downstream of ASYMMETRIC LEAVES 2 to affect sepal flatness in Arabidopsis

The development of flattened organs such as leaves and sepals is essential for proper plant function. While much research has focused on leaf flatness, little is known about how sepals achieve flat organ morphology. Previous study has shown that in Arabidopsis an ASYMMETRIC LEAVES 2 (AS2) gene mutation as2-7D causes ectopic AS2 expression on the abaxial sepal epidermis, which leads to growth discoordination between the two sides of sepals, resulting in outgrowth formation on abaxial sepal epidermis and sepal flatness disruption. Here we report that the PRESSED FLOWER (PRS) works downstream of AS2 in affecting sepal flatness. Genetic analysis showed that PRS mutations suppressed the outgrowth formation on the abaxial sepal epidermis in as2-7D mutant. Through tracking the PRS expression dynamics at a cellular resolution throughout the early developmental stages in WT and as2-7D sepals, we found that on the abaxial epidermis of as2-7D sepals, ectopic AS2 expression up-regulated PRS expression, leading to the epidermal outgrowth initiation. AS2 affected PRS activity on multiple levels: AS2 activated PRS expression through direct binding to PRS promoter region; AS2 also physically interacted with PRS. Our study highlights the complex interplay between AS2 and PRS in modulating sepal flatness.

developmental biology↗

Multimodal Spatial Profiling Reveals Immune Suppression and Microenvironment Remodeling in Fallopian Tube Precursors to High-Grade Serous Ovarian Carcinoma

High-Grade Serous Ovarian Cancer (HGSOC) originates from fallopian tube (FT) precursors. However, the molecular changes that occur as precancerous lesions progress to HGSOC are not well understood. To address this, we integrated high-plex imaging and spatial transcriptomics to analyze human tissue samples at different stages of HGSOC development, including p53 signatures, serous tubal intraepithelial carcinomas (STIC), and invasive HGSOC. Our findings reveal immune modulating mechanisms within precursor epithelium, characterized by chromosomal instability, persistent interferon (IFN) signaling, and dysregulated innate and adaptive immunity. FT precursors display elevated expression of MHC-class I, including HLA-E, and IFN-stimulated genes, typically linked to later-stage tumorigenesis. These molecular alterations coincide with progressive shifts in the tumor microenvironment, transitioning from immune surveillance in early STICs to immune suppression in advanced STICs and cancer. These insights identify potential biomarkers and therapeutic targets for HGSOC interception and clarify the molecular transitions from precancer to cancer. STATEMENT OF SIGNIFICANCEThis study maps the immune response in fallopian tube precursors of high-grade serous ovarian cancer, highlighting localized interferon signaling, CIN, and competing immune surveillance and suppression along the progression axis. It provides an explorable public spatial profiling atlas for investigating precancer mechanisms, biomarkers, and early detection and interception strategies.

cancer biology↗

Identification of conserved and tissue-restricted transcriptional profiles for lipid associated macrophages (LAMs)

Macrophages are essential immune cells present in all tissues, and are vital for maintaining tissue homeostasis, immune surveillance, and immune responses. Considerable efforts have identified shared and tissue-specific gene programs for macrophages across organs during homeostasis. This information has dramatically enhanced our understanding of tissue-restricted macrophage programming and function. However, few studies have addressed the overlapping and tissue-specific responses of macrophage subsets following inflammatory responses. One subset of macrophages that has been observed across several studies, lipid-associated macrophages (LAMs), have gained interest due to their unique role in lipid metabolism and potential as a therapeutic target. LAMs have been associated with regulating disease outcomes in metabolically related disorders including atherosclerosis, obesity, and nonalcoholic fatty liver disease (NAFLD). In this study, we utilized single-cell RNA sequencing (scRNAseq) data to profile LAMs across multiple tissues and sterile inflammatory conditions in mice and humans. Integration of data from various disease models revealed that LAMs share a set of conserved transcriptional profiles, including Trem2 and Lpl, but also identified key sets of tissue-specific LAM gene programs. Importantly, the shared LAM markers were highly conserved with human LAM populations that also emerge in chronic inflammatory settings. Overall, this analysis provides a detailed transcriptional landscape of tissue-restricted and shared LAM gene programs and offers insights into their roles in metabolic and chronic inflammatory diseases. These data may help instruct appropriate targets for broad or tissue-restricted therapeutic interventions to modulate LAM populations in disease.

