Biology subjects

Glaser, K.

Publications and source records attributed to Glaser, K..

5 recordsLinked to original sources

bioRxiv2025

Oncogenic Role of Aberrant EZH2 in Hepatoblastoma

Hepatoblastoma (HB) is the most common pediatric liver malignancy. However, its cellular origin and molecular drivers remain poorly defined. Using single-nuclear RNA sequencing (snRNA-seq), we identified a proliferative, hepatocyte-derived tumor cell population (cycling HepT) enriched for Enhancer of Zeste Homolog 2 (EZH2) expression, particularly in the aggressive embryonal subtype. Integrative genomic and transcriptomic profiling confirmed EZH2 overexpression. Disruption of the PRC2 complex was evident through mislocalization and reduced expression of SUZ12, a core component. EZH2 overexpression correlated with upregulation of mitotic regulators such as AURKB and Ki67 in human HB gene expression analysis as compared to background liver. Targeted sequencing identified variants of uncertain significance in EZH2 and SUZ12 in 11 of 11 patient tumors. Pharmacologic inhibition of EZH2 with EPZ-6438 reduced proliferation and sensitized HB cells to cisplatin through gene regulation, potentially modulating platinum accumulation both in vitro and in vivo. In summary, EZH2 promotes HB progression through epigenetic silencing and noncanonical signaling pathways. These findings support EZH2s contribution to HB pathogenesis, therefore identifying it as a novel therapeutic target. STATEMENT OF SIGNIFICANCEEZH2 is enriched in hepatoblastoma, suggesting its role in early tumorigenesis. Its inhibition, combined with cisplatin, produces synergistic anti-tumor effects, supporting EZH2 as both an oncogenic and therapeutic target.

cancer biology↗

bioRxiv2025

Primitive Hepatoblasts Driving Early Liver Development

The embryonic development of the liver is initiated by the emergence of hepatoblasts, originating from the ventral foregut endoderm adjacent to the heart. Here, we identify and characterize a previously unrecognized population of early hepatoblasts at the ventroposterior part of the emerging liver bud, traced from Cdx2-positive endoderm progenitors, which we term primitive hepatoblasts. Mouse and human single-cell transcriptomics reveals the expression of both canonical hepatoblast markers TBX3, FGB, and KRT8/18 and primitive-specific mesenchymal markers ID3, VIM, and GATA4. Lineage tracing revealed the notable contribution up to 12.6% of LIV2+ hepatoblasts at E11.5 but diminishes in late fetal and postnatal development. Epigenetic and functional perturbation studies further uncover that primitive hepatoblast emergence is primed by WNT-suppression on RA-permissive CDX2+FOXA2+ progenitors. Furthermore, human pluripotent stem cell-derived primitive hepatoblast-like cells secrete pleiotrophin and midkine to amplify hepatoblast populations and develop epithelial-mesenchymal hybrid tissues in vivo. Our results provide a new framework for understanding lineage heterogeneity during early hepatogenesis and offer revised insights into strategies to model normal and abnormal liver development.

developmental biology↗

bioRxiv2024

Self-Assembled Generation of Multi-zonal Liver Organoids from Human Pluripotent Stem Cells

Distinct hepatocyte subpopulations are spatially segregated along the portal-central axis and critical to understanding metabolic homeostasis and liver injury. While several bioactive molecules have been described to play a role in directing zonal fates, including ascorbate and bilirubin, in vitro replication of zonal liver architecture has not been achieved to date. In order to evaluate hepatic zonal polarity, we developed a self-assembling zone-specific liver organoid culture by co-culturing ascorbate and bilirubin enriched hepatic progenitors derived from human induced pluripotent stem cells. We found that preconditioned hepatocyte-like cells exhibited zone-specific functions associated with urea cycle, glutathione synthesis and glutamate synthesis. Single nucleus RNA sequencing analysis of these zonally patterned organoids identifies hepatoblast differentiation trajectory that mimics periportal-, interzonal-, and pericentral human hepatocytes. Epigenetic and transcriptomic analysis showed that zonal identity is orchestrated by ascorbate or bilirubin dependent binding of histone acetyltransferase p300 (EP300) to methylcytosine dioxygenase TET1 or hypoxia-inducible factor 1-alpha (HIF1). Transplantation of the self-assembled zonally patterned human organoids improved survival of immunodeficient rats who underwent bile duct ligation by ameliorating the hyperammonemia and hyperbilirubinemia. Overall, this multi-zonal organoid system serves as an in vitro human model to better recapitulate hepatic architecture relevant to liver development and disease.

