Biology subjects

Quinn, M. A.

Publications and source records attributed to Quinn, M. A..

6 recordsLinked to original sources

bioRxiv2023

Itaconate stabilizes CPT1a to enhance lipid utilization during inflammation

One primary metabolic manifestation of inflammation is the diversion of cis-aconitate within the tricarboxylic acid (TCA) cycle to synthesize the immunometabolite itaconate. Itaconate is well established to possess immunomodulatory and metabolic effects within myeloid cells and lymphocytes, however, its effects in other organ systems during sepsis remain less clear. Utilizing Irg1 knockout mice that are deficient in synthesizing itaconate, we aimed at understanding the metabolic role of itaconate in the liver and systemically during sepsis. We find itaconate aids in lipid metabolism during sepsis. Specifically, Irg1 KO mice develop a heightened level of hepatic steatosis when induced with polymicrobial sepsis. Proteomics analysis reveal enhanced expression of enzymes involved in fatty acid oxidation in following 4-ocytl itaconate (4-OI) treatment in vitro. Downstream analysis reveals itaconate stabilizes the expression of the mitochondrial fatty acid uptake enzyme CPT1a, mediated by its hypoubiquitination. Chemoproteomic analysis revealed itaconate interacts with proteins involved in protein ubiquitination as a potential mechanism underlying its stabilizing effect on CPT1a. From a systemic perspective, we find itaconate deficiency triggers a hypothermic response following endotoxin stimulation, potentially mediated by brown adipose tissue (BAT) dysfunction. Finally, by use of metabolic cage studies, we demonstrate Irg1 KO mice rely more heavily on carbohydrates versus fatty acid sources for systemic fuel utilization in response to endotoxin treatment. Our data reveal a novel metabolic role of itaconate in modulating fatty acid oxidation during polymicrobial sepsis.

physiology↗

bioRxiv2021

Dichloroacetate improves systemic energy balance and feeding behavior during sepsis

Sepsis is a life-threatening organ dysfunction by dysregulated host response to an infection. The metabolic aberrations associated with sepsis underly an acute and organism wide hyper-inflammatory response and multiple organ dysfunction; however, crosstalk between systemic metabolomic alterations and metabolic reprograming at organ levels remains unknown. We analyzed substrate utilization by the respiratory exchange ratio, energy expenditure, metabolomic screening and transcriptional profiling in a cecal ligation and puncture (CLP) model, to show that sepsis increases circulating free fatty acids and acylcarnitines but decreases levels of amino acids and carbohydrates leading to a drastic shift in systemic fuel preference. Comparative analysis of previously published metabolomics from septic liver indicates a positive correlation with hepatic and plasma metabolites during sepsis. In particular, glycine deficiency was a common abnormality of both plasma and the liver during sepsis. Interrogation of the hepatic transcriptome in septic mice suggests that the septic liver may contribute to systemic glycine deficiency by downregulating genes involved in glycine synthesis. Interestingly, intraperitoneal injection of the pyruvate dehydrogenase kinase (PDK) inhibitor dichloroacetate (DCA) reverses sepsis-induced anorexia, energy imbalance, dyslipidemia, hypoglycemia, and glycine deficiency. Collectively, our data indicate that PDK inhibition rescues systemic energy imbalance and metabolic dysfunction in sepsis partly through restoration of hepatic fuel metabolism.

immunology↗

bioRxiv2021

Itaconate and its derivatives repress C2C12 myogenesis via succinate dehydrogenase inhibition

A Krebs cycle intermediate metabolite, itaconate, has gained attention as a potential antimicrobial and autoimmune disease treatment due to its anti-inflammatory effects. While itaconate and its derivatives pose an attractive therapeutic option for the treatment of inflammatory diseases, the effects outside the immune system still remain limited, particularly in the muscle. Therefore, we endeavored to determine if itaconate signaling impacts muscle differentiation. Utilizing the well-established C2C12 model of in vitro myogenesis, we evaluated the effects of itaconate and its derivatives on transcriptional and protein markers of muscle differentiation as well as mitochondrial function. We found itaconate and the derivatives dimethyl itaconate and 4-octyl itaconate disrupt differentiation media-induced myogenesis. A primary biological effect of itaconate is a succinate dehydrogenase (SDH) inhibitor. We find the SDH inhibitors dimethyl malonate and harzianopyridone phenocopie the anti-myogenic effects of itaconate. Furthermore, we find treatment with exogenous succinate results in blunted myogenesis. Together our data indicate itaconate and its derivatives interfere with in vitro myogenesis, potentially through inhibition of SDH and subsequent succinate accumulation. More importantly, our findings suggest the therapeutic potential of itaconate and its derivatives could be limited due to deleterious effects on myogenesis.

