Biology subjects

Schmitz, W.

Publications and source records attributed to Schmitz, W..

18 recordsLinked to original sources

bioRxiv2026

Pharmacological arginine deprivation renders pancreatic cancer cells susceptible to senolysis and inhibition of the integrated stress response

Pancreatic ductal adenocarcinoma (PDAC) is almost inevitably fatal and largely resistant to current chemotherapy regimens. Senolysis, i. e. the selective elimination of senescent cells, and the targeting of cancer specific cellular metabolism are two novel treatment approaches that have proven to be effective for a variety of cancer types in pre-clinical studies. We now demonstrate that pharmacological depletion of arginine with pegylated recombinant human arginase 1 (PEG-rhARG1) induced senescence and activated the integrated stress response (IRS) in PDAC cells. Cells treated in such a manner were strikingly susceptible towards senolysis with ABT-263 (navitoclax) and also sensitive towards inhibition of the IRS. These results demonstrate a novel mechanism for an induced sensitivity of PDAC cells that could be exploited for cancer therapy.

cancer biology↗

bioRxiv2026

MYC/MIZ1 suppression of lysosomal protein degradation drives immune evasion in pancreatic ductal adenocarcinoma

The MYC oncoprotein promotes immune evasion of pancreatic ductal adenocarcinoma (PDAC), but the underlying molecular mechanisms are not fully understood. Here we show that MYC protects PDAC tumors from CD4+ T cell-dependent elimination. Single cell sequencing shows that MYC suppression in tumor cells increases amino acid availability and broadly activates amino acid-responsive gene expression programs in immune cell populations. This occurs because MYC-driven uptake depletes free amino acids from tumor interstitial fluid and plasma, while MYC compromises macropinocytosis and autophagy, both of which depend on lysosomal protein degradation. MYC engages the POZ/BTB transcription factor MIZ1 to suppress lysosomal genes regulated by the TFE3/TFEB/MITF network or by free MIZ1, thereby inhibiting lysosomal protein degradation. An orthogonal genetic model enabling transient, selective inhibition of amino acid uptake in tumor cells recapitulates the effects of MYC depletion on amino acid levels in the tumor microenvironment and induces complete, CD4+ T cell-dependent tumor eradication with long-term survival. We propose that MYC-mediated, cell-autonomous disruption of lysosome function coupled to non-cell-autonomous protection from immune clearance allows MYC-low cells to benefit from MYC-high neighbors, such that intratumoral heterogeneity in MYC expression confers a selective advantage to the entire tumor. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/740267v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@140d2ccorg.highwire.dtl.DTLVardef@cf5f1borg.highwire.dtl.DTLVardef@6d132aorg.highwire.dtl.DTLVardef@10535e6_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2026

Profound CD4+ T-Cell Reprogramming by Melphalan-Driven Oxidative Stress in High-Risk Multiple Myeloma

T cell-based immunotherapies have become central to the treatment of multiple myeloma (MM), yet their efficacy depends on the functionality of endogenous T cells. How cumulative treatment exposure, particularly high-dose melphalan, together with disease-intrinsic high-risk features shapes T-cell composition and immune competence remains incompletely understood. Here, we analyzed T cell composition and function in bone marrow (BM) and peripheral blood (PB) samples from MM patients across different stages of their treatment journey using flow cytometry (BM, n=162; PB, n=1,733), single-cell RNA sequencing (n=19), and cytotoxicity assays (n=20). We reveal reduced overall T cell frequencies and CD4+/CD8+ T cell ratio, associated with lines of therapy and driven in part by depletion of naive CD4+ T cells in gene-expression defined high risk (HR) disease. Among therapeutic agents, melphalan exerted the strongest effects on T cell populations and induced pronounced redox stress in both T cells and myeloma cell lines. This oxidative stress signature was enriched in HR patients and was reversible with N-acetyl-L-cysteine treatment. Together, these findings identify immune dysregulation as a defining feature of HR MM that extends beyond tumor-intrinsic genomic alterations and is further shaped by treatment-induced remodeling of the BM microenvironment. Given the association between higher CD4+ T cell numbers and improved CAR-T cell outcomes, our data highlight the translational importance of treatment sequencing, particularly in HR MM. One Sentence SummaryMelphalan-induced redox stress depletes CD4+ naive T cells, particularly in patients with high-risk multiple myeloma.

