Biology subjects

Seldin, M.

Publications and source records attributed to Seldin, M..

5 recordsLinked to original sources

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

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↗

bioRxiv2021

Systems genetics uncovers microbe-lipid-host connections in the murine gut

The molecular bases of how host genetic variation impact gut microbiome remain largely unknown. Here, we used a genetically diverse mouse population and systems genetics strategies to identify interactions between molecular phenotypes, including microbial functions, intestinal transcripts and cecal lipids that influence microbe-host dynamics. Quantitative trait loci (QTL) analysis identified genomic regions associated with variations in bacterial taxa, bacterial functions, including motility, sporulation and lipopolysaccharide production, and levels of bacterial- and host-derived lipids. We found overlapping QTL for the abundance of Akkermansia muciniphila and cecal levels of ornithine lipids (OL). Follow-up studies revealed that A. muciniphila is a major source of these lipids in the gut, provided evidence that OL have immunomodulatory effects and identified intestinal transcripts co-regulated with these traits. Collectively, these results suggest that OL are key players in A. muciniphila-host interactions and support the role of host genetics as a determinant of responses to gut microbes.

genetics↗

bioRxiv2020

GOLIATH regulates LDLR availability and plasma LDL cholesterol levels

Increasing the availability of hepatic low-density lipoprotein receptors (LDLR) remains a major clinical target for reducing circulating plasma LDL cholesterol (LDL-C) levels. Here, we identify the molecular mechanism underlying genome-wide significant associations in the GOLIATH locus with plasma LDL-C levels. We demonstrate that GOLIATH is an E3 ubiquitin ligase that ubiquitinates the LDL Receptor resulting in redistribution away from the plasma membrane. Overexpression of GOLIATH decreases hepatic LDLR and increases plasma LDL-C levels. Silencing of Goliath using antisense oligonucleotides, germline deletion, or AAV-CRISPR in vivo strategies increases hepatic LDLR abundance and availability, thus decreasing plasma LDL-C. In vitro ubiquitination assays demonstrate RING-dependent regulation of LDLR abundance at the plasma membrane. Our studies identify GOLIATH as a novel post-translational regulator of LDL-C levels via modulation of LDLR availability, which is likely important for understanding the complex regulation of hepatic LDLR.

molecular biology↗

bioRxiv2017

Epigenome-wide association in adipose tissue from the METSIM cohort identifies novel loci and the involvement of adipocytes and macrophages in diabetes traits

Most epigenome-wide association studies to date have been conducted in blood. However, metabolic syndrome is mediated by a dysregulation of adiposity and therefore it is critical to study adipose tissue in order to understand the effects of this syndrome on epigenomes. To determine if natural variation in DNA methylation was associated with metabolic syndrome traits, we profiled global methylation levels in subcutaneous abdominal adipose tissue. We measured association between 32 clinical traits related to diabetes and obesity in 201 people from the Metabolic Syndrome In Men cohort. We performed epigenome-wide association studies between DNA methylation levels and traits, and identified associations for 13 clinical traits in 21 loci. We prioritized candidate genes in these loci using eQTL, and identified 18 high confidence candidate genes, including known and novel genes associated with diabetes and obesity traits. Using methylation deconvolution, we examined which cell types may be mediating the associations, and concluded that most of the loci we identified were specific to adipocytes. We determined whether the abundance of cell types varies with metabolic traits, and found that macrophages increased in abundance with the severity of metabolic syndrome traits. Finally, we developed a DNA methylation based biomarker to assess type II diabetes risk in adipose tissue. In conclusion, our results demonstrate that profiling DNA methylation in adipose tissue is a powerful tool for understanding the molecular effects of metabolic syndrome on adipose tissue, and can be used in conjunction with traditional genetic analyses to further characterize this disorder.

genetics↗