Biology subjects

Frickel, E.-M.

Publications and source records attributed to Frickel, E.-M..

4 recordsLinked to original sources

bioRxiv2026

Golgi-localised Guanylate-binding protein 5 enhances glycolysis in macrophages

Guanylate-binding proteins (GBPs) are part of a family of large interferon gamma (IFN{psi})-inducible GTPases, with ascribed roles in infection control and induction of programmed cell death. While pathogen-specific functions of GBPs have been studied in detail, their broader regulation of frontline immune defences remain unexplored. Here, we analysed the global contribution of human GBP1-5 to cellular metabolism in IFN{psi}-stimulated macrophages. We found a robust role of GBP2 and GBP5 in macrophage glycolysis. Only GBP5, and not GBP2 deficiency impaired surface expression and cytokine production of classically IFN{psi}/LPS-activated macrophages. The GTPase activity of GBP5 was required for the regulation of glycolysis and cytokine production. We found that GBP5 deficiency impaired cellular glucose uptake and lactate production specifically. Isotopic tracing with [U-13C6]-Glucose confirmed a decrease in several glycolytic intermediates, including glucose 6-phosphate, pyruvate, and lactate, but stable levels of traced tricarboxylic acid cycle (TCA) intermediates. Elevated ribose-5-phosphate and glycerol levels suggest an altered cytosolic redox balance and enhanced breakdown of fatty acids. GBP5 localised predominantly to the cis-Golgi and in the absence of GBP5 we observed increased Golgi fragmentation, however the total Golgi size remained unchanged. Our results underscore the fundamental role of GBP5 in glycolytic fluxes and Golgi integrity in IFN{psi}-stimulated macrophages, highlighting its significance in immune function in general and immunometabolism specifically.

immunology↗

bioRxiv2025

GBP1 recruitment to actin-rich pedestals induced by extracellular Gram-negative bacteria promotes pyroptosis.

The IFN{gamma}-induced GTPase guanylate binding protein 1 (GBP1) binds to lipopolysaccharide (LPS) on cytosolic Gram-negative bacteria and promotes pyroptosis via the recruitment and activation of caspase-4 on the bacterial outer membrane. Enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC, respectively) are extracellular pathogens that also induce LPS-and caspase-4-dependent pyroptosis. However, whether GBP1 is involved in this process remains unknown. EPEC and EHEC adhere intimately to intestinal epithelial cells via avid interactions between the bacterial adhesin Intimin and Tir (Translocated intimin receptor), a type 3 secretion system effector protein. Intimin-mediated clustering of Tir triggers actin polymerisation, leading to pedestal-like structures at bacterial attachment sites. Here we show that GBP1 is recruited to actin-rich pedestals in human cells infected with EPEC and EHEC in vitro and mouse colonocytes infected with the EPEC-like murine pathogen Citrobacter rodentium in vivo. GBP1-dependent caspase-4 trafficking to these sites leads to pyroptosis and IL-18 release. GBP1 mutants defective in LPS coatomer formation also localised to EPEC pedestals, pointing to LPS-independent mobilisation of GBP1 by actin polymerisation induced by extracellular A/E pathogens. To further dissect the underlying mechanism, we engineered a chimeric receptor (Fc{gamma}R-Tir) by combining the intracellular signalling domain of Tir and the extracellular ligand-binding domain of the Fc{gamma} receptor. Clustering of Fc{gamma}R-Tir with IgG-coated beads produced sterile actin-rich pedestals that were sufficient to recruit GBP1 independently of bacteria. Our findings reveal that cytosolic GBP1 is mobilised to sites of pathogen-induced actin remodelling independently of LPS. We establish that GBP1 not only operates as a pattern-recognition receptor but also orchestrates effector-triggered immunity against pathogens that hijack the actin cytoskeleton. 175-word AbstractThe IFN{gamma}-induced GTPase guanylate binding protein 1 (GBP1) binds to lipopolysaccharide (LPS) on cytosolic Gram-negative bacteria and promotes pyroptosis via the recruitment and activation of caspase-4 on the bacterial outer membrane. Enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC, respectively) are extracellular pathogens that adhere to host cells and stimulate dense actin polymerisation underneath their attachment sites, generating structures called actin-rich pedestals. Here we show that GBP1 traffics to actin-rich pedestals in human cells infected with EPEC and EHEC in vitro and mouse colonocytes infected with the EPEC-like murine pathogen Citrobacter rodentium in vivo. GBP1 promotes caspase-4 recruitment to actin-rich pedestals, leading to pyroptosis and IL-18 release. GBP1 mutants defective in LPS coatomer formation also localised to EPEC pedestals. Our novel assay that mimics pathogenic effector activity revealed GBP1 recruitment to sterile actin polymerisation sites. We conclude that cytosolic GBP1 is mobilised to sites of pathogen-induced actin remodelling independently of LPS. Our study establishes that GBP1 not only operates as a pattern-recognition receptor but also orchestrates effector-triggered immunity against pathogens that hijack the actin cytoskeleton.

