Biology subjects

Bender, D.

Publications and source records attributed to Bender, D..

5 recordsLinked to original sources

bioRxiv2026

The intertwined fate: exploring the hepatitis C virus/Nrf1 crosstalk

BACKGROUNDDespite advances in knowledge and medicine, hepatitis C virus (HCV) infection remains a global challenge. The viral life cycle depends heavily on lipid metabolism; consequently, HCV infection is associated with significant alterations to host lipid homeostasis. One of the regulators maintaining this homeostasis is the transcription factor nuclear factor erythroid 2-related factor 1 (Nrf1). There are multiple Nrf1 proteoforms that differ in their capacity to act as a cholesterol sensor or to activate or inhibit gene expression. Previously, we identified that the amount of full-length Nrf1 protein in HCV-replicating cells is significantly reduced. In this study, we investigate whether HCV affects the formation and functionality of the different Nrf1 proteoforms, and whether this contributes to the HCV-dependent dysregulation of cellular lipid metabolism. METHODSThe HCV-Nrf1 crosstalk was characterized using robust methods including: Western blot, FRET Acceptor Photobleaching assay, reverse transcriptase-polymerase chain reaction and confocal laser scanning microscopy-based approaches. RESULTSHCV infection does not alter the onset of Nrf1 proteoforms generated through proteasomal cleavage of the protein. However, the amount of different Nrf1 proteoforms is significantly reduced in HCV-positive cells due to enhanced Nrf1 turnover. Furthermore, the Nrf1 proteoforms with transcriptional activator functions are prevented from translocation into the nucleus. Reduced Nrf1 activity contributes to elevated cholesterol levels and favors lipid droplets formation. Conversely, rescue of Nrf1 activity in HCV-replicating cells is associated with decreased intracellular cholesterol levels, reduced number of lipid droplets and impaired viral release reflected by intracellular accumulation of the core protein and intact viral particles. CONCLUSIONSOverall, our results identify Nrf1 as a significant factor in the deregulation of host lipid metabolism induced by HCV. The inhibition of Nrf1 functionality driven by HCV leads to intracellular cholesterol accumulation, resulting in enhanced lipid droplet formation that supports the HCV life cycle and contributes to HCV-associated pathogenesis.

microbiology↗

bioRxiv2024

Late stages of the Zika virus life cycle are impaired by a selective TRPML2 agonist

The flavivirus genus includes human pathogenic viruses such as Dengue (DENV), West Nile (WNV) and Zika virus (ZIKV) posing a global health threat due to limited treatment options. Ion channels are crucial for various viral life cycle stages, but their potential as targets for antivirals is often not fully realized due to the lack of selective modulators. Here, we observe that the human endolysosomal cation channel TRPML2 agonist ML2-SA1 impairs the late life cycle stages of ZIKV, thus underscoring TRPML2 as a promising antiviral target. Upon treatment with ML2-SA1, levels of intracellular genomes and number of released virus particles of two different ZIKV isolates were significantly reduced. ML2-SA1-treated cells displayed enlarged vesicular structures and multivesicular bodies with ZIKV envelope protein accumulation. However, no increased ZIKV degradation in lysosomal compartments was observed. Rather, the antiviral effect of ML2-SA1 seemed to manifest by the compounds negative impact on genome replication. Moreover, ML2-SA1 treatment also led to intracellular cholesterol accumulation. ZIKV as well as many other viruses including the Orthohepevirus Hepatitis E virus (HEV) rely on the endolysosomal system and are affected by intracellular cholesterol levels to complete their life cycle. Since we observed ML2-SA1 to also negatively impact HEV infections in vitro, this compound may harbor a broader antiviral potential through perturbing the intracellular cholesterol distribution. Besides underscoring the potential of TRPML2 as a promising target for combatting viral infections, we uncover a tentative connection between this protein and cholesterol distribution within the context of infectious diseases.

cell biology↗

bioRxiv2023

Differential chromatin accessibility and transcriptional dynamics define breast cancer subtypes and their lineages

