GCN2 regulates pancreatic β cell mass by sensing intracellular amino acid levels
Ayumi Kanno, … , Masato Kasuga, Yoshiaki Kido
Ayumi Kanno, … , Masato Kasuga, Yoshiaki Kido
Published May 7, 2020
Citation Information: JCI Insight. 2020;5(9):e128820. https://doi.org/10.1172/jci.insight.128820.
View: Text | PDF
Research Article Endocrinology Metabolism

GCN2 regulates pancreatic β cell mass by sensing intracellular amino acid levels

Abstract

EIF2AK4, which encodes the amino acid deficiency–sensing protein GCN2, has been implicated as a susceptibility gene for type 2 diabetes in the Japanese population. However, the mechanism by which GCN2 affects glucose homeostasis is unclear. Here, we show that insulin secretion is reduced in individuals harboring the risk allele of EIF2AK4 and that maintenance of GCN2-deficient mice on a high-fat diet results in a loss of pancreatic β cell mass. Our data suggest that GCN2 senses amino acid deficiency in β cells and limits signaling by mechanistic target of rapamycin complex 1 to prevent β cell failure during the consumption of a high-fat diet.

Authors

Ayumi Kanno, Shun-ichiro Asahara, Ayuko Furubayashi, Katsuhisa Masuda, Risa Yoshitomi, Emi Suzuki, Tomoko Takai, Maki Kimura-Koyanagi, Tomokazu Matsuda, Alberto Bartolome, Yushi Hirota, Norihide Yokoi, Yuka Inaba, Hiroshi Inoue, Michihiro Matsumoto, Kenichi Inoue, Takaya Abe, Fan-Yan Wei, Kazuhito Tomizawa, Wataru Ogawa, Susumu Seino, Masato Kasuga, Yoshiaki Kido

×

Figure 4

Activation of mTORC1 signaling is the result of impaired ATF4 and Sestrin2 expression in HFD-fed GCN2–/– mice.

Options: View larger image (or click on image) Download as PowerPoint
Activation of mTORC1 signaling is the result of impaired ATF4 and Sestri...
(A and B) Immunoblot analysis of ATF4 in pancreatic islets of 24-week-old HFD-fed GCN2+/+ and GCN2–/– mice (A) and in INS-1 cells transfected with scramble (control) or GCN2 siRNAs (GCN2 KD) (B). Duplicate samples in B and Figure 3J were run on same blot; the samples in B share the same loading control as in Figure 3J. (C) Immunoblot analysis of mTORC1 and insulin signaling in INS-1 cells transfected with scramble or ATF4 siRNAs. (D and E) Pancreatic islets of mice as in A (D) and INS-1 cells transfected with scramble or GCN2 siRNAs (E) were subjected to immunoblot analysis with antibodies to GADD34, REDD1, and Sestrin2. (F) INS-1 cells transfected with scramble or ATF4 siRNAs were subjected to immunoblot analysis with antibodies to Sestrin2. (G) Immunoblot analysis of mTORC1 and insulin signaling in INS-1 cells transfected with scramble or Sestrin2 (Sesn2) siRNAs. (H) Immunoblot analysis of mTORC1 and insulin signaling in INS-1 cells transfected with scramble or GCN2 siRNAs, infected with an adenovirus (Ad) encoding Sestrin2 or a control virus. In B, C, E, F, G, and H, INS-1 cells were deprived of leucine, lysine, and arginine for 24 hours. In all panels, representative blots and quantitative data (mean ± SEM from at least 4 independent experiments) normalized by the amount of β-actin are shown. *P < 0.05, **P < 0.01 (2-tailed Student’s t test).