Biology subjects

D'Alessandro, A.

Publications and source records attributed to D'Alessandro, A..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

Therapy resistance in AML is mediated by cytoplasmic sequestration of the transcriptional repressor IRF2BP2

While the development of venetoclax with azacitidine (ven/aza) has improved AML therapy, drug resistance remains a major challenge. Notably, primary ven/aza-resistant AML are frequently reliant on MCL1, however, the underlying mechanisms remain unclear. Co-immunoprecipitation of MCL1 from ven/aza-resistant AML samples coupled with mass spectrometry analysis identified the transcriptional repressor Interferon Regulatory Factor 2 Binding Protein 2 (IRF2BP2) as an MCL1 binding partner. This interaction results in cytoplasmic IRF2BP2 localization and loss of transcriptional repression within ven/aza-resistant leukemic stem cells (LSC). Consequently, ven/aza-resistant LSC have increased IRF2BP2 target gene expression, including acyl-CoA synthetase long-chain family member 1 (ACSL1), an essential rate-limiting enzyme for fatty acid oxidation (FAO). Inhibition of ACSL1 functionally impaired ven/aza-resistant LSC through a depletion of long-chain acyl-carnitine metabolites and FAO. Collectively, these data provide evidence for a previously undescribed mechanism by which MCL1 mediates IRF2BP2 cytoplasmic sequestration and consequent de-repression of ACSL1, thereby promoting ven/aza-resistance in AML.

cancer biology↗

bioRxiv2025

Compartmentalization of mRNA and Translation by Desmosomes

Subcellular compartmentalization enables cells to concentrate and locally regulate functions. Here we find that translational machinery is compartmentalized to the cell cortex in epidermal cells. Furthermore, we observed broad enrichment of transcripts at the cortex, establishing a novel axis of mRNA organization in these cells. Mechanistically, we identified the desmosomal protein, desmoplakin, to be essential for cortical recruitment of both ribosomes and mRNAs, through distinct mechanisms. While mRNA localization is usually proposed to promote local translation, we found that most cortical transcripts were translationally repressed. These findings reveal spatial and transcript-dependent features of the cortical translatome. One mediator of this regulation is the RNA-induced Silencing Complex (RISC) which is also cortically enriched in a desmoplakin-dependent manner. Under homeostatic conditions, cortical RISC associates with transcripts for cell adhesion and the cytoskeleton. Upon wounding RISC is delocalized from the cortex and its associated transcripts become translationally upregulated. Together our data demonstrate a desmosome-dependent cortical compartmentalization of translation that dynamically responds to barrier perturbations, including wounding.

cell biology↗

bioRxiv2025

Long-Distance Trail Running Induces Inflammatory-Associated Protein, Lipid, and Purine Oxidation in Red Blood Cells

Ultra-endurance exercise places extreme physiological demands on oxygen transport, yet its impact on red blood cells (RBCs) remains underexplored. We conducted a multi-omics analysis of plasma and RBCs from endurance athletes before and after a 40-km trail race (MCC) and a 171-km ultramarathon (UTMB(R)). Ultra-running led to oxidative stress, metabolic shifts, and inflammation-driven RBC damage, including increased acylcarnitines, kynurenine accumulation, oxidative lipid and protein modifications, reduced RBC deformability, enhanced microparticle release, and increased senescence markers such as externalized phosphatidylserine (PS). Post-race interleukin-6 strongly correlated with kynurenine elevation, mirroring inflammatory responses in severe infections. These findings challenge the assumption that RBC damage in endurance exercise is primarily mechanical, revealing systemic inflammation and metabolic remodeling as key drivers. This study underscores RBCs as both mediators and casualties of extreme exercise stress, with implications for optimizing athlete recovery, endurance training, and understanding inflammation-linked RBC dysfunction in clinical settings. TeaserMarathon running imparts molecular damage to red blood cells, the effects of which are exacerbated by increased distances of ultramarathons.

