Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Liver alanine catabolism promotes skeletal muscle atrophy and hyperglycaemia in type 2 diabetes

Nature Metabolism volume 3, pages 394–409 (2021)Cite this article

Subjects

Abstract

Both obesity and sarcopenia are frequently associated in ageing, and together may promote the progression of related conditions such as diabetes and frailty. However, little is known about the pathophysiological mechanisms underpinning this association. Here we show that systemic alanine metabolism is linked to glycaemic control. We find that expression of alanine aminotransferases is increased in the liver in mice with obesity and diabetes, as well as in humans with type 2 diabetes. Hepatocyte-selective silencing of both alanine aminotransferase enzymes in mice with obesity and diabetes retards hyperglycaemia and reverses skeletal muscle atrophy through restoration of skeletal muscle protein synthesis. Mechanistically, liver alanine catabolism driven by chronic glucocorticoid and glucagon signalling promotes hyperglycaemia and skeletal muscle wasting. We further provide evidence for amino acid–induced metabolic cross-talk between the liver and skeletal muscle in ex vivo experiments. Taken together, we reveal a metabolic inter-tissue cross-talk that links skeletal muscle atrophy and hyperglycaemia in type 2 diabetes.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Alanine metabolism and liver ALT isoform expression is upregulated in obesity and type 2 diabetes.
Fig. 2: Silencing of both, but not individual, liver ALT isoforms affects systemic alanine and glucose homeostasis after diverse nutritional challenges.
Fig. 3: Silencing of both, but not individual, liver alanine aminotransferase isoforms retards hyperglycaemia in mouse models of obesity-related type 2 diabetes.
Fig. 4: Disrupting the heightened liver alanine catabolism improves skeletal muscle size and function in mouse models of type 2 diabetes.
Fig. 5: A glucocorticoid–liver glucocorticoid receptor axis links heightened liver alanine catabolism with hyperglycaemia and muscle atrophy in type 2 diabetes.
Fig. 6: Chronic liver glucagon action affects hyperglycaemia and skeletal muscle atrophy via hepatic alanine catabolism.
Fig. 7: Disrupting the heightened liver alanine catabolism reverses the reduced skeletal muscle protein synthesis and branched-chain amino acid levels in type 2 diabetes.

Similar content being viewed by others

Data availability

Correspondence and requests for materials including data that support the findings of this study should be made to the corresponding author. Source data are provided with this paper.

References

  1. Zamboni, M., Mazzali, G., Fantin, F., Rossi, A. & Di Francesco, V. Sarcopenic obesity: a new category of obesity in the elderly. Nutr. Metab. Cardiovas. Dis. 18, 388–395 (2008).

    Article  CAS  Google Scholar 

  2. Parr, E. B., Coffey, V. G. & Hawley, J. A. ‘Sarcobesity’: a metabolic conundrum. Maturitas 74, 109–113 (2013).

    Article  PubMed  Google Scholar 

  3. Tian, S. & Xu, Y. Association of sarcopenic obesity with the risk of all-cause mortality: a meta-analysis of prospective cohort studies. Geriatr. Gerontol. Int. 16, 155–166 (2016).

    Article  PubMed  Google Scholar 

  4. Kob, R. et al. Sarcopenic obesity: molecular clues to a better understanding of its pathogenesis? Biogerontology 16, 15–29 (2015).

    Article  CAS  PubMed  Google Scholar 

  5. Srikanthan, P., Hevener, A. L. & Karlamangla, A. S. Sarcopenia exacerbates obesity-associated insulin resistance and dysglycemia: findings from the national health and nutrition examination survey III. PLoS ONE 5, e10805 (2010).

    Article  PubMed  PubMed Central  Google Scholar 

  6. DeFronzo, R. A. Lilly lecture 1987. The triumvirate: beta-cell, muscle, liver. A collusion responsible for NIDDM. Diabetes 37, 667–687 (1988).

    Article  CAS  PubMed  Google Scholar 

  7. Wu, C., Okar, D. A., Kang, J. & Lange, A. J. Reduction of hepatic glucose production as a therapeutic target in the treatment of diabetes. Curr. Drug Targets Immune Endocr. Metabol. Disord. 5, 51–59 (2005).

    Article  CAS  PubMed  Google Scholar 

  8. Wahren, J. & Ekberg, K. Splanchnic regulation of glucose production. Annu. Rev. Nutr. 27, 329–345 (2007).

    Article  CAS  PubMed  Google Scholar 

  9. Felig, P. The glucose–alanine cycle. Metabolism 22, 179–207 (1973).

    Article  CAS  PubMed  Google Scholar 

  10. Christensen, H. N. Interorgan amino acid nutrition. Physiol. Rev. 62, 1193–1233 (1982).

    Article  CAS  PubMed  Google Scholar 

  11. Felig, P., Pozefsky, T., Marliss, E. & Cahill, G. F. Jr. Alanine: key role in gluconeogenesis. Science 167, 1003–1004 (1970).

