The purpose of this project report is to introduce the European "GOLIATH" project, a new research project which addresses one of the most urgent regulatory needs in the testing of endocrine-disrupting chemicals (EDCs), namely the lack of methods for testing EDCs that disrupt metabolism and metabolic functions. These chemicals collectively referred to as "metabolism disrupting compounds" (MDCs) are natural and anthropogenic chemicals that can promote metabolic changes that can ultimately result in obesity, diabetes, and/or fatty liver in humans. This project report introduces the main approaches of the project and provides a focused review of the evidence of metabolic disruption for selected EDCs. GOLIATH will generate the world's first integrated approach to testing and assessment (IATA) specifically tailored to MDCs. GOLIATH will focus on the main cellular targets of metabolic disruption-hepatocytes, pancreatic endocrine cells, myocytes and adipocytes-and using an adverse outcome pathway (AOP) framework will provide key information on MDC-related mode of action by incorporating multi-omic analyses and translating results from in silico, in vitro, and in vivo models and assays to adverse metabolic health outcomes in humans at real-life exposures. Given the importance of international acceptance of the developed test methods for regulatory use, GOLIATH will link with ongoing initiatives of the Organisation for Economic Development (OECD) for test method (pre-)validation, IATA, and AOP development.

Hereditary retinal dystrophies (HRD) represent a significant cause of blindness, affecting mostly retinal pigment epithelium (RPE) and photoreceptors (PRs), and currently suffer from a lack of effective treatments. Highly specialized RPE and PR cells interact mutually in the functional retina, therefore primary HRD affecting one cell type leading to a secondary HRD in the other cells. Phagocytosis is one of the primary functions of the RPE and studies have discovered that mutations in the phagocytosis-associated gene Mer tyrosine kinase receptor (MERTK) lead to primary RPE dystrophy. Treatment strategies for this rare disease include the replacement of diseased RPE with healthy autologous RPE to prevent PR degeneration. The generation and directed differentiation of patient-derived human-induced pluripotent stem cells (hiPSCs) may provide a means to generate autologous therapeutically-relevant adult cells, including RPE and PR. However, the continued presence of the MERTK gene mutation in patient-derived hiPSCs represents a significant drawback. Recently, we reported the generation of a hiPSC model of MERTK-associated Retinitis Pigmentosa (RP) that recapitulates disease phenotype and the subsequent creation of gene-corrected RP-hiPSCs using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9. In this study, we differentiated gene-corrected RP-hiPSCs into RPE and found that these cells had recovered both wild-type MERTK protein expression and the lost phagocytosis of fluorescently-labeled photoreceptor outer segments observed in uncorrected RP-hiPSC-RPE. These findings provide proof-of-principle for the utility of gene-corrected hiPSCs as an unlimited cell source for personalized cell therapy of rare vision disorders.

As glucose-dependent insulinotropic polypeptide (GIP) possesses pro-adipogenic action, the suppression of the GIP hypersecretion seen in obesity might represent a novel therapeutic approach to the treatment of obesity. However, the mechanism of GIP hypersecretion remains largely unknown. In the present study, we investigated GIP secretion in two mouse models of obesity: High-fat diet-induced obese (DIO) mice and leptin-deficient Lepob/ob mice. In DIO mice, plasma GIP was increased along with an increase in GIP mRNA expression in the lower small intestine. Despite the robust alteration in the gut microbiome in DIO mice, co-administration of maltose and the α-glucosidase inhibitor (α-GI) miglitol induced the microbiome-mediated suppression of GIP secretion. The plasma GIP levels of Lepob/ob mice were also elevated and were suppressed by fat transplantation. The GIP mRNA expression in fat tissue was not increased in Lepob/ob mice, while the expression of an interleukin-1 receptor antagonist (IL-1Ra) was increased. Fat transplantation suppressed the expression of IL-1Ra. The plasma IL-1Ra levels were positively correlated with the plasma GIP levels. Accordingly, although circulating GIP levels are increased in both DIO and Lepob/ob mice, the underlying mechanisms differ, and the anti-obesity actions of α-GIs and leptin sensitizers may be mediated partly by the suppression of GIP secretion.

Papillary thyroid carcinoma (PTC), is characterized by a heterogeneous group of cells, including cancer stem cells (CSCs), crucially involved in tumor initiation, progression and recurrence. CSCs appear to have a distinct metabolic phenotype, compared to non-stem cancer cells. How they adapt their metabolism to the cancer process is still unclear, and no data are yet available for PTC. We recently isolated thyrospheres, containing cancer stem-like cells, from B-CPAP and TPC-1 cell lines derived from PTC of the BRAF-like expression profile class, and stem-like cells from Nthy-ori3-1 normal thyreocyte-derived cell line. In the present study, gas chromatography/mass spectrometry metabolomic profiles of cancer thyrospheres were compared to cancer parental adherent cells and to non cancer thyrospheres profiles. A statistically significant decrease of glycolytic pathway metabolites and variations in Krebs cycle metabolites was found in thyrospheres versus parental cells. Moreover, cancer stem-like cells showed statistically significant differences in Krebs cycle intermediates, amino acids, cholesterol, and fatty acids content, compared to non-cancer stem-like cells. For the first time, data are reported on the metabolic profile of PTC cancer stem-like cells and confirm that changes in metabolic pathways can be explored as new biomarkers and targets for therapy in this tumor.

CBL is rapidly phosphorylated upon insulin receptor activation. Mice whole body CBL depletion improved insulin sensitivity and glucose clearance; however, the precise mechanisms remain unknown. We depleted either CBL or its associated protein SORBS1/CAP independently in myocytes and assessed mitochondrial function and metabolism compared to control cells. CBL- and CAP-depleted cells showed increased mitochondrial mass with greater proton leak. Mitochondrial respiratory complex I activity and assembly into respirasomes were reduced. Proteome profiling revealed alterations in proteins involved in glycolysis and fatty acid degradation. Our findings demonstrate CBL/CAP pathway couples insulin signaling to efficient mitochondrial respiratory function and metabolism in muscle.