Biology subjects

Jang, C.

Publications and source records attributed to Jang, C..

At least 19 recordsLinked to original sources

bioRxiv2026

Role of Uridine Phosphorylase 1 (UPP1) in Pancreatic β-Cell Physiology and Its Dysregulation in Obesity and Type 2 Diabetes

Aims/hypothesis Fasting plasma uridine concentrations are elevated in obese mice and in individuals with type 2 diabetes (T2D), suggesting that uridine may function as a metabolic signal that adjusts insulin secretion to changes in metabolic demand. Here, we tested this hypothesis by determining whether uridine potentiates glucose-stimulated insulin secretion (GSIS) in mouse and human islets and by identifying uridine phosphorylase 1 (UPP1), the principal enzyme responsible for systemic uridine catabolism, as a key mediator of this effect. Methods Whole-body Upp1 knockout (KO) and {beta}-cell-specific Upp1 knockout (KO{beta}) mice were used to determine the requirement for UPP1 in uridine-potentiated glucose-stimulated insulin secretion (GSIS) and glucose-stimulated MAPK activation. Leptin-deficient and diet-induced obese mouse models were used to assess the impact of obesity on uridine responsiveness. UPP1 protein abundance and subcellular localization were examined in islets from obese mice and human donors spanning a range of glycemic control. Integrated single-nucleus RNA sequencing and ATAC sequencing were performed on wild-type and Upp1 KO mouse islets to characterize {beta}-cell molecular remodeling associated with UPP1 deficiency and altered responses to uridine. Results Uridine potentiated GSIS in islets from chow-fed and high-fat diet-fed mice, but not in leptin-deficient obese mice. Uridine also potentiated GSIS in human islets, although this effect progressively declined with worsening glycemic control. In mouse islets, uridine potentiation was accompanied by transient activation of the MAPK pathway. Both uridine-potentiated GSIS and uridine-enhanced glucose-stimulated MAPK activation were abolished in islets from Upp1 KO and KO{beta} mice. The requirement for a transient MAPK signaling was further supported by pharmacological inhibition of MEK and constitutive activation of MEK1. Leptin-deficient islets exhibited impaired glucose-induced MAPK activation together with increased UPP1 protein expression. In human islets, UPP1 protein abundance positively correlated with donor HbA1c and displayed heterogeneous subcellular localization. Integrated single-nucleus multiomic analysis identified UPP1 as an important regulator of {beta}-cell identity, function, and transcriptional responses to uridine. Conclusions These findings establish UPP1 as a key regulator linking pyrimidine metabolism to {beta}-cell function and identify impaired uridine responsiveness as a potential contributor to and/or consequence of {beta}-cell dysfunction during the progression of T2D.

molecular biology↗

bioRxiv2026

Metabolic control of smooth muscle cell phenotype switching in atherosclerosis

The loss of smooth muscle cell (SMC) contractile phenotype contributes to various diseases including atherosclerosis. However, its metabolic basis is not entirely elucidated. Since the transforming growth factor beta (TGF{beta}) signaling is among principal regulators of SMC contractility, we studied metabolic regulation of TGF{beta} signaling in SMCs in vitro and atherosclerotic mouse models and human lesions. We found that TGF{beta} induced Ac-CoA synthetase 2 (ACSS2)-dependent Ac-CoA production, by suppressing pyruvate dehydrogenase kinase 4 (PDK4). This stabilized R-SMADs and TGF{beta} receptor 1, preserving SMC contractile phenotype. SMC-specific PDK4 knockout mimicked the effect of TGF{beta} signaling both metabolically and phenotypically, increasing glucose-derived synthesis of Ac-CoA and SMC contractile phenotype. SMC-specific Pdk4 knockout in ApoE knockout mice reduced atherosclerosis. Furthermore, human specimens demonstrated a strong correlation between PDK4 level and atherosclerosis severity. These findings indicate that continuous TGF{beta} signaling, critical to the maintenance of the normal SMC contractile state and is regulated by PDK4 and carbohydrate metabolism. TeaserReducing PDK4 metabolically restricts aortic plaque growth via TGF{beta}-dependent SMC contractility.

