Biology subjects

Gonzalez-Lopez, C.

Publications and source records attributed to Gonzalez-Lopez, C..

4 recordsLinked to original sources

bioRxiv2025

A Modular Toolkit For Theophylline-Dependent Synthetic Auxotrophs Via Riboswitch-Gated Essential Genes

Synthetic auxotrophs are a useful means for developing genetically encoded biocontainment systems. Current methods for developing synthetic auxotrophs are complicated or expensive, limiting access and adoption of biocontainment technologies. To address this gap, we developed a simple and modular platform for creating synthetic auxotrophs based on ligand-dependent translational gating of essential genes. By inserting a theophylline-responsive riboswitch upstream of essential genes in Escherichia coli, we created strains whose viability depends on the presence of theophylline. We systematically applied this approach to 29 essential genes, obtained ligand-dependent growth phenotypes for 19 targets, and found that 18 of these essential genes yielded stringent live-die synthetic auxotrophs. These strains exhibited robust theophylline dependence with escape frequencies ranging from 1 x 10-5 to 1 x 10-6 (most below limit of detection). Our modular design allows for the rapid (<1 week), low-cost, and reliable generation of synthetic auxotrophs. This work introduces ligand-dependent translational control as a new mechanism for engineering synthetic auxotrophy and provides an accessible platform that expands the biocontainment toolkit.

synthetic biology↗

bioRxiv2025

Epigenetic Control of TERRA by FTSJ3 is Critical for Telomerase-Driven Cancers

Telomerase reverse transcriptase (hTERT) overexpression, a hallmark of most cancers, drives tumorigenesis by enabling limitless replicative potential. Direct targeting of hTERT is challenging, necessitating alternative strategies. Through genome-wide synthetic dosage lethality (SDL) screening in cancer models, including patient-derived organoids, we identify FTSJ3, an RNA 2-O-methyltransferase, as a critical vulnerability in hTERT-overexpressing cells. FTSJ3 methylates telomeric repeat-containing RNA (TERRA), a modification essential for recruiting SUV39H1 to telomeric ends to mediate H3K9 trimethylation and establish stable heterochromatin. Loss of FTSJ3 disrupts this cascade, impairing H3K9 trimethylation, HP1-alpha recruitment, and telomeric heterochromatin maintenance. Notably, this reveals an unexpected dependency on TERRA methylation for telomeric heterochromatin stability in hTERT-driven cancers. Non-malignant cells, lacking telomerase activity and de novo telomere repeat synthesis, are unaffected by FTSJ3 suppression. Our findings establish the FTSJ3/TERRA/SUV39H1 axis as a critical mechanism supporting telomeric heterochromatin stability in hTERT-driven cancers. This telomere-directed epigenetic strategy provides a robust framework for translational therapeutic innovation.

cancer biology↗

bioRxiv2021

The P5-ATPase ATP13A1 modulates MR1-mediated antigen presentation

The monomorphic antigen presenting molecule MHC-I-related protein 1 (MR1) presents small molecule metabolites to mucosal-associated invariant T (MAIT) cells. The MR1-MAIT cell axis has been implicated in a variety of infectious and non-communicable diseases and recent studies have begun to develop an understanding of the molecular mechanisms underlying this specialised antigen presentation pathway. Yet, the proteins regulating MR1 folding, loading, stability, and surface expression remain to be identified. Here, we performed a gene trap screen to discover novel modulators of MR1 surface expression through insertional mutagenesis of an MR1-overexpressing clone derived from the near-haploid human cell line HAP1 (HAP1.MR1). The most significant positive regulators identified included {beta}2-microglobulin, a known regulator of MR1 surface expression, and ATP13A1, a P5-ATPase in the endoplasmic reticulum (ER) with putative transporter function not previously associated with MR1-mediated antigen presentation. CRISPR/Cas9-mediated knock-out of ATP13A1 in both HAP1.MR1 and THP-1 cell lines revealed a profound reduction in MR1 protein levels and a concomitant functional defect specific to MR1-mediated antigen presentation. Collectively, these data are consistent with the ER-resident ATP13A1 as a key post-transcriptional determinant of MR1 surface expression.

immunology↗

bioRxiv2020

Deep analysis of the USP18-dependent ISGylome and proteome unveils important roles for USP18 in tumour cell antigenicity and radiosensitivity

The deubiquitylating enzyme USP18 is a major negative regulator of the interferon (IFN) signalling cascade. IFN pathways contribute to resistance to conventional chemotherapy, radiotherapy, and immunotherapy and are often deregulated in cancer. USP18 is the predominant human protease that cleaves interferon-stimulated gene ISG15, a ubiquitin-like protein tightly regulated in the context of innate immunity, from its modified substrate proteins in vivo. In this study, using advanced proteomic techniques, we have expanded the USP18-dependent ISGylome and proteome in a chronic myeloid leukaemia (CML)-derived cell line (HAP1) treated with type I IFN. Novel ISGylation targets were characterised that modulate the sensing of innate ligands, antigen presentation and secretion of cytokines. Consequently, CML USP18-deficient cells are more antigenic, driving increased activation of cytotoxic T lymphocytes (CTLs) and are more susceptible to irradiation. Our results suggest USP18 as a pharmacological target in cancer immunotherapy and radiotherapy.

cancer biology↗