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The complex relationship between metabolic syndrome and sweeteners.
Gómez-Fernández, AR, Santacruz, A, Jacobo-Velázquez, DA
Journal of food science. 2021;(5):1511-1531
Abstract
Metabolic syndrome is a multifactorial disorder originating from central obesity through a high caloric intake and a sedentary lifestyle. Metabolic syndrome increases the risk of type 2 diabetes (T2D) disease, converting it to one of the costliest chronic diseases, which reduces life quality. A strategy proposed by the food industry to reduce this problem is the generation of low-caloric products using sweeteners, which are compounds that can substitute sucrose, given their sweet taste. For many years, it was assumed that sweeteners did not have a relevant interaction in metabolism. However, recent studies have demonstrated that sweeteners interact either with metabolism or with gut microbiota, in which sweet-taste receptors play an essential role. This review presents an overview of the industrial application of most commonly consumed sweeteners. In addition, the interaction of sweeteners within the body, including their absorption, distribution, metabolism, gut microbiota metabolism, and excretion is also reviewed. Furthermore, the complex relationship between metabolic syndrome and sweeteners is also discussed, presenting results from in vivo and clinical trials. Findings from this review indicate that, in order to formulate sugar-free or noncaloric food products for the metabolic syndrome market, several factors need to be considered, including the dose, proportions, human metabolism, and interaction of sweeteners with gut microbiota and sweet-taste receptors. More clinical studies, including the metabolic syndrome, are needed to better understand the interaction of sweeteners with the human body, as well as their possible effect on the generation of dysbiosis.
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DNA sequencing and copy number variation analysis of MCHR2 in a cohort of Prader Willi like (PWL) patients.
Geets, E, Aerts, E, Verrijken, A, Van Hoorenbeeck, K, Verhulst, S, Van Gaal, L, Van Hul, W
Obesity research & clinical practice. 2018;(2):158-166
Abstract
BACKGROUND Prader Willi Syndrome (PWS) is a syndromic form of obesity caused by a chromosomal aberration on chromosome 15q11.2-q13. Patients with a comparable phenotype to PWS not carrying the 15q11.2-q13 defect are classified as Prader Willi like (PWL). In literature, PWL patients do frequently harbor deletions at 6q16, which led to the identification of the single-minded 1 (SIM1) gene as a possible cause for the presence of obesity in these patients. However, our previous work in a PWL cohort showed a rather limited involvement of SIM1 in the obesity phenotype. In this paper, we investigated the causal role of the melanin-concentrating hormone receptor 2 (MCHR2) gene in PWL patients, as most of the reported 6q16 deletions also encompass this gene and it is suggested to be active in the control of feeding behavior and energy metabolism. METHODS Copy number variation analysis of the MCHR2 genomic region followed by mutation analysis of MCHR2 was performed in a PWL cohort. RESULTS Genome-wide microarray analysis of 109 patients with PWL did not show any gene harboring deletions on chromosome 6q16. Mutation analysis in 92 patients with PWL demonstrated three MCHR2 variants: p.T47A (c.139A>G), p.A76A (c.228T>C) and c.*16A>G. We identified a significantly higher prevalence of the c.228T>C C allele in our PWL cohort compared to previously published results and controls of the ExAC Database. CONCLUSION Overall, our results are in line with some previously performed studies suggesting that MCHR2 is not a major contributor to human obesity and the PWL phenotype.
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Decoding the vasoregulatory activities of bile acid-activated receptors in systemic and portal circulation: role of gaseous mediators.
Fiorucci, S, Zampella, A, Cirino, G, Bucci, M, Distrutti, E
American journal of physiology. Heart and circulatory physiology. 2017;(1):H21-H32
Abstract
Bile acids are end products of cholesterol metabolism generated in the liver and released in the intestine. Primary and secondary bile acids are the result of the symbiotic relation between the host and intestinal microbiota. In addition to their role in nutrient absorption, bile acids are increasingly recognized as regulatory signals that exert their function beyond the intestine by activating a network of membrane and nuclear receptors. The best characterized of these bile acid-activated receptors, GPBAR1 (also known as TGR5) and the farnesosid-X-receptor (FXR), have also been detected in the vascular system and their activation mediates the vasodilatory effects of bile acids in the systemic and splanchnic circulation. GPBAR1, is a G protein-coupled receptor, that is preferentially activated by lithocholic acid (LCA) a secondary bile acid. GPBAR1 is expressed in endothelial cells and liver sinusoidal cells (LSECs) and responds to LCA by regulating the expression of both endothelial nitric oxide synthase (eNOS) and cystathionine-γ-lyase (CSE), an enzyme involved in generation of hydrogen sulfide (H2S). Activation of CSE by GPBAR1 ligands in LSECs is due to genomic and nongenomic effects, involves protein phosphorylation, and leads to release of H2S. Despite that species-specific effects have been described, vasodilation caused by GPBAR1 ligands in the liver microcirculation and aortic rings is abrogated by inhibition of CSE but not by eNOS inhibitor. Vasodilation caused by GPBAR1 (and FXR) ligands also involves large conductance calcium-activated potassium channels likely acting downstream to H2S. The identification of GPBAR1 as a vasodilatory receptor is of relevance in the treatment of complex disorders including metabolic syndrome-associated diseases, liver steatohepatitis, and portal hypertension.
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Genetic coding variants in the niacin receptor, hydroxyl-carboxylic acid receptor 2, and response to niacin therapy.