    Article  CAS  PubMed  Google Scholar 

  12. Snell, K. & Duff, D. A. The hepato–muscular metabolic axis and gluconeogenesis. Prog. Clin. Biol. Res. 102, 279–291 (1982).

    CAS  PubMed  Google Scholar 

  13. Wahren, J., Felig, P., Cerasi, E. & Luft, R. Splanchnic and peripheral glucose and amino acid metabolism in diabetes mellitus. J. Clin. Invest. 51, 1870–1878 (1972).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  14. Felig, P., Wahren, J., Hendler, R. & Brundin, T. Splanchnic glucose and amino acid metabolism in obesity. J. Clin. Invest. 53, 582–590 (1974).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  15. Fuhrmeister, J. et al. Fasting-induced liver GADD45β restrains hepatic fatty acid uptake and improves metabolic health. EMBO Mol. Med. 8, 654–669 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  16. Rose, A. J. et al. Molecular control of systemic bile acid homeostasis by the liver glucocorticoid receptor. Cell Metab. 14, 123–130 (2011).

    Article  CAS  PubMed  Google Scholar 

  17. McCommis, K. S. et al. Loss of mitochondrial pyruvate carrier 2 in the liver leads to defects in gluconeogenesis and compensation via pyruvate–alanine cycling. Cell Metab. 22, 682–694 (2015).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  18. Celis, K. et al. Loss-of-function mutation in glutamic pyruvate transaminase 2 (GPT2) causes developmental encephalopathy. J. Inherit. Metab. Dis. 38, 941–948 (2015).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  19. Rose, A. J., Vegiopoulos, A. & Herzig, S. Role of glucocorticoids and the glucocorticoid receptor in metabolism: insights from genetic manipulations. J. Steroid Biochem. Mol. Biol. 122, 10–20 (2010).

    Article  CAS  PubMed  Google Scholar 

  20. Maida, A. et al. A liver stress-endocrine nexus promotes metabolic integrity during dietary protein dilution. J. Clin. Invest. 126, 3263–3278 (2016).

    Article  PubMed  PubMed Central  Google Scholar 

  21. Sivabalan, S., Renuka, S. & Menon, V. P. Fat feeding potentiates the diabetogenic effect of dexamethasone in Wistar rats. Int. Arch. Med. 1, 7 (2008).

    Article  PubMed  PubMed Central  Google Scholar 

  22. Shpilberg, Y. et al. A rodent model of rapid-onset diabetes induced by glucocorticoids and high-fat feeding. Dis. Model Mech. 5, 671–680 (2012).

    CAS  PubMed  Google Scholar 

  23. Harvey, I. et al. Glucocorticoid-induced metabolic disturbances are exacerbated in obese male mice. Endocrinology 159, 2275–2287 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  24. Grontved, L. et al. C/EBP maintains chromatin accessibility in liver and facilitates glucocorticoid receptor recruitment to steroid response elements. EMBO J. 32, 1568–1583 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Watson, M. L. et al. A cell-autonomous role for the glucocorticoid receptor in skeletal muscle atrophy induced by systemic glucocorticoid exposure. Am. J. Physiol. Endocrinol. Metab. 302, E1210–E1220 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  26. Hu, Z., Wang, H., Lee, I. H., Du, J. & Mitch, W. E. Endogenous glucocorticoids and impaired insulin signaling are both required to stimulate muscle wasting under pathophysiological conditions in mice. J. Clin. Invest. 119, 3059–3069 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  27. Wise, J. K., Hendler, R. & Felig, P. Influence of glucocorticoids on glucagon secretion and plasma amino acid concentrations in man. J. Clin. Invest. 52, 2774–2782 (1973).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  28. Solloway, M. J. et al. Glucagon couples hepatic amino acid catabolism to mTOR-dependent regulation of alpha-cell mass. Cell Rep. 12, 495–510 (2015).

    Article  CAS  PubMed  Google Scholar 

  29. Kim, J. et al. Amino acid transporter Slc38a5 controls glucagon receptor inhibition-induced pancreatic alpha-cell hyperplasia in mice. Cell Metab. 25, 1348–1361 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  30. Kim, T. et al. Glucagon receptor signaling regulates energy metabolism via hepatic farnesoid X receptor and fibroblast growth factor 21. Diabetes 67, 1773–1782 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  31. Miller, R. A. & Birnbaum, M. J. Glucagon: acute actions on hepatic metabolism. Diabetologia 59, 1376–1381 (2016).

    Article  CAS  PubMed  Google Scholar 

  32. Wahren, J. & Felig, P. Influence of protein ingestion on the amino acid metabolism in diabetes mellitus. Journ. Annu. Diabetol. Hotel Dieu, 7–20 (1976).

  33. Lee, Y. H., Wang, M. Y., Yu, X. X. & Unger, R. H. Glucagon is the key factor in the development of diabetes. Diabetologia 59, 1372–1375 (2016).

    Article  CAS  PubMed  Google Scholar 

  34. Habegger, K. M. et al. Fibroblast growth factor 21 mediates specific glucagon actions. Diabetes 62, 1453–1463 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  35. Muller, T. D., Finan, B., Clemmensen, C., DiMarchi, R. D. & Tschop, M. H. The new biology and pharmacology of glucagon. Physiol. Rev. 97, 721–766 (2017).