cell biology↗

bioRxiv2026

A systemic circadian nicotinic acid riboside (NaR) signal engages the unfolded protein response and adipogenesis via the prefoldin complex

Daily light-dark cycles impose predictable environmental fluctuations that require coordinated temporal regulation of cellular physiology. This coordination is mediated by the circadian clock, which operates as a network of tissue oscillators; however, the molecular signals that convey circadian information between organs remain incompletely defined. Here, we identify nicotinic acid riboside (NaR) as a circulating metabolite whose rhythmicity depends on the liver clock. In differentiating 3T3-L1 adipocytes, NaR engages unfolded protein response (UPR) gene programs and modulates adipogenic competence. Proteome-wide stability profiling implicates the prefoldin complex as a molecular target of NaR signaling, linking NaR exposure to altered proteostasis. Functionally, NaR-induced UPR signaling converges on the adipogenic transcription factor CEBPA, which is a central regulator of adipogenesis. Importantly, sustained NaR exposure suppresses adipocyte lipid deposition, whereas temporally restricted NaR stimulation enhances adipogenesis, indicating that NaR acts in a time-dependent manner. Together, these findings identify NaR as a liver clock-controlled circulating metabolite that couples systemic circadian metabolism to adipocyte proteostasis and differentiation, revealing a mechanism by which temporal metabolic signals shape tissue-specific physiological outcomes. HighlightsO_LIThe circadian clock is required for rhythmic regulation of circulating nicotinic acid riboside (NaR). C_LIO_LIThe liver clock is sufficient to generate NaR rhythmicity. C_LIO_LINaR engages the prefoldin complex to regulate unfolded protein response signaling and Cebpa expression. C_LIO_LITime-dependent NaR exposure differentially regulates CEBPA levels and adipocyte lipid deposition. C_LI

systems biology↗

bioRxiv2026

Single-cell profiling of synchronous multi-organ metastasis reveals a systemic CD74+ lipid-associated macrophage niche driving polymetastatic breast cancer

Systemic, multi-organ metastasis is the primary cause of breast cancer mortality, yet the biological mechanisms that allow disseminated tumor cells to simultaneously colonize physiologically diverse tissues remain poorly understood. Current paradigms focus on organ-specific tropism, largely overlooking the potential for systemic, conserved and synchronized programs that facilitate widespread colonization. Here, we present a high-resolution, multi-organ atlas of metastatic ecosystems and their niches using a synchronous model of brain, lung, liver, and bone metastasis combined with in vivo proximal niche labeling and single-cell RNA sequencing. We identify a remarkably conserved proximal niche program defined by the accumulation of CD74+ lipid-associated, metastasis-associated macrophages (LA-MAMs) across all metastatic sites. CD74+ LA-MAMs are characterized by a unique metabolic-immune signature and drive T cell suppression. We show that the cytokine Macrophage Migration Inhibitory Factor (MIF), secreted by metastatic cells, acts as the universal paracrine mediator that instructs the LA-MAM phenotype via the CD74 receptor. Interference of the MIF-CD74 axis effectively disrupts the LA-MAM niche, mitigates T cell exhaustion, and reduces metastatic burden across all organs. Analysis of a 100-patient cohort of metastasis samples from different sites confirms that the MIF-CD74 axis is a hallmark of human multi-organ colonization and independently predicts poor post-metastasis survival. Our findings define a synchronized and systemic metastatic niche that can be targeted, providing a mechanistic rationale for neutralizing the MIF-CD74 axis to treat polymetastatic breast cancer.

cancer biology↗

bioRxiv2026

Metabolic reallocation in spinal cord oligodendrocytes drives chronic pain via neuronal β-amyloid production

