Biology subjects

Lo, Y.

Publications and source records attributed to Lo, Y..

7 recordsLinked to original sources

bioRxiv2024

Comprehensive single cell transcriptomics analysis of murine osteosarcoma uncovers Skp2 function in metastasis, genomic instability and immune activation and reveals additional target pathways

Osteosarcoma (OS) is the most common primary pediatric bone malignancy. One promising new therapeutic target is SKP2, encoding a substrate recognition factor of the SCF E3 ubiquitin ligase responsible for ubiquitination and proteasome degradation of substrate p27, thus driving cellular proliferation. We have shown previously that knockout of Skp2 in an immunocompetent transgenic mouse model of OS improved survival, drove apoptosis, and induced tumor inflammation. Here, we applied single-cell RNA-sequencing (scRNA-seq) to study primary OS tumors derived from Osx-Cre driven conditional knockout of Rb1 and Trp53. We showed that murine OS models recapitulate the tumor heterogeneity and microenvironment complexity observed in patient tumors. We further compared this model with OS models with functional disruption of Skp2: one with Skp2 knockout and the other with the Skp2-p27 interaction disrupted (resulting in p27 overexpression). We found reduction of T cell exhaustion and upregulation of interferon activation, along with evidence of replicative and endoplasmic reticulum-related stress in the Skp2 disruption models, and showed that interferon induction was correlated with improved survival in OS patients. Additionally, our scRNA-seq analysis uncovered decreased activities of metastasis-related gene signatures in the Skp2-disrupted OS, which we validated by observation of a strong reduction in lung metastasis in the Skp2 knockout mice. Finally, we report several potential mechanisms of escape from targeting Skp2 in OS, including upregulation of Myc targets, DNA copy number amplification and overexpression of alternative E3 ligase genes, and potential alternative lineage activation. These mechanistic insights into OS tumor biology and Skp2 function suggest novel targets for new, synergistic therapies, while the data and our comprehensive analysis may serve as a public resource for further big data-driven OS research.

cancer biology↗

bioRxiv2024

Thetis cells induce food-specific Treg cell differentiation and oral tolerance

The intestinal immune system must establish tolerance to food antigens to prevent onset of allergic and inflammatory diseases. Peripherally generated regulatory T (pTreg) cells play an essential role in suppressing inflammatory responses to allergens; however, the antigen-presenting cell (APC) that instructs food-specific pTreg cells is not known. Here, we show that antigen presentation and TGF-{beta} activation by a subset of ROR{gamma}t+ antigen-presenting cells (APC), Thetis cells IV (TC IV), is required for food-induced pTreg cell differentiation and oral tolerance. By contrast, antigen presentation by dendritic cells (DCs) was dispensable for pTreg induction but required for TH1 effector responses, highlighting a division of labor between tolerogenic TCs and pro-inflammatory DCs. While antigen presentation by TCs was required for food-specific pTreg generation both in early life and adulthood, the increased abundance of TCs in the peri-weaning period was associated with a window of opportunity for enhanced pTreg differentiation. These findings establish a critical role for TCs in oral tolerance and suggest that these cells may represent a key therapeutic target for the treatment of food-associated allergic and inflammatory diseases.

immunology↗

bioRxiv2023

Glioblastoma initiation, migration, and cell types are regulated by core bHLH transcription factors ASCL1 and OLIG2

Glioblastomas (GBMs) are highly aggressive, infiltrative, and heterogeneous brain tumors driven by complex driver mutations and glioma stem cells (GSCs). The neurodevelopmental transcription factors ASCL1 and OLIG2 are co-expressed in GBMs, but their role in regulating the heterogeneity and hierarchy of GBM tumor cells is unclear. Here, we show that oncogenic driver mutations lead to dysregulation of ASCL1 and OLIG2, which function redundantly to initiate brain tumor formation in a mouse model of GBM. Subsequently, the dynamic levels and reciprocal binding of ASCL1 and OLIG2 to each other and to downstream target genes then determine the cell types and degree of migration of tumor cells. Single-cell RNA sequencing (scRNA-seq) reveals that a high level of ASCL1 is key in defining GSCs by upregulating a collection of ribosomal protein, mitochondrial, neural stem cell (NSC), and cancer metastasis genes - all essential for sustaining the high proliferation, migration, and therapeutic resistance of GSCs.

neuroscience↗

bioRxiv2023

Targeted inhibition of SCF-SKP2 confers anti-tumor activities resulting in a survival benefit in osteosarcoma

Osteosarcoma(OS) is a highly aggressive bone cancer for which treatment has remained essentially unchanged for decades. Although OS is characterized by extensive genomic heterogeneity and instability, RB1 and TP53 have been shown to be the most commonly inactivated tumor suppressors in OS. We previously generated a mouse model with a double knockout (DKO) of Rb1 and Trp53 within cells of the osteoblastic lineage, which largely recapitulates human OS with nearly complete penetrance. SKP2 is a repression target of pRb and serves as a substrate recruiting subunit of the SCFSKP2 complex. In addition, SKP2 plays a central role in regulating the cell cycle by ubiquitinating and promoting the degradation of p27. We previously reported the DKOAA transgenic model, which harbored a knock-in mutation in p27 that impaired its binding to SKP2. Here, we generated a novel p53-Rb1-SKP2 triple-knockout model (TKO) to examine SKP2 function and its potential as a therapeutic target in OS. First, we observed that OS tumorigenesis was significantly delayed in TKO mice and their overall survival was markedly improved. In addition, the loss of SKP2 also promoted an apoptotic microenvironment and reduced the stemness of DKO tumors. Furthermore, we found that small-molecule inhibitors of SKP2 exhibited anti-tumor activities in vivo and in OS organoids as well as synergistic effects when combined with a standard chemotherapeutic agent. Taken together, our results suggest that SKP2 inhibitors may reduce the stemness plasticity of OS and should be leveraged as next-generation adjuvants in this cancer.

