Amino Acid Transporter Slc38a5 Controls Glucagon Receptor Inhibition-Induced Pancreatic α Cell Hyperplasia in Mice

• Published in: Cell metabolism Vol. 25; no. 6; pp. 1348 - 1361.e8
• Main Authors: Kim, Jinrang, Okamoto, Haruka, Huang, ZhiJiang, Anguiano, Guillermo, Chen, Shiuhwei, Liu, Qing, Cavino, Katie, Xin, Yurong, Na, Erqian, Hamid, Rachid, Lee, Joseph, Zambrowicz, Brian, Unger, Roger, Murphy, Andrew J., Xu, Yan, Yancopoulos, George D., Li, Wen-hong, Gromada, Jesper
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 06-06-2017
• Subjects: Amino Acid Transport Systems, Neutral - genetics; Amino Acid Transport Systems, Neutral - metabolism; amino acid transporter; Animals; glucagon; Glucagon - genetics; Glucagon - metabolism; glucagon receptor; glucagon receptor knockout; Glucagon-Secreting Cells - metabolism; Glucagon-Secreting Cells - pathology; hyperaminoacidemia; Hyperplasia; Male; Mice; Mice, Inbred ICR; Mice, Knockout; mTORC1; pancreatic alpha cell; proliferation; Receptors, Glucagon - genetics; Receptors, Glucagon - metabolism; Signal Transduction; Slc38a5; pancreatic alpha cell; hyperaminoacidemia; proliferation; glucagon receptor; Slc38a5; glucagon receptor knockout; glucagon; mTORC1; amino acid transporter
• ISSN: 1550-4131; 1932-7420
• DOI: 10.1016/j.cmet.2017.05.006

Glucagon supports glucose homeostasis by stimulating hepatic gluconeogenesis, in part by promoting the uptake and conversion of amino acids into gluconeogenic precursors. Genetic disruption or pharmacologic inhibition of glucagon signaling results in elevated plasma amino acids and compensatory glucagon hypersecretion involving expansion of pancreatic α cell mass. Recent findings indicate that hyperaminoacidemia triggers pancreatic α cell proliferation via an mTOR-dependent pathway. We confirm and extend these findings by demonstrating that glucagon pathway blockade selectively increases expression of the sodium-coupled neutral amino acid transporter Slc38a5 in a subset of highly proliferative α cells and that Slc38a5 controls the pancreatic response to glucagon pathway blockade; most notably, mice deficient in Slc38a5 exhibit markedly decreased α cell hyperplasia to glucagon pathway blockade-induced hyperaminoacidemia. These results show that Slc38a5 is a key component of the feedback circuit between glucagon receptor signaling in the liver and amino-acid-dependent regulation of pancreatic α cell mass in mice.
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•Glucagon receptor inhibition reduces hepatic uptake and catabolism of amino acids•Elevated circulating amino acids induce Slc38a5 expression in pancreatic α cells•Slc38a5 links plasma amino acids to α cell proliferation•mTOR controls Slc38a5 expression and α cell proliferation
Glucagon receptor inhibition reduces hepatic uptake and catabolism of amino acids. Kim et al. show that Slc38a5 is a key component of the amino acid sensing machinery linking circulating amino acids to control of pancreatic α cell function and mass.