biochemistry↗

bioRxiv2025

New alleles of D-2-hydroxyglutarate dehydrogenase enable studies of oncometabolite function in Drosophila melanogaster

D-2-hydroxyglutarate (D-2HG) is a potent oncometabolite capable of disrupting chromatin architecture, altering metabolism, and promoting cellular dedifferentiation. As a result, ectopic D-2HG accumulation induces neurometabolic disorders and promotes progression of multiple cancers. However, the disease-associated effects of ectopic D-2HG accumulation are dependent on genetic context. Specifically, neomorphic mutations in the mammalian genes Isocitrate dehydrogenase 1 (IDH1) and IDH2 result in the production of enzymes that inappropriately generate D-2HG from -ketoglutarate (KG). Within this genetic background, D-2HG acts as an oncometabolite and is associated with multiple cancers, including several diffuse gliomas. In contrast, loss-of-function mutations in the gene D-2-hydroxyglutarate dehydrogenase (D2hgdh) render cells unable to degrade D-2HG, resulting in excessive buildup of this molecule. D2hgdh mutations, however, are not generally associated with elevated cancer risk. This discrepancy raises the question as to why ectopic D-2HG accumulation in humans induces context-dependent disease outcomes. To enable such genetic studies in vivo, we generated two novel loss-of-function mutations in the Drosophila melanogaster gene D2hgdh and validated that these alleles result in ectopic D-2HG. Moreover, we observed that D2hgdh mutations induce developmental and metabolomic phenotypes indicative of elevated D-2HG accumulation. Overall, our efforts provide the Drosophila community with new mutant strains that can be used to study D-2HG function in human disease models as well as in the context of normal growth, metabolism, and physiology.

genetics↗

bioRxiv2025

Ontogeny Dictates Oncogenic Potential, Lineage Hierarchy, and Therapy Response in Pediatric Leukemia

Accumulating evidence links pediatric cancers to prenatal transformation events, yet the influence of the developmental stage on oncogenesis remains elusive. We investigated how hematopoietic stem cell developmental stages affect leukemic transformation, disease progression, and therapy response using a novel, humanized model of NUP98::NSD1-driven pediatric acute myeloid leukemia, that is particularly aggressive with WT1 co-mutations. Fetal-derived hematopoietic stem cells readily transform into leukemia, and WT1 mutations further enhance stemness and alter lineage hierarchy. In contrast, stem cells from later developmental stages become progressively resistant to transformation. Single-cell analyses revealed that fetal-origin leukemia stem cells exhibit greater quiescence and reliance on oxidative phosphorylation than their postnatal counterparts. These differences drive distinct therapeutic responses, despite identical oncogenic mutations. In patients, onco-fetal transcriptional programs correlate with worse outcomes. By targeting key vulnerabilities of fetal-origin leukemia cells, we identified combination therapies that significantly reduce aggressiveness, highlighting the critical role of ontogeny in pediatric cancer treatment.

cancer biology↗

bioRxiv2025

Editing strigolactone biosynthesis genes in tomato reveals novel phenotypic effects and highlights D27 as a key target for parasitic weed resistance

Parasitic weed infestations pose an increasing threat to agriculture worldwide, especially in the Mediterranean region. Phelipanche ramosa and P. aegyptiaca (broomrapes) cause severe damage to field-grown tomato (Solanum lycopersicum L.). Strigolactones (SLs), apocarotenoid phytohormones, play a critical role in plant physiology and development, and are also the primary signals that trigger the germination of parasitic weed seeds. We generated CRISPR/Cas9 tomato knock-out lines for the SlD27 gene, as well as three other key genes involved in SL biosynthesis (SlCCD7, SlCCD8, SlMAX1), all within the same genetic background. The edited lines exhibited a marked reduction in SL content in root exudates, along with impaired broomrape seed germination. A comprehensive analysis of morphological, reproductive, and fruit-related traits revealed gene-specific effects on plant phenotype, including vegetative traits, fruit set, fruit development, and volatilome. Specifically, the knock-out of two CCDs and the MAX1 had a specific impact not only on plant development but also on the production of volatile organic compounds during fruit ripening. In contrast, the Sld27 lines, produced for the first time in this study, displayed a phenotype similar to the control non-edited plants, suggesting that the D27 gene holds promise as a breeding target for enhancing resistance to parasitic weeds in tomato. HighlightThe characterization of tomato CRISPR/Cas9-edited lines for the four core genes involved in strigolactone biosynthesis revealed gene-specific effects on plant phenotype, with D27 emerging as a potential target for resistance to parasitic weeds.