Peripheral injury reprograms metabolism in spinal cord oligodendrocytes, initiating a molecular cascade that drives chronic pain via neuronal {beta}-amyloid (A{beta}) release. After injury, mouse spinal oligodendrocytes downregulate myelin protein synthesis and upregulate lipid biosynthesis--but reroute lipids toward neuroplastic remodeling and away from myelin maintenance. This metabolic reallocation disrupts myelin integrity and axonal function, causing neuronal accumulation of amyloid precursor protein, enhanced expression of its processing {beta}-secretase BACE1, and local release of A{beta} peptides. Blocking A{beta} production or clearing A{beta} deposits stops the transition to pain chronicity. Deleting the lysosomal lipid hydrolase NAAA in oligodendrocytes prevents both injury-induced A{beta} production and chronic pain development. The findings identify an unexpected mechanistic link between chronic pain and Alzheimers-like neurodegeneration, positioning A{beta} as a target for therapeutic intervention.

neuroscience↗

bioRxiv2025

De Novo Hepatic Pyrimidine Synthesis Regulates Systemic Energy Homeostasis

Fasting blood uridine is increased in obesity and type 2 diabetes (T2D), but the significance of hepatic uridine biosynthesis to the etiology of both remains elusive. We found that de novo pyrimidine synthesis in the liver is reduced by fasting and diet-induced obesity, while suppression of hepatic pyrimidine synthesis promotes obesity and insulin resistance. The metabolic sequalae of hepatic pyrimidine synthesis suppression, however, is not associated with altered plasma uridine concentration. Instead, it is associated with an increased hepatic glucose production and a decreased hepatic insulin clearance, two key functions of hepatocytes in regulating systemic energy homeostasis. We found that enhanced gluconeogenesis is the primary reason for increased hepatic glucose production. Moreover, uridine, which was maintained stable in the circulation by adipose tissue and the liver, preferentially shut down pyrimidine synthesis in hepatocytes but not adipocytes at blood concentrations that occur with fasting. Remarkably, uridine, at fasting levels, increases gluconeogenesis further in hepatocytes when de novo pyrimidine synthesis is suppressed, indicating a synergistical action of uridine and its biosynthesis pathway in promoting hepatic glucose production, a mechanism highly relevant to the pathophysiology of insulin resistance in obesity. Theologically, maintenance of blood uridine within the narrow range protects mammals from high-rate spontaneous tumorigenesis. Since obesity promotes an increase in blood uridine from adipocytes, suppressing uridine synthesis in hepatocytes becomes a critical response to lower spontaneous tumorigenesis. Pyrimidine synthesis suppression in hepatocytes, however, promotes gluconeogenesis and ultimately triggers obesity and T2D. These findings suggest a new paradigm for the etiology of metabolic deterioration in diet-induced obesity, in which perturbations in uridine promotes obesity and T2D.

pathology↗

bioRxiv2025

Pitavastatin counteracts venetoclax resistance mechanisms in acute myeloid leukemia

The BCL2 inhibitor venetoclax has therapeutic activity in several hematological malignancies. In acute myeloid leukemia (AML), venetoclax combined with hypomethylating agents is the standard of care for patients unfit for intensive chemotherapy, but intrinsic and acquired resistance are common. Loss of p53 function is strongly associated with venetoclax resistance, and adding venetoclax to 5-azacitidine provides no overall survival benefit in TP53-mutant AML. Other frequent mechanisms of venetoclax resistance in AML include FLT3 mutations, MCL-1 upregulation, and altered mitochondrial metabolism. Unfortunately, it has been challenging to develop agents that target these mechanisms directly and combinatorially. Here we report that pitavastatin, an inhibitor of HMG-CoA-reductase, promotes apoptosis and overcomes several venetoclax resistance mechanisms in human AML cells. At clinically achievable concentrations, pitavastatin treatment has potent cytotoxic activity in cells with mutations in TP53 or FLT3. The apoptotic mechanism involves p53-independent PUMA upregulation and reduced MCL-1 expression. Pitavastatin also suppresses mitochondrial gene expression and oxidative metabolism. The pro-apoptotic actions of pitavastatin depend on depletion of geranylgeranyl pyrophosphate (GGPP) and can be recapitulated by inhibiting GGPP synthase or geranylgeranyltransferase-1 enzymes. These results provide a mechanistic rationale for adding pitavastatin to AML regimens to prevent or overcome venetoclax resistance.

