Biology subjects

Abramovich, I.

Publications and source records attributed to Abramovich, I..

10 recordsLinked to original sources

bioRxiv2026

Cyclin D-CDK4/6 couple proliferation to membrane and mitochondrial protein supply through a DeSI1 phospho-switch

Cyclin D-CDK4/6 complexes drive cell-cycle entry through an RB-E2F-dependent transcriptional program, but how they coordinate proliferation with the membrane and organelle protein supply required for growth is unclear. We identify DeSI1 as a cyclin D-CDK4/6 substrate whose phosphorylation at S25 converts a latent homodimer into an active monomeric deubiquitylase that recognizes hydrophobic proteins such as those bearing transmembrane domains and mitochondrial targeting sequences. Phosphorylated DeSI1 extends the lifetime of newly synthesized hydrophobic proteins that support membrane and mitochondrial capacity. Constitutive DeSI1 activation uncouples this proteostatic program from metabolic supply, creating a cytidine-nucleotide supply-demand imbalance associated with impaired CTP-dependent phospholipid homeostasis, cardiolipin depletion, and mitochondrial decompensation - defects that cytidine reverses. In mice, constitutive DeSI1 activation causes progressive cerebellar degeneration with membrane-protein accumulation, respiratory-chain loss, and phospholipid depletion. These findings define a post-translational mechanism coupling cell-cycle entry to membrane and mitochondrial capacity, and reveal the cost of uncoupling this program from its metabolic support.

cell biology↗

bioRxiv2026

Peripheral CB1R Blockade Suppresses AKI-to-CKD Maladaptive Repair

BackgroundAcute kidney injury (AKI) frequently progresses to chronic kidney disease (CKD), yet mechanisms governing this transition remain poorly understood. The endocannabinoid system (ECS), particularly cannabinoid-1 receptor (CB1R), regulates inflammation and metabolism in various organs, but its role in post-AKI maladaptive repair is less established. MethodsWe analyzed CB1R expression in kidney biopsies from pre- and post-transplant recipients and in murine AKI models (ischemia-reperfusion injury [IRI] and folic acid [FA]-induced AKI). Peripheral CB1R blockade was evaluated in FA-AKI model and in human primary kidney proximal tubule cells (hKPTCs). Spatial metabolomics, semi-targeted metabolomic profiling, and gene and protein expression characterized molecular mechanisms. ResultsCB1R expression was increased in kidneys undergoing maladaptive repair in both humans and mice, but remained unchanged during acute injury. In the FA-induced AKI model, the ECS showed stage-specific alterations, with temporal and spatial fluctuations in endocannabinoid levels and their enzymatic regulators. Peripheral CB1R blockade during the repair phase preserved kidney function, reduced injury, and maintained systemic glucose homeostasis. Metabolomic and molecular analyses revealed that CB1R blockade restored dysregulated arginine metabolism and reduced AKT/NF-{kappa}B-p65 pathway in post-AKI kidneys, linking CB1R activation to inflammatory signaling. In hKPTCs, 2-AG-induced activation of CB1R increased VCAM1 expression, a failed-repair marker, while its antagonism reduced TNF/2-AG-induced expression of pro-inflammatory adhesion molecules, chemokines, cytokines, and arginine metabolism enzymes. ConclusionsCB1R overactivation drives AKI-to-CKD progression by promoting inflammatory signaling and metabolic dysregulation. Peripheral CB1R blockade during the repair phase represents a novel therapeutic strategy to prevent maladaptive repair and CKD development after AKI. These findings establish CB1R as a phase-specific therapeutic target for post-AKI intervention. Translational StatementPeripheral CB1R antagonists offer a first-in-class therapeutic strategy to halt progression from acute kidney injury (AKI) to chronic kidney disease (CKD) by selectively targeting maladaptive tubular repair. By blocking CB1R signaling specifically in the kidney, these agents attenuate inflammation, metabolic dysregulation, and fibrogenic pathways that drive failed repair, while sparing central nervous system CB1R and thereby minimizing neuropsychiatric adverse effects. This phase-specific, peripherally restricted approach supports the development of peripheral CB1R antagonists as a viable translational therapy to improve long-term renal outcomes after AKI.

pharmacology and toxicology↗

bioRxiv2026

The mitochondrial chaperone HSPD1 folds MTHFD2 independently of its co-chaperone HSPE1