immunology↗

A novel OsIAA3-OsARF16-OsBUL1 module regulates grain size in rice

Auxin plays an important role in almost every aspect of plant growth and development. However, the molecular mechanism underlying the control of grain size via auxin signaling pathways is still obscure. Here, we reported that the rice Aux/IAA gene OsIAA3 positively regulates grain size by promoting the cell expansion and proliferation of spikelet hulls. OsIAA3 interacted with 11 OsARFs, among which the interaction with OsARF16 was the strongest. Knockout of osarf16 led to smaller grain with decreased grain length, grain width, grain thickness and 1,000-grain weight. Meanwhile, transgenic plants overexpressing OsARF16 produced apparently bigger grain with increased grain length and 1,000-grain weight. Additionally, OsBUL1, which positive regulates grain size by promoting cell expansion is a direct target gene of OsARF16. Results demonstrated that the interaction between OsIAA3 and OsARF16 repressed the transcriptional activation of OsARF16 on OsBUL1. Taken together, our study revealed a novel OsIAA3-OsARF16-OsBUL1 module which regulates grain size, enriching the molecular mechanism of auxin signaling pathway involved in regulating grain size.

genetics↗

DNA-templated spatially controlled proteolysis targeting chimeras for CyclinD1-CDK4/6 complex protein degradation

Constraining proximity-based drugs, such as proteolysis-targeting chimeras (PROTACs), into its bioactive conformation can significantly impact their selectivity and potency. However, traditional methods for achieving this often involve complex and time-consuming synthetic procedures. Here, we introduced an alternative approach by demonstrating DNA-templated spatially controlled PROTACs (DTACs), which leverage the programmability of nucleic-acid based self-assembly for efficient synthesis, providing precise control over inhibitors spacing and orientation. The resulting constructs revealed distance- and orientation-dependent selectivity and degradation potency for the CyclinD1-CDK4/6 protein complex in cancer cells. Notably, an optimal construct DTAC-V1 demonstrated the unprecedented synchronous degradation of entire CyclinD1-CDK4/6 complex. This resulted in the effective cell cycle arrest in G1 phase, and further therapeutic studies showed its potent anti-tumor effects compared to inhibitors alone. These findings present a novel framework for PROTACs design, offering critical insights that may inform the development of other proximity-induced therapeutic modalities.

synthetic biology↗

Ethylene Modulates the Phenylpropanoid Pathway by Enhancing VvMYB14 Expression via the ERF5-Melatonin-ERF104 Pathway in Grape Seeds

Ethylene plays a crucial role in regulating polyphenol metabolism, however the underlying mechanism remains largely unknown. This work demonstrated that ethylene release occurred earlier than melatonin during seed ripening. Ethylene treatment increased the VvASMT expression and melatonin content. VvERF5 was elucidated to bind to the ERE element in the VvASMT promoter. VvERF5 overexpression increased ASMT expression and melatonin content while its suppression generated the opposite results in grape seeds, calli and/or Arabidopsis seeds. Using the promoter of VvMYB14, which was strongly induced by melatonin, a melatonin responsive element (MTRE) was identified. VvERF104 was revealed not only to be strongly induced by melatonin but to bind to the MTRE of the VvMYB14. VvERF104 overexpression and suppression largely increased and decreased the MYB14 expression, respectively, in grape seeds, calli and/or Arabidopsis seeds. VvMYB14 overexpression widely modified the expression of genes in phenylpropanoid pathway and phenolic compound content in grape seeds. DAP-seq revealed that the MEME-1 motif was the most likely binding sites of VvMYB14. VvPAL, VvC4H and VvCHS were verified to be the target genes of VvMYB14. Additionally, the roles of VvERF5, VvASMT and VvERF104 in mediating ethylene-induced changes in phenylpropanoid pathway were elucidated using their suppressing seeds. Collectively, ethylene increased the VvMYB14 expression via the pathway of ERF5-melatonin-ERF104 and thereby modified phenylpropanoid pathway.

plant biology↗

PSMA-specific CAR-engineered macrophages for therapy of prostate cancer

Chimeric antigen receptor (CAR)-modified macrophages (CAR-Ms) are a promising approach for the treatment of solid tumors due to its high infiltration and immune-regulation activity. Prostate cancer is a typical solid tumor associated with highly immunosuppressive microenvironment. To date, the potential application of CAR-M cell therapy in prostate cancer has been infrequently explored. The prostate-specific membrane antigen (PSMA) functions as a specific biomarker for prostate cancer. In this study, we assessed the antitumor efficacy of PSMA-targeted CAR-Ms in preclinical models. CAR-Ms were engineered to express a PSMA-specific single-chain variable fragment (scFv) and co-stimulatory domains. In vitro data demonstrated specific cytotoxicity of CAR-Ms against PSMA-expressing prostate cancer cells, which was further supported by transcriptome analysis demonstrating the pro-inflammatory phenotypes of CAR-Ms. In vivo studies using xenograft mouse models confirmed significant tumor regression after administration of PSMA-targeted CAR-Ms compared to controls. Histopathological analysis showed infiltration of CAR-Ms into tumor tissues without off-target toxicity. These results highlight the strong antitumor activity and safety of PSMA-targeted CAR-Ms, supporting their potential as a new immunotherapy for prostate cancer.