cancer biology↗

bioRxiv2025

Mevalonate Biosynthesis is a Metabolic Vulnerability of Gemcitabine-resistant Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy with a devastating prognosis. Gemcitabine, a pyrimidine anti-metabolite, is a cornerstone in PDAC therapy. However, resistance remains a major hurdle in clinical care. Resistance can arise from microenvironmental metabolites or through direct metabolic reprogramming of pancreatic cancer cells. Here, we generated PDAC models of acquired gemcitabine resistance to determine the relationship between these mechanisms. We observed that physiological levels of exogenous pyrimidines have a diminished ability to impact gemcitabine response in PDAC cells with acquired resistance. This occurs as the metabolic reprogramming of PDAC cells in response to gemcitabine treatment forces a suppression of the pyrimidine salvage pathway. Importantly, this metabolic rewiring renders gemcitabine-resistant PDAC cells highly susceptible to inhibition of the rate limiting enzyme of the mevalonate biosynthesis pathway, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), using statins. Notably, statin treatment inhibits the growth of gemcitabine-resistant tumors in immunocompetent mouse models. Through metabolite rescue experiments, we identified geranylgeranyl pyrophosphate as the critical metabolite lost during statin treatment, resulting in reduced protein geranylation in PDAC cells. Finally, as downregulation of the HMGCR is gradually acquired during gemcitabine resistance, we observed that HMGCR expression predicts patient response to gemcitabine. Collectively, these data demonstrate that the mevalonate biosynthesis pathway represents a promising therapeutic target in gemcitabine resistance and may serve as a biomarker to stratify treatment selection in PDAC patients.

cancer biology↗

bioRxiv2025

Intestinal catabolism of dietary fructose promotes obesity and insulin resistance via ileal lacteal remodeling

High-fructose corn syrup (HFCS) consumption is a risk factor for obesity and metabolic syndrome, yet the underlying mechanisms are incompletely understood. Catabolism of dietary fructose primarily occurs in the small intestine and liver, with fructose breakdown in the liver being pathological, while small intestinal fructose clearance protects the liver. Here, we unexpectedly found that inhibition of fructose catabolism specifically in the small intestine mitigates fructose-induced obesity and insulin resistance. Mechanistically, blocking intestinal fructose catabolism reduces dietary fat absorption, which is associated with a decrease in the surface area of the ileal lacteals and alterations in gut microbiome. Fecal transplantation experiments revealed that such a microbiome stimulates the intestine-resident macrophages, promoting lacteal growth and boosting dietary fat absorption. Given the preclinical and clinical studies reporting the effect of fructose catabolism suppression on mitigating diet-induced obesity, our data suggest that such effects are partly mediated by intestinal lacteal remodeling. Significance StatementHere, we uncover a previously unappreciated link between intestinal fructose catabolism and ileal lacteal remodeling, suggesting the mechanisms by which fructose intake promotes obesity. Using mice lacking the fructose-processing enzyme specifically in the intestine, we show that blocking intestinal fructose metabolism protects against diet-induced obesity by reducing fat absorption. Changes in gut microbiome and immune cell interactions drive this effect.

physiology↗

bioRxiv2025

UCP1 Mitigates Hepatic Steatosis and Fibrosis Independent of Cold Exposure

Non-shivering thermogenesis by brown adipose tissue (BAT) is a promising target for anti-obesity therapies, making its regulatory mechanisms of significant translational interest. While cold-induced BAT thermogenesis (CIT) is well characterized, certain high-calorie diets can also activate BAT in the absence of cold, a process known as diet-induced thermogenesis (DIT). Despite its potential relevance to modern human diets and lifestyles, the mechanisms and physiological relevance underlying DIT remain poorly understood. Here, we show that DIT reduces adiposity and protects against hepatic steatosis and fibrosis in males but not female mice. Moreover, adipose tissue-specific ablation of uncoupling protein 1 (UCP1) reveals that BAT is the primary mediator of DIT but that non-adipocyte UCP1 also contributes to body weight regulation. Transcriptome analysis suggests that DIT is triggered by intrinsic metabolic stress, distinguishing it from CIT, which is driven by sympathetic tone. Finally, BAT-specific arteriovenous metabolomics identifies glucose as the predominant circulating fuel for DIT. These findings uncover distinct molecular and metabolic features of DIT, highlighting opportunities to harness BAT activity for treating obesity and metabolic diseases without requiring cold exposure.

