Biology subjects

Reumiller, C. M.

Publications and source records attributed to Reumiller, C. M..

4 recordsLinked to original sources

bioRxiv2026

Genome-scale modelling and stable isotope tracing reveal dynamic metabolic reprogramming in a human cardiac hypertrophy model

Pathological cardiac hypertrophy is associated with metabolic remodelling; however the temporal dynamics of this remodelling remain poorly defined in human cardiomyocyte systems. Here, we combined transcriptomic profiling, genome-scale metabolic modelling and stable isotope-resolved metabolomics (SIRM) to map the metabolic consequences of endothelin-1 (ET-1) stimulation in human iPSC-derived cardiomyocytes (hiPSC-CMs). Integration of RNA sequencing data obtained after 8 and 48 hours of ET-1 treatment with the Human2.0 genome-scale metabolic model predicted time-dependent remodelling, characterised by progressive increases in glycolytic flux, enhanced glucose carbon entry into the TCA cycle, and a decrease in fatty acid {beta}-oxidation. Computational flux predictions were independently confirmed by extracellular flux analysis and 13C-substrate tracing, with concordance between modelled and measured fluxes. Extracellular flux analysis showed increased glycolytic capacity and mitochondrial respiration after 48 hours, with greater sensitivity to inhibition of mitochondrial pyruvate transport. Glucose tracing revealed increased 13C enrichment of glycolytic, pentose phosphate pathway, serine-glycine and TCA cycle metabolites, consistent with altered glucose-derived carbon allocation. Increased m+3 labelling of selected TCA-related metabolites was compatible with pyruvate anaplerosis, although pathway-specific fluxes were not resolved. In three-dimensional engineered heart tissue (EHTs) treated with ET-1 for 7 days, increased hypertrophic marker expression was accompanied by a blunted inotropic response, and metabolomics showed similar changes in metabolite abundance and glucose-derived labelling to 2D cultures. These findings support hiPSC-CMs and EHTs as complementary platforms for studying early metabolic remodelling in pathological cardiac hypertrophy and provide an integrated framework linking model predictions to functional and isotope-tracing measurements.

cell biology↗

bioRxiv2026

Redox-activated induction of Warburg-type metabolism in the adult heart

Proliferating cells rewire glucose metabolism away from oxidative ATP production towards glycolysis and anabolic branch pathways (the Warburg effect). In contrast, the contractile function of terminally differentiated cardiomyocytes in the heart critically depends upon mitochondrial ATP generation. Adult cardiomyocytes are largely non-proliferative but undergo hypertrophy in response to increased heart workload. A fundamental question in the field is how cardiac metabolism is modified to balance competing energetic and anabolic demands. We previously reported that the redox-signalling H2O2-generating enzyme, NADPH oxidase 4 (NOX4), facilitates compensated cardiac function in hearts undergoing hypertrophic remodelling. Here, we show that NOX4 induces Warburg-type reprogramming of glucose metabolism in the healthy heart, with increased flux into the pentose phosphate, serine and nucleotide biosynthetic pathways. Using an integrated multiomics approach, we uncover a NOX4-regulated network involving interplay between direct transcriptional activation of metabolic genes via NRF2 [aka NFE2L2] and ATF4 and a broader epigenetic regulation. This reprogramming of glucose intermediary metabolism along with previously reported NOX4-mediated enhancement of fatty acid oxidation may serve to optimally support the dual requirements of increased energy demand and remodelling in the heart. Our findings identify a novel paradigm for redox-regulated Warburg-type metabolic reprogramming in the terminally differentiated heart.

physiology↗

bioRxiv2023

NRF2 activation in the heart induces glucose metabolic reprogramming and mediates cardioprotection via upregulation of the pentose phosphate pathway.

RationaleThe transcription factor NRF2 is well recognized as a master regulator of antioxidant responses and cytoprotective genes. Previous studies showed that NRF2 protects mouse hearts during chronic hemodynamic overload at least in part by reducing oxidative stress. Evidence from other tissues suggests that NRF2 may modulate glucose intermediary metabolism but whether NRF2 has such effects in the heart is unclear. ObjectiveTo investigate the role of NRF2 in regulating glucose intermediary metabolism and cardiac function during disease stress. Methods and ResultsCardiomyocyte-specific Keap1 knockout (csKeap1KO) mice, deficient in the endogenous inhibitor of NRF2, were used as a novel model of constitutively active NRF2 signaling. Targeted metabolomics and isotopomer analysis were employed in studies with 13C6-glucose in csKeap1KO and wild-type (WT) mice. Pharmacological and genetic approaches were utilized in neonatal rat ventricular cardiomyocytes (NRVM) to explore molecular mechanisms. We found that cardiac-specific activation of NRF2 upregulated key enzymes of the Pentose Phosphate Pathway (PPP), redirected glucose metabolism towards the PPP and protected the heart against pressure overload-induced cardiac dysfunction. In vitro, knockdown of Keap1 upregulated PPP enzymes and reduced cell death in NRVM subjected to chronic neurohumoral stimulation. These pro-survival effects were abolished by pharmacological inhibition of the PPP or silencing of the PPP rate-limiting enzyme glucose-6-phosphate dehydrogenase (G6PD). Knockdown of NRF2 in NRVM increased stress-induced DNA damage which was rescued by supplementing the cells with either NADPH or nucleosides, the two main products of the PPP. Activation of NRF2 also protected the heart against myocardial infarction-induced DNA damage, dysfunction, and adverse remodeling. ConclusionsThese results indicate that NRF2 regulates cardiac metabolic reprogramming by stimulating the diversion of glucose into the PPP, thereby providing cardiac protection during stress by generating NADPH and providing nucleotides to prevent stress-induced DNA damage.

physiology↗

bioRxiv2022

Human blood vessel organoids reveal a critical role for CTGF in maintaining microvascular integrity

The microvasculature plays a key role in tissue perfusion, transport of mediators, and exchange of gases and metabolites to and from tissues. Microvascular dysfunction has emerged as an important contributor to cardiovascular diseases. In this study we used human blood vessel organoids (BVOs) as a model of the microvasculature to delineate the mechanisms of microvascular dysfunction caused by metabolic rewiring. BVOs fully recapitulated key features of the normal human microvasculature, including reliance of mature endothelial cells (ECs) on glycolytic metabolism, as concluded from metabolic flux assays using 13C-glucose labelling and mass spectrometry-based metabolomics. Treatment of BVOs with PFK15, a pharmacological inhibitor of glycolysis, resulted in rapid tissue restructuring, vessel regression with reduced pericyte coverage and alterations in tight junction morphology. Proteomic analysis of the BVO secretome revealed remodelling of the extracellular matrix and differential expression of paracrine mediators such as CTGF. Treatment with recombinant CTGF recovered tight junction formation and increased pericyte coverage in microvessels. Our metabolic and proteomics findings demonstrate that BVOs rapidly undergo restructuring in response to metabolic changes and identify CTGF as a critical paracrine regulator of microvascular integrity.

cell biology↗