genetics↗

bioRxiv2025

Hypoxia-inducible factor 1α is required to establish the larval glycolytic program in Drosophila melanogaster

The rapid growth that occurs during Drosophila larval development requires a dramatic rewiring of central carbon metabolism to support biosynthesis. Larvae achieve this metabolic state, in part, by coordinately up-regulating the expression of genes involved in carbohydrate metabolism. The resulting metabolic program exhibits hallmark characteristics of aerobic glycolysis and establishes a physiological state that supports growth. To date, the only factor known to activate the larval glycolytic program is the Drosophila Estrogen-Related Receptor (dERR). However, dERR is dynamically regulated during the onset of this metabolic switch, indicating that other factors must be involved. Here we discover that Sima, the Drosophila ortholog of Hif1, is also essential for establishing the larval glycolytic program. Using a multi-omics approach, we demonstrate that sima mutants fail to properly activate aerobic glycolysis and die during larval development with metabolic defects that phenocopy dERR mutants. Moreover, we demonstrate that dERR and Sima/Hif1 protein accumulation is mutually dependent, as loss of either transcription factor results in decreased abundance of the other protein. Considering that the mammalian homologs of ERR and Hif1 also cooperatively regulate aerobic glycolysis in cancer cells, our findings establish the fly as a powerful genetic model for studying the interaction between these two key metabolic regulators. STRUCTURED ABSTRACTO_ST_ABSObjectivesC_ST_ABSThe rapid growth that occurs during Drosophila larval development requires a dramatic rewiring of central carbon metabolism to support biosynthesis. Larvae achieve this metabolic state, in part, by coordinately up-regulating the expression of genes involved in carbohydrate metabolism. The resulting metabolic program exhibits hallmark characteristics of aerobic glycolysis and establishes a physiological state that supports growth. To date, the only factor known to activate the larval glycolytic program is the Drosophila Estrogen-Related Receptor (dERR). However, dERR is dynamically regulated during the onset of this metabolic switch, indicating that other factors must be involved. Here we examine the possibility the Drosophila ortholog of Hypoxia inducible factor 1 (Hif1) is also required to activate the larval glycolytic program. MethodsCRISPR/Cas9 was used to generate new loss-of-function alleles in the Drosophila gene similar (sima), which encodes the sole fly ortholog of Hif1. The resulting mutant strains were analyzed using a combination of metabolomics and RNAseq for defects in carbohydrate metabolism. ResultsOur studies reveal that sima mutants fail to activate aerobic glycolysis and die during larval development with metabolic phenotypes that mimic those displayed by dERR mutants. Moreover, we demonstrate that dERR and Sima/Hif1 protein accumulation is mutually dependent, as loss of either transcription factor results in decreased abundance the other protein. ConclusionsThese findings demonstrate that Sima/HIF1 is required during embryogenesis to coordinately up-regulate carbohydrate metabolism in preparation for larval growth. Notably, our study also reveals that the Sima-dependent gene expression profile shares considerable overlap with that observed in dERR mutant, suggesting that Sima/HIF1 and dERR cooperatively regulate embryonic and larval glycolytic gene expression. HIGHLIGHTSO_LIThe Drosophila melanogaster gene similar (sima), which encodes the sole fly ortholog of Hif1, is required to up-regulate glycolysis in preparation for larval growth. C_LIO_LIsima mutant larvae exhibit severe defects in carbohydrate metabolism and die during the second larval instar. C_LIO_LIsima mutant larvae exhibit the same metabolic phenotypes as Drosophila Estrogen Related Receptor (dERR) mutants, suggesting that these two transcription factors coordinately regulate the larval glycolytic program. C_LIO_LISima/Hif1 and dERR accumulation is mutually dependent, as loss of either transcription factor results in decreased abundance of the other. C_LI