Acquiring new cellular states entails metabolic reprogramming driven by changes in the expression of cytosolic and mitochondrial metabolic enzymes. Most mitochondrial proteins are synthesized in the cytosol and imported into the mitochondria in a linear form, after which they are folded by a network of mitochondrial chaperones and co-chaperones. Which mitochondrial protein is dependent upon which chaperone for its folding is largely unknown. HSPD1/HSPE1 (HSP60/HSP10) are evolutionarily conserved mammalian homologues of the bacterial proteins GroEL/GroES, forming a chamber-and-lid chaperonin to facilitate the folding of client proteins. We used gene knockdown and SILAC-based proteomics to identify HSPD1 client proteins. We found that HSPD1 supports the expression of Methylenetetrahydrofolate Dehydrogenase 2 (MTHFD2), a key essential protein in the mitochondrial one-carbon (1C) pathway, in cells and tumors, and directly folds MTHFD2, independently of its co-chaperone HSPE1. HSPD1 interacts with MTHFD2 in mitochondria, and MTHFD2 is degraded by LONP1 in HSPD1 knockdown cells. Consequently, we observed reduced nucleotide and S-adenosylmethionine (SAM) levels in HSPD1 knockdown and found minimal overlap in the transcriptional and metabolic cellular responses to HSPD1 vs. HSPE1 depletion. In C. elegans, knockout of HSP60 triggers the mitochondrial stress response in the gut, while HSP10 knockout triggers the mitochondrial stress response in muscle tissue. Our data support that HSPD1 is an MTHFD2 chaperone and that, in addition to working together, HSPD1 and HSPE1 have distinct biological functions.

cell biology↗

bioRxiv2024

Limiting mitochondrial-derived ATP transfer to the cytosol enhances T-cell activation

T-cell activation requires a substantial increase in NAD+ production, often exceeding the capacity of oxidative phosphorylation (OXPHOS). To investigate how T cells adapt to this metabolic challenge, we generated T cell-specific ADP/ATP translocase-2 knockout (Ant2-/-) mice. Loss of Ant2, a crucial protein mediating ADP/ATP exchange between mitochondria and cytoplasm, induces OXPHOS restriction by limiting ATP synthase activity, impeding NAD+ regeneration. Interestingly, Ant2-/- naive T cells exhibited enhanced activation, proliferation, and effector functions compared to wild-type controls. Metabolic profiling revealed that these cells adopt an activated-like metabolic program with increased mitobiogenesis and anabolism. Pharmacological inhibition of ANT in wild-type T cells recapitulated the Ant2-/- phenotype, and improved adoptive cell therapy of cancer. Our findings suggest that Ant2-deficient T cells bypass the typical metabolic reprogramming required for activation, leading to enhanced T-cell function. These results highlight the critical role of mitochondrial metabolism in regulating T-cell fate and underscore the therapeutic potential of targeting ANT for immune modulation.

immunology↗

bioRxiv2022

Population level genetic memory of prior metabolic adaptation in E. coli

Bacteria must often survive following the exhaustion of their external growth resources. Fitting with this need, many bacterial species that cannot sporulate, can enter a state known as long term stationary phase (LTSP) in which they can persist for years within spent media. Several recent studies have revealed the dynamics of genetic adaptation of Escherichia coli under LTSP. Yet, the metabolic consequences of such genetic adaptation were not addressed. Here, we characterized the metabolic changes LTSP populations experience and link them to their genetic adaptation. We observed that during growth within fresh resources E. coli produces the short chain fatty acid butyrate, which wildtype E. coli cannot consume. Once resources are otherwise exhausted, E. coli adapts genetically to consume butyrate through the convergent, temporally precise emergence of mutation combinations within genes that regulate fatty acid metabolism. These mutations appear to negatively affect bacterial fitness when butyrate is not available, and hence rapidly decrease in frequency, once all butyrate is consumed. Yet despite this, E. coli populations show a remarkable capability of maintaining a population-level genetic memory of prior adaptation to consume butyrate. The maintenance of such a memory allows bacteria to rapidly re-adapt, at an ecological, rather than an evolutionary timeframe, to re-consume previously encountered metabolites.

evolutionary biology↗

bioRxiv2022

Enhanced methionine cycle suppresses naïve CD8+ T-cell maturation

The metabolic pathways controlling naive CD8+ T (Tn) cell maturation following thymic egress remain mostly undefined. This is important because immature Tn are a major component of peripheral immune tolerance in newborns and under lymphopenia. In this study we demonstrate that TMRM, a mitochondrial membrane potential marker, could be applied to rapidly identify an immature Tn cell population in the periphery. Applying this marker to perform metabolic and proteomic analysis, we show that immature Tn cells maintain accelerated methionine cycle in respect to mature Tn. This unique metabolic state was associated with restricted Tbx21 locus and diminished immune response in vitro and in vivo. Following our findings, we demonstrate that inhibition of methionine cycle leads to rapid functional maturation of Tn and recovery of immune response to stimuli. Our work provides insight into the way the rate of methionine cycling regulates T cell maturation, opening a path for metabolic manipulation of immune tolerance.

immunology↗

bioRxiv2022

A multiomics comparison of weight loss interventions shows the distinct effects of bariatric surgery and intermittent fasting on hepatic metabolism

