Biology subjects

Cooney, G. J.

Publications and source records attributed to Cooney, G. J..

6 recordsLinked to original sources

bioRxiv2026

Systems genetics identifies ETS1 as a stress-dependent regulator of adipocyte insulin action and heme-iron homeostasis

White adipose tissue plays a central role in systemic energy homeostasis by buffering nutrient excess through insulin-stimulated glucose uptake and triglyceride storage. Despite its importance, the genetic and molecular mechanisms governing adipose tissue insulin action remain poorly defined because tissue-specific insulin responsiveness has been difficult to quantify at the scale required for genetic discovery. Here, we developed the first scalable platform for high-throughput genetic mapping of tissue-specific insulin action in adipose tissue, enabling systems genetic analysis across 559 genetically diverse Diversity Outbred Australia (DOz) mice. Genetic analysis accounting for adiposity identified 39 loci associated with adipose tissue insulin action, demonstrating that adipose insulin responsiveness is a genetically encoded trait that captures a dimension of metabolic health beyond adiposity. Among these, a strong diet-dependent locus on chromosome 9 encompassed the transcription factor Ets1. Functional studies demonstrated that Ets1 silencing selectively restored insulin-stimulated glucose uptake in insulin-resistant adipocytes. Proteomic profiling revealed that ETS1 orchestrates a stress-responsive program involving heme metabolism, iron handling and redox homeostasis. Consistent with this, ETS1 knockdown reduced cellular heme and labile iron levels and attenuated oxidative stress under insulin-resistant conditions. Collectively, these findings demonstrate the power of systems genetics to identify previously unrecognised regulators of adipose insulin action and establish the heme-iron axis as a critical determinant of adipocyte insulin responsiveness.

systems biology↗

bioRxiv2024

Genetic variance in the murine defensin locus modulates glucose homeostasis

Insulin resistance is a heritable risk factor for many chronic diseases; however, the genetic drivers remain elusive. In seeking these, we performed genetic mapping of insulin sensitivity in 670 chow-fed Diversity Outbred in Australia (DOz) mice and identified a genome-wide significant locus (QTL) on chromosome 8 encompassing 17 defensin genes. By taking a systems genetics approach, we ultimately identified alpha-defensin 26 (Defa26) as the causal gene in this region. To validate these findings, we synthesized Defa26 and performed diet supplementation experiments in two mouse strains with distinct endogenous Defa26 expression levels. In the strain with relatively lower endogenous expression (C57BL/6J) supplementation improved insulin sensitivity and reduced gut permeability, while in the strain with higher endogenous expression (A/J) it caused hypoinsulinemia, glucose intolerance and muscle wasting. Based on gut microbiome and plasma bile acid profiling this appeared to be the result of disrupted microbial bile acid metabolism. These data illustrate the danger of single strain over-reliance and provide the first evidence of a link between host-genetics and insulin sensitivity which is mediated by the microbiome.

systems biology↗

bioRxiv2023

Hepatic Lipid Droplet-Associated Proteome Changes Distinguish Dietary-Induced Fatty Liver from Insulin Resistance in Male Mice.

Fatty liver is characterised by the expansion of lipid droplets and is associated with the development of many metabolic diseases, including insulin resistance, dyslipidaemia and cardiovascular disease. We assessed the morphology of hepatic lipid droplets and performed quantitative proteomics in lean, glucose-tolerant mice compared to high-fat diet (HFD) fed mice that displayed hepatic steatosis and glucose intolerance as well as high-starch diet (HStD) fed mice who exhibited similar levels of hepatic steatosis but remained glucose tolerant. Both HFD and HStD-fed mice had more and larger lipid droplets than Chow-fed animals. We observed striking differences in liver lipid droplet proteomes of HFD and HStD-fed mice compared to Chow-fed mice, with fewer differences between HFD and HStD. Taking advantage of our diet strategy, we identified a fatty liver lipid droplet proteome consisting of proteins common in HFD- and HStD-fed mice. Likewise, a proteome associated with glucose tolerance that included proteins common in Chow and HStD but not HFD-fed mice was identified. Notably, glucose intolerance was associated with changes in the ratio of adipose triglyceride lipase (ATGL) to perilipin 5 (PLIN5) in the lipid droplet proteome, suggesting dysregulation of neutral lipid homeostasis in glucose-intolerant fatty liver, which supports bioactive lipid synthesis and impairs hepatic insulin action. We conclude that our novel dietary approach uncouples ectopic lipid burden from insulin resistance-associated changes in the hepatic lipid droplet proteome.

cell biology↗

bioRxiv2023

Leveraging genetic diversity to identify small molecules that reverse mouse skeletal muscle insulin resistance

