Biology subjects

Gottlieb, R. A.

Publications and source records attributed to Gottlieb, R. A..

7 recordsLinked to original sources

bioRxiv2024

Targeted glycophagy ATG8 therapy for diabetic heart disease

Diabetic heart disease is highly prevalent and is associated with the early development of impaired diastolic relaxation. The mechanisms of diabetic heart disease are poorly understood and it is a condition for which there are no targeted therapies. Recently, disrupted glycogen-autophagy (glycophagy) and glycogen accumulation have been identified in the diabetic heart. Glycophagy involves glycogen receptor binding and linking with an ATG8 protein to locate and degrade glycogen within an intracellular phago-lysosome. Here we show that glycogen receptor protein STBD1 (starch-binding-domain-protein-1) is mobilized early in the cardiac glycogen response to metabolic challenge in vivo, and that deficiency of a specific ATG8 family protein, Gabarapl1 ({gamma}-aminobutyric-acid-receptor-associated-protein-like-1) is associated with diastolic dysfunction in diabetes. Gabarapl1 gene delivery treatment remediated cardiomyocyte and cardiac diastolic dysfunction in type 2 diabetic mice and diastolic performance of diabetic human iPSC-derived cardiac organoids. We identify glycophagy dysregulation as a mechanism and potential treatment target for diabetic heart disease.

physiology↗

bioRxiv2024

Methods for detection of cardiac glycogen-autophagy

Glycogen-autophagy ( glycophagy) is a selective autophagy process involved in delivering glycogen to the lysosome for bulk degradation. Glycophagy protein intermediaries include STBD1 as a glycogen tagging receptor, delivering the glycogen cargo into the forming phagosome by partnering with the Atg8 homolog, GABARAPL1. Glycophagy is emerging as a key process of energy metabolism and development of reliable tools for assessment of glycophagy activity is an important priority. Here we show that antibodies raised against the N-terminus of the GABARAPL1 protein (but not the full-length protein) detected a specific endogenous GABARAPL1 immunoblot band at 18kDa. A stable GFP-GABARAPL1 cardiac cell line was used to quantify GABARAPL1 lysosomal flux via measurement of GFP puncta in response to lysosomal inhibition with bafilomycin. Endogenous glycophagy flux was quantified in primary rat ventricular myocytes by the extent of glycogen accumulation with bafilomycin combined with chloroquine treatment (no effect observed with bafilomycin or chloroquine alone). In wild-type isolated mouse hearts, bafilomycin alone and bafilomycin combined with chloroquine (but not chloroquine alone) elicited a significant increase in glycogen content signifying basal glycophagy flux. Collectively, these methodologies provide a comprehensive toolbox for tracking cardiac glycophagy activity to advance research into the role of glycophagy in health and disease.

molecular biology↗

bioRxiv2021

Protective role of the Atg8 1 homologue Gabarapl1 in regulating cardiomyocyte glycophagy in diabetic heart disease

Diabetic heart disease is highly prevalent and characterized by diastolic dysfunction. The mechanisms of diabetic heart disease are poorly understood and no targeted therapies are available. Here we show that the diabetic myocardium (type 1 and type 2) is characterized by marked glycogen elevation and ectopic cellular localization - a paradoxical metabolic pathology given suppressed cardiomyocyte glucose uptake in diabetes. We demonstrate involvement of a glycogen-selective autophagy pathway ( glycophagy) defect in mediating this pathology. Genetically manipulated deficiency of Gabarapl1, an Atg8 autophagy homologue, induces cardiac glycogen accumulation and diastolic dysfunction. Stbd1, the Gabarapl1 cognate autophagosome partner is identified as a unique component of the early glycoproteome response to hyperglycemia in cardiac, but not skeletal muscle. Cardiac-targeted in vivo Gabarapl1 gene delivery normalizes glycogen levels, diastolic function and cardiomyocyte mechanics. These findings reveal that cardiac glycophagy is a key metabolic homeostatic process perturbed in diabetes that can be remediated by Gabarapl1 intervention.

molecular biology↗

bioRxiv2020

Oncometabolism Drives Autophagy Activation in Skeletal Muscle

About 20-30% of cancer-associated deaths are due to complications from cachexia which is characterized by skeletal muscle atrophy. Metabolic reprogramming in cancer cells causes body-wide metabolic and proteomic remodeling, which remain poorly understood. Here, we present evidence that the oncometabolite D-2-hydroxylgutarate (D2-HG) impairs NAD+ redox homeostasis in skeletal myotubes, causing atrophy via deacetylation of LC3-II by the nuclear deacetylase Sirt1. Overexpression of p300 or silencing of Sirt1 abrogate its interaction with LC3, and subsequently reduced levels of LC3 lipidation. Using RNA-sequencing and mass spectrometry-based metabolomics and proteomics, we demonstrate that prolonged treatment with the oncometabolite D2-HG in mice promotes cachexia in vivo and increases the abundance of proteins and metabolites, which are involved in energy substrate metabolism, chromatin acetylation and autophagy regulation. We further show that D2-HG promotes a sex-dependent adaptation in skeletal muscle using network modeling and machine learning algorithms. Our multi-omics approach exposes new metabolic vulnerabilities in response to D2-HG in skeletal muscle and provides a conceptual framework for identifying therapeutic targets in cachexia.

