Machine learning designs new GCGR/GLP-1R dual agonists with enhanced biological potency.

Several peptide dual agonists of the human glucagon receptor (GCGR) and the glucagon-like peptide-1 receptor (GLP-1R) are in development for the treatment of type 2 diabetes, obesity and their associated complications. Candidates must have high potency at both receptors, but it is unclear whether the limited experimental data available can be used to train models that accurately predict the activity at both receptors of new peptide variants. Here we use peptide sequence data labelled with in vitro potency at human GCGR and GLP-1R to train several models, including a deep multi-task neural-network model using multiple loss optimization. Model-guided sequence optimization was used to design three groups of peptide variants, with distinct ranges of predicted dual activity. We found that three of the model-designed sequences are potent dual agonists with superior biological activity. With our designs we were able to achieve up to sevenfold potency improvement at both receptors simultaneously compared to the best dual-agonist in the training set.

Sex-specific effects of CD248 on metabolism and the adipose tissue lipidome.

Cd248 has recently been associated with adipose tissue physiology, demonstrated by reduced weight gain in high fat diet-fed mice with genetic deletion of Cd248 relative to controls. Here we set out to determine the metabolic consequences of loss of Cd248. Strikingly, we find these to be sex specific; By subjecting Cd248-/- and Cd248+/+ mice to a high fat diet and indirect calorimetry study, we identified that only male Cd248-/- mice show reduced weight gain compared to littermate control wildtype mice. In addition, male (but not female) mice showed a lower respiratory exchange ratio on both chow and high fat diets, indicating a predisposition to metabolise lipid. Lipidomic studies on specific fat depots found reduced triglyceride and diglyceride deposition in male Cd248-/- mice, and this was supported by reduced expression of lipogenic and adipogenic genes. Finally, metabolomic analysis of isolated, differentiated preadipocytes found alterations in metabolic pathways associated with lipid deposition in cells isolated from male, but not female, Cd248-/- mice. Overall, our results highlight the importance of sex controls in animal studies and point to a role for Cd248 in sex- and depot-specific regulation of lipid metabolism.

Long-chain ceramides are cell non-autonomous signals linking lipotoxicity to endoplasmic reticulum stress in skeletal muscle.

The endoplasmic reticulum (ER) regulates cellular protein and lipid biosynthesis. ER dysfunction leads to protein misfolding and the unfolded protein response (UPR), which limits protein synthesis to prevent cytotoxicity. Chronic ER stress in skeletal muscle is a unifying mechanism linking lipotoxicity to metabolic disease. Unidentified signals from cells undergoing ER stress propagate paracrine and systemic UPR activation. Here, we induce ER stress and lipotoxicity in myotubes. We observe ER stress-inducing lipid cell non-autonomous signal(s). Lipidomics identifies that palmitate-induced cell stress induces long-chain ceramide 40:1 and 42:1 secretion. Ceramide synthesis through the ceramide synthase 2 de novo pathway is regulated by UPR kinase Perk. Inactivation of CerS2 in mice reduces systemic and muscle ceramide signals and muscle UPR activation. The ceramides are packaged into extracellular vesicles, secreted and induce UPR activation in naïve myotubes through dihydroceramide accumulation. This study furthers our understanding of ER stress by identifying UPR-inducing cell non-autonomous signals.

Brown and beige adipose tissue regulate systemic metabolism through a metabolite interorgan signaling axis.

Brown and beige adipose tissue are emerging as distinct endocrine organs. These tissues are functionally associated with skeletal muscle, adipose tissue metabolism and systemic energy expenditure, suggesting an interorgan signaling network. Using metabolomics, we identify 3-methyl-2-oxovaleric acid, 5-oxoproline, and ß-hydroxyisobutyric acid as small molecule metabokines synthesized in browning adipocytes and secreted via monocarboxylate transporters. 3-methyl-2-oxovaleric acid, 5-oxoproline and ß-hydroxyisobutyric acid induce a brown adipocyte-specific phenotype in white adipocytes and mitochondrial oxidative energy metabolism in skeletal myocytes both in vitro and in vivo. 3-methyl-2-oxovaleric acid and 5-oxoproline signal through cAMP-PKA-p38 MAPK and ß-hydroxyisobutyric acid via mTOR. In humans, plasma and adipose tissue 3-methyl-2-oxovaleric acid, 5-oxoproline and ß-hydroxyisobutyric acid concentrations correlate with markers of adipose browning and inversely associate with body mass index. These metabolites reduce adiposity, increase energy expenditure and improve glucose and insulin homeostasis in mouse models of obesity and diabetes. Our findings identify beige adipose-brown adipose-muscle physiological metabokine crosstalk.

Induction of UCP1 and thermogenesis by a small molecule via AKAP1/PKA modulation.