developmental biology↗

bioRxiv2024

Metabolic Switch in Endocrine Resistant Estrogen Receptor Positive Breast Cancer

PurposeThe development of endocrine resistance remains a significant challenge in the clinical management of estrogen receptor-positive (ER+) breast cancer. Metabolic reprogramming is a prominent component of endocrine resistance and a potential therapeutic intervention point. However, a limited understanding of which metabolic changes are conserved across the heterogeneous landscape of ER+ breast cancer or how metabolic changes factor into ER DNA binding patterns hinder our ability to target metabolic adaptation as a treatment strategy. This study uses dimethyl fumarate (DMF) to restore tamoxifen (Tam) and fulvestrant (Fulv) sensitivity in endocrine-resistant cell lines and investigates how metabolic changes influence ER DNA-binding patterns. Experimental DesignTo address the challenge of metabolic adaptation in anti-endocrine resistance, we generated Tam and Fulv resistance in six ER+ breast cancer (BC) cell lines, representing ductal (MCF7, T47D, ZR75-1, and UCD12), lobular (MDA-MB-134--VI), and HER2 amplified (BT474) BC molecular phenotypes. Metabolomic profiling, RNA sequencing, proteomics, and CUT&RUN assays were completed to characterize metabolic shifts, transcriptional and protein changes, and ER DNA-binding patterns in resistant cells. Dimethyl fumarate was assessed for its ability to reverse Tam and Fulv resistance, restore tricarboxylic acid cycle (TCA) cycle function, and restore parental cell (endocrine sensitive) ER DNA binding patterns. ResultsTamoxifen-resistant (TamR) and fulvestrant-resistant (FulvR) cells exhibited disrupted TCA cycle activity, reduced glutathione levels, and altered nucleotide and amino acid metabolism. DMF treatment replenished TCA cycle intermediates and reversed resistance in both TamR and FulvR cells. DMF also increased mevalonate pathway enzyme expression in both TamR and FulvR cells, with TamR cells upregulating enzymes in the cholesterol synthesis phase and FulvR enhancing enzymes in the early part of the pathway. DMF restored ER DNA-binding patterns in TamR cells to resemble parental cells, re-sensitizing them to Tam. In FulvR cells, DMF reversed resistance by modulating ER-cofactor interactions but did not restore parental ER DNA-binding signatures. ConclusionsOur findings provide new insights into how metabolic reprogramming affects ER DNA-binding activity in endocrine-resistant breast cancer. We demonstrate how altering metabolism can reprogram ER signaling and influence resistance mechanisms by targeting metabolic vulnerabilities, such as TCA cycle disruptions. Additionally, our data provide a comprehensive metabolomic, RNA-seq, and CUT&RUN data set relevant to tumor metabolic adaptation leading to acquired endocrine resistance in highly utilized ER+ breast cancer cell lines. This study improves our understanding of how metabolic states alter ER function in endocrine-resistant breast cancer.

cancer biology↗

bioRxiv2024

Metabolic vulnerabilities in Down syndrome B-cell acute lymphoblastic leukemia can be targeted using Venetoclax