The prevalence of obesity and non-alcoholic fatty liver (NAFL) is steadily increasing. Weight loss can lead to improvement in NAFL in patients and in model organisms. Weight loss can be achieved through either dietary and lifestyle interventions, pharmacotherapy, and bariatric surgery. Some interventions, such as intermittent fasting, have been purported to have benefits beyond those conferred by weight loss alone. In this study, rats were provided a high-fat, high-sucrose diet for 7 weeks and then were assigned to strict caloric restriction with intermittent fasting (IF-CR) or to sleeve gastrectomy (SG) bariatric surgery, achieving equivalent weight loss. The two interventions were compared to ad-libitum fed controls. The metabolome of the blood entering the liver was analyzed in the three experimental groups, as well as the metabolome and transcriptome of the liver under fasting conditions, to test how different means of weight loss affect the input of the liver and hepatic metabolism. Surprisingly, the two interventions had different and often opposite effects on the composition of portal blood and liver metabolites. IF-CR resulted in sweeping changes across multiple central metabolic pathways, including an increase in de novo lipogenesis and triglyceride export, and upregulation of glycolysis, citric acid cycle, and the pentose phosphate pathway, as well as an increase in glycogen storage. Meanwhile, the effects of SG concentrated on one-carbon metabolic pathways, with changes in metabolite and transcript levels pointing to decreased transmethylation and methionine cycle activity, with downstream effects on levels of glutathione and the hepatic oxidative state. In conclusion, our study highlights how different means of weight loss affect distinct metabolic pathways and demonstrates a unique effect of bariatric surgery on hepatic one-carbon and redox pathways.

physiology↗

bioRxiv2022

Sexual deprivation induces a CRF independent stress response and decreases resistance to stressors in Drosophila via a subpopulation of Neuropeptide F receptor-expressing neurons

Living in a changing environment composed of other behaving animals entails both opportunities and challenges to obtain resources and mating partners. Actions that promote survival and reproduction are reinforced by the brain reward systems, whereas coping with the challenges associated with obtaining these rewards are mediated by stress response pathways. The activation of the latter can impair health and shorten lifespan. Although similar responses to social opportunity and challenge exist across the animal kingdom, little is known about the mechanisms that process reward and stress under different social conditions. Here, we studied the interplay between deprivation of sexual reward and stress response in Drosophila melanogaster and discovered that repeated failures to obtain sexual reward induces a frustration-like state that is characterized by increased arousal, persistent sexual motivation, and impaired ability to cope with starvation and oxidative stressors. We show that this increased arousal and sensitivity to starvation is mediated by disinhibition of neurons that express receptors for the fly homologue of neuropeptide Y (neuropeptide F, NPF). We furthermore demonstrate the existence of an anatomical overlap between stress and reward systems in the fly brain in the form of neurons that co-express receptors for NPF (NPFR) and the corticotropin-releasing factor (CRF)-like homologue Diuretic hormone 44 (Dh44), and that deprivation of sexual reward leads to translocation of forkhead box-subgroup O (FoxO) to the cytoplasm in these neurons. Nevertheless, the activity of Dh44 neurons alone does not mediate sensitivity to starvation and aroused behavior following sexual deprivation, instead, these responses are mediated by disinhibition of ~12-16 NPFR-expressing neurons via a dynamin-independent synaptic signaling mechanism, suggesting the existence of a NPFR mediated stress pathway which is Dh44-independent. This paves the path for using simple model organisms to dissect mechanisms behind anticipation of reward, and more specifically, to determine what happens when expectations to obtain natural and drug rewards are not met.

animal behavior and cognition↗

bioRxiv2020

Host autophagy mediates organ wasting and nutrient mobilization for tumor growth

During tumor growth - when nutrient and anabolic demands are high - autophagy supports tumor metabolism and growth through lysosomal organelle turnover and nutrient recycling1. Ras-driven tumors additionally invoke non-autonomous autophagy in the microenvironment to support tumor growth, in part through transfer of amino acids2-4. Here we uncover a third critical role of autophagy in mediating systemic organ wasting and nutrient mobilization for tumor growth using a well-characterized malignant tumor model in Drosophila melanogaster. Micro-computed X-ray tomography and metabolic profiling reveal that RasV12; scrib-/- tumors grow 10-fold in volume, while systemic organ wasting unfolds with progressive muscle atrophy, loss of body mass, -motility, -feeding and eventually death. Tissue wasting is found to be mediated by autophagy and results in host mobilization of amino acids and sugars into circulation. Natural abundance Carbon 13 tracing demonstrates that tumor biomass is increasingly derived from host tissues as a nutrient source as wasting progresses. We conclude that host autophagy mediates organ wasting and nutrient mobilization that is utilized for tumor growth.

cell biology↗

bioRxiv2020

Cellular water analysis in T cells reveals a switch from metabolic water gain to water influx

Cell growth is driven by the acquisition and synthesis of dry biomass and water mass. This study examines the increase of water in T cells biomass during cell growth. We found that T cell growth is initiated by a phase of slow increase of cellular water, followed by a second phase of rapid increase in water content. To study the origin of the water gain, we developed a novel method, Cold Aqua Trap - Isotope Ratio Mass Spectrometry (CAT-IRMS), which allows analysis of intracellular water isotope composition. Applying CAT-IRMS, we discovered that glycolysis-coupled metabolic water accounts on average for 11 femtoliter (fL) out of the 20 fL of water gained per cell during the slow phase. At the end of the rapid phase, before initiation of cell division, a water influx occurs, increasing the water level by three-fold. Thus, activated T cells switch from acquiring metabolic water to incorporating water from the extracellular medium. Our work provides a method to analyze cell water content and an insight into the way cells regulate their water mass.

biochemistry↗