physiology↗

bioRxiv2025

Cardiac metabolite exchange measured in pigs during myocardial ischemia and reperfusion

Myocardial ischemia and reperfusion (I/R) injury are the primary contributors to death in patients with cardiovascular disease. While decades of research have elucidated the molecular players and biochemical mechanisms underlying I/R injury, how these pathologies influence the metabolic activities of the heart remains incompletely understood. Such a knowledge gap hampers the development of therapies aimed at mitigating the metabolic stresses of the heart during injury. Using comprehensive arteriovenous metabolomics in a highly relevant porcine I/R model, we report the metabolic landscape of cardiac metabolic changes after ischemia and during the reperfusion time course. Paradoxically, ischemia increases the cardiac uptake of circulating fatty acids while reperfusion for 60 minutes reverses this activity. By 120 minutes of reperfusion, the hearts resume the uptake of fatty acids, suggesting restoration of their metabolism. On the other hand, we found a strong release of amino acids by the heart only after 60-minute reperfusion, but not after 120-minute reperfusion, implicating I/R-induced transient protein degradation. In addition to these findings, we identified several previously unrecognized changes in cardiac metabolic inputs and outputs during I/R, including nucleotides, TCA cycle intermediates and creatine/creatinine. These data highlight the dynamic alterations in cardiac metabolism in response to I/R, providing insights into how to mitigate myocardial I/R injury.

biochemistry↗

bioRxiv2025

A low protein diet drives short- and long-term improvements in metabolic health in a mouse model of sleeve gastrectomy

Despite the largely beneficial impact of bariatric surgery on obesity and metabolic disease, continued post-surgical obesity and weight recurrence is common and may be impacted by diet. While guidelines recommend a high-protein diet based on the theory that this will preserve lean mass, emerging evidence suggests that both humans and mice are metabolically healthier on low protein diets. We assessed the effect of varying dietary protein levels on post-surgical weight loss and weight regain in a mouse model of one type of bariatric surgery, sleeve gastrectomy. We found that a low protein diet optimally drives post-surgical weight loss, boosting energy expenditure and improving blood glucose regulation. Using a multi-omics approach, we identified clusters of differentially expressed genes and metabolites that correlated with these phenotypes and found that diet heavily influences the livers molecular response to sleeve gastrectomy. These results suggest that current post-surgical high protein guidelines may limit both the short-and long-term benefits of surgery, and a low protein diet may improve patient outcomes.

physiology↗

bioRxiv2025

Metabolic reprogramming in the spinal cord drives the transition to pain chronicity

Acute injuries can progress into painful states that endure long after healing. The mechanisms underlying this transition remain unclear, but metabolic adaptations to the bioenergy demands imposed by injury are plausible contributors. Here we show that peripheral injury activates AKT/mTORC1 in afferent segments of the mouse spinal cord, redirecting local core metabolism toward biomass production while simultaneously suppressing autophagy-mediated biomass reclamation. This metabolic shift supports neuroplasticity, but creates a resource bottleneck that depletes critical spinal cord nutrients. Preventing this depletion with a modified diet normalizes biomass generation and autophagy and halts the transition to chronic pain. This effect, observed across multiple pain models, requires activation of the nutrient sensors, sirtuin-1 and AMPK, as well as restoration of autophagy. The findings identify metabolic reprogramming and consequent autophagy suppression as key drivers of the progression to pain chronicity and highlight nutritional and pharmacological interventions that could prevent this progression after surgery or other physical traumas.