Children with Down syndrome (DS) and B-cell acute lymphoblastic leukemia (B-ALL) are at increased risk for treatment-related mortality and relapse, highlighting the need for new therapies. Leukemia cell lines (CLs) have been fundamental to understanding therapeutic responses to pharmacological agents. We generated three DS B-ALL CLs characterized with diverse genomic alterations, including IGH::CRLF2 rearrangement (BCR::ABL1 like), mutations in FLT3 and TP53, and a novel ERG::CEBPD rearrangement. DS CLs had diminished proliferation, metabolism, and mitochondrial function when compared to non-DS (NDS) CLs and interestingly, these findings were similar to NDS Philadelphia chromosome-like (Ph-like) B-ALL CLs. Based on similar mitochondrial defects and prior preclinical data using Venetoclax for Ph-like B-ALL, we hypothesized that Venetoclax would be effective in DS. Intriguingly, Venetoclax was more effective in DS when compared to both NDS and Ph-like CLs. Efficacy was observed in DS patient derived xenografts (PDXs) and diagnostic/relapsed patient samples treated with Venetoclax, which synergized with Trametinib and Vincristine. Mass spectrometry-based multiomics analyses in DS and NDS B-ALL patient samples revealed an enriched metabolite profile in DS, particularly in the hubs of glucose metabolism and polyunsaturated phosphatidylcholines and phosphatidylinositols. Transcriptome analyses in DS B-ALL patients (n=249) supported enhanced glucose and fatty acid metabolism. Glucose regulated B-ALL viability through de novo serine biosynthesis. Targeting serine synergized with Venetoclax in DS B-ALL CLs. In summary, we have generated novel tools for studying DS B-ALL and identify altered metabolism in DS that responds to Venetoclax.

cancer biology↗

bioRxiv2024

Novel preclinical model of human lung cancer cachexia

Cancer cachexia (CC), a syndrome of skeletal muscle and adipose wasting, reduces responsiveness to therapies and increases mortality. There are no approved treatments for CC, which may relate to discordance between pre-clinical models and human CC. To address the need for clinically relevant models of lung CC, we generated inducible, lung epithelial cell specific KrasG12D/+ (G12D) mice. G12D mice develop CC over a protracted time course and phenocopy tissue and tumor, cellular, mutational, transcriptomic, and metabolic characteristics of human lung CC. G12D mice demonstrate early loss of adipose, a phenotype that was apparent across numerous models of CC and translates to patients with lung cancer. Tumor-released factors promote adipocyte lipolysis, a driver of adipose wasting in CC, and adipose wasting was inversely related to tumor burden. Thus, G12D mice model key features of human lung CC and highlight a role for early tumor metabolic reprogramming of adipose tissue in CC. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/615385v3_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@66d87dorg.highwire.dtl.DTLVardef@f1cb4org.highwire.dtl.DTLVardef@2580f1org.highwire.dtl.DTLVardef@3463d5_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2024

Proteostasis and metabolic dysfunction in a distinct subset of storage-induced senescent erythrocytes targeted for clearance

Although refrigerated storage slows the metabolism of volunteer donor RBCs, cellular aging still occurs throughout this in vitro process, which is essential in transfusion medicine. Storage-induced microerythrocytes (SMEs) are morphologically-altered senescent RBCs that accumulate during storage and which are cleared from circulation following transfusion. However, the molecular and cellular alterations that trigger clearance of this RBC subset remain to be identified. Using a staining protocol that sorts long-stored SMEs (i.e., CFSEhigh) and morphologically-normal RBCs (CFSElow), these in vitro aged cells were characterized. Metabolomics analysis identified depletion of energy, lipid-repair, and antioxidant metabolites in CFSEhigh RBCs. By redox proteomics, irreversible protein oxidation primarily affected CFSEhigh RBCs. By proteomics, 96 proteins, mostly in the proteostasis family, had relocated to CFSEhigh RBC membranes. CFSEhigh RBCs exhibited decreased proteasome activity and deformability; increased phosphatidylserine exposure, osmotic fragility, and endothelial cell adherence; and were cleared from the circulation during human spleen ex vivo perfusion. Conversely, molecular, cellular, and circulatory properties of long-stored CFSElow RBCs resembled those of short-stored RBCs. CFSEhigh RBCs are morphologically and metabolically altered, have irreversibly oxidized and membrane-relocated proteins, and exhibit decreased proteasome activity. In vitro aging during storage selectively alters metabolism and proteostasis in SMEs, targeting these senescent cells for clearance.

