Biology subjects

Agathocleous, M.

Publications and source records attributed to Agathocleous, M..

9 recordsLinked to original sources

bioRxiv2026

Ascorbate and TET2 couple balanced hematopoiesis to disease tolerance

Infections stimulate myelopoiesis but this comes at the cost of reduced production of other lineages. It is unclear if this imbalance is protective or damaging, and if factors that promote balanced hematopoiesis can impact infection pathology. Here we show that the ascorbate-TET axis limits excessive myelopoiesis, promotes balanced hematopoiesis, and is essential for surviving malaria. Hematopoietic-specific ascorbate depletion promoted myelopoiesis. The effects of ascorbate were mediated by TET2/TET3 activity in myeloid progenitors. Combined ascorbate and TET2 depletion markedly skewed hematopoiesis to the myeloid lineage and impaired erythropoiesis. Ascorbate is commonly depleted in infections, but the functional significance of this remains unclear. In the absence of ascorbate and TET2, mice infected with Plasmodium parasites could clear the pathogen, but had exacerbated myeloid and impaired erythroid response, anemia, and tissue damage and they succumbed to infection, indicating compromised disease tolerance. Therefore ascorbate and TET2 promote balanced hematopoiesis to impart tolerance to malaria.

immunology↗

bioRxiv2026

Ascorbate is a physiological tumor suppressor metabolite in leukemia

Accumulation of oncometabolites promotes tumorigenesis, but it is not known if there are naturally occurring tumor suppressor metabolites whose deficiency within cancer-initiating cells causes cancer. Many leukemia patients are ascorbate deficient. Here we show that hematopoietic-specific ascorbate depletion in mice is sufficient to cause or promote leukemogenesis. Hematopoietic-specific ascorbate depletion promoted leukemogenesis by acting within leukemia initiating cells. Ascorbate depletion in myeloid leukemia expanded plasmacytoid dendritic cells, an effect mediated by the ascorbate molecular targets TET2 and TET3. Leukemia cells accumulated ascorbate as part of a tumor suppressor response to neoplastic proliferation that limited progression but depleted circulating ascorbate. Ascorbate restoration in mice with established leukemias extended survival. Hematopoietic-specific ascorbate depletion caused leukemia in collaboration with TET2 loss and was sufficient to cause leukemia with high penetrance even in the absence of other engineered mutations. These results identify ascorbate as a physiological tumor suppressor metabolite in blood cancers.

cancer biology↗

bioRxiv2026

Loss of TCA cycle turning promotes stem cell function

The citric acid cycle (TCA cycle) is the common terminal pathway for the oxidation of all nutrients. Citrate oxidation to oxaloacetate produces CO2, and citrate synthase (CS) uses nutrient-derived acetyl groups to regenerate citrate and fuel cycle turning. However, the essentiality of cycle fueling and turning in vivo remains unclear. Here we use hematopoiesis, the most proliferative system in the body, as a model to show that, contrary to common assumptions, TCA cycle turning is dispensable for respiration, survival, and proliferation of stem and progenitor cells in vivo, and its loss promotes stem cell function. Hematopoietic-specific Cs deletion in adult mice blocked citrate cycling without reducing the frequency of hematopoietic stem (HSC) and progenitor cells. HSCs and progenitor cells adapted to TCA cycle loss by markedly increasing nutrient consumption and biosynthesis. Disruption of cycle turning increased HSC regeneration, myeloid progenitor proliferation, and myelopoiesis in vivo. HSCs without a turning TCA cycle outcompeted wild-type HSCs within the same environment. The effect of CS deletion on HSC function was not phenocopied by genetic ablation of cytosolic citrate use and was rescued by ablation of glutamine use in biosynthesis. Therefore, TCA cycle turning restrains nutrient uptake, biosynthesis, cell proliferation, and stem cell function. These results suggest an explanation for the reduction in cycle activity observed in many normal proliferating cells and cancer cells.

biochemistry↗

bioRxiv2026

Stem cell function in vivo is supported by an alternative glycolysis endpoint

Carbohydrates are classically catabolized by fermentation or oxidation, a choice that impacts many cellular functions including proliferation. Proliferating cells including somatic stem and progenitor cells are thought to favor fermentation over oxidation, and most proliferating cells in vitro depend on lactate production. However, it has not been tested if fermentation and oxidation are the universal obligatory terminal fates for carbohydrates in vivo because the key enzymes, lactate dehydrogenase (LDH) and pyruvate dehydrogenase (PDH), have not been simultaneously deleted in any cell type. Here we show that both fermentation and oxidation are dispensable for the survival and function of hematopoietic stem cells (HSC). Combined LDHA and LDHB deletion to ablate LDH did not impair HSC function, suggesting that HSCs and rapidly proliferating hematopoietic progenitors surprisingly do not require fermentation. Combined LDHA, LDHB, and PDH deletion abolished both glucose oxidation and fermentation, but did not impair HSC function. Glycolysis was preserved, suggesting the operation of an alternative endpoint. LDH/PDH-deficient HSCs terminated glycolysis through pyruvate export. Pyruvate export by HSCs and progenitors was a physiological response to changing nutrient levels. Quadruple deletion of LDHA/B, PDH, and the pyruvate transporter MCT1 impaired HSC function. This suggested that an essential role of glycolysis termination is not to produce acetyl-CoA or lactate but to remove pyruvate. Therefore, in contrast to classical theories and to in vitro metabolism, carbohydrate metabolism in vivo does not require oxidation or fermentation but can terminate directly in pyruvate export, and this alternative pathway is sufficient to support stem cell function.