immunology↗

bioRxiv2019

Differential spatiotemporal targeting of Toxoplasma and Salmonella by GBP1 assembles caspase signalling platforms

Guanylate binding proteins (GBPs), a family of interferon (IFN)-inducible GTPases, can promote cell-intrinsic defense by removal of intracellular microbial replicative niches through host cell death. GBPs target pathogen-containing vacuoles or the pathogen itself, and assist in membrane-disruption and release of microbial molecules that trigger cell death by activating the inflammasomes. We previously showed that GBP1 mediates atypical apoptosis or pyroptosis of human macrophages infected with Toxoplasma gondii (Tg) or Salmonella enterica Typhimurium (STm), respectively. In mice, the p47 Immunity-related GTPases (IRGs) control the recruitment of GBPs to microbe-containing vacuoles and subsequent cell death. However, humans are devoid of functional IRGs, and the pathogen-proximal immune detection mechanisms by GBP1 are poorly understood. Here, we describe two novel single-cell assays which show that GBP1 promotes the lysis of Tg-containing vacuoles and Tg plasma membrane, resulting in the cytosolic detection of Tg-DNA. In contrast, we show GBP1 only targets cytosolic STm and does not contribute to bacterial escape into the cytosol of human macrophages. GBP1 interacts with caspase-4 and recruits it directly to the bacterial surface, where caspase-4 can be activated by LPS. During STm infection, caspase-1 cleaves and inactivates GBP1 at Asp192, a site conserved in related mammalian GBP1 proteins but not in murine Gbps. STm-infected human macrophages expressing a cleavage-deficient GBP1 mutant exhibit higher pyroptosis due to the absence of caspase-1-mediated feedback inhibition of the GBP1-caspase-4 pathway. Our comparative studies elucidate microbe-specific spatiotemporal roles of GBP1 in detecting infection and the assembly and regulation of divergent caspase signaling platforms.

microbiology↗

bioRxiv2018

An Artificial Intelligence Workflow for Defining Host-Pathogen Interactions

For image-based infection biology, accurate unbiased quantification of host-pathogen interactions is essential, yet often performed manually or using limited enumeration employing simple image analysis algorithms based on image segmentation. Host protein recruitment to pathogens is often refractory to accurate automated assessment due to its heterogeneous nature. An intuitive intelligent image analysis program to assess host protein recruitment within general cellular pathogen defense is lacking. We present HRMAn (Host Response to Microbe Analysis), an open-source image analysis platform based on machine learning algorithms and deep learning. We show that HRMAn has the capability to learn phenotypes from the data, without relying on researcher-based assumptions. Using Toxoplasma gondii and Salmonella typhimurium we demonstrate HRMAns capacity to recognize, classify and quantify pathogen killing, replication and cellular defense responses.

microbiology↗