Systems genetics has begun to tackle the complexity of insulin resistance by capitalising on computational advances to study high-diversity populations. "Diversity Outbred in Australia (DOz)" is a population of genetically unique mice with profound metabolic heterogeneity. We leveraged this variance to explore skeletal muscles contribution to whole-body insulin action through metabolic phenotyping and skeletal muscle proteomics of 215 DOz mice. Linear modelling identified 553 proteins that associated with whole-body insulin sensitivity (Matsuda Index) including regulators of endocytosis and muscle proteostasis. To enrich for causality, we refined this network by focussing on negatively associated, genetically regulated proteins, resulting in a 76-protein fingerprint of insulin resistance. We sought to perturb this network and restore insulin action with small molecules by integrating the Broad Institute Connectivity Map platform and in vitro assays of insulin action using the Prestwick chemical library. These complimentary approaches identified the antibiotic thiostrepton as an insulin resistance reversal agent. Subsequent validation in ex vivo insulin resistant mouse muscle, and palmitate induced insulin resistant myotubes demonstrated potent insulin action restoration, potentially via up-regulation of glycolysis. This work demonstrates the value of a drug-centric framework to validate systems level analysis by identifying potential therapeutics for insulin resistance.

systems biology↗

bioRxiv2022

Insulin sensitivity is preserved in mice made obese by feeding a high starch diet

Obesity is generally associated with insulin resistance in liver and muscle and increased risk of developing type 2 diabetes, however there is a population of obese people that remain insulin sensitive. Similarly, recent work suggests that mice fed high carbohydrate diets can become obese without apparent glucose intolerance. To investigate this phenomenon further, we fed mice either a high fat (Hi-F) or high starch (Hi-ST) diet and measured adiposity, glucose tolerance, insulin sensitivity and tissue lipids compared to control mice fed a standard laboratory chow. Both Hi-ST and Hi-F mice accumulated a similar amount of fat and tissue triglyceride compared to chow-fed mice. However while Hi-F diet mice developed glucose intolerance as well as liver and muscle insulin resistance (assessed via euglycemic/hyperinsulinemic clamp), obese Hi-ST mice maintained glucose tolerance and insulin action similar to lean, chow-fed controls. This preservation of insulin action despite obesity in Hi-ST mice was associated with differences in de novo lipogenesis and levels of C22:0 ceramide in liver and C18:0 ceramide in muscle. This indicates that dietary manipulation can influence insulin action independently of the level of adiposity and that the presence of specific ceramide species correlate with these differences.

physiology↗

bioRxiv2018

Fibroblast activation protein enzyme deficiency prevents liver steatosis, insulin resistance and glucose intolerance and increases fibroblast growth factor-21 in diet induced obese mice

Background & AimsFibroblast activation protein-a (FAP) is a post-proline peptidase closely related to dipeptidyl peptidase-4. FAP degrades bioactive peptides including fibroblast growth factor-21 (FGF-21) and neuropeptide Y. We examined metabolic outcomes of specific genetic ablation of FAP and its enzyme activity in a mouse model of diet-induced obesity (DIO) causing fatty liver.\n\nMethodsWildtype (WT) and genetically modified FAP deficient mice that specifically lacked either the FAP protein or FAP enzyme activity received chow, or an atherogenic diet for 8 to 20 weeks of DIO.\n\nResultsFAP deficient male and female mice in the DIO model were more metabolically healthy than controls. The FAP deficient mice had less glucose intolerance, liver lipid, adiposity, insulin resistance, pancreatic and plasma insulin, pancreatic {beta}-cell hyperplasia, serum alanine transaminase and circulating cholesterol compared to wild type controls. Furthermore, FAP deficiency lowered respiratory exchange ratio and greatly increased intrahepatic non-esterified free fatty acids, indicative of increased lipolysis and {beta}-oxidation. Concordantly, lipogenic genes (Pparg, Gck, Acc, Fasn) and hepatic triglyceride and fatty acid uptake genes (Cd36, Apoc3, Ldlr) and plasma low-density lipoprotein cholesterol were downregulated. Glucagon like peptide-1 levels were unaltered. FAP was localized to human pancreatic {beta}-cells and pancreas from diabetes mellitus patients contained elevated FAP activity. Comparable data from a FAP gene knockout mouse and a novel mouse lacking FAP enzyme activity indicated that these metabolic changes depended upon the enzymatic activity of FAP. These changes may be driven by FGF-21, which was upregulated in livers of FAP deficient DIO mice.\n\nConclusionThis is the first study to show that specific genetic ablation of FAP activity or protein protects against DIO-driven glucose intolerance, hyperinsulinaemia, insulin resistance, hypercholesterolaemia and liver steatosis in mice and provide mechanistic insights.

pathology↗