Cancer Biology↗

bioRxiv2025

HMOX1 controls a heme/ferritin switch that protects cells from ferroptosis

Modulating the intracellular labile iron pool (LIP) has emerged as a promising strategy to induce ferroptosis in cancer cells, offering a way to overcome resistance to apoptosis-based therapies. One of the main contributors to LIP is heme catabolism mediated by heme oxygenase-1 (HMOX1), which promotes ferroptosis sensitivity by releasing free iron. Beyond its role as an iron donor, heme can influence diverse proteins and signaling pathways that drive tumor progression, but how heme regulates ferroptosis remains poorly understood. Here, we uncover a paradoxical, protective function of heme in the absence of HMOX1 activity. When HMOX1 is inactive, heme becomes stabilized, leading to ferritin upregulation, suppression of ferroptosis, and rescue of cell death induced by both pharmacological and genetic inhibition of GPX4. Our findings reveal an unrecognized heme-HMOX1-ferritin axis that controls ferroptosis sensitivity. Targeting this pathway may offer a new therapeutic strategy to modulate ferroptosis in cancer.

cancer biology↗

bioRxiv2025

Glucose Metabolism Controls Oxidative Burst and Lipid Mediator Production in Neutrophils upon Microbial Challenge

Neutrophils are frontline responders against bacterial and fungal pathogens, requiring rapid energy and biosynthetic precursors to mount effective antimicrobial responses. To meet these demands, they primarily rely on aerobic glycolysis, making glucose uptake essential. Murine and human neutrophils express the glucose transporters GLUT1 and GLUT3; however, their specific roles in neutrophil immunobiology have not yet been fully elucidated. Here, we show that neutrophilic immune responses to Candida albicans and Staphylococcus aureus critically depend on GLUT1/3-dependent glucose uptake and glycolysis. Combined deletion of GLUT1 and GLUT3 almost completely abolished glucose uptake and aerobic glycolysis in murine neutrophils, yet did not impair granulopoiesis, indicating that homeostatic neutrophil development is largely independent of extracellular glucose. By contrast, during microbial challenge, loss of GLUT1/3 severely compromised NADPH-dependent ROS production, oxidative burst and cyclooxygenase-derived lipid mediator (LM) biosynthesis, demonstrating that glucose uptake via GLUT1/3 controls inflammatory effector functions of neutrophils. Moreover, genetic and pharmacologic inhibition of GLUT1/3-mediated glucose utilization reprograms neutrophil metabolism and LM biosynthesis toward an immunomodulatory phenotype. These findings identify a conserved nutrient-sensing metabolic checkpoint that governs neutrophil reprogramming and highlight novel opportunities for therapeutic immunomodulation.

immunology↗

bioRxiv2025

Tafazzin-Mediated Cardiolipin Remodeling Controls Metabolic Stress Response and Effector Function of Inflammatory T Cells

Clonal expansion and effector differentiation of T cells require extensive metabolic reprogramming. This includes the restructuring of the inner mitochondrial membrane (IMM) to enhance respiration by increasing chemiosmotic coupling efficiency. Cardiolipin, a unique phospholipid that is exclusively synthesized and localized in the IMM, modulates the biophysical properties of the electron transport chain (ETC) in tissues with high energy demands, such as cardiomyocytes and skeletal muscle. However, it remains unclear whether cardiolipin is also important for metabolic remodeling during T helper (Th) cell differentiation. In this study, we show that cardiolipin transacylation, catalyzed by the enzyme Tafazzin, supports the clonal expansion and effector function of inflammatory Th1 and Th17 cells in vitro and in models of autoimmune colitis and encephalomyelitis. At the molecular level, we demonstrate that loss of Tafazzin-mediated cardiolipin maturation induces a metabolic and transcriptional stress response in Th cells to compensate for impaired coupling efficiency of the ETC complexes and disrupted cellular redox homeostasis. However, the genetic program that restores cellular homeostasis and mitigates oxidative stress concurrently impairs the effector functions of inflammatory T cells, such as cytokine production. Our findings also provide insights into the complex clinical manifestation of patients with Barth syndrome (BTHS) caused by mutations in the human TAFAZZIN gene. BTHS is characterized by cardiac and skeletal myopathy as well as neutropenia and an increased susceptibility to infections. Although the molecular basis of the immunodeficiency remains poorly understood, our findings suggest that impaired Th cell function contributes to the immunopathology observed in BTHS patients.