    Article  CAS  PubMed  Google Scholar 

  36. Wewer Albrechtsen, N. J. et al. The liver–alpha-cell axis and type 2 diabetes. Endocr. Rev. 40, 1353–1366 (2019).

    Article  PubMed  Google Scholar 

  37. James, H. A., O’Neill, B. T. & Nair, K. S. Insulin regulation of proteostasis and clinical implications. Cell Metab. 26, 310–323 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  38. Hirata, Y. et al. Hyperglycemia induces skeletal muscle atrophy via a WWP1–KLF15 axis. JCI Insight 4, e124952 (2019).

  39. Ostler, J. E. et al. Effects of insulin resistance on skeletal muscle growth and exercise capacity in type 2 diabetic mouse models. Am. J. Physiol. Endocrinol. Metab. 306, E592–E605 (2014).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  40. Snell, K. & Duff, D. A. Branched-chain amino acid metabolism and alanine formation in rat muscles in vitro. Mitochondrial–cytosolic interrelationships. Biochem. J. 225, 737–743 (1985).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  41. Hutson, S. M., Sweatt, A. J. & Lanoue, K. F. Branched-chain amino acid metabolism: implications for establishing safe intakes. J. Nutr. 135, 1557S–1564S (2005).

    Article  CAS  PubMed  Google Scholar 

  42. Deng, H. et al. Discovery and optimization of potent, selective and in vivo efficacious 2-aryl benzimidazole BCATm inhibitors. ACS Med. Chem. Lett. 7, 379–384 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  43. Maida, A. et al. Repletion of branched chain amino acids reverses mTORC1 signaling but not improved metabolism during dietary protein dilution. Mol. Metab. 6, 873–881 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  44. Castets, P. et al. mTORC1 and PKB/Akt control the muscle response to denervation by regulating autophagy and HDAC4. Nat. Commun. 10, 3187 (2019).

    Article  PubMed  PubMed Central  Google Scholar 

  45. Jadhao, S. B. et al. Murine alanine aminotransferase: cDNA cloning, functional expression and differential gene regulation in mouse fatty liver. Hepatology 39, 1297–1302 (2004).

    Article  PubMed  Google Scholar 

  46. Qian, K. et al. Hepatic ALT isoenzymes are elevated in gluconeogenic conditions including diabetes and suppressed by insulin at the protein level. Diabetes Metab. Res Rev. 31, 562–571 (2015).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  47. Okun, J. G. et al. Molecular regulation of urea cycle function by the liver glucocorticoid receptor. Mol. Metab. 4, 732–740 (2015).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  48. Lam, T. et al. Testosterone prevents protein loss via the hepatic urea cycle in human. Eur. J. Endocrinol. 176, 489–496 (2017).

    Article  CAS  PubMed  Google Scholar 

  49. Just, P. A. et al. Lkb1 suppresses amino acid-driven gluconeogenesis in the liver. Nat. Commun. 11, 6127 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  50. Halvatsiotis, P., Short, K. R., Bigelow, M. & Nair, K. S. Synthesis rate of muscle proteins, muscle functions, and amino acid kinetics in type 2 diabetes. Diabetes 51, 2395–2404 (2002).

    Article  CAS  PubMed  Google Scholar 

  51. Park, S. W. et al. Excessive loss of skeletal muscle mass in older adults with type 2 diabetes. Diabetes Care 32, 1993–1997 (2009).

    Article  PubMed  PubMed Central  Google Scholar 

  52. Kalyani, R. R., Metter, E. J., Egan, J., Golden, S. H. & Ferrucci, L. Hyperglycemia predicts persistently lower muscle strength with aging. Diabetes Care 38, 82–90 (2015).

    Article  PubMed  Google Scholar 

  53. Bell, J. A. et al. Skeletal muscle protein anabolic response to increased energy and insulin is preserved in poorly controlled type 2 diabetes. J. Nutr. 136, 1249–1255 (2006).

    Article  CAS  PubMed  Google Scholar 

  54. Short, K. R. et al. Effects of type 2 diabetes and insulin on whole-body, splanchnic and leg protein metabolism. J. Clin. Endocrinol. Metab. 97, 4733–4741 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  55. Nilsson, M. I. et al. Abnormal protein turnover and anabolic resistance to exercise in sarcopenic obesity. FASEB J. 27, 3905–3916 (2013).

    Article  CAS  PubMed  Google Scholar 

  56. Drey, M. et al. Cushing’s syndrome: a model for sarcopenic obesity. Endocrine 57, 481–485 (2017).

  57. Halvatsiotis, P. G. et al. Insulin effect on leucine kinetics in type 2 diabetes mellitus. Diabetes Nutr. Metab. 15, 136–142 (2002).

