A liver stress-endocrine nexus promotes metabolic integrity during dietary protein dilution
Adriano Maida, … , Stephan Herzig, Adam J. Rose
Adriano Maida, … , Stephan Herzig, Adam J. Rose
Published August 22, 2016
Citation Information: J Clin Invest. 2016;126(9):e85946. https://doi.org/10.1172/JCI85946.
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Research Article Metabolism

A liver stress-endocrine nexus promotes metabolic integrity during dietary protein dilution

Abstract

Dietary protein intake is linked to an increased incidence of type 2 diabetes (T2D). Although dietary protein dilution (DPD) can slow the progression of some aging-related disorders, whether this strategy affects the development and risk for obesity-associated metabolic disease such as T2D is unclear. Here, we determined that DPD in mice and humans increases serum markers of metabolic health. In lean mice, DPD promoted metabolic inefficiency by increasing carbohydrate and fat oxidation. In nutritional and polygenic murine models of obesity, DPD prevented and curtailed the development of impaired glucose homeostasis independently of obesity and food intake. DPD-mediated metabolic inefficiency and improvement of glucose homeostasis were independent of uncoupling protein 1 (UCP1), but required expression of liver-derived fibroblast growth factor 21 (FGF21) in both lean and obese mice. FGF21 expression and secretion as well as the associated metabolic remodeling induced by DPD also required induction of liver-integrated stress response–driven nuclear protein 1 (NUPR1). Insufficiency of select nonessential amino acids (NEAAs) was necessary and adequate for NUPR1 and subsequent FGF21 induction and secretion in hepatocytes in vitro and in vivo. Taken together, these data indicate that DPD promotes improved glucose homeostasis through an NEAA insufficiency–induced liver NUPR1/FGF21 axis.

Authors

Adriano Maida, Annika Zota, Kim A. Sjøberg, Jonas Schumacher, Tjeerd P. Sijmonsma, Anja Pfenninger, Marie M. Christensen, Thomas Gantert, Jessica Fuhrmeister, Ulrike Rothermel, Dieter Schmoll, Mathias Heikenwälder, Juan L. Iovanna, Kerstin Stemmer, Bente Kiens, Stephan Herzig, Adam J. Rose

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Figure 7

Nonessential amino acid dilution triggers the liver integrated stress response and FGF21 production.

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Nonessential amino acid dilution triggers the liver integrated stress re...
(A) Hepatic portal vein blood serum amino acid (AA) profile in mice adapted to and then fasted and refed control (CD) or protein-diluted (PD) diet. n = 4 or 5/group. (B) In situ hybridization of PD-refed mouse livers serially cut and stained with probes for either Fgf21 or the central vein (cv) marker glutamine synthetase (GluI). Fgf21 transcripts surround vessels negative for GluI, suggesting portal space (ps) localization. Representative images are from liver sections taken from 2 different mice. Magnification: ×100. (C) Fasting insulin sensitivity index [ISI(f)] in C57Bl/6N mice fed diets with protein replaced by a casein-based AA mixture (18 kcal% or 4.5 kcal%) for ~3.5 months. n = 6 or 7/group. (D) ISI(f) in NZO mice fed diets with protein replaced by a casein-based AA mixture (18 kcal% or 4.5 kcal%) for ~10 weeks. n = 5 or 6/group. (E) Liver Fgf21 mRNA levels from mice treated as in C. (F) Liver Fgf21 mRNA levels from mice treated as in D. (G) Effect of media total AA restriction on Fgf21 mRNA in cultured primary mouse hepatocytes (hepa). n = 4/group. (H) Media FGF21 levels from hepatocytes treated as in G. (I) Effect of media total AA restriction, with or without differential essential (EAA) or nonessential (NEAA) amino acid supplementations on media FGF21 levels in cultured primary mouse hepatocytes. n = 4/group. (J) Nupr1 mRNA levels from hepatocytes treated as in I. (K) Select NEAAs (A, E, D, N, and Q), but not others (C, G, P, R, S, and Y) attenuate media FGF21 induction by AA restriction in cultured primary mouse hepatocytes. The indicated AAs were added to match their concentration in the 1× AA group. n = 4/group. (L) Serum FGF21 levels following overnight fasting and refeeding in mice adapted for 2 weeks to CD or PD combined with intraperitoneal administration of vehicle (0.9% NaCl), select EAA (i.e., Phe, Leu, Met [FLM]), or NEAA (i.e., Ala, Asn, Gln [ANQ]) (8 mg each, 24 mg; ~1 mg/g body mass). n = 4/group. (M) Liver phospho-Ser51-eukaryotic elongation factor 2α (p-S51-eIF2α) levels from mice treated as in L. Representative images shown are from the same samples blotted on different membranes on separate occasions. (N) Liver Nupr1 mRNA levels from mice treated as in L. Data are presented as the mean ± SEM. *P < 0.05 for differences between diets/AA level. #P < 0.05 for effect of AA administration. Statistical tests used were unpaired t test (A and C–F), 2-way ANOVA with Holm-Sidak post-hoc test (I, J, and L–N), or 1-way ANOVA with Holm-Sidak post-hoc test (G, H, K). See also Supplemental Figure 7.