immunology↗

bioRxiv2025

Metabolic silencing via methionine-based amino acid restriction in multiple myeloma cell lines reveals a potential new strategy for cancer therapy

Nutrient restriction, from caloric to amino acid to protein restriction, promotes cell switching to low-energy metabolism (LEM), which is characterized primarily by inhibited cell proliferation. In the long term, nutrient restriction has enormous impacts on life span and age-associated diseases such as type 2 diabetes and cancer. Owing to their antiproliferative effects, nutrient restriction approaches with a focus on amino acids are receiving increasing attention for use in tumour therapy. However, to date, the effects of amino acid restriction (AAR) have rarely been reported in patients with multiple myeloma (MM). In this work, we analysed AAR implemented via methionine restriction (MetR) in the MPC11 murine cell line and two human cell lines, KMS12-BM and L363. MetR exerted profound antiproliferative effects without causing cell death. In addition, methionine dependency was demonstrated in the cell lines investigated via homocysteine compensation. Additionally, mass spectrometry analyses of MPC11 cells revealed metabolic reprogramming, indicating that MetR led to a dramatic decrease in the (aerobic) glycolysis rate and in the abundances of energy equivalents and nucleotide synthesis metabolites. Taken together, the results of this study suggest that MetR is an important therapeutic option for MM.

cancer biology↗

bioRxiv2025

Riboflavin metabolism shapes FSP1-driven ferroptosis resistance

Membrane protection against oxidative insults is achieved by the concerted action of glutathione peroxidase 4 (GPX4) and endogenous lipophilic antioxidants such as ubiquinone and vitamin E. Deficiencies in these protective systems lead to an increased propensity to phospholipid peroxidation and ferroptosis. More recently, ferroptosis suppressor protein 1 (FSP1) was identified as a critical ferroptosis inhibitor acting via regeneration of membrane-embedded antioxidants. Yet, regulators of FSP1 are largely uncharacterised, and their identification is essential for understanding the mechanisms buffering phospholipid peroxidation and ferroptosis. Here, we conducted a focused CRISPR-Cas9 screen to uncover factors influencing FSP1 function, identifying riboflavin (vitamin B2) as a new modulator of ferroptosis sensitivity. We demonstrate that riboflavin, unlike other vitamins that act as radical-trapping antioxidants, supports FSP1 stability and the recycling of lipid-soluble antioxidants, thereby mitigating phospholipid peroxidation. Furthermore, we show that the riboflavin antimetabolite roseoflavin markedly impairs FSP1 function and sensitises cancer cells to ferroptosis. Thus, we uncover a direct and actionable role for riboflavin in maintaining membrane integrity by promoting membrane tolerance to lipid peroxidation. Our findings provide a rational strategy to modulate the FSP1-antioxidant recycling pathway and underscore the therapeutic potential of targeting riboflavin metabolism, with implications for understanding the interaction of nutrients and their contributions to a cells antioxidant capacity.

cell biology↗

bioRxiv2025

Metabolic role of the LutACB operon in Neisseria gonorrhoeae resistance to neutrophil-mediated clearance

Neisseria gonorrhoeae, an obligate human pathogen, causes the sexually transmitted disease gonorrhoea and primarily colonizes the human genitourinary tract. An infection triggers a strong neutrophil-driven inflammatory response; however, viable gonococci are frequently recovered from neutrophil-rich patient exudates, indicating that these pathogens can survive neutrophil-mediated killing in vivo. To identify bacterial factors involved in this interaction, we screened a N. gonorrhoeae transposon library for mutants with reduced survival in polymorphonuclear leukocytes (PMNs). Among the identified candidates was NGFG_RS05085 (lutB), encoding an L-lactate oxidation FeS protein within the LutACB operon, which includes lutA (NGFG_RS05075), an FeS-binding protein, and lutC, the lactate utilisation protein C, (NGFG_RS05080). Deletion of lutA, lutB, or lutC did not significantly impair growth in standard culture medium or in minimal medium complemented with glucose, L-Lactate, or pyruvate. lutB and lutC, but not lutA, knockout significantly reduced bacterial survival within neutrophils compared to the wild-type strain. Polar effects of the mutations were ruled out by monitoring gene expression in deletion mutants. Metabolic profiling revealed disruption in nucleotide and glutathione synthesis, connecting the LutACB operon with sulfur metabolism, which could be required for a defence against neutrophil-derived reactive oxygen species (ROS). These findings highlight the important novel role of the LutACB operon, which connects lactate utilization and sulfur metabolism, and enables N. gonorrhoeae to withstand neutrophil-mediated oxidative stress during infection.