    CAS  PubMed  Google Scholar 

  58. Bentzinger, C. F. et al. Differential response of skeletal muscles to mTORC1 signaling during atrophy and hypertrophy. Skelet. Muscle 3, 6 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  59. Wahren, J., Felig, P. & Hagenfeldt, L. Effect of protein ingestion on splanchnic and leg metabolism in normal man and in patients with diabetes mellitus. J. Clin. Invest. 57, 987–999 (1976).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  60. Yang, R. Z. et al. Alanine aminotransferase isoenzymes: molecular cloning and quantitative analysis of tissue expression in rats and serum elevation in liver toxicity. Hepatology 49, 598–607 (2009).

    Article  CAS  PubMed  Google Scholar 

  61. Gray, S. et al. Regulation of gluconeogenesis by Kruppel-like factor 15. Cell Metab. 5, 305–312 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  62. Bujak, A. L. et al. AMPK activation of muscle autophagy prevents fasting-induced hypoglycemia and myopathy during aging. Cell Metab. 21, 883–890 (2015).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  63. Ouyang, Q. et al. Mutations in mitochondrial enzyme GPT2 cause metabolic dysfunction and neurological disease with developmental and progressive features. Proc. Natl Acad. Sci. USA 113, E5598–E5607 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  64. Gray, L. R. et al. Hepatic mitochondrial pyruvate carrier 1 is required for efficient regulation of gluconeogenesis and whole-body glucose homeostasis. Cell Metab. 22, 669–681 (2015).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  65. Houten, S. M. et al. Impaired amino acid metabolism contributes to fasting-induced hypoglycemia in fatty acid oxidation defects. Hum. Mol. Genet 22, 5249–5261 (2013).

    Article  CAS  PubMed  Google Scholar 

  66. Madiraju, A. K. et al. Argininosuccinate synthetase regulates hepatic AMPK linking protein catabolism and ureagenesis to hepatic lipid metabolism. Proc. Natl Acad. Sci. USA 113, E3423–E3430 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  67. Reagan, W. J. et al. Metabolic adaptive ALT isoenzyme response in livers of C57BL/6 mice treated with dexamethasone. Toxicol. Pathol. 40, 1117–1127 (2012).

    Article  PubMed  PubMed Central  Google Scholar 

  68. Lin, H. V. & Accili, D. Hormonal regulation of hepatic glucose production in health and disease. Cell Metab. 14, 9–19 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  69. Yang, J. et al. Polyomic profiling reveals significant hepatic metabolic alterations in glucagon-receptor (GCGR) knockout mice: implications on anti-glucagon therapies for diabetes. BMC Genomics 12, 281 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  70. Sandhu, S. & Jialal, I. Glucagonoma Syndrome. in StatPearls (Treasure Island: StatPearls Publishing, 2020).

  71. Ostertag, A. et al. Control of adipose tissue inflammation through TRB1. Diabetes 59, 1991–2000 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  72. Lemke, U. et al. The glucocorticoid receptor controls hepatic dyslipidemia through Hes1. Cell Metab. 8, 212–223 (2008).

    Article  CAS  PubMed  Google Scholar 

  73. Luo, J. et al. Nongenetic mouse models of non-insulin-dependent diabetes mellitus. Metabolism 47, 663–668 (1998).

    Article  CAS  PubMed  Google Scholar 

  74. Gilbert, E. R., Fu, Z. & Liu, D. Development of a nongenetic mouse model of type 2 diabetes. Exp. Diabetes Res. 2011, 416254 (2011).

    Article  PubMed  PubMed Central  Google Scholar 

  75. Yan, H. et al. Fully human monoclonal antibodies antagonizing the glucagon receptor improve glucose homeostasis in mice and monkeys. J. Pharmacol. Exp. Ther. 329, 102–111 (2009).

    Article  CAS  PubMed  Google Scholar 

  76. Kloting, N. et al. Insulin-sensitive obesity. Am. J. Physiol. Endocrinol. Metab. 299, E506–E515 (2010).

    Article  PubMed  Google Scholar 

  77. Graham, T., McIntosh, J., Work, L. M., Nathwani, A. & Baker, A. H. Performance of AAV8 vectors expressing human factor IX from a hepatic-selective promoter following intravenous injection into rats. Genet. Vaccines Ther. 6, 9 (2008).

    Article  PubMed  PubMed Central  Google Scholar 

  78. Jungmann, A., Leuchs, B., Rommelaere, J., Katus, H. A. & Muller, O. J. Protocol for efficient generation and characterization of adeno-associated viral vectors. Hum. Gene Ther. Methods 28, 235–246 (2017).

    Article  CAS  PubMed  Google Scholar 

  79. Vary, T. C. & Lang, C. H. Assessing effects of alcohol consumption on protein synthesis in striated muscles. Methods Mol. Biol. 447, 343–355 (2008).

    Article  CAS  PubMed  Google Scholar 

  80. de Graaf, I. A. et al. Preparation and incubation of precision-cut liver and intestinal slices for application in drug metabolism and toxicity studies. Nat. Protoc. 5, 1540–1551 (2010).

