Lilium is a large genus that includes approximately 110 species distributed throughout cold and temperate regions of the Northern Hemisphere. The species-level phylogeny of Lilium remains unclear; previous studies have found universal markers but insufficient phylogenetic signals. In this study, we present the use of complete chloroplast genomes to explore the phylogeny of this genus. We sequenced nine Lilium chloroplast genomes and retrieved seven published chloroplast genomes for comparative and phylogenetic analyses. The genomes ranged from 151,655 bp to 153,235 bp in length and had a typical quadripartite structure with a conserved genome arrangement and moderate divergence. A comparison of sixteen Lilium chloroplast genomes revealed ten mutation hotspots. Single nucleotide polymorphisms (SNPs) for any two Lilium chloroplast genomes ranged from 8 to 1,178 and provided robust data for phylogeny. Except for some of the shortest internodes, phylogenetic relationships of the Lilium species inferred from the chloroplast genome obtained high support, indicating that chloroplast genome data will be useful to help resolve the deeper branches of phylogeny.
Among the 22 fibroblast growth factors (FGFs), FGF21 has now emerged as a key metabolic regulator. However, the mechanism whereby FGF21 mediates its metabolic actions per se remains largely unknown. Here, we show that FGF21 represses mammalian target of rapamycin complex 1 (mTORC1) and improves insulin sensitivity and glycogen storage in a hepatocyte-autonomous manner. Administration of FGF21 in mice inhibits mTORC1 in the liver, whereas FGF21-deficient mice display pronounced insulin-stimulated mTORC1 activation and exacerbated hepatic insulin resistance (IR). FGF21 inhibits insulin- or nutrient-stimulated activation of mTORC1 to enhance phosphorylation of Akt in HepG2 cells at both normal and IR condition. TSC1 deficiency abrogates FGF21-mediated inhibition of mTORC1 and augmentation of insulin signaling and glycogen synthesis. Strikingly, hepatic βKlotho knockdown or hepatic hyperactivation of mTORC1/ribosomal protein S6 kinase 1 abrogates hepatic insulin-sensitizing and glycemic-control effects of FGF21 in diet-induced insulin-resistant mice. Moreover, FGF21 improves methionine- and choline-deficient diet-induced steatohepatitis. Conclusions: FGF21 acts as an inhibitor of mTORC1 to control hepatic insulin action and maintain glucose homeostasis, and mTORC1 inhibition by FGF21 has the therapeutic potential for treating IR and type 2 diabetes.
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