Publications by authors named "Emanuel Gasser"

Reducing body weight to improve metabolic health and related comorbidities is a primary goal in treating obesity. However, maintaining weight loss is a considerable challenge, especially as the body seems to retain an obesogenic memory that defends against body weight changes. Overcoming this barrier for long-term treatment success is difficult because the molecular mechanisms underpinning this phenomenon remain largely unknown.

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While fibroblast growth factor (FGF) 1 is expressed in multiple tissues, only adipose-derived and brain FGF1 have been implicated in the regulation of metabolism. Adipose FGF1 production is upregulated in response to dietary stress and is essential for adipose tissue plasticity in these conditions. Similarly, in the brain, FGF1 secretion into the ventricular space and the adjacent parenchyma is increased after a hypercaloric challenge induced by either feeding or glucose infusion.

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Article Synopsis
  • Increases in insulin resistance and glucose production are key characteristics of type 2 diabetes, and previous research showed that fibroblast growth factor 1 (FGF1) delivery can have strong anti-diabetic effects.
  • The study reveals that FGF1 lowers hepatic glucose production by inhibiting fat breakdown in adipose tissue through a specific molecular mechanism involving phosphodiesterase 4D (PDE4D).
  • This research also identifies a new phosphorylation site in PDE4D that is affected by feeding and fasting, establishing the FGF1/PDE4 pathway as an important regulator in maintaining fatty acid balance in the body.
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Islets derived from stem cells hold promise as a therapy for insulin-dependent diabetes, but there remain challenges towards achieving this goal. Here we generate human islet-like organoids (HILOs) from induced pluripotent stem cells and show that non-canonical WNT4 signalling drives the metabolic maturation necessary for robust ex vivo glucose-stimulated insulin secretion. These functionally mature HILOs contain endocrine-like cell types that, upon transplantation, rapidly re-establish glucose homeostasis in diabetic NOD/SCID mice.

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Increased levels of intestinal bile acids (BAs) are a risk factor for colorectal cancer (CRC). Here, we show that the convergence of dietary factors (high-fat diet) and dysregulated WNT signaling (APC mutation) alters BA profiles to drive malignant transformations in Lgr5-expressing (Lgr5) cancer stem cells and promote an adenoma-to-adenocarcinoma progression. Mechanistically, we show that BAs that antagonize intestinal farnesoid X receptor (FXR) function, including tauro-β-muricholic acid (T-βMCA) and deoxycholic acid (DCA), induce proliferation and DNA damage in Lgr5 cells.

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A hypercaloric diet combined with a sedentary lifestyle is a major risk factor for the development of insulin resistance, type 2 diabetes mellitus (T2DM) and associated comorbidities. Standard treatment for T2DM begins with lifestyle modification, and includes oral medications and insulin therapy to compensate for progressive β-cell failure. However, current pharmaceutical options for T2DM are limited in that they do not maintain stable, durable glucose control without the need for treatment intensification.

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MicroRNAs (miRNAs) are negative modulators of gene expression that fine-tune numerous biological processes. miRNA loss-of-function rarely results in highly penetrant phenotypes, but rather, influences cellular responses to physiologic and pathophysiologic stresses. Here, we have reported that a single member of the evolutionarily conserved miR-7 family, miR-7a2, is essential for normal pituitary development and hypothalamic-pituitary-gonadal (HPG) function in adulthood.

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Inactivation of transcription factor Foxa1 in mice results in neonatal mortality of unknown cause. Here, we report that ablation of Foxa1 causes impaired development and loss of the subthalamic nucleus (STN). Functional deficits in the STN have been implicated in the etiology of Huntington's and Parkinson's disease.

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Circulating levels of insulin and glucagon reflect the nutritional state of animals and elicit regulatory responses in the liver that maintain glucose and lipid homeostasis. The transcription factor Foxa2 activates lipid metabolism and ketogenesis during fasting and is inhibited via insulin-PI3K-Akt signaling-mediated phosphorylation at Thr156 and nuclear exclusion. Here we show that, in addition, Foxa2 is acetylated at the conserved residue Lys259 following inhibition of histone deacetylases (HDACs) class I-III and the cofactors p300 and SirT1 are involved in Foxa2 acetylation and deacetylation, respectively.

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