bioengineering↗

bioRxiv2024

Inhibition of epithelial Na+ transport: novel mechanism of Ureaplasma-driven lung disease

BackgroundRespiratory tract colonisation with Ureaplasma species has been associated with the development of acute and long-term pulmonary morbidity in preterm infants. Apart from inflammation, the underlying mechanisms of Ureaplasma-driven lung disease are mainly unknown. The present investigation is the first to examine the influence of acute Ureaplasma infection on critical mechanisms of alveolar fluid clearance in the immature lung. MethodsPrimary rat fetal distal lung epithelial (FDLE) cells were incubated with viable Ureaplasma in the absence or presence of the urease inhibitor flurofamide. Na+ transport and activity of the epithelial Na+ channel (ENaC) and the Na,K-ATPase were determined in Ussing chambers. Barrier integrity, metabolic activity, gene expression, and kinase signalling were also assessed. ResultsWe found a 30-90% decrease of epithelial Na+ transport upon 24 hours of Ureaplasma infection resulting from significant inhibition of ENaC and Na,K-ATPase activities. Notably, Ureaplasma induced phosphorylation of Erk1/2 - a well-known inhibitor of ENaC activity. Moreover, Ureaplasma-driven NH3 production - and not the accompanying pH shift - inhibited the epithelial Na+ transport. Co-incubation with flurofamide entirely restored Na+ transport in Ureaplasma-infected FDLE cells. ConclusionOur data demonstrate that Ureaplasma infection significantly impairs epithelial Na+ transport and subsequent fluid clearance in fetal alveolar cells - most likely by Erk1/2 phosphorylation. We identified NH3 as the mediating virulence factor and were able to restore Na+ transport by inhibiting the Ureaplasma-specific urease. This is the first study to show a functional impairment of pulmonary epithelial cells upon Ureaplasma infection, revealing a potential mechanism of Ureaplasma-driven preterm lung disease. Take HomeWe report Ureaplasma-induced inhibition of epithelial Na+ transport as a potential mechanism of Ureaplasma-driven preterm lung disease. NH3 is identified as a virulence factor offering a potential therapeutic role for urease inhibitors in colonised infants.

microbiology↗

bioRxiv2017

New barcoded primers for efficient retrieval of cercozoan sequences in high-throughput environmental diversity surveys, with emphasis on worldwide biological soil crusts

We describe the performance of a new metabarcoding approach to investigate the environmental diversity of a prominent group of widespread unicellular organisms, the Cercozoa. Cercozoa is an immensely large group of protists and although it may dominate in soil and aquatic ecosystems, its environmental diversity remains undersampled. We designed PCR primers targeting the hyper-variable region V4 of the small subunit ribosomal RNA (SSU or 18S) gene, which is the recommended barcode marker for Cercozoa. The length of the amplified fragment (ca. 350 bp) is suitable for Illumina MiSeq, the most cost-effective platform for molecular environmental surveys. We provide barcoded primers, an economical alternative to multiple libraries for multiplex sequencing of over a hundred samples. In silico, our primers matched 68% of the cercozoan sequences of the reference database and performed better than previously proposed new generation sequencing primers. In mountain grasslands soils and in biological soil crusts from a variety of climatic regions, we were able to detect cercozoan sequences encompassing nearly the whole range of the phylum. We obtained 901 OTUs at 97% similarity threshold from 26 samples, with ca. 50,000 sequences per site, and only 8% of non-cercozoan sequences. We could contribute to a further increase of the diversity of Cercozoa, since only 43% of the OTUs were 97-100% similar to any known sequence. Our study thus provides an advanced tool for cercozoan metabarcoding and to investigate their diversity and distribution in the environment.

bioinformatics↗