cell biology↗

bioRxiv2024

Metabolic and Cellular Differences Between Sedentary and Active Individuals at Rest and During Exercise

BackgroundPhysical inactivity is a major contributor to cardiometabolic disease and mortality. Although mitochondrial dysfunction characterizes overt pathology, whether a distinct mitochondrial phenotype is present in apparently healthy sedentary adults remains unclear. MethodsNine sedentary (SED) and ten physically active (AC) healthy males (42 {+/-} 14 yr) were studied. Skeletal muscle bioenergetics were assessed using high-resolution respirometry, fluxomics, metabolomics and protein expression analyses. Whole-body physiology was evaluated using cardiopulmonary exercise testing (CPET) including fat oxidation and blood lactate measurements. ResultsAt rest, SED exhibited marked reductions in mitochondrial capacity, including Complex I (-36%), Complex II (-28%), electron transport system capacity (-34%), and ATP-synthase-coupled respiration (-30%, all p < 0.01). The most pronounced alteration was a 49% reduction in mitochondrial pyruvate carrier (MPC1) expression, which closely correlated with reduced pyruvate oxidation (-37%, p = 0.006) and lower TCA intermediates. SED also showed reduced MCT1 abundance, impaired fatty acid oxidation capacity (-32% to -35%), decreased CPT1 activity (-51%), altered cardiolipin composition and elevated ROS/O flux ratios. During exercise, SED demonstrated lower VO max (-38%), reduced fat oxidation (-35%) and higher blood lactate accumulation (>60%, p < 0.001). Mitochondrial function was strongly associated with exercise performance (r = 0.57-0.78, p < 0.01). ConclusionsHealthy sedentary adults are characterized by reduced mitochondrial function characterized by decreased substrate entry and oxidation, reduced oxidative capacity and diminished metabolic flexibility. CPET-derived fat oxidation and blood lactate responses closely reflect skeletal muscle mitochondrial function, providing non-invasive physiological markers of metabolic health. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=178 SRC="FIGDIR/small/608601v2_fig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@1a3a629org.highwire.dtl.DTLVardef@f1ea48org.highwire.dtl.DTLVardef@4c4a96org.highwire.dtl.DTLVardef@b4f879_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Schematic of skeletal muscle mitochondrion: SED side shows reduced MPC, CPT1, L4CL, and TCA flux with elevated ROS; AC side shows robust OXPHOS, fat oxidation, and lactate clearance. Arrows link to CPET as a non-invasive diagnostic tool for mitochondrial health. C_FIG

biochemistry↗

bioRxiv2024

STAT3 modulates mitochondrial function and plays a critical role in the survival of leukemic stem cells

Signal transducer and activator of transcription 3 (STAT3) is a well-described transcription factor that mediates oxidative phosphorylation and glutamine uptake in bulk acute myeloid leukemia (AML) cells and leukemic stem cells (LSCs). STAT3 has also been shown to translocate to the mitochondria in AML cells, particularly when phosphorylated at the serine 727 (pSTAT3 S727) residue. Inhibition of STAT3 results in impaired mitochondrial function and decreased leukemia cell viability. We discovered a novel interaction of STAT3 with voltage-dependent anion channel 1 (VDAC1) in the mitochondria that provides a mechanism through which STAT3 modulates mitochondrial function and cell survival. Through VDAC1, STAT3 regulates calcium and oxidative phosphorylation in the mitochondria. STAT3 and VDAC1 inhibition also results in significantly reduced engraftment potential of LSCs, including primary samples resistant to venetoclax. These results implicate STAT3 as a therapeutic target in AML.