neuroscience↗

bioRxiv2024

Cold-inducible GOT1 activates the malate-aspartate shuttle in brown adipose tissue to support fuel preference for fatty acids

Brown adipose tissue (BAT) simultaneously metabolizes fatty acids (FA) and glucose under cold stress but favors FA as the primary fuel for heat production. It remains unclear how BAT steer fuel preference toward FA over glucose. Here we show that the malate-aspartate shuttle (MAS) is activated by cold in BAT and plays a crucial role in promoting mitochondrial FA utilization. Mechanistically, cold stress selectively induces glutamic-oxaloacetic transaminase (GOT1), a key MAS enzyme, via the {beta}-adrenergic receptor-PKA-PGC-1 axis. The increase in GOT1 activates MAS, transferring reducing equivalents from the cytosol to mitochondria. This process enhances FA oxidation in mitochondria while limiting glucose oxidation. In contrast, loss of MAS activity by GOT1 deficiency reduces FA oxidation, leading to increased glucose oxidation. Together, our work uncovers a unique regulatory mechanism and role for MAS in mitochondrial fuel selection and advances our understanding of how BAT maintains fuel preference for FA under cold conditions. HighlightsO_LIGot1 is markedly induced by cold in BAT via a {beta}-adrenergic receptor-PKA-PGC-1 axis C_LIO_LIThe increase in cytosolic GOT1 activates the malate-aspartate shuttle (MAS) C_LIO_LIMAS activation promotes fatty acid oxidation while reducing glucose oxidation C_LIO_LILoss of MAS activity in BAT by Got1 deletion shifts the fuel preference to glucose C_LI

cell biology↗

bioRxiv2024

Sex-dependent metabolic remodeling of kidneys revealed by arteriovenous metabolomics

Sex is a fundamental biological variable important in biomedical research, drug development, clinical trials, and prevention approaches. Among many organs, kidneys are known to exhibit remarkable structural, histological, and pathological differences between sexes. However, whether and how kidneys display distinct metabolic activities between sexes is poorly understood. By developing kidney-specific arteriovenous (AV) metabolomics combined with transcriptomics, we report striking sex differences in both basal metabolic activities and adaptive metabolic remodeling of kidneys after a fat-enriched ketogenic diet (KD), a regimen known to mitigate kidney diseases and improve immunotherapy for renal cancer. At the basal state, female kidneys show highly accumulated aldosterone and various acylcarnitines. In response to the KD, aldosterone levels remain high selectively in females but the sex difference in acylcarnitines disappears. AV data revealed that, under KD, female kidneys avidly take up circulating fatty acids and release 3-hydroxybutyrate (3-HB) whereas male kidneys barely absorb fatty acids but consistently take up 3-HB. Although both male and female kidneys take up gluconeogenic substrates such as glycerol, glutamine and lactate, only female kidneys exhibit net glucose release. Kidney transcriptomics data incompletely predict these sex differences, suggesting post-transcriptional/translational regulation mechanisms. This study provides foundational insights into the sex-dependent and diet-elicited metabolic flexibility of the kidneys in vivo, serving as a unique resource for understanding variable disease prevalence and drug responses between male and female kidneys.

biochemistry↗

bioRxiv2024

Spatial variability of agricultural soil carbon dioxide and nitrous oxide fluxes: characterization and recommendations from spatially high-resolution, multi-year dataset

