Biology subjects

Zierhut, C.

Publications and source records attributed to Zierhut, C..

4 recordsLinked to original sources

bioRxiv2026

TMEM33 deletion potentiates anti-tumor CD8+ T cell immunity

Improving responses to cancer immunotherapies requires deeper insight into the cellular mechanisms governing T cell-mediated anti-tumor immunity. TMEM33 is an endoplasmic reticulum-resident transmembrane protein enriched across multiple tumor types, with reported functions in anti-viral immunity as well as calcium and lipid homeostasis, yet its role in tumor immunosurveillance remains unknown. Using murine genetic models, we demonstrate that host TMEM33 constrains anti-tumor CD8+ T cell responses. Constitutive Tmem33-/- mice exhibited delayed melanoma tumor growth and increased CD8+ T cell infiltration. Antigen-specific CD8+ compartments in tumors of Tmem33-/- mice showed TCF-1+PD-1+ progenitor-exhausted cell (Tpex) enrichment, elevated effector function and reduced exhaustion, alongside improved effector memory expansion and T-bet expression in draining lymph nodes. We highlight that TMEM33 functions intrinsically within the T cell compartment, as TMEM33 deletion (1) enhanced polyclonal activation of naive CD8+ T cells ex vivo, (2) promoted preferential Tpex accumulation among adoptively transferred naive OT-I cells in B16F10-OVA tumors and draining lymph nodes, and (3) improved the potency of ex vivo-expanded OT-I cells in controlling tumor growth during adoptive cell therapy. Finally, in a large, prospectively recruited metastatic melanoma cohort, lower TMEM33 expression in patient CD8+ T cells significantly correlated with improved survival and elevated TCF-7 (encoding TCF-1). Collectively, our findings define TMEM33 as a formerly unrecognized intrinsic determinant of tumor-directed CD8+ T cell fate that limits Tpex maintenance, and restrains cell therapy responses, suggesting that its modulation may strengthen immunotherapeutic efficacy. One sentence summaryTMEM33 intrinsically limits progenitor exhausted CD8+ T cells, scales anti-tumor responses and predicts melanoma patient survival.

immunology↗

bioRxiv2024

A microscopy reporter for cGAMP reveals rare cGAS activation following DNA damage, and a lack of correlation with micronuclear cGAS enrichment

Cyclic GMP-AMP (cGAMP) synthase (cGAS) is the primary intracellular responder to pathogen DNA. Upon DNA-binding, cGAS generates cGAMP, which binds to STING, ultimately driving inflammatory signalling. Although normally silenced on self-DNA, cGAS can be activated during genotoxic stress. A universal by-product of these conditions are micronuclei, which accumulate cGAS, and which are therefore thought to be major cGAS activators. However, due to the inability to visualise cGAS activation in single cells, this hypothesis remains largely untested. Here we solve this question with an improved intracellular cGAMP reporter, which is compatible with microscopy, flow-cytometry and plate reader setups. Surprisingly, cGAS activation in response to multiple types of genotoxic stress is limited to a subfraction of cells and does not correlate with cGAS enrichment in micronuclei. Overall, our findings suggest a revised model of innate immune signalling in response to genotoxic stress, and introduce a novel and flexible tool with which to examine this model in future.

cell biology↗

bioRxiv2021

Vaccinia E5 is a major inhibitor of the DNA sensor cGAS

The DNA sensor cyclic GMP-AMP synthase (cGAS) is critical in host antiviral immunity. Vaccinia virus (VACV) is a large cytoplasmic DNA virus that belongs to the poxvirus family. How vaccinia virus antagonizes the cGAS-mediated cytosolic DNA-sensing pathway is largely unknown. In this study, we screened 82 vaccinia viral genes to identify potential viral inhibitors of the cGAS/Stimulator of interferon gene (STING) pathway. We discovered that vaccinia E5 is a virulence factor and a major inhibitor of cGAS that elicits proteasome-dependent cGAS degradation. E5 localizes to the cytoplasm and nuclei of infected cells. Cytosolic E5 triggers K48-linked ubiquitination of cGAS and proteasome-dependent degradation via interacting with cGAS. E5 itself also undergoes ubiquitination and degradation. Deleting the E5R gene from the Modified vaccinia virus Ankara (MVA) genome strongly induces type I IFN production by dendritic cells (DCs) and promotes DC maturation, thereby improving the immunogenicity of the viral vector.

microbiology↗

bioRxiv2017

The cytoplasmic DNA sensor cGAS promotes mitotic cell death

The cyclic GMP-AMP (cGAMP) synthase cGAS counteracts infections by detecting and binding foreign cytoplasmic DNA1. DNA-induced synthesis of cGAMP activates innate immune signalling and apoptosis through the cGAMP receptor STING and the downstream effector IRF31-7. During interphase the nuclear envelope protects chromosomal self-DNA from cGAS, but the consequences of exposing chromosomes to cGAS following mitotic nuclear envelope disassembly are unknown. Here we demonstrate that cGAS associates with chromosomes during mitosis and binds nucleosomes with even higher affinity than naked DNA in vitro. Nucleosomes nevertheless competitively inhibit the DNA-dependent stimulation of cGAS, and accordingly, chromosomal cGAS does not affect mitotic progression under normal conditions. This suggests that nucleosomes prevent the inappropriate activation of cGAS during mitosis by acting as a signature of self-DNA. During prolonged mitotic arrest, however, cGAS becomes activated to promote cell death, limiting the fraction of cells that can survive and escape mitotic arrest induced by the chemotherapeutic drug taxol. Induction of mitotic cell death involves cGAMP synthesis by cGAS, as well as signal transduction to IRF3 by STING. We thus propose that cGAS plays a previously unappreciated role in guarding against mitotic errors, promoting cell death during prolonged mitotic arrest. Our data also indicate that the cGAS pathway, whose activity differs widely among cell lines, impacts cell fate determination upon treatment with taxol and other anti-mitotic drugs. Thus, we propose the innate immune system may be harnessed to selectively target cells with mitotic abnormalities.

cell biology↗