cancer biology↗

bioRxiv2023

Interferon epsilon restricts Zika virus infection in the female reproductive tract

Interferon {varepsilon} (IFN{varepsilon}) is a unique type I IFN that has been implicated in host defense against sexually transmitted infections (STIs). Zika virus (ZIKV), an emerging pathogen, can infect the female reproductive tract (FRT) and cause devastating diseases, particularly in pregnant women. How IFN{varepsilon} contributes to protection against ZIKV infection in vivo is unknown. Here, we show that IFN{varepsilon} plays a critical role in host protection against vaginal ZIKV infection in mice. We found that IFN{varepsilon} was expressed not only by epithelial cells in the FRT, but also by certain immune and other cells at baseline or after exposure to viruses or specific TLR agonists. IFN{varepsilon}-deficient mice exhibited abnormalities in the epithelial border and underlying tissue in the cervicovaginal tract, and these defects were associated with increased susceptibility to vaginal, but not subcutaneous ZIKV infection. IFN{varepsilon}-deficiency resulted in an increase in magnitude, duration, and depth of ZIKV infection in the FRT. Critically, intravaginal administration of recombinant IFN{varepsilon} protected Ifn{varepsilon}-/- mice and highly susceptible Ifnar1-/-mice against vaginal ZIKV infection, indicating that IFN{varepsilon} was sufficient to provide protection even in the absence of signals from other type I IFNs and in an IFNAR1-independent manner. Our findings reveal a potentially critical role for IFN{varepsilon} in mediating protection against transmission of ZIKV in the context of sexual contact. SignificanceInterferon {varepsilon} (IFN{varepsilon}), a unique Type I IFN that is highly expressed in the epithelium of the female reproductive tract (FRT), is thought to protect the host against sexually transmitted infections (STIs) but the mechanism of action is not defined. Zika virus (ZIKV), a causative agent for preterm birth and other severe diseases in pregnant women, can be spread through vaginal transmission. Here, we show that mice lacking the Ifn{varepsilon} gene have abnormal epithelial development and tissue architecture in the cervicovaginal tract. The role of IFN{varepsilon} in protecting host against ZIKV is FRT-specific and is independent of IFNAR1 signaling. Our findings suggest potential preventive strategies based on harnessing mucosal immunity against STIs.

immunology↗

bioRxiv2020

Activity-specificity trade-off gives PI5P4Kβ a nucleotide preference to function as a GTP-sensing kinase.

Most kinases function with ATP. However, contrary to the prevailing dogma, phosphatidylinositol 5-phosphate 4-kinase {beta} (PI5P4K{beta}) utilizes GTP as a primary phosphate donor with a unique binding mode for GTP. Although PI5P4K{beta} is evolved from a primordial ATP-utilizing enzyme, PI4P5K, how PI5P4K{beta} evolutionarily acquired the GTP preference to function as a cellular GTP sensor remains unclear. In this study, we show that the short nucleotide base-recognition motif, TRNVF, is responsible for the GTP binding of PI5P4K{beta}, and also confers onto PI5P4K{beta} an unexpected specificity that extends to inosine triphosphate (ITP) and xanthosine triphosphate (XTP). A mutational study with GTP analogues suggests that the extended specificity is an obligatory consequence to the acquisition of GTP-dependent activity. However, as the cellular concentrations of ITP and XTP are typically negligible, PI5P4K{beta} can still function as a GTP sensor, suggesting that the cellular physiological conditions leave room for the functional evolution of PI5P4K{beta}.

biochemistry↗

bioRxiv2020

Multidimensional Analysis of Bronchoalveolar Lavage Cytokines and Mast Cell Proteases Reveals Interferon-γ as a Key Biomarker in Equine Asthma Syndrome

Naturally-occurring equine asthma is an inflammatory lung disease characterized by chronic, partially reversible airway obstruction, pulmonary remodeling and lower airway inflammation. The cytokine profiles that distinguish asthma groups or subtypes in horses have not been systematically classified, and mast cell phenotypes, which, in human asthma, correlate with asthma type, lung function, and response to therapy, have not been well-described in horses. The purpose of this study was to: (1) compare mast cell protease mRNA expression between healthy and asthmatic horses, (2) analyze the cytokine profile present in BALF of currently defined equine asthma groups, and (3) use these data to evaluate potential biomarkers of defined asthma groups. Mast cell protease gene expression and select cytokine gene expression in cells isolated from BALF, and BALF multiplex cytokine assays were performed. Multidimensional analysis demonstrated that IFN{gamma} differentiates severe from moderate asthma, and that TNF and CXCL8 are key biomarkers of equine asthma subtype. Expression of chymase mRNA, a mast cell-specific protease, was significantly decreased in horses with mastocytic asthma. These results will help further define EAS immunopathology, which could improve understanding and definitions of asthma groups, while also potentially identify novel therapeutic strategies.

immunology↗