Strategies to increase energy expenditure are an attractive approach to reduce excess fat storage and body weight to improve metabolic health. In mammals, uncoupling protein-1 (UCP1) in brown and beige adipocytes uncouples fatty acid oxidation from ATP generation in mitochondria and promotes energy dissipation as heat. We set out to identify small molecules that enhance UCP1 levels and activity using a high-throughput screen of nearly 12,000 compounds in mouse brown adipocytes. We identified a family of compounds that increase Ucp1 expression and mitochondrial activity (including un-coupled respiration) in mouse brown adipocytes and human brown and white adipocytes. The mechanism of action may be through compound binding to A kinase anchoring protein (AKAP) 1, modulating its localization to mitochondria and its interaction with protein kinase A (PKA), a known node in the ß-adrenergic signaling pathway. In mice, the hit compound increased body temperature, UCP1 protein levels, and thermogenic gene expression. Some of the compound effects on mitochondrial function were UCP1- or AKAP1-independent, suggesting compound effects on multiple nodes of energy regulation. Overall, our results highlight a role for AKAP1 in thermogenesis, uncoupled respiration, and regulation energy balance.

Transcriptional analysis of adipose tissue during development reveals depot-specific responsiveness to maternal dietary supplementation.

Brown adipose tissue (BAT) undergoes pronounced changes after birth coincident with the loss of the BAT-specific uncoupling protein (UCP)1 and rapid fat growth. The extent to which this adaptation may vary between anatomical locations remains unknown, or whether the process is sensitive to maternal dietary supplementation. We, therefore, conducted a data mining based study on the major fat depots (i.e. epicardial, perirenal, sternal (which possess UCP1 at 7 days), subcutaneous and omental) (that do not possess UCP1) of young sheep during the first month of life. Initially we determined what effect adding 3% canola oil to the maternal diet has on mitochondrial protein abundance in those depots which possessed UCP1. This demonstrated that maternal dietary supplementation delayed the loss of mitochondrial proteins, with the amount of cytochrome C actually being increased. Using machine learning algorithms followed by weighted gene co-expression network analysis, we demonstrated that each depot could be segregated into a unique and concise set of modules containing co-expressed genes involved in adipose function. Finally using lipidomic analysis following the maternal dietary intervention, we confirmed the perirenal depot to be most responsive. These insights point at new research avenues for examining interventions to modulate fat development in early life.

'Browning' the cardiac and peri-vascular adipose tissues to modulate cardiovascular risk.

Excess visceral adiposity, in particular that located adjacent to the heart and coronary arteries is associated with increased cardiovascular risk. In the pathophysiological state, dysfunctional adipose tissue secretes an array of factors modulating vascular function and driving atherogenesis. Conversely, brown and beige adipose tissues utilise glucose and lipids to generate heat and are associated with improved cardiometabolic health. The cardiac and thoracic perivascular adipose tissues are now understood to be composed of brown adipose tissue in the healthy state and undergo a brown-to-white transition i.e. during obesity which may be a driving factor of cardiovascular disease. In this review we discuss the risks of excess cardiac and vascular adiposity and potential mechanisms by which restoring the brown phenotype i.e. "re-browning" could potentially be achieved in clinically relevant populations.

Adipocyte Browning and Higher Mitochondrial Function in Periadrenal But Not SC Fat in Pheochromocytoma.

CONTEXT: Patients with pheochromocytoma (pheo) show presence of multilocular adipocytes that express uncoupling protein 1 within periadrenal (pADR) and omental (OME) fat depots. It has been hypothesized that this is due to adrenergic stimulation by catecholamines produced by the pheo tumors. OBJECTIVE: To characterize the prevalence and respiratory activity of brown-like adipocytes within pADR, OME, and SC fat depots in human adult pheo patients. DESIGN: This was an observational cohort study. SETTING: The study took place in a university hospital. PATIENTS: We studied 46 patients who underwent surgery for benign adrenal tumors (21 pheos and 25 controls with adrenocortical adenomas). MAIN OUTCOME MEASURE: We characterized adipocyte browning in pADR, SC, and OME fat depots for histological and immunohistological features, mitochondrial respiration rate, and gene expression. We also determined circulating levels of catecholamines and other browning-related hormones. RESULTS: Eleven of 21 pheo pADR adipose samples, but only one of 25 pADR samples from control patients exhibited multilocular adipocytes. The pADR browning phenotype was associated with higher plasma catecholamines and raised uncoupling protein 1. Mitochondria from multilocular pADR fat of pheo patients exhibited increased rates of coupled and uncoupled respiration. Global gene expression analysis in pADR fat revealed enrichment in ß-oxidation genes in pheo patients with multilocular adipocytes. No SC or OME fat depots exhibited aspects of browning. CONCLUSION: Browning of the pADR depot occurred in half of pheo patients and was associated with increased catecholamines and mitochondrial activity. No browning was detected in other fat depots, suggesting that other factors are required to promote browning in these depots.

Cognitive screening using a tape recorder: a pilot study.

OBJECTIVES: To determine whether a tape recorder can be used to administer cognitive tests efficiently and yield valid results. DESIGN: Convenience sample. Administration of cognitive test materials by tape recorder and conventional technique. SETTING: Outpatient clinic. PARTICIPANTS: Subjects from memory disorder clinic, hostel accommodation, and community. MEASUREMENTS: Responses to Hopkins Verbal Learning Test-revised, verbal fluency items from the controlled oral word association test, 10-item naming task, a construction task, and speed writing task. RESULTS: Performances on the tape- and clinician-administered battery of tests were highly correlated. Memory impairment was accurately detected using the tape battery. Data from 30 minutes of testing via tape were obtained at the cost to the clinician of 2 to 3 minutes of scoring time. CONCLUSION: Tape-administration of cognitive test material warrants further study as an efficient means of cognitive screening.