Fig 1: Aminotransferases including Agxt are crucial effectors of the suppressor function of Lkb1 in amino acid-driven gluconeogenesis.a, b Pharmacological inhibition of aminotransferase, in vivo, by AOA. Lkb1KOlivad (KO) and WT mice were left untreated (−) or were treated with AOA (10 mg/kg) 2 h before the determination of fasting blood glucose levels (a) or the alanine tolerance test (b). The area under the curve (AUC) of glucose level in the ATT is shown. AOA-treated animals, KO: n = 5, WT: n = 6. Animals not treated with AOA, KO: n = 5, WT: n = 4. Mice were fasted for 22 h before treatment with AOA or were left untreated for the same time period. c Scheme of the dual function of Agxt. d, e Agxt protein and mRNA levels in Lkb1KOlivad (KO) mice. d immunoblot of Agxt in fasted and refed mutant (KO, n = 3) and control (WT, n = 3) mice. Representative blot of two independent experiments. e Agxt gene expression levels, as assessed by RT-qPCR in fasted (KO: n = 10, WT: n = 6) and refed (KO: n = 7, WT: n = 5) mice. f, g Phenotypes of mice lacking both Lkb1 and Agxt in the hepatocytes (DKO), as compared with mice with a single deficiency of Lkb1 in hepatocytes (Lkb1KOlivad, KO) and controls (WT and AgxtKO). e Glycemia in fasting (WT: n = 11, KO: n = 19, DKO: n = 17, AgxtKO: n = 18) and refed (WT: n = 8, KO: n = 6, DKO: n = 10, AgxtKO: n = 12) mice. f Kaplan–Meier survival curves for Lkb1KOlivad mice (n = 18), mice lacking both Lkb1 and Agxt (DKO n = 23) and controls (WT, n = 10). All graphical data are means ± SD. P values were determined by unpaired two-tailed t-test. ns: not significant. *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001; ****p ≤ 0.0001. Source data are provided as a Source data file.
Fig 2: Lkb1 controls the hepatic amino acid-driven gluconeogenesis independently of Ampk and likely via the phosphorylation of RNA binding proteins.a Immunoblot of liver of mutant Ampk mice. Liver of double knockout of Ampkα1 and Ampkα2 catalytic subunits (KO, n = 3) and controls (WT, n = 3) were analyzed by western blot analysis for expression of Ampk, Agxt, Got1, and Gapdh. Representative blot of two independent experiments. b IPA analysis of the significantly deregulated phosphoproteins both in the fasted and refed state. A comprehensive phosphoproteomic analysis of the liver of Lkb1KOlivadmutant and control was performed and the significant differentially expressed phosphoproteins were analyzed for enrichment in GO terms. c Venn diagram comparing the canonical RBP repertoire common to HuH7, HEK293, and Hela cells28 with the significantly DE phosphoproteins of liver of both fasted and refed mutant mice. Enrichment for RBP was done using IPA. d Heatmap of the significantly deregulated phospho-RBP in livers of Lkb1KOlivad and control animals. The phospho-RBP that were shared between the fasted and refed state were highlighted with a red point. Note that most of the phophosites differed and had opposite phosphorylation status between the two nutritional states for most of the phosphoproteins. Heatmap was done using the Genesis software. e Subcellular distribution of Agxt in liver of mutant Lkb1KOlivad and control mice. Subcellular distribution of immunoreactive Agxt was determined by post-embedding protein A gold immuno-electron microscopy. Labeling intensity was obtained by counting the number of gold particles in each organelles. A total of at least 50 fields were analyzed for both the mutant and control liver. Data are represented as means ± SD of two mice per group. P values were determined by unpaired two-tailed t-test. p ≤ 0.0001. f General scheme summarizing how Lkb1 controls liver gluconeogenesis and more specifically the amino acid driven gluconeogenesis. Source data are provided as a Source data file.
Supplier Page from Abcam for Anti-AGXT antibody [EPR13232]