    Article  PubMed  Google Scholar 

  81. Patti, M. E., Brambilla, E., Luzi, L., Landaker, E. J. & Kahn, C. R. Bidirectional modulation of insulin action by amino acids. J. Clin. Invest. 101, 1519–1529 (1998).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  82. Rose, A. J. et al. A Ca2+–calmodulin–eEF2K–eEF2 signalling cascade, but not AMPK, contributes to the suppression of skeletal muscle protein synthesis during contractions. J. Physiol. 587, 1547–1563 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  83. Sauer, S. W. et al. Intracerebral accumulation of glutaric and 3-hydroxyglutaric acids secondary to limited flux across the blood-brain barrier constitute a biochemical risk factor for neurodegeneration in glutaryl-CoA dehydrogenase deficiency. J. Neurochem. 97, 899–910 (2006).

    Article  CAS  PubMed  Google Scholar 

Download references

Acknowledgements

The authors thank J. Fuhrmeister, A. Maida and T. Gantert (A170, DKFZ), L. Figur (A171, DKFZ), as well as J. Hetzer and D. Heide (F180, DKFZ) for experimental support. J.S. was supported by a fellowship from the Helmholtz International Graduate School for Cancer Research. M.H. was supported by an ERC Consolidator grant (HepatoMetaboPath), SFBTR 209 (Liver Cancer) and SFBTR179. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 667273. This work was funded by the Helmholtz Future Topic ‘Aging and metabolic reprogramming’ (to S.H.). This work was was also funded by a project grant from the EFSD/Lilly European Diabetes Research Programme, as well as a Medical Research Grant from the Sir Edward Dunlop Medical Research Foundation (to A.J.R.).

Author information

Authors and Affiliations

  1. Division of Inherited Metabolic Diseases, University Children’s Hospital, Heidelberg, Germany

    Jürgen G. Okun & Kathrin V. Schmidt

  2. Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia

    Patricia M. Rusu, Andrea Y. Chan, Yuqin Wu, Yann W. Yap, Thomas Sharkie & Adam J. Rose

  3. Division of Molecular Metabolic Control, German Cancer Research Center (DKFZ), Heidelberg, Germany

    Jonas Schumacher, Annika Zota, Ludovico Maggi, Stephan Herzig & Adam J. Rose

  4. Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia

    Katherine M. Roberts-Thomson & Michelle A. Keske

  5. Department of Health and Human Performance, College of Health Professions, University of Texas Rio Grande Valley, Brownsville, TX, USA

    Ryan D. Russell

  6. Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich, Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine I, Heidelberg University Hospital and Chair Molecular Metabolic Control, Technical University Munich, Neuherberg, Germany

    Annika Zota & Stephan Herzig

  7. Department of Internal Medicine III, University of Kiel, Kiel, Germany

    Susanne Hille & Oliver J. Müller

  8. German Center for Cardiovascular Research (DZHK), Heidelberg and Kiel sites, Germany

    Susanne Hille, Andreas Jungmann & Oliver J. Müller

  9. Department of Internal Medicine III, University Hospital Heidelberg, Heidelberg, Germany

    Andreas Jungmann

  10. Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA

    Young Lee

  11. Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München at the University of Leipzig, Leipzig, Germany

    Matthias Blüher

  12. Division of Chronic Inflammation and Cancer, German Cancer Research Center, Heidelberg, Germany

    Mathias Heikenwalder

Authors
  1. Jürgen G. Okun
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Patricia M. Rusu
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Andrea Y. Chan
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Yuqin Wu
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Yann W. Yap
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Thomas Sharkie
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Jonas Schumacher
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Kathrin V. Schmidt
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Katherine M. Roberts-Thomson
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Ryan D. Russell
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Annika Zota
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Susanne Hille
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. Andreas Jungmann
    View author publications

    You can also search for this author in PubMed Google Scholar

  14. Ludovico Maggi
    View author publications

    You can also search for this author in PubMed Google Scholar

  15. Young Lee
    View author publications

    You can also search for this author in PubMed Google Scholar

  16. Matthias Blüher
    View author publications

    You can also search for this author in PubMed Google Scholar

  17. Stephan Herzig
    View author publications

    You can also search for this author in PubMed Google Scholar

  18. Michelle A. Keske
    View author publications

    You can also search for this author in PubMed Google Scholar

  19. Mathias Heikenwalder
    View author publications

    You can also search for this author in PubMed Google Scholar

  20. Oliver J. Müller
    View author publications

    You can also search for this author in PubMed Google Scholar

  21. Adam J. Rose
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

Project conceptualization, administration and management: A.J.R. Resources: J.G.O., M.B., S.H., O.J.M., M.A.K., M.H. and A.J.R. Investigation: J.G.O., J.S., K.V.S., K.M.R.-T., R.D.R., A.Z., A.J., L.M., M.B., M.H. and A.J.R. Software and formal analysis: P.R. and A.J.R. Writing, original draft: A.J.R. Writing, editing: J.G.O., P.M.R., J.S., R.D.R., M.B., S.H., O.J.M., M.A.K., M.H. and A.J.R. Visualization: P.R., M.H. and A.J.R. Funding acquisition: S.H., M.H. and A.J.R.

Corresponding author

Correspondence to Adam J. Rose.

