👤 Dennis Kwiatkowski

While the plasma phylloquinone (PK) concentration is inversely correlated with cardiovascular risk, the involvement of PK in regulating endothelial function has not been directly investigated. Therefore, in this study we assessed the effects of short-term treatment with PK-deficient diets (5-10 weeks) on endothelial function in normolipidemic 14-week-old male C57BL/6JCmd mice and age-matched dyslipidaemic male E3L.CETP mice. Our results show that in normolipidemic mice dietary PK deficiency was associated with a marked reduction of PK levels in the plasma and liver (liquid chromatography-mass spectrometry measurements) and with impaired endothelium-dependent vasodilation assessed in vivo by magnetic resonance imaging (MRI). Dietary PK deficiency-induced endothelial dysfunction was fully reversed by PK supplementation. In dyslipidaemic E3L.CETP mice, dietary PK deficiency exacerbated preexisting endothelial dysfunction. Furthermore, dietary PK deficiency decreased menaquinone-4 (MK-4) levels in the aorta but did not affect blood coagulation (calibrated automated thrombography), microbiota composition (culturing and next-generation sequencing), and gut menaquinone production. In conclusion, our study demonstrated for the first time that sufficient dietary PK intake supports endothelial function in normolipidemic and dyslipidaemic mice indicating nutritional significance of dietary PK in the maintenance of endothelial function in humans. Show less

The melanocortin-4 receptor (MC4R), a hypothalamic master regulator of energy homeostasis and appetite, is a class A G-protein-coupled receptor and a prime target for the pharmacological treatment of obesity. Here, we present cryo-electron microscopy structures of MC4R-Gs-protein complexes with two drugs recently approved by the FDA, the peptide agonists NDP-α-MSH and setmelanotide, with 2.9 Å and 2.6 Å resolution. Together with signaling data from structure-derived MC4R mutants, the complex structures reveal the agonist-induced origin of transmembrane helix (TM) 6-regulated receptor activation. The ligand-binding modes of NDP-α-MSH, a high-affinity linear variant of the endogenous agonist α-MSH, and setmelanotide, a cyclic anti-obesity drug with biased signaling toward Gq/11, underline the key role of TM3 in ligand-specific interactions and of calcium ion as a ligand-adaptable cofactor. The agonist-specific TM3 interplay subsequently impacts receptor-Gs-protein interfaces at intracellular loop 2, which also regulates the G-protein coupling profile of this promiscuous receptor. Finally, our structures reveal mechanistic details of MC4R activation/inhibition, and provide important insights into the regulation of the receptor signaling profile which will facilitate the development of tailored anti-obesity drugs. Show less

The melanocortin-4 receptor (MC4R) can be endogenously activated by binding of melanocyte-stimulating hormones (MSH), which mediates anorexigenic effects. In contrast, the agouti-related peptide (AgRP) acts as an endogenous inverse agonist and suppresses ligand-independent basal signaling activity (orexigenic effects). Binding of ligands to MC4R leads to the activation of different G-protein subtypes or arrestin and concomitant signaling pathways. This receptor is a key protein in the hypothalamic regulation of food intake and energy expenditure and naturally-occurring inactivating Show less

Genome-wide genetic association analysis represents an opportunity for a comprehensive survey of the genes governing lipid metabolism, potentially revealing new insights or even therapeutic strategies for cardiovascular disease and related metabolic disorders. We have performed large-scale, genome-wide genetic analysis among 6382 white women with replication in 2 cohorts of 970 additional white men and women for associations between common single-nucleotide polymorphisms and low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, apolipoprotein(Apo) A1, and ApoB. Genome-wide associations (P < 5 x 10(-8)) were found at the PCSK9 gene, the APOB gene, theLPL gene, the APOA1-APOA5 locus, the LIPC gene, the CETP gene, the LDLR gene, and the APOE locus. In addition,genome-wide associations with triglycerides at the GCKR gene confirm and extend emerging links between glucose and lipid metabolism. Still other genome-wide associations at the 1p13.3 locus are consistent with emerging biological properties for a region of the genome, possibly related to the SORT1 gene. Below genome-wide significance, our study provides confirmatory evidence for associations at 5 novel loci with low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or triglycerides reported recently in separate genome-wide association studies. The total proportion of variance explained by common variation at the genome-wide candidate loci ranges from 4.3% for triglycerides to 12.6% for ApoB. Genome-wide associations at the GCKR gene and near the SORT1 gene, as well as confirmatory associations at 5 additional novel loci, suggest emerging biological pathways for lipid metabolism among white women. Show less