cell biology↗

bioRxiv2020

Rapid conversion of replicating and integrating Saccharomyces cerevisiae plasmid vectors via Cre recombinase

Plasmid shuttle vectors capable of replication in both Saccharomyces cerevisiae and Escherichia coli and optimized for controlled modification in vitro and in vivo are a key resource supporting yeast as a premier system for genetics research and synthetic biology. We have engineered a series of yeast shuttle vectors optimized for efficient insertion, removal and substitution of plasmid yeast replication loci, allowing generation of a complete set of integrating, low copy and high copy plasmids via predictable operations as an alternative to traditional subcloning. We demonstrate the utility of this system through modification of replication loci via Cre recombinase, both in vitro and in vivo, and restriction endonuclease treatments.

molecular biology↗

bioRxiv2020

Dichloroacetate improves hepatic and systemic energy metabolism during sepsis

Dramatic metabolic reprogramming between an anabolic resistance and catabolic tolerance state occurs within the immune system in response to systemic infection with the sepsis syndrome. While metabolic tissues such as the liver are subject to end-organ damage during sepsis and are the primary cause of sepsis death, how their metabolic and energy reprogramming during sepsis state ensures survival is unclear. Employing comprehensive metabolomic screening, targeted lipidomic screening, and transcriptional profiling in a mouse model of septic shock, we show that hepatocyte lipid metabolism, mitochondrial TCA energetics, and redox balance are significantly reprogramed after cecal ligation and puncture (CLP). We identify increases in TCA cycle metabolites citrate, cis-aconitate, and itaconate with reduced fumarate and triglyceride accumulation in septic hepatocytes. Transcription analysis of liver tissue supports and extends the hepatocyte findings. Strikingly, the administration of the pyruvate dehydrogenase kinase (PDK) inhibitor dichloroacetate (DCA) reverses dysregulated hepatocyte metabolism and mitochondrial dysfunction. Our data indicate sepsis promotes hepatic metabolic dysfunction. Furthermore, our data indicate that targeting the mitochondrial PDC/PDK energy home-ostat rebalances transcriptional and metabolic manifestations of sepsis within the liver.

immunology↗

bioRxiv2020

Impact of Advanced Maternal Age on Physiologic Adaptations to Pregnancy in Vervet Monkeys

ContextThe trend to delay pregnancy in the United States has resulted in the number of advanced maternal age (AMA) pregnancies to also increase. In humans, AMA is associated with a variety of pregnancy-related pathologies such as preeclampsia (PE). While AMA is known to be a factor which contributes to the development of pregnancy-induced diseases, the molecular and cellular mechanisms giving rise to this phenomenon are still very limited. This is due in part to lack of a pre-clinical model which has physiologic relevance to human pregnancy while also allowing control of environmental and genetic variability inherent in human studies. ObjectiveTo determine potential physiologic relevance of the vervet/African green monkey (Chlorocebus aethiops sabaeus) as a pre-clinical model to study the effects of AMA on adaptations to pregnancy. DesignThirteen age-diverse pregnant vervet monkeys (3-16 y.o.) were utilized to measure third trimester blood pressure (BP), complete blood count, iron measurements and hormone levels. ResultsSignificant associations were observed between third trimester diastolic BP and maternal age. Furthermore, the presence of leukocytosis with enhanced circulating neutrophils was observed in AMA mothers compared to younger mothers. Moreover, we observed a negative relationship between maternal age and estradiol, progesterone and cortisol levels. Finally, offspring born to AMA mothers displayed a postnatal growth retardation phenotype. ConclusionsThese studies demonstrate physiologic impairment in the adaptation to pregnancy in AMA vervet/African green monkeys. Our data indicate the vervet/African green monkey may serve as a useful pre-clinical model and tool for deciphering pathological mediators of maternal disease in AMA pregnancy.

physiology↗