bioengineering↗

Molecular mechanisms of uric acid transport by the native human URAT1 and its inhibition by anti-gout drugs

Gout, a common and painful disease, stems from hyperuricemia, where elevated blood uric acid levels lead to urate crystal formation in joints and kidneys. The human urate transporter 1 (hURAT1) plays a critical role in urate homeostasis by facilitating urate reabsorption in the renal proximal tubule, making it a key target for gout therapy. Pharmacological inhibition of hURAT1 with drugs such as dotinurad, benzbromarone, lesinurad, and verinurad promotes uric acid excretion and alleviates gout symptoms. Here we present cryo-electron microscopy structures of native hURAT1 bound with these anti-gout drugs in the inward-open state, and with uric acid in inward-open, outward-open, and occluded states. Complemented by mutagenesis and cell-based assays, these structures reveal the mechanisms of uric acid reabsorption and hURAT1 inhibition. Our findings elucidate the molecular basis of uric acid transport and anti-gout medication action, and provide a structural framework for the rational design of next-generation therapies for hyperuricemia and gout.

biochemistry↗

A secondary β-hydroxybutyrate metabolic pathway linked to energy balance

{beta}-hydroxybutyrate (BHB) is an abundant ketone body. To date, all known pathways of BHB metabolism involve interconversion of BHB and primary energy intermediates. Here we show that CNDP2 controls a previously undescribed secondary BHB metabolic pathway via enzymatic conjugation of BHB and free amino acids. This BHB-ylation reaction produces a family of endogenous ketone metabolites, the BHB-amino acids. Genetic ablation of CNDP2 in mice eliminates tissue amino acid BHB-ylation activity and reduces BHB-amino acid levels. Administration of BHB-Phe, the most abundant BHB-amino acid, to obese mice activates neural populations in the hypothalamus and brainstem and suppresses feeding and body weight. Conversely, CNDP2-KO mice exhibit increased food intake and body weight upon ketosis stimuli. CNDP2-dependent amino acid BHB-ylation and BHB-amino acid metabolites are also conserved in humans. Therefore, the metabolic pathways of BHB extend beyond primary metabolism and include secondary ketone metabolites linked to energy balance.

biochemistry↗

Neutralization and Stability of JN.1-derived LB.1, KP.2.3, KP.3 and KP.3.1.1 Subvariants

During the summer of 2024, COVID-19 cases surged globally, driven by variants derived from JN.1 subvariants of SARS-CoV-2 that feature new mutations, particularly in the N-terminal domain (NTD) of the spike protein. In this study, we report on the neutralizing antibody (nAb) escape, infectivity, fusion, and stability of these subvariants--LB.1, KP.2.3, KP.3, and KP.3.1.1. Our findings demonstrate that all of these subvariants are highly evasive of nAbs elicited by the bivalent mRNA vaccine, the XBB.1.5 monovalent mumps virus-based vaccine, or from infections during the BA.2.86/JN.1 wave. This reduction in nAb titers is primarily driven by a single serine deletion (DelS31) in the NTD of the spike, leading to a distinct antigenic profile compared to the parental JN.1 and other variants. We also found that the DelS31 mutation decreases pseudovirus infectivity in CaLu-3 cells, which correlates with impaired cell-cell fusion. Additionally, the spike protein of DelS31 variants appears more conformationally stable, as indicated by reduced S1 shedding both with and without stimulation by soluble ACE2, and increased resistance to elevated temperatures. Molecular modeling suggests that the DelS31 mutation induces a conformational change that stabilizes the NTD and strengthens the NTD-Receptor-Binding Domain (RBD) interaction, thus favoring the down conformation of RBD and reducing accessibility to both the ACE2 receptor and certain nAbs. Additionally, the DelS31 mutation introduces an N-linked glycan modification at N30, which shields the underlying NTD region from antibody recognition. Our data highlight the critical role of NTD mutations in the spike protein for nAb evasion, stability, and viral infectivity, and suggest consideration of updating COVID-19 vaccines with antigens containing DelS31.

molecular biology↗