microbiology↗

bioRxiv2024

L-Asparaginase treatment induces reversible immunoregulatory and immunosuppressive effects in non-malignant B cells in a model of T-cell dependent B cell activation

Metabolic reprogramming is critical for immune cell adaptation upon activation to exert full functionality with amino acids being a key metabolic factor. While L-asparagine is a non- essential amino acid it turns out to be conditionally essential in malignant B cells due to defective asparagine synthetase making L-asparaginase a commonly used chemotherapeutic agent. Off-target enzymatic activity including glutaminolysis impacting crucial immune function. However, its effects on healthy B cells remain unclear, therefore in this study, we explored how L-asparaginase modulates the biology and function of CD40-activated B cells, using an in-vitro model. B cells from healthy donors were treated with increasing L- asparaginase concentrations and analyzed for proliferation, immune phenotype, and metabolic changes. Results showed L-asparaginase reduced B cell proliferation and homotypic clustering without inducing apoptosis, instead impairing metabolic pathways, lowering glycolysis and oxidative phosphorylation, and reducing surface markers associated with antigen-presenting cell (APC) function. Functional assays confirmed that L-asparaginase- treated B cells had diminished ability to activate T cells. Supplementing with asparagine or glutamine restored B cell proliferation and function, with glutamine slightly more effective than asparagine. Interestingly, L-asparaginase induced a regulatory B cell phenotype, marked by CD24+CD38+CD27+ expression and increased interleukin-10 and TGF-beta, suggesting a potential immunosuppressive mechanism. These findings indicate that L-asparaginase not only affects malignant cells but also impacts the function of non-malignant B cells, proposing potential therapeutic applications in B cell-driven autoimmune disorders. Further studies are needed to explore its effects at lower, clinically relevant concentrations. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/625617v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@1ae8d10org.highwire.dtl.DTLVardef@af405borg.highwire.dtl.DTLVardef@1aa4c0eorg.highwire.dtl.DTLVardef@16750ea_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2024

Assessment of neurobehavioural traits under axenic conditions: an approach for multiple longitudinal analyses in the same mouse.

The gut-microbiota-brain axis influences neuroinflammation, neural development and behaviour such as sociability, memory and anxiety. To study these traits in vivo, especially during development or disease, it is crucial to analyse them over time and with multiple analyses in the same animal. With a growing understanding of the role of specific bacteria in neurodegenerative disease and behaviour, the demand for gnotobiotic mouse models has increased. However, maintaining stable hygienic conditions during behavioural testing is challenging, as exposure to conventional environments can alter the hygienic status of mice and affect behaviour. We established protocols to perform behavioural tests assessing memory, anxiety, exploration, learning and recognition under axenic conditions using flexible film isolators. Our study compared the behaviour of germ-free mice with mice carrying a defined minimal or moderately diverse microbiota. The results showed no effect of the microbiota on short- and long-term memory or novel object recognition. However, we showed for the first time that mice colonised with defined commensal bacteria exhibited more anxiety-like behaviour than germ-free mice. In addition, we showed that microbiota complexity is important, as only mice colonised with moderately diverse microbiota exhibited anxiety-like behaviour, allowing us to disentangle the contribution of specific microbial species or community interactions to this phenotype. This phenotype correlated with differences in hippocampal and serum metabolic profiles between colonised and germ-free mice. We propose a novel approach to study rodent behaviour at different physiological and pathological stages in their life without compromising hygiene, thus promoting the refinement and reduction of mice used in experiments.