biochemistry↗

bioRxiv2025

Loss of vitamin C biosynthesis protects from a parasitic infection

The ability to synthesize essential molecules is sometimes lost in evolution. A classic example is ascorbate (Vitamin C), which is synthesized in most animals by L-Gulonolactone Oxidase (GULO), an enzyme lost multiple independent times in animal evolution. This event is thought to be evolutionarily neutral, however, GULO-deficient animals including humans need to obtain ascorbate from their diet and are susceptible to ascorbate deficiency and scurvy. We therefore hypothesized that this disadvantage of GULO loss is offset by physiological benefits. Here we show that ascorbate deficiency protects mice from schistosomiasis, a debilitating parasitic disease which afflicts 250 million people. Schistosoma mansoni worms required host ascorbate to produce eggs in vivo. Consequently, ascorbate-deficient mice were protected from schistosomiasis pathologies and transmission. Intermittent ascorbate deficiency protected Gulo-deficient mice from both scurvy and schistosomiasis mortality. The effects of ascorbate on schistosome reproduction were mediated by ascorbate-dependent histone demethylation which promoted vitellocyte development in female schistosomes. We propose that vitamin deficiencies are not always detrimental but can protect animals from pathogens which need to obtain vitamins from their host.

biochemistry↗

bioRxiv2025

A transcriptional biosensor reveals mechanisms of α-ketoglutarate signaling to chromatin

Alpha-ketoglutarate (KG) is required for chromatin demethylation but mechanisms controlling KG abundance in the nucleus are poorly defined. Therefore, we designed a biosensor system to monitor this metabolite pool in human cells using an KG-responsive cyanobacterial transcription factor, NtcA. We then coupled this system with a genetic screen to identify genes that regulate KG in the nucleus, defining an inter-organelle pathway in which sequential mitochondrial activities of the GPT2 transaminase and SLC25A11 transporter supply nuclear KG. Using a mouse model of GPT2 deficiency, a human inborn error of metabolism, we found that this pathway controls chromatin methylation in the developing brain. Our work provides a tool to assess KG signaling to chromatin and a framework for leveraging forward genetics to study nuclear metabolite pools.

synthetic biology↗

bioRxiv2023

Helminth infection impacts hematopoiesis

Helminth infections are common in animals. However, the impact of a helminth infection on the function of hematopoietic stem cells (HSCs) and other hematopoietic cells has not been comprehensively defined. Here we describe the hematopoietic response to infection of mice with Schistosoma mansoni, a parasitic flatworm which causes schistosomiasis. We analyzed the frequency or number of hematopoietic cell types in the bone marrow, spleen, liver, thymus, and blood, and observed multiple hematopoietic changes caused by infection. Schistosome infection impaired bone marrow HSC function after serial transplantation. Functional HSCs were present in the infected liver. Infection blocked bone marrow erythropoiesis and augmented spleen erythropoiesis, observations consistent with the anemia and splenomegaly prevalent in schistosomiasis patients. This work defines the hematopoietic response to schistosomiasis, a debilitating disease afflicting more than 200 million people, and identifies impairments in HSC function and erythropoiesis.

immunology↗

bioRxiv2021

Cell-type specific requirement for pyruvate dehydrogenase in hematopoiesis and leukemia development.

Cancer cells have different metabolic requirements as compared to their corresponding normal tissues. This is thought to reflect metabolic reprogramming during transformation. An alternative possibility is that some metabolic requirements of cancer cells reflect a maintenance of the metabolism of the specific normal cell type from which cancer cells originate. Here, we investigate this hypothesis by comparing glucose use in normal hematopoiesis and in leukemia. T cell progenitors in the thymus were glucose avid and oxidized more glucose in the tricarboxylic acid (TCA) cycle through pyruvate dehydrogenase (PDH) as compared to hematopoietic stem cells (HSCs) or other hematopoietic cells. PDH deletion reduced the number of double positive (DP) T cell progenitors but had no effect on HSCs, myeloid progenitors and other hematopoietic cells we examined. PDH deletion blocked the development of T cell leukemia from Pten-deficient DP progenitors, but not the development of a myeloid neoplasm from Pten-deficient HSCs or myeloid progenitors. Therefore, the requirement of glucose oxidation for leukemia development is inherited from the normal cell of origin and occurs independently of the driver genetic lesion. PDH was not required in vivo to generate acetyl-CoA or maintain levels of TCA cycle metabolites but to prevent pyruvate accumulation and to maintain glutathione levels and redox homeostasis.

cancer biology↗

bioRxiv2020

Metabolomic profiling of rare cell populations isolated by flow cytometry from tissues

Little is known about the metabolic regulation of rare cell populations because most metabolites are hard to detect in small numbers of cells. We previously described a method for metabolomic profiling of flow cytometrically-isolated hematopoietic stem cells (HSCs) that detects approximately 60 metabolites in 10,000 cells (Agathocleous et al., 2017). Here we describe a new method involving hydrophilic liquid interaction chromatography (HILIC) and high-sensitivity orbitrap mass spectrometry that detected approximately 160 metabolites in 10,000 HSCs, including many more glycolytic and lipid intermediates. We improved chromatographic separation, increased mass resolution, minimized ion suppression, extracted with acetonitrile, and eliminated sample drying. Most metabolites did not significantly change during cell preparation and sorting. We used this method to profile HSCs and circulating melanoma cells. HSCs exhibited increased glycerophospholipid metabolites relative to unfractionated bone marrow cells and altered purine biosynthesis after methotrexate treatment in vivo. Circulating melanoma cells were depleted for purine intermediates relative to subcutaneous tumors, suggesting they decrease purine synthesis during metastasis. These methods facilitate the routine metabolomic analysis of rare cell populations from tissues. Impact statementWe developed a method for metabolomic analysis of small numbers of flow cytometrically isolated cells from rare cell populations such as hematopoietic stem cells and circulating cancer cells.

cell biology↗