Breast cancer is a heterogeneous disease, and treatment is guided by biomarker profiles representing distinct molecular subtypes. Breast cancer arises from the breast ductal epithelium, and experimental data suggests breast cancer subtypes have different cells of origin within that lineage. The precise cells of origin for each subtype and the transcriptional networks that characterize these tumor-normal lineages are not established. In this work, we applied bulk, single-cell (sc), and single-nucleus (sn) multi-omic techniques as well as spatial transcriptomics and multiplex imaging on 61 samples from 37 breast cancer patients to show characteristic links in gene expression and chromatin accessibility between breast cancer subtypes and their putative cells of origin. We applied the PAM50 subtyping algorithm in tandem with bulk RNA-seq and snRNA-seq to reliably subtype even low-purity tumor samples and confirm promoter accessibility using snATAC. Trajectory analysis of chromatin accessibility and differentially accessible motifs clearly connected progenitor populations with breast cancer subtypes supporting the cell of origin for basal-like and luminal A and B tumors. Regulatory network analysis of transcription factors underscored the importance of BHLHE40 in luminal breast cancer and luminal mature cells, and KLF5 in basal-like tumors and luminal progenitor cells. Furthermore, we identify key genes defining the basal-like (PRKCA, SOX6, RGS6, KCNQ3) and luminal A/B (FAM155A, LRP1B) lineages, with expression in both precursor and cancer cells and further upregulation in tumors. Exhausted CTLA4-expressing CD8+ T cells were enriched in basal-like breast cancer, suggesting altered means of immune dysfunction among breast cancer subtypes. We used spatial transcriptomics and multiplex imaging to provide spatial detail for key markers of benign and malignant cell types and immune cell colocation. These findings demonstrate analysis of paired transcription and chromatin accessibility at the single cell level is a powerful tool for investigating breast cancer lineage development and highlight transcriptional networks that define basal and luminal breast cancer lineages.

cancer biology↗

bioRxiv2021

Single Cell Atlas of Human Dura Reveals Cellular Meningeal Landscape and Insights into Meningioma Immune Response

Recent investigation of the meninges, specifically the dura layer, has highlighted its importance in CNS immune surveillance beyond a purely structural role. However, most of our understanding of the meninges stems from the use of pre-clinical models rather than human samples. In this study, we use single cell RNA-sequencing to perform the first characterization of both non-tumor-associated human dura and meningioma samples. First, we reveal a complex immune microenvironment in human dura that is transcriptionally distinct from that of meningioma. In addition, through T cell receptor sequencing, we show significant TCR overlap between matched dura and meningioma samples. We also identify a functionally heterogeneous population of non-immune cell types and report copy-number variant heterogeneity within our meningioma samples. Our comprehensive investigation of both the immune and non-immune cell landscapes of human dura and meningioma at a single cell resolution provide new insight into previously uncharacterized roles of human dura.

immunology↗

bioRxiv2019

Multivalent interaction of ESCO2 with the replication machinery is required for cohesion

The tethering together of sister chromatids by the cohesin complex ensures their accurate alignment and segregation during cell division. In vertebrates, the establishment of cohesion between sister chromatids requires the activity of the ESCO2 acetyltransferase, which modifies the Smc3 subunit of cohesin. It was shown recently that ESCO2 promotes cohesion through interaction with the MCM replicative helicase. However, ESCO2 does not significantly colocalize with the MCM helicase, suggesting there may be additional interactions that are important for ESCO2 function. Here we show that ESCO2 is recruited to replication factories, the sites of DNA replication. We show that ESCO2 contains multiple conserved PCNA-interaction motifs in its N-terminus, and that each of these motifs are essential to ESCO2s ability to establish sister chromatid cohesion. We propose that multiple PCNA interaction motifs embedded in a largely flexible and disordered region of the protein underlie the ability of ESCO2 to establish cohesion between sister chromatids precisely as they are born during DNA replication.\n\nSummaryCohesin modification by the ESCO2 acetyltransferase is required for cohesion between sister chromatids. Here we identify multiple motifs in ESCO2 that mediate its interaction with the replication processivity factor PCNA, and show that their mutation abrogates the ability of ESCO2 to ensure cohesion.

cell biology↗