Fibroblast growth factor 21 reflects liver fat accumulation and dysregulation of signalling pathways in the liver of C57BL/6J mice

Fibroblast growth factor 21 (Fgf21) has emerged as a potential plasma marker to diagnose non-alcoholic fatty liver disease (NAFLD). To study the molecular processes underlying the association of plasma Fgf21 with NAFLD, we explored the liver transcriptome data of a mild NAFLD model of aging C57BL/6J mice at 12, 24, and 28 months of age. The plasma Fgf21 level significantly correlated with intrahepatic triglyceride content. At the molecular level, elevated plasma Fgf21 levels were associated with dysregulated metabolic and cancerrelated pathways. The up-regulated Fgf21 levels in NAFLD were implied to be a protective response against the NAFLD-induced adverse effects, e.g. lipotoxicity, oxidative stress and endoplasmic reticulum stress. An in vivo PPARα challenge demonstrated the dysregulation of PPARα signalling in the presence of NAFLD, which resulted in a stochastically increasing hepatic expression of Fgf21. Notably, elevated plasma Fgf21 was associated with declining expression of Klb, Fgf21’s crucial co-receptor, which suggests a resistance to Fgf21. Therefore, although liver fat accumulation is a benign stage of NAFLD, the elevated plasma Fgf21 likely indicated vulnerability to metabolic stressors that may contribute towards progression to end-stage NAFLD. In conclusion, plasma levels of Fgf21 reflect liver fat accumulation and dysregulation of metabolic pathways in the liver

Systems Genetics of Hepatic Metabolome Reveals Octopamine as a Target for Non-Alcoholic Fatty Liver Disease Treatment.

Non-alcoholic fatty liver disease (NAFLD) is often associated with obesity and type 2 diabetes. To disentangle etiological relationships between these conditions and identify genetically-determined metabolites involved in NAFLD processes, we mapped 1H nuclear magnetic resonance (NMR) metabolomic and disease-related phenotypes in a mouse F2 cross derived from strains showing resistance (BALB/c) and increased susceptibility (129S6) to these diseases. Quantitative trait locus (QTL) analysis based on single nucleotide polymorphism (SNP) genotypes identified diet responsive QTLs in F2 mice fed control or high fat diet (HFD). In HFD fed F2 mice we mapped on chromosome 18 a QTL regulating liver micro- and macrovesicular steatosis and inflammation, independently from glucose intolerance and adiposity, which was linked to chromosome 4. Linkage analysis of liver metabolomic profiling data identified a QTL for octopamine, which co-localised with the QTL for liver histopathology in the cross. Functional relationship between these two QTLs was validated in vivo in mice chronically treated with octopamine, which exhibited reduction in liver histopathology and metabolic benefits, underlining its role as a mechanistic biomarker of fatty liver with potential therapeutic applications

Angel investor's selection criteria: a comparative institutional perspective

Despite the important role of angel investors as critical financial providers for new ventures, little is known regarding how institutions make their investment decisions. While angels make decisions based on selection criteria during the first stage, they are also embedded within and affected by different institutional settings and as a result weight these criteria differently than other investors. We compare angel investors' selection criteria in China and Denmark using the comparative institutional perspective. We use a policy capturing approach and hierarchy linear modeling, revealing that since Chinese angels are embedded within relationship-based institutional settings they tend to reply more on strong ties such as family and friends in management team, as well as weighting risks less compared to Danish angels operating within more rule-based institutional contexts

Resistance to diet-induced obesity and associated metabolic perturbations in haploinsufficient monocarboxylate transporter 1 mice

The monocarboxylate transporter 1 (MCT1 or SLC16A1) is a carrier of short-chain fatty acids, ketone bodies, and lactate in several tissues. Genetically modified C57BL/6J mice were produced by targeted disruption of the mct1 gene in order to understand the role of this transporter in energy homeostasis. Null mutation was embryonically lethal, but MCT1 (+/-) mice developed normally. However, when fed high fat diet (HFD), MCT1 (+/-) mice displayed resistance to development of diet-induced obesity (24.8% lower body weight after 16 weeks of HFD), as well as less insulin resistance and no hepatic steatosis as compared to littermate MCT1 (+/+) mice used as controls. Body composition analysis revealed that reduced weight gain in MCT1 (+/-) mice was due to decreased fat accumulation (50.0% less after 9 months of HFD) notably in liver and white adipose tissue. This phenotype was associated with reduced food intake under HFD (12.3% less over 10 weeks) and decreased intestinal energy absorption (9.6% higher stool energy content). Indirect calorimetry measurements showed ∼ 15% increase in O2 consumption and CO2 production during the resting phase, without any changes in physical activity. Determination of plasma concentrations for various metabolites and hormones did not reveal significant changes in lactate and ketone bodies levels between the two genotypes, but both insulin and leptin levels, which were elevated in MCT1 (+/+) mice when fed HFD, were reduced in MCT1 (+/-) mice under HFD. Interestingly, the enhancement in expression of several genes involved in lipid metabolism in the liver of MCT1 (+/+) mice under high fat diet was prevented in the liver of MCT1 (+/-) mice under the same diet, thus likely contributing to the observed phenotype. These findings uncover the critical role of MCT1 in the regulation of energy balance when animals are exposed to an obesogenic diet