Biology subjects

Neufer, P. D.

Publications and source records attributed to Neufer, P. D..

4 recordsLinked to original sources

bioRxiv2023

XPA tumor variants lead to defects in NER that sensitize cells to cisplatin

Nucleotide excision repair (NER) neutralizes treatment with platinum (Pt)-based chemotherapy by removing Pt lesions from DNA. Previous study has identified that missense mutation or loss of either of the NER genes Excision Repair Cross Complementation Group 1 and 2 (ERCC1 and ERCC2) leads to improved patient outcomes after treatment with Pt-based chemotherapies. Although most NER gene alterations found in patient tumors are missense mutations, the impact of such mutations in the remaining nearly 20 NER genes is unknown. Towards this goal, we previously developed a machine learning strategy to predict genetic variants in an essential NER scaffold protein, Xeroderma Pigmentosum Complementation Group A (XPA), that disrupt repair activity on a UV-damaged substrate. In this study, we report in-depth analyses of a subset of the predicted NER-deficient XPA variants, including in vitro analyses of purified recombinant protein and cell-based assays to test Pt agent sensitivity in cells and determine mechanisms of NER dysfunction. The most NER deficient variant Y148D had reduced protein stability, weaker DNA binding, disrupted recruitment to damage, and degradation resulting from tumor missense mutation. Our findings demonstrate that tumor mutations in XPA impact cell survival after cisplatin treatment and provide valuable mechanistic insights to further improve variant effect prediction efforts. More broadly, these findings suggest XPA tumor variants should be considered when predicting patient response to Pt-based chemotherapy. SignificanceA destabilized, readily degraded tumor variant identified in the NER scaffold protein XPA sensitizes cells to cisplatin, suggesting that XPA variants can be used to predict response to chemotherapy.

cancer biology↗

bioRxiv2021

Neuronal glucose metabolism sets cholinergic tone and controls thermo-regulated signaling at the neuromuscular junction

Cholinergic and sympathetic counter-regulatory networks control numerous physiologic functions including learning/memory/cognition, stress responsiveness, blood pressure, heart rate and energy balance. As neurons primarily utilize glucose as their primary metabolic energy source, we generated mice with increased glycolysis in cholinergic neurons by specific deletion of the fructose-2,6-phosphatase protein TIGAR. Steady-state and stable isotope flux analyses demonstrated increased rates of glycolysis, acetyl-CoA production, acetylcholine levels and density of neuromuscular synaptic junction clusters with enhanced acetylcholine release. The increase in cholinergic signaling reduced blood pressure and heart rate with a remarkable resistance to cold-induced hypothermia. These data directly demonstrate that increased cholinergic signaling through the modulation of glycolysis has several metabolic benefits particularly to increase energy expenditure and heat production upon cold exposure. HighlightsO_LIDeficiency of a negative regulator of glycolysis (TIGAR) in cholinergic neurons increases the biosynthesis and content of the neurotransmitter acetylcholine. C_LIO_LIIncreased cholinergic tone reduces blood pressure and heart rate while enhancing signaling at neuromuscular junction. C_LIO_LIUpregulation of neuromuscular junction activation provides protection against the paralytic curare and cold-induced hypothermia. C_LIO_LIModulation of cholinergic neuron glycolysis may provide a novel therapeutic approach for treatment of diseases stemming from reduced acetylcholine signaling such as myasthenia gravis and sarcopenic pre-synaptic dysfunction. C_LI

cell biology↗

bioRxiv2019

Targeting the resolvin E1 - eicosapentaenoic acid axis improves hyperinsulinemia and hyperglycemia in a host genetic dependent manner

ObjectiveEicosapentaenoic acid (EPA) has recently garnered strong attention given the success of the REDUCE-IT trial, which overturned previous conclusions on EPA and led to its FDA approval for lowering cardiovascular disease risk. Therefore, there is a need to study EPA for cardiometabolic risk factors. Here we focused on EPAs preventative role on hyperglycemia and hyperinsulinemia. MethodsC57BL/6J male mice were fed a high fat diet in the absence or presence of pure EPA. Mass spectrometry was used to identify how EPA prevents hyperinsulinemia and hyperglycemia that drove subsequent experiments with resolvin E1 (RvE1) across inbred and outbred models. ResultsAdministration of EPA to C57BL/6J mice prevented obesity-induced glucose intolerance, hyperinsulinemia, and hyperglycemia. Supporting analyses of National Health and Nutrition Examination Survey data showed fasting glucose levels of obese adults were inversely related to EPA intake in a sex-specific manner. We next investigated how EPA improved murine hyperinsulinemia and hyperglycemia. Mass spectrometry revealed EPA overturned the obesity-driven decrement in the concentration of 18-hydroxyeicosapentaenoic acid (18-HEPE) in white adipose tissue and liver. Treatment of obese mice with RvE1, the immunoresolvant metabolite of 18-HEPE, reversed hyperinsulinemia and hyperglycemia through the G-protein coupled receptor ERV1/ChemR23. RvE1s effects were not mediated by macrophage enrichment in white adipose tissue. Finally, we determined if the metabolic effects of RvE1 were dependent on host genetics. RvE1s effects on hyperinsulinemia and hyperglycemia were divergent in diversity outbred mice that model human genetic variation. Secondary SNP analyses further revealed extensive genetic variation in human RvE1- and EPA- metabolizing genes. ConclusionsThe data suggest EPA prevents hyperinsulinemia and hyperglycemia through the endogenous bioactive metabolite RvE1 that activates ERV1/ChemR23. Importantly, the studies reveal host genetics are an overlooked but critical factor in the metabolic response to RvE1. These results underscore the need for personalized administration of EPA-derived RvE1 based on genetic/metabolic enzyme profiles.

biochemistry↗

bioRxiv2019

Mitochondrial PE potentiates respiratory enzymes to amplify skeletal muscle aerobic capacity

Exercise capacity is a strong predictor of all-cause mortality. Skeletal muscle mitochondrial respiratory capacity, its biggest contributor, adapts robustly to changes in energy demands induced by contractile activity. While transcriptional regulation of mitochondrial enzymes has been extensively studied, there is limited information on how mitochondrial membrane lipids are regulated. Herein, we show that exercise training or muscle disuse alters mitochondrial membrane phospholipids including phosphatidylethanolamine (PE). Addition of PE promoted, whereas removal of PE diminished, mitochondrial respiratory capacity. Surprisingly, skeletal muscle-specific inhibition of mitochondrial-autonomous synthesis of PE caused a respiratory failure due to metabolic insults in the diaphragm muscle. While mitochondrial PE deficiency coincided with increased oxidative stress, neutralization of the latter did not rescue lethality. These findings highlight the previously underappreciated role of mitochondrial membrane phospholipids in dynamically controlling skeletal muscle energetics and function.

physiology↗