systems biology↗

bioRxiv2019

MitoPlex: A Targeted Multiple Reaction Monitoring Assay for Quantification of a Curated Set of Mitochondrial Proteins

Mitochondria are the major source of cellular energy (ATP), as well as critical mediators of widespread functions such as cellular redox balance, apoptosis, and metabolic flux. Methods to quantify mitochondrial content are limited to low throughput immunoassays, measurement of mitochondrial DNA, or relative quantification by untargeted mass spectrometry. Here, we present a high throughput, reproducible and quantitative mass spectrometry multiple reaction monitoring based assay of 37 proteins critical to central carbon chain metabolism and overall mitochondrial function termed MitoPlex. We coupled this protein multiplex with a parallel analysis of the central carbon chain metabolites (218 metabolite assay) extracted in tandem from the same sample, be it cells or tissue. In tests of its biological applicability in cells and tissues, MitoPlex plus metabolites indicated profound effects of HMG-CoA Reductase inhibition (e.g., statin treatment) on mitochondria of i) differentiating C2C12 skeletal myoblasts, as well as a clear opposite trend of statins to promote mitochondrial protein expression and metabolism in heart and liver, while suppressing mitochondrial protein and ii) aspects of metabolism in the skeletal muscle obtained from C57Bl6 mice. Our results not only reveal new insights into the metabolic effect of statins in skeletal muscle, but present a new high throughput, reliable MS-based tool to study mitochondrial dynamics in both cell culture and in vivo models.

molecular biology↗

bioRxiv2018

Metagenomic analysis uncovers strong relationship between periodontal pathogens and vascular dysfunction in American Indian population

Periodontal disease (PD) is a well-known risk factor for cardiovascular disease (CVD) but the casual relationship is unclear. American Indians/Alaskan Natives (AI/AN) have high rate of both PD and CVD and a better understanding of how PD might affect heart health would be particularly helpful in this population. In this study, we sequenced the bacterial biofilms of periodontal (gum) pockets and used metagenomic sequencing and vascular health measurements (immune cytokine profiles and vascular flow) to determine the relationship of microbial pathogens and CVD. Twelve subjects were sequenced before and after standard periodontal treatment. Other measures taken before and after treatment included a full dental screening; serum concentration of key immune cytokines from blood samples; lipid profiles from fasting venous blood; and plasma glucose concentrations. The non-invasive Laser Doppler Fluxmetry (LDF) procedure was conducted to measures the microvascular vasodilation. We found highly significant relationships between the total abundance of 4 periodontal pathogens, Porphyromonas gingivalis, Fusobacterium nucleatum, Tannerella forsythia and Treponema denticola, and the inflammatory cytokine interleukin 1 beta (IL-1{beta}) (r=0.63; p=0.009) as well as with vascular flow post sodium nitroprusside (SNP) treatment (r=p=0.006). Two bacterial species that correlated most with IL-1{beta} were F. nucleatum and P. gingivalis. IL-1{beta} has been strongly implicated as a causal factor in atherosclerosis and in periodontal bone loss. To our knowledge, this is the first direct link between abundance of specific periodontal pathogens and cardiovascular disease in humans, and suggests that these pathogens could be used as warning signs for cardiovascular risk.

microbiology↗

bioRxiv2017

Reversal of cardiac and skeletal manifestations of Duchenne muscular dystrophy by cardiosphere-derived cells and their exosomes in mdx dystrophic mice and in human Duchenne cardiomyocytes

Genetic deficiency of dystrophin leads to disability and premature death in Duchenne muscular dystrophy, affecting the heart as well as skeletal muscle. Here we report that cardiosphere-derived cells (CDCs), which are being tested clinically for the treatment of Duchenne cardiomyopathy, improve cardiac and skeletal myopathy in the mdx mouse model of DMD and in human Duchenne cardiomyocytes. Injection of CDCs into the hearts of mdx mice augments cardiac function, ambulatory capacity and survival. Exosomes secreted by human CDCs reproduce the benefits of CDCs in mdx mice and in human Duchenne cardiomyocytes. The findings further motivate the testing of CDCs in Duchenne patients, while identifying exosomes as next-generation therapeutic candidates.

physiology↗