cancer biology↗

bioRxiv2024

Ferroptosis regulates hemolysis in stored murine and human red blood cells

Red blood cell (RBC) metabolism regulates hemolysis during aging in vivo and in the blood bank. Here, we leveraged a diversity outbred mouse population to map the genetic drivers of fresh/stored RBC metabolism and extravascular hemolysis upon storage and transfusion in 350 mice. We identify the ferrireductase Steap3 as a critical regulator of a ferroptosis-like process of lipid peroxidation. Steap3 polymorphisms were associated with RBC iron content, in vitro hemolysis, and in vivo extravascular hemolysis both in mice and 13,091 blood donors from the Recipient Epidemiology and Donor evaluation Study. Using metabolite Quantitative Trait Loci analyses, we identified a network of gene products (FADS1/2, EPHX2 and LPCAT3) - enriched in donors of African descent - associated with oxylipin metabolism in stored human RBCs and related to Steap3 or its transcriptional regulator, the tumor protein TP53. Genetic variants were associated with lower in vivo hemolysis in thousands of single-unit transfusion recipients. HighlightsO_LISteap3 regulates lipid peroxidation and extravascular hemolysis in 350 diversity outbred mice C_LIO_LISteap3 SNPs are linked to RBC iron, hemolysis, vesiculation in 13,091 blood donors C_LIO_LImQTL analyses of oxylipins identified ferroptosis-related gene products FADS1/2, EPHX2, LPCAT3 C_LIO_LIFerroptosis markers are linked to hemoglobin increments in transfusion recipients C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/598512v1_ufig1.gif" ALT="Figure 1"> View larger version (117K): org.highwire.dtl.DTLVardef@150fec2org.highwire.dtl.DTLVardef@859c43org.highwire.dtl.DTLVardef@1d60156org.highwire.dtl.DTLVardef@f1b91e_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

Chemoresistance of TP53 mutant AML requires the mevalonate byproduct, GGPP, for regulation of ROS and induction of a mitochondria stress response

Acute myeloid leukemia (AML) with mutations in the tumor suppressor gene, TP53 (TP53mut AML), is fatal with a median survival of only 6 months. RNA sequencing on purified AML patient samples show TP53mut AML has higher expression of mevalonate pathway genes. We retrospectively identified a survival benefit in TP53mut AML patients who received chemotherapy concurrently with a statin, which inhibits the mevalonate pathway. Mechanistically, TP53mut AML resistance to standard AML chemotherapy, cytarabine (AraC), correlates with increased mevalonate pathway activity and a mitochondria stress response with increased mitochondria mass and oxidative phosphorylation. Pretreatment with a statin reverses these effects and chemosensitizes TP53mut AML cell lines and primary samples in vitro and in vivo. Mitochondria-dependent chemoresistance requires the geranylgeranyl pyrophosphate (GGPP) branch of the mevalonate pathway and novel GGPP-dependent synthesis of glutathione to manage AraC-induced reactive oxygen species (ROS). Overall, we show that the mevalonate pathway is a novel therapeutic target in TP53mut AML. SignificanceChemotherapy-persisting TP53mut AML cells induce a mitochondria stress response that requires mevalonate byproduct, GGPP, through its novel role in glutathione synthesis and regulation of mitochondria metabolism. We provide insight into prior failures of the statin family of mevalonate pathway inhibitors in AML. We identify clinical settings and strategies to successfully target the mevalonate pathway, particularly to address the unmet need of TP53mut AML.

cancer biology↗

bioRxiv2024

Glycolytic Disruption Triggers Interorgan Signaling to Nonautonomously Restrict Drosophila melanogaster Larval Growth