Tuteja, S, Wang, L, Dunbar, RL, Chen, J, DerOhannessian, S, Marcovina, SM, Elam, M, Lader, E, Rader, DJ
Pharmacogenetics and genomics. 2017;(8):285-293
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Abstract
OBJECTIVE Niacin has been used for seven decades to modulate plasma lipids, but its mechanism of action is still unclear. We sought to determine whether variants in the niacin receptor gene, hydroxyl-carboxylic receptor 2 (HCAR2), are associated with lipid response to treatment. PARTICIPANTS AND METHODS Coding variants, rs7314976 (p.R311C) and rs2454727 (p.M317I), were genotyped in 2067 participants from the Atherothrombosis Intervention in Metabolic Syndrome with Low HDL/High Triglycerides and Impact on Global Health Outcomes (AIM-HIGH) trial. AIM-HIGH was a randomized, placebo-controlled trial that was conducted to assess the effect of extended-release niacin in patients with cardiovascular disease aggressively treated with low-density lipoprotein cholesterol-lowering therapy. RESULTS There was no association of p.R311C or p.M317I with changes in low-density lipoprotein cholesterol, triglycerides, or high-density lipoprotein cholesterol at 1 year in groups receiving placebo or extended-release niacin. In White patients, the reduction in lipoprotein (a) [Lp(a)] in response to niacin was greater in homozygous carriers of the major 317M allele (-22.7%; P=0.005) compared with minor allele carriers (-15.3%). This was directionally consistent in the Black participants. Upon combining both groups, the reduction in Lp(a) in response to niacin was significantly greater in the homozygous major allele carriers (-23.0%; P=0.003) compared with minor allele carriers (-15.2%). CONCLUSION Understanding the genetic contribution toward variation in response to niacin therapy, including Lp(a) reduction, could uncover mechanisms by which niacin decreases Lp(a), an important independent risk factor for cardiovascular disease.
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Taste receptors of the gut: emerging roles in health and disease.
Depoortere, I
Gut. 2014;(1):179-90
Abstract
Recent progress in unravelling the nutrient-sensing mechanisms in the taste buds of the tongue has triggered studies on the existence and role of chemosensory cells in the gut. Indeed, the gastrointestinal tract is the key interface between food and the human body and can sense basic tastes in much the same way as the tongue, through the use of similar G-protein-coupled taste receptors. These receptors 'taste' the luminal content and transmit signals that regulate nutrient transporter expression and nutrient uptake, and also the release of gut hormones and neurotransmitters involved in the regulation of energy and glucose homeostasis. Hence, they play a prominent role in the communication between the lumen, epithelium, smooth muscle cells, afferent nerve fibres and the brain to trigger adaptive responses that affect gastrointestinal function, food intake and glucose metabolism. This review summarises how sensing of nutrients by taste receptors along the gut plays a key role in the process of digestion, and how disturbances or adaptations of these chemosensory signalling pathways may contribute to the induction or resolution of a number of pathological conditions related to diabetes, obesity, or diet-induced symptom generation in irritable bowel syndrome. Targeting these receptors may represent a promising novel route for the treatment of a number of these diseases.
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Acyl hydroxypyrazoles as novel agonists for high-affinity nicotinic acid receptor GPR109A: WO2008051403.
Shen, HC
Expert opinion on therapeutic patents. 2009;(8):1149-55
Abstract
BACKGROUND Acyl hydroxypyrazoles were discovered and claimed by Merck as novel agonists for the high-affinity nicotinic acid receptor, G-protein coupled receptor 109A (GPR109A). The fused bicyclic core contains a hydroxypyrazole that mimics the anthranilide moiety described in their earlier patents and patent publications. OBJECTIVE This article evaluates new GPR109A receptor agonists disclosed by Merck in the recent patent WO2008051403. CONCLUSION The aim of this invention was to provide potential therapy to reduce free fatty acids (FFA), low-density lipoprotein cholesterol (LDL-C), total cholesterol, and serum triglycerides (TG), and to raise high-density lipoprotein cholesterol (HDL-C). Thus, these agonists could - potentially - be used to treat dyslipidemia, atherosclerosis, and metabolic syndromes such as diabetes.
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Inherited diseases involving g proteins and g protein-coupled receptors.
Spiegel, AM, Weinstein, LS
Annual review of medicine. 2004;:27-39
Abstract
Heterotrimeric G proteins couple seven-transmembrane receptors for diverse extracellular signals to effectors that generate intracellular signals altering cell function. Mutations in the gene encoding the alpha subunit of the G protein-coupling receptors to stimulation of adenylyl cyclase cause developmental abnormalities of bone, as well as hormone resistance (pseudohypoparathyroidism caused by loss-of-function mutations) and hormone hypersecretion (McCune-Albright syndrome caused by gain-of-function mutations). Loss- and gain-of-function mutations in genes encoding G protein-coupled receptors (GPCRs) have been identified as the cause of an increasing number of retinal, endocrine, metabolic, and developmental disorders. GPCRs comprise an evolutionarily conserved gene superfamily ( 1 ). By coupling to heterotrimeric G proteins, GPCRs transduce a wide variety of extracellular signals including monoamine, amino acid, and nucleoside neurotransmitters, as well as photons, chemical odorants, divalent cations, hormones, lipids, peptides and proteins. Following a brief overview of G protein-coupled signal transduction, we review the growing body of evidence that mutations in genes encoding GPCRs and G proteins are an important cause of human disease.