Ethics declarations

Competing interests

All authors declare no competing interests.

Additional information

Peer review information Nature Metabolism thanks Sue Bodine, Kei Sakamoto and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editor: Christoph Schmitt.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Alanine metabolism and liver ALT isoform expression is upregulated in obesity and type 2 diabetes. Related to Fig. 1.

a, Serum alanine levels in wildtype C57Bl/6 J (wt) and obese/diabetic BKS-db/db mice from ad libitum feeding (fed), 24 h fasted (fasted) and 24 h fasted, 6 h refeeding (refed). Data are mean ± SEM, N = 4/group. Effect of genotype: * P > 0.05. Effect of nutritional state versus fed: # P < 0.05. b, Serum alanine levels in New Zealand Black (NZB) and New Zealand Obese (NZO) mice from 24h fasting (fasted) and 24h fasted, 6h refeeding (refed). Data are mean ± SEM, N = 4/group. Effect of genotype: * P > 0.05. Effect of nutritional state vs. fasted: # P < 0.05. c, Plasma alanine levels during an intraperitoneal alanine tolerance test (ipATT) in mice on low fat diet (LFD) or an obesogenic high-fat diet with (HFD-STZ) or without (HFD) streptozotocin (STZ) pre-treatment to exacerbate the progression of frank diabetes. Data are mean ± SEM, N = 6/group. Different than LFD: * P > 0.05. Different than HFD: # P < 0.05. d, Blood glucose levels in mice as in C. e, Plasma insulin levels during an intraperitoneal alanine tolerance test (ipATT) in C57Bl/6J (WT) and BKS-db/db (db/db) mice. N = 4/group. Genotype difference: *P < 0.05. f: Plasma insulin levels of mice as in C. g, Blood glucose levels during an intraperitoneal pyruvate tolerance test (ipPTT) in C57Bl/6J (WT) and BKS-db/db (db/db) mice. N = 4/group. Genotype difference: *P < 0.05. h, Blood glucose levels during an intraperitoneal alanine tolerance test (ipPTT) in in mice on low fat diet (LFD) or an obesogenic high-fat diet with (HFD-STZ) or without (HFD) streptozotocin (STZ) pre-treatment to exacerbate the progression of frank diabetes. Data are mean ± SEM, N = 6/group. Different than LFD: * P > 0.05. Different than HFD: # P < 0.05. i, Blood glucose levels from type 2 diabetic (T2D; N = 11) and age-matched normal glucose tolerant (NGT; N = 12) individuals undergoing a mixed-meal tolerance test (MMTT). *: cohort difference, *p < 0.05, **p < 0.01, ***P < 0.001. #: effect of time, #p < 0.05, ##p < 0.01, ###P < 0.001. j, Blood plasma insulin levels of individuals as in I. k, Blood plasma glucagon levels of individuals as in I. l, Blood plasma cortisol levels of individuals as in I. Statistical tests: A, B: 2-way ANOVA with Holm-Sidak posthoc hoc tests. C-L: 2-way repeated measures ANOVA with Holm-Sidak posthoc hoc tests.

Extended Data Fig. 2 Silencing of both, but not individual, liver ALT isoforms affects systemic alanine and glucose homeostasis after diverse nutritional challenges. Related to Fig. 2.

a, Liver mRNA expression from mice with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) and alanine-glyoxylate aminotransferase (Agxt) isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 6/group. b, Representative western blots of GPT isoforms as well as the housekeeping protein heat shock protein 90 (HSP90) from mice as in A. 3 samples/group were analyzed and are shown. c, Body mass of mice as in A. d, Liver mass of mice as in A. e, Gastrocnemius complex skeletal muscle (GCM) mass of mice as in A. f, Perigonadal white adipose tissue (pgWAT) mass of mice as in A. g, Food intake during a 6h refeeding period following 24h fasting from mice as in A. h, Plasma alanine levels from mice as in G. i, Blood glucose levels from mice as in G. j, Plasma lactate levels from mice as in G. k, Plasma glycerol levels rom mice as in G. l, Plasma non-esterified fatty acid (NEFA) levels from mice as in G. m, Plasma ketone body levels from mice as in G. n, Liver mRNA levels from mice pre-treated with adeno-associated viruses to express a negative control micro-RNA (NC miR) and green fluorescent protein (GFP), Gpt and Gpt2-specfific miRs, human Gpt and Gpt2 mRNAs (HsGpt OE, HsGpt2 OE), and mutants of human Gpt and Gpt2 mRNAs to produce enzymatically inactive proteins (HsGptmut OE, HsGPT2mut OE). . Data are mean ± SEM, N = 6/ group. o, Liver mRNA expression of glutamic-pyruvic transaminase (Gpt) isoforms in mice fed a ketogenic diet with hepatocyte selective AAV-miR mediated silencing of Gpt isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 6/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. p, Body mass from mice as in O. q, Liver mass from mice as in O. r, Serum triglyceride (TG) levels from mice as in O. s, Serum NEFA levels from mice as in O. t, Serum glycerol levels from mice as in O. u, Serum cholesterol levels from mice as in O. v, The change (Δ) in fat mass as determined by ECHO-MRI before and after ketogenic diet feeding from mice as in O. w, Blood glucose levels in mice in the ad libitum fed state following adaptation to a protein-enriched (80%E) diet with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 6/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. x, Body mass from mice as in W. y, Liver mass from mice as in W. z, Gastrocnemius complex skeletal muscle (GCM) mass from mice as in W. Statistical tests: C, D, E, F, P, Q, R, S, T, U, V: 1-way ANOVA with Holm-Sidak posthoc hoc tests. I, J, K, L, M, N: 2-way repeated measures ANOVA with Holm-Sidak posthoc hoc tests. W, X, Y, z: Students t-tests.