animal behavior and cognition↗

bioRxiv2024

NEAT1 promotes genome stability via m6A methylation-dependent regulation of CHD4

Long non-coding (lnc)RNA emerge as regulators of genome stability. The nuclear enriched abundant transcript 1 (NEAT1) locus encodes two lncRNA isoforms that modulate gene expression, growth and proliferation in mammals. Interestingly, NEAT1 transcripts are overexpressed in many tumours and induced by DNA damage, suggesting a genome-protective function. However, the precise role of NEAT1 in the DNA damage response (DDR) is unclear. Here, we investigate the expression, modification levels, localization and structure of NEAT1 in response to DNA double-strand breaks (DSBs) induced by the topoisomerase-II inhibitor etoposide or the locus-specific endonuclease AsiSI. We find that induction of DSBs increases both the levels and N6-methyladenosine (m6A) marks on NEAT1, which promotes alterations in NEAT1 secondary structure and accumulation of hyper-methylated NEAT1 at a subset of promoter-associated DSBs to facilitate efficient DSB signalling. The depletion of NEAT1, in turn, delays the response to DSBs and triggers elevated DNA damage. The genome-protective role of NEAT1 is mediated by the RNA methyltransferase 3 (METTL3) and involves spreading of the chromodomain helicase DNA binding protein 4 (CHD4) upon release from NEAT1. Together, we describe a novel RNA-dependent DDR pathway that couples NEAT1 to the recognition and repair of DSBs.

molecular biology↗

bioRxiv2023

HIF-1α-mediated mitochondrial-glycolytic reprogramming controls the transition of precursor to terminally exhausted T cells

Functional exhaustion of T cells in cancer and persistent infections is characterized by the upregulation of inhibitory receptors, the progressive decline in cytokine secretion and impaired cytolytic activity. Terminally exhausted T cells are steadily replenished by a precursor population (Tpex) with phenotypic features of memory T cells and a stem-like capacity to self-renew. However, the metabolic principles of Tpex maintenance and the regulatory circuits that control the exhaustion of their progeny remain incompletely understood. Using a combination of gene-deficient mice, single-cell transcriptomics and metabolomic analyses, we here show that mitochondrial insufficiency is a cell-intrinsic trigger that initiates the T cell exhaustion program. At the molecular level, we found that diminished mitochondrial respiration and metabolic remodeling cause oxidative stress, which inhibits the proteasomal degradation of hypoxia inducible factor 1 alpha (HIF-1) in Tpex cells. HIF-1 mediates the transcriptional-glycolytic reprogramming of Tpex cells as an initial step towards terminal differentiation and functional exhaustion. Finally, we show that enhancing respiration by limiting the glycolytic activity of CAR T cells is a feasible metabolic intervention strategy to preserve the stemness of Tpex cells during chronic viral infection and cancer immunotherapy.

immunology↗

bioRxiv2022

Increased glycolysis and functional mitochondria fuel acinar-ductal metaplasia in the pancreas

Reprogramming of the cellular metabolism is a hallmark of pancreatic cancer, yet it remains unclear at what stage during carcinogenesis it occurs. Here, we investigated the metabolic requirements for acinar-to-ductal metaplasia (ADM), the first step in pancreatic carcinogenesis. We detected increased glycolytic marker expression in human ADM suggesting that a metabolic switch occurs during ADM formation. We report that this switch was similarly required for ADM formation in different oncogenic mouse models (KRAS, PI3K, and MEK1) and in ligand-induced ADM in mouse wild-type acini. In addition, we show that a functional electron transport chain (ETC), but not mitochondrial ATP production, was essential to ADM formation. We conclude that the ETC provides NAD+ for the de novo synthesis of serine from glycolysis intermediates. Our findings demonstrate that metabolic programming is essential for the initiation of pancreatic carcinogenesis and thus identifies potential targets for metabolic intervention.

cancer biology↗

bioRxiv2022

Selenocysteine metabolism is a targetable vulnerability in MYCN-amplified cancers

Understanding the operational molecular, and metabolic networks that determine the balance between pro- and anti-ferroptotic regulatory pathways could unravel unique vulnerabilities to be exploited for cancer therapy. Here we identify the selenoprotein P (SELENOP) receptor, LRP8, as a key determinant protecting MYCN-amplified neuroblastoma cells from ferroptosis in vitro and in orthotopic neuroblastoma mouse models. Specifically, the exquisite dependency on LRP8-mediated selenocysteine import is caused by the failure of MYCN-amplified cells to efficiently utilize alternative forms of selenium/selenocysteine based uptake necessary for selenoprotein biosynthesis. Increased activity of one of such transporters, SLC7A11, in MYCN-amplified cells leads to cysteine overload, progressive mitochondrial decline and impaired proliferation. These data reveal in LRP8 a targetable, and specific vulnerability of MYCN-amplified neuroblastoma cells and disclose a yet-unaccounted mechanism for selective ferroptosis induction that has the potential to become an important therapeutic entry point for MYCN-amplified neuroblastoma. Statement of significanceGiven the largely unsuccessful repurposing of adult oncology drugs for the treatment of neuroblastoma, our discoveries pave the way for novel ferroptosis based strategies for this entity. Specifically, targeting of LRP8 may offer novel therapeutic and safer opportunities for a number of pediatric malignancies and MYCN driven cancers.

