van Elsland, D. M. | bioRxiv Science

bioRxiv2023

Colon cancer and cell transformation by clinical Salmonella strains are associated with bacterial virulence and intracellular fitness

Non-typhoidal Salmonella (NTS) are facultative intracellular pathogens that are associated epidemiologically and experimentally with colon cancer development. Yet, the driving factors of Salmonella-induced cell transformation are mostly unknown. We compared 30 (case) NTS clinical strains isolated from patients who were diagnosed with colon cancer >1 year after NTS infection, versus 30 (control) strains from patients who did not develop colon cancer. While we observed diverse cell invasion and transformation efficiencies among the 60 NTS strains, case strains showed higher transformation efficiency than matching control strains. Genomic and transcriptomic analyses showed that transformation efficiency could not be attributed to specific genomic features, but was associated with gene expression, particularly metabolic genes and regulons. Moreover, high-transforming NTS strains display increased capacity to utilize various nutrient sources, including carbohydrates and amino acids, and grow significantly faster intracellularly than low-transforming NTS. Our results link NTS intracellular virulence to cancer promotion. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=198 SRC="FIGDIR/small/562874v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@137c6bcorg.highwire.dtl.DTLVardef@d874c1org.highwire.dtl.DTLVardef@d94b22org.highwire.dtl.DTLVardef@1d3e11c_HPS_FORMAT_FIGEXP M_FIG C_FIG In briefNon-typhoidal Salmonella (NTS) infections can promote cell transformation and colon cancer progression. Yet, little is known about the driving factors of Salmonella-induced transformation. Stevenin et al. performed a multi-omic characterization of clinical NTS strains identified in a nation-wide epidemiological study as associated with colon cancer and revealed a link between bacterial virulence, intracellular fitness, and host cell transformation. Highlights- Cancer-associated clinical NTS generate more cell transformation than matching control NTS. - NTS transformation efficiency did not correlate with specific genetic features. - NTS transformation efficiency correlates with gene expression and bacterial metabolic needs. - High-transforming NTS display increased virulence and intracellular fitness.

microbiology↗

bioRxiv2019

A trimeric Rab7 GEF controls NPC1-dependent lysosomal cholesterol export

Cholesterol import in mammalian cells is mediated by the LDL receptor pathway. Here, using an endogenous cholesterol reporter in a genome-wide CRISPR screen we identify >70 genes involved in LDL-cholesterol import. We characterise C18orf8 as a core component of the mammalian Mon1-Ccz1 guanidine exchange factor (GEF) for Rab7, required for complex stability and function. C18orf8-deficient cells lack Rab7 activation and show severe defects in late endosome morphology and endosomal LDL trafficking, resulting in cellular cholesterol deficiency. Unexpectedly, free cholesterol accumulates within swollen lysosomes, suggesting a critical additional defect in lysosomal cholesterol export. We find that active Rab7 interacts with the NPC1 cholesterol transporter and licenses lysosomal cholesterol export. This process is abolished in C18orf8-, Ccz1- and Mon1A/B-deficient cells and restored by a constitutively active Rab7. The trimeric Mon1-Ccz1-C18orf8 (MCC) GEF therefore plays a central role in cellular cholesterol homeostasis coordinating Rab7 activation, endosomal LDL trafficking and NPC1-dependent lysosomal cholesterol export.

cell biology↗