An optimized pipeline for high-throughput bulk RNA-Seq deconvolution illustrates the impact of obesity and weight loss on cell composition of human adipose tissue.

Cellular heterogeneity of human adipose tissue, is linked to the pathophysiology of obesity and may impact the response to energy restriction and changes in fat mass. Here, we provide an optimized pipeline to estimate cellular composition in human abdominal subcutaneous adipose tissue (ASAT) from publicly available bulk RNA-Seq using signature profiles from our previously published full-length single nuclei (sn)RNA-Seq of the same depot. Individuals with obesity had greater proportions of macrophages and lower proportions of adipocyte sub-populations and vascular cells compared with lean individuals.

Isolation of Nuclei from Human Intermuscular Adipose Tissue and Downstream Single-Nuclei RNA Sequencing.

Intermuscular adipose tissue (IMAT) is a relatively understudied adipose depot located between muscle fibers. IMAT content increases with age and BMI and is associated with metabolic and muscle degenerative diseases; however, an understanding of the biological properties of IMAT and its interplay with the surrounding muscle fibers is severely lacking. In recent years, single-cell and nuclei RNA sequencing have provided us with cell type-specific atlases of several human tissues.

Sexual dimorphism and the multi-omic response to exercise training in rat subcutaneous white adipose tissue.

Subcutaneous white adipose tissue (scWAT) is a dynamic storage and secretory organ that regulates systemic homeostasis, yet the impact of endurance exercise training (ExT) and sex on its molecular landscape is not fully established. Utilizing an integrative multi-omics approach, and leveraging data generated by the Molecular Transducers of Physical Activity Consortium (MoTrPAC), we show profound sexual dimorphism in the scWAT of sedentary rats and in the dynamic response of this tissue to ExT. Specifically, the scWAT of sedentary females displays -omic signatures related to insulin signaling and adipogenesis, whereas the scWAT of sedentary males is enriched in terms related to aerobic metabolism.

Distinct subpopulations of human subcutaneous adipose tissue precursor cells revealed by single-cell RNA sequencing.

Adipose-derived stem cells (ADSCs) play an important role in the differential capacity for excess energy storage between upper body abdominal (ABD) adipose tissue (AT) and lower body gluteofemoral (GF) AT. We cultured ADSCs from subcutaneous ABD AT and GF AT isolated from eight women with differential body fat distribution and performed single-cell RNA sequencing. Six populations of ADSCs were identified and segregated according to their anatomical origin.

Comprehensive interrogation of human skeletal muscle reveals a dissociation between insulin resistance and mitochondrial capacity.

Insulin resistance and blunted mitochondrial capacity in skeletal muscle are often synonymous, however, this association remains controversial. The aim of this study was to perform an in-depth multifactorial comparison of skeletal muscle mitochondrial capacity between individuals who were lean and active (Active, = 9), individuals with obesity (Obese, = 9), and individuals with obesity, insulin resistance, and type 2 diabetes (T2D, = 22). Mitochondrial capacity was assessed by ex vivo mitochondrial respiration with fatty-acid and glycolytic-supported protocols adjusted for mitochondrial content (mtDNA and citrate synthase activity).

Isolation of nuclei from frozen human subcutaneous adipose tissue for full-length single-nuclei transcriptional profiling.

Automated single-cell dispensing is incompatible with white adipose tissue (WAT) due to lipid-laden adipocytes. Single-nuclei RNA-Seq permits transcriptional profiling of all cells from WAT. Human WAT faces unique technical challenges in isolating nuclei compared to rodent tissue due to greater extra-cellular matrix content and larger lipid droplets.

Single cell full-length transcriptome of human subcutaneous adipose tissue reveals unique and heterogeneous cell populations.

White adipose tissue (WAT) is a complex mixture of adipocytes and non-adipogenic cells. Characterizing the cellular composition of WAT is critical for identifying where potential alterations occur that impact metabolism. Most single-cell (sc) RNA-Seq studies focused on the stromal vascular fraction (SVF) which does not contain adipocytes and have used technology that has a 3' or 5' bias.

A Metabolomic Signature of Glucagon Action in Healthy Individuals With Overweight/Obesity.

Context: Glucagon is produced and released from the pancreatic alpha-cell to regulate glucose levels during periods of fasting. The main target for glucagon action is the liver, where it activates gluconeogenesis and glycogen breakdown; however, glucagon is postulated to have other roles within the body.

Objective: We sought to identify the circulating metabolites that would serve as markers of glucagon action in humans.

Prolonged Glucagon Infusion Does Not Affect Energy Expenditure in Individuals with Overweight/Obesity: A Randomized Trial.

Objective: The aim of this study was to determine the effects of prolonged (72 hours) glucagon administration at a low dose (LD) (12.5 ng/kg/min) and high dose (HD) (25 ng/kg/min) on energy expenditure (EE) in healthy individuals with overweight or obesity.

Methods: Thirty-one healthy participants with overweight or obesity (BMI of 27-45 kg/m , 26-55 years old, 23 females) were randomized into LD, HD, or placebo groups and underwent 72-hour intravenous infusion of glucagon.

Metabolic adaptation characterizes short-term resistance to weight loss induced by a low-calorie diet in overweight/obese individuals.

Background: Low-calorie diet (LCD)-induced weight loss demonstrates response heterogeneity. Physiologically, a decrease in energy expenditure lower than what is predicted based on body composition (metabolic adaptation) and/or an impaired capacity to increase fat oxidation may hinder weight loss. Understanding the metabolic components that characterize weight loss success is important for optimizing weight loss strategies.

Young, healthy males and females present cardiometabolic protection against the detrimental effects of a 7-day high-fat high-calorie diet.

Purpose: High-fat, high-calorie (HFHC) diets have been used as a model to investigate lipid-induced insulin resistance. Short-term HFHC diets reduce insulin sensitivity in young healthy males, but to date, no study has directly compared males and females to elucidate sex-specific differences in the effects of a HFHC diet on functional metabolic and cardiovascular outcomes.

Methods: Eleven males (24 ± 4 years; BMI 23 ± 2 kg.

High-Fat Overfeeding Impairs Peripheral Glucose Metabolism and Muscle Microvascular eNOS Ser1177 Phosphorylation.

Context: The mechanisms responsible for dietary fat-induced insulin resistance of skeletal muscle and its microvasculature are only partially understood.

Objective: To determine the impact of high-fat overfeeding on postprandial glucose fluxes, muscle insulin signaling, and muscle microvascular endothelial nitric oxide synthase (eNOS) content and activation.

Design: Fifteen non-obese volunteers consumed a high-fat (64%) high-energy (+47%) diet for 7 days.

Hormone-sensitive lipase preferentially redistributes to lipid droplets associated with perilipin-5 in human skeletal muscle during moderate-intensity exercise.

Key Points: Hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) are the key enzymes involved in intramuscular triglyceride (IMTG) lipolysis. In isolated rat skeletal muscle, HSL translocates to IMTG-containing lipid droplets (LDs) following electrical stimulation, but whether HSL translocation occurs in human skeletal muscle during moderate-intensity exercise is currently unknown. Perilipin-2 (PLIN2) and perilipin-5 (PLIN5) proteins have been implicated in regulating IMTG lipolysis by interacting with HSL and ATGL in cell culture and rat skeletal muscle studies.