cancer biology↗

bioRxiv2021

c-Myc plays a key role in IFN-γ induced persistence of Chlamydia trachomatis

Chlamydia trachomatis (Ctr) can persist over long periods of time within their host cell and thereby establish chronic infections. One of the major inducers of chlamydial persistence is interferon-gamma (IFN-{gamma}) released by immune cells as a mechanism of immune defence. IFN-{gamma} activates the catabolic depletion of L-tryptophan (Trp) via indoleamine 2,3-dioxygenase (IDO), resulting in persistent Chlamydia. Here we show that IFN-{gamma} depletes c-Myc, the key regulator of host cell metabolism, in a STAT1-dependent manner. Expression of c-Myc rescued Chlamydia from IFN-{gamma}-induced persistence in cultured cell lines, but also in human fallopian tube organoids. L-tryptophan concentrations control c-Myc levels via the PI3K-GSK3{beta} axis. Unbiased metabolic analysis revealed that Chlamydia infection reprograms the host cell tricarboxylic acid (TCA) cycle to support pyrimidine biosynthesis. Addition of TCA cycle intermediates or pyrimidine/purine nucleosides to infected cells rescued Chlamydia from IFN-{gamma}-induced persistence. Thus, our results challenge the longstanding hypothesis of L-tryptophan depletion through IDO as the major mechanism of IFN-{gamma}-induced metabolic immune defence and significantly extends the understanding of the role IFN-{gamma} as a broad modulator of host cell metabolism.

microbiology↗

bioRxiv2020

A phosphoproteomic approach reveals that PKD3 controls phenylalanine and tyrosine metabolism

Members of the Protein Kinase D (PKD) family (PKD1, 2, and 3) integrate hormonal and nutritional inputs to regulate complex cellular metabolism. Despite the fact that a number of functions have been annotated to particular PKDs, their molecular targets are relatively poorly explored. PKD3 promotes insulin sensitivity and suppresses lipogenesis in the liver. However, its substrates are largely unknown. Here we applied proteomic approaches to determine PKD3 targets. We identified over three-hundred putative targets of PKD3. Among them phenylalanine hydroxylase (PAH). PAH catalyses the conversion of phenylalanine to tyrosine and its activity is regulated by, phenylalanine concentration and glucagon-induced signaling. Consistently, we showed that PKD3 is activated by glucagon and promotes tyrosine levels in primary hepatocytes and liver of mice. Taken together, our comprehensive proteomic approach established that PKD3 determine the rate of phenylalanine to tyrosine conversion in the liver. Therefore, our data indicate that PKD3 might play a role in development of diseases related to the defective tyrosine and phenylalanine metabolism.

biochemistry↗

bioRxiv2019

A central role of glutamine in Chlamydia infection

Obligate intracellular bacteria like Chlamydia trachomatis undergo a complex developmental cycle between infectious non-replicative (EBs) and non-infectious replicative (RBs) forms. EBs shortly after entering a host cell transform to RBs, a crucial process in infection, initiating chlamydial replication. As Chlamydia fail to replicate outside the host cell it is currently unknown how the transition from EBs to RBs is initiated. Here we show in a cell-free approach in axenic media that uptake of glutamine by the bacteria is critical to initiate EB-RB transition. These bacteria utilize glutamine to synthesize cell wall peptidoglycan which has recently been detected in the septa of replicating intracellular Chlamydia. The increased requirement for glutamine in infected cells is achieved by reprogramming the glutamine metabolism in a c-Myc-dependent manner. Glutamine was effectively taken up by the glutamine transporter SLC1A5 and metabolized via glutaminase. Interference with this metabolic reprogramming limited growth of Chlamydia. Intriguingly, Chlamydia failed to produce progeny in SLC1A5 knockout mice. Thus, we report on the central role of glutamine for the development of an obligate intracellular pathogenic bacterium and the reprogramming of host glutamine metabolism, which may provide a basis for innovative anti-infective strategies.

microbiology↗