Source data

Extended Data Fig. 3 Silencing of both, but not individual, liver alanine aminotransferase isoforms retards hyperglycaemia in mouse models of obesity-related type 2 diabetes. Related to Fig. 3.

a, Liver glutamic-pyruvic transaminase isoform mRNA expression in obese/diabetic BKS-db/db mice with hepatocyte selective AAV-miR mediated silencing of Gpt isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 6/group. b, Liver GPT activity from mice as in A. Different than NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Different than Gpt or Gpt2 miR: ### P < 0.001. c, Blood glucose levels during an intraperitoneal alanine tolerance test (ipATT) in obese/diabetic BKS-db/db mice as in A. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. d, Body mass of mice as in A. e, Liver mass of mice as in A. f, Blood glucose levels after an overnight fast and following a 6h refeed from mice as in A. g, Food intake during a 6h refeeding period following fasting from mice as in F. h, Ad libitum fed serum triglyceride (TG) levels from mice as in A. i, Serum ketone body (KB) levels from mice as in H. j, Serum non-esterified fatty acid (NEFA) levels from mice as in H. k, Serum cholesterol levels from mice as in H. l, Liver GPT activity in lean C57Bl/6J (Bl6) and age-matched obese/diabetic BKS-db/db mice with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 4/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of genotype: # P < 0.05, ## P < 0.01, ### P < 0.001. m, Plasma insulin levels of mice as in Fig. 3b during an alanine tolerance test (ipATT). Data are mean ± SEM, N = 4/ group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of genotype: # P < 0.05, ## P < 0.01, ### P < 0.001. n, Blood glucose levels during an intraperitoneal pyruvate tolerance test (ipPTT) in lean C57Bl/6J (Bl6) and age-matched obese/diabetic BKS-db/db mice with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 4/ group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of genotype: # P < 0.05, ## P < 0.01, ### P < 0.001. o, Blood glucose levels during an intraperitoneal glycerol tolerance test (ipGyTT) of mice as in N. p, Representative western blots images of liver glucose-6-phosphatase (G6PC), phosphoenolpyruvate carboxykinase 1 (PCK1), GPT isoforms, as well as the housekeeping protein vinculin (VCL) in lean C57Bl/6J (Bl6) and age-matched obese/diabetic BKS-db/db mice with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. 3 samples per group were analyzed and are shown. q, Liver GPT activity of mice on an obesogenic high-fat diet with (HFD-STZ) or without (HFD) streptozocin (STZ) pre-treatment to exacerbate the progression of frank diabetes; with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. Data are mean ± SEM, N = 6/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of STZ: # P < 0.05, ## P < 0.01, ### P < 0.001. r, Micrographs of liver glutamic-pyruvic transaminase (GPT) immunohistochemical staining of sections taken from HFD-STZ mice as in Q. Shown are 2 representative images taken from 2 individual mice per group (2/group were stained and imaged). Scale bar: 200µm. Statistical tests: B, D, E, G-K: 1-way ANOVA with Holm-Sidak posthoc hoc tests. C, F, M-O: 2-way repeated measures ANOVA with Holm-Sidak posthoc hoc tests. L, Q: 2-way ANOVA with Holm-Sidak posthoc hoc tests.

Source data

Extended Data Fig. 4 Disrupting the heightened liver alanine catabolism improves skeletal muscle size and function in mouse models of type 2 diabetes. Related to Fig. 4.

a, Body mass of lean C57Bl/6J (Bl6) and age-matched obese/diabetic BKS-db/db mice with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 4/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of genotype: # P < 0.05, ## P < 0.01, ### P < 0.001. b, Lean body mass as determined by ECHO-MRI of mice as in A. c, Fat body mass as determined by ECHO-MRI of mice as in A. d, Body mass of mice on an obesogenic high-fat diet with (HFD-STZ) or without (HFD) streptozocin (STZ) pre-treatment to exacerbate the progression of frank diabetes; with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. Data are mean ± SEM, N = 6/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of STZ: # P < 0.05, ## P < 0.01, ### P < 0.001. e, Lean body mass as determined by ECHO-MRI of mice as in D. f, Fat body mass as determined by ECHO-MRI of mice as in D. Statistical tests: A, B, C, D, E, F: 2-way ANOVA with Holm-Sidak posthoc hoc tests.