Mitigating agricultural soil greenhouse gas (GHG) emissions can contribute to meeting the global climate goals. High spatial and temporal resolution, large-scale, and multi-year data are necessary to characterize and predict spatial patterns of soil GHG fluxes to establish well-informed mitigation strategies, but not many of such datasets are currently available. To address this gap in data we collected two years of high spatial resolution (7.4 sampling points ha-1 over 2.0 to 5.4 ha area) in-season soil carbon dioxide (CO2) and nitrous oxide (N2O) fluxes from three commercial sites in central Illinois, one conventionally managed continuous corn and two under conservation practices in corn-soybean rotations typical of the region. At the field-scale, the spatial variability of CO2 was comparable across sites, years, and management practices, but N2O was on average 77% more spatially variable in the conventionally managed site. Analysis of N2O hotspots revealed that although they represent a similar proportion of the sampling areas across sites (conventional: 12%; conservation: 13%), hotspot contribution to field-wide emission was greater in the conventional site than in the conservation sites (conventional: 51%; conservation: 34%). Also, the spatial patterns, especially hotspot locations, of both gases were inter-annually inconsistent, with hotspots rarely occurring in the same location. Overall, our result indicated that traditional field-scale monitoring with gas chambers may not be the optimal approach to detect GHG hotspots in row crop systems, due to the unpredictable spatial heterogeneity of management practices. Still, our sensitivity analysis on the dataset demonstrated that sampling at a spatial resolution of 1.6 and 5.6 points ha-1 can provide reliable (< 25% error) estimates of field-scale soil CO2 and N2O fluxes, respectively.

biochemistry↗

bioRxiv2024

Dietary isoleucine content defines the metabolic and molecular response to a Western diet

The amino acid composition of the diet has recently emerged as a critical regulator of metabolic health. Consumption of the branched-chain amino acid isoleucine is positively correlated with body mass index in humans, and reducing dietary levels of isoleucine rapidly improves the metabolic health of diet-induced obese male C57BL/6J mice. However, it is unknown how sex, strain, and dietary isoleucine intake may interact to impact the response to a Western Diet (WD). Here, we find that although the magnitude of the effect varies by sex and strain, reducing dietary levels of isoleucine protects C57BL/6J and DBA/2J mice of both sexes from the deleterious metabolic effects of a WD, while increasing dietary levels of isoleucine impairs aspects of metabolic health. Despite broadly positive responses across all sexes and strains to reduced isoleucine, the molecular response of each sex and strain is highly distinctive. Using a multi-omics approach, we identify a core sex- and strain-independent molecular response to dietary isoleucine, and identify mega-clusters of differentially expressed hepatic genes, metabolites, and lipids associated with each phenotype. Intriguingly, the metabolic effects of reduced isoleucine in mice are not associated with FGF21 - and we find that in humans plasma FGF21 levels are likewise not associated with dietary levels of isoleucine. Finally, we find that foods contain a range of isoleucine levels, and that consumption of dietary isoleucine is lower in humans with healthy eating habits. Our results demonstrate that the dietary level of isoleucine is critical in the metabolic and molecular response to a WD, and suggest that lowering dietary levels of isoleucine may be an innovative and translatable strategy to protect from the negative metabolic consequences of a WD.

physiology↗

bioRxiv2024

HIF2α-dependent inhibition of mitochondrial clustering of glutaminase suppresses clear cell renal cell carcinoma

Clear cell renal cell carcinomas (ccRCC) are largely driven by HIF2 and are avid consumers of glutamine. However, inhibitors of glutaminase1 (GLS1), the first step in glutaminolysis, have not shown benefit in phase III trials, and HIF2 inhibition, recently FDA-approved for treatment of ccRCC, shows great but incomplete benefits, underscoring the need to better understand the roles of glutamine and HIF2 in ccRCC. Here, we report that glutamine deprivation rapidly redistributes GLS1 into isolated clusters within mitochondria across diverse cell types, but not in ccRCC. GLS1 clustering is rapid (1-3 hours) and reversible, is specifically driven by reduced intracellular glutamate, and is mediated by mitochondrial fission. Clustered GLS1 markedly enhances glutaminase activity and promotes cell death under glutamine-deprived conditions. HIF2 prevents GLS1 clustering, independently of its transcriptional activity, thereby protecting ccRCC cells from cell death induced by glutamine deprivation. Reversing this protection, by genetic expression of GLS1 mutants that constitutively cluster, enhances ccRCC cell death in culture and suppresses ccRCC growth in vivo. These findings provide multiple insights into cellular glutamine handling, including a novel metabolic pathway by which HIF2 promotes ccRCC, and reveals a potential therapeutic avenue to synergize with HIF2 inhibition in the treatment of ccRCC.

cancer biology↗