Drosophila larval growth requires efficient conversion of dietary nutrients into biomass. Lactate Dehydrogenase (Ldh) and Glycerol-3-phosphate dehydrogenase (Gpdh1) support larval biosynthetic metabolism by maintaining NAD+/NADH redox balance and promoting glycolytic flux. Consistent with the cooperative functions of Ldh and Gpdh1, the loss of both enzymes, but neither single enzyme, induces a developmental arrest. However, Ldh and Gpdh1 exhibit complex and often mutually exclusive expression patterns, suggesting that the Gpdh1; Ldh double mutant lethal phenotype could be mediated nonautonomously. Here we find that the developmental arrest displayed by the double mutants extends beyond simple metabolic disruption and instead stems, in part, from changes in systemic growth factor signaling. Specifically, we demonstrate that this synthetic lethality is linked to the upregulation of Upd3, a cytokine involved in the Jak/Stat signaling pathway. Moreover, we demonstrate that either loss of the Upd3 or dietary administration of the steroid hormone 20-hydroxyecdysone (20E) rescue the synthetic lethal phenotype of Gpdh1; Ldh double mutants. Together, these findings demonstrate that metabolic disruptions within a single tissue can nonautonomously modulate interorgan signaling to ensure synchronous developmental growth. SUMMARY STATEMENTWe used the fruit fly Drosophila melanogaster to demonstrate that disruption of glycolysis within a single larval tissue alters systemic cytokine signaling and nonautonomously inhibits development of the entire animal.

developmental biology↗

bioRxiv2024

Renal L-2-hydroxyglutarate dehydrogenase activity promotes hypoxia tolerance and mitochondrial metabolism in Drosophila melanogaster

The mitochondrial enzyme L-2-hydroxyglutarate dehydrogenase (L2HGDH) regulates the abundance of L-2-hydroxyglutarate (L-2HG), a potent signaling metabolite capable of influencing chromatin architecture, mitochondrial metabolism, and cell fate decisions. Loss of L2hgdh activity in humans induces ectopic L-2HG accumulation, resulting in neurodevelopmental defects, altered immune cell function, and enhanced growth of clear cell renal cell carcinomas. To better understand the molecular mechanisms that underlie these disease pathologies, we used the fruit fly Drosophila melanogaster to investigate the endogenous functions of L2hgdh. Our studies revealed that while L2hgdh is not essential for growth or viability under standard culture conditions, L2hgdh mutants are hypersensitive to hypoxia and expire during the reoxygenation phase with severe disruptions of mitochondrial metabolism. Moreover, we find that the fly renal system (Malpighian tubules; MTs) is a key site of L2hgdh activity, as L2hgdh mutants that express a rescuing transgene within the MTs survive hypoxia treatment and exhibit normal levels of mitochondrial metabolites. We also demonstrate that even under normoxic conditions, L2hgdh mutant MTs experience significant metabolic stress and are sensitized to aberrant growth upon Egfr activation. Overall, our findings present a model in which renal L2hgdh activity limits systemic L-2HG accumulation, thus indirectly regulating the balance between glycolytic and mitochondrial metabolism, enabling successful recovery from hypoxia exposure, and ensuring renal tissue integrity.

genetics↗

bioRxiv2024

Identification of high sugar diet-induced dysregulated metabolic pathways in muscle using tissue-specific metabolic models in Drosophila

Individual tissues perform highly specialized metabolic functions to maintain whole-body metabolic homeostasis. Although Drosophila serves as a powerful model for studying human metabolic diseases, modeling tissue-specific metabolism has been limited in this organism. To address this gap, we reconstruct 32 tissue-specific genome-scale metabolic models (GEMs) by integrating a curated Drosophila metabolic network with pseudo-bulk single-nuclei transcriptomics data, revealing distinct metabolic network structures and subsystem coverage across tissues. We validate enriched pathways identified through tissue-specific GEMs, particularly in muscle and fat body, using metabolomics and pathway analysis. Moreover, to demonstrate the utility in disease modeling, we apply muscle-GEM to investigate high sugar diet (HSD)-induced metabolic dysregulation. Constraint-based semi-quantitative flux and sensitivity analyses identify altered NAD(H)-dependent reactions and distributed control of glycolytic flux, including GAPDH. This prediction is further validated through in vivo 13C-glucose isotope tracing study. Notably, decreased glycolytic flux, including GAPDH, is linked to increased redox modifications. Finally, our pathway-level flux analyses identify dysregulation in fructose metabolism. Together, this work establishes a quantitative framework for tissue-specific metabolic modeling in Drosophila, demonstrating its utility for identifying dysregulated reactions and pathways in muscle in response to HSD.

systems biology↗