Extended Data Fig. 5 A glucocorticoid–liver glucocorticoid receptor axis links heightened liver alanine catabolism with hyperglycaemia and muscle atrophy in type 2 diabetes. Related to Fig. 5.

a, Serum corticosterone levels in lean New Zealand Black (NZB) and obese/diabetic New Zealand Obese (NZO) mice. Data are mean ± SEM, N = 6/group. d, Liver GPT activity of mice chronically treated with the synthetic glucocorticoid dexamethasone (Dex; 1mg/kg per day, 14d) or vehicle control (Veh). Data are mean ± SEM, N = 7/group. Effect of Dex: # P < 0.05, ## P < 0.01, ### P < 0.001. c, Liver glutamic-pyruvic transaminase (Gpt) isoform mRNA expression of C57Bl/6N in mice chronically treated with the synthetic glucocorticoid dexamethasone (Dex; 1mg/kg per day, 14d) or vehicle control (Veh) with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. miR: micro-RNA.. Data are mean ± SEM, N = 8/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of Dex: # P < 0.05, ## P < 0.01, ### P < 0.001. d, Blood glucose levels of mice as in C. e, Gastrocnemius complex (GCM), triceps brachii (TB) and tibialis anterior (TA) skeletal muscle mass’ of mice as in C. f, Forelimb grip strength of mice as in C. g, Body mass of mice as in C. h, Liver mass of mice as in C. i, Perigonadal white adipose tissue (pgWAT) mass of mice as in C. j, Liver and perigonal white adipose tissue mass’ of mice chronically treated with the synthetic glucocorticoid dexamethasone (Dex; 1mg/kg per day, 14d) or vehicle control (Veh) with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 8/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of Dex: # P < 0.05, ## P < 0.01, ### P < 0.001. k, ENSEMBL genome browser images of DNAse hypersensitivity sites as well as CEBPb and GR ChIP-seq peaks of the Gpt and Gpt2 gene, and flanking regions, in mouse liver. Statistical tests: A, B: Students t-tests (two sided). C, D, E, F, G, H, I, J: 2-way ANOVA with Holm-Sidak posthoc hoc tests.

Extended Data Fig. 6 Chronic liver glucagon action affects hyperglycaemia and skeletal muscle atrophy via hepatic alanine catabolism. Related to Fig. 6.

a, Messenger RNA (mRNA) levels of glutamic-pyruvic transaminase (Gpt) and Gpt2 in precision cut liver slices treated ex vivo with the synthetic glucocorticoid dexamethasone (DEX), glucagon (GCG) or a combination thereof (DEX + GCG). N = 6 individual slices per treatment group. One way ANOVA: different than VEH: * p < 0.05, ** p < 0.01, *** p < 0.001. b, Western blot images of liver glutamic-pyruvic transaminase (GPT), GPT2, and loading control heat shock protein 90 (HSP90) of C57Bl6/J (Bl6/J) and obese/diabetic C57BKS mice with homozygous leptin receptor mutation (BKS-db/db) chronically treated with a glucagon receptor antagonist (REMD). 2 samples per group were analyzed and are shown. c, Body mass of mice of C57Bl/6J mice chronically (3wk) treated with the acyl-glucagon (acyl-GCG; 1 nmol/g/d) or vehicle control (Veh) with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 8/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of Dex: # P < 0.05, ## P < 0.01, ### P < 0.001. d, Liver and perigonadal white adipose tissue (PGWAT) mass’ of mice of C57Bl/6J mice chronically treated with the acyl-glucagon (acyl-GCG; 1 nmol/g/d) or vehicle control (Veh) with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 8/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of Dex: # P < 0.05, ## P < 0.01, ### P < 0.001. Statistical tests: A, D: 1-way ANOVA with Holm-Sidak posthoc hoc tests. C: 2-way repeated meaures ANOVA with Holm-Sidak posthoc hoc tests.

Source data

Extended Data Fig. 7 Disrupting the heightened liver alanine catabolism reverses the reduced skeletal muscle protein synthesis and branched-chain amino acid levels in type 2 diabetes. Related to Fig. 7.

a, Gastroconemius complex skeletal muscle mRNA expression of transcripts of atrophy related genes Trim63 (aka Murf1), Fbxo32 (aka MAFbx or Atrogin-1), Ddit4 (aka Redd1), Klf15 and Foxo3a from lean C57Bl/6J (Bl6) and age-matched obese/diabetic BKS-db/db mice with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. Data are from mice 6 wk after AAV administration. NC: negative control. miR: micro-RNA. GCM: gastrocnemius complex muscle. TB: Triceps brachii. TA: tibialis anterior. Data are mean ± SEM, N = 4/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of genotype: # P < 0.05, ## P < 0.01, ### P < 0.001. b, Skeletal muscle mass’ of overnight fasted, 4h refed lean C57Bl/6J (Bl6) and age-matched obese/diabetic BKS-db/db mice with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. Study was conducted 10d after AAV administrations. NC: negative control. miR: micro-RNA. GCM: gastrocnemius complex muscle. TB: Triceps brachii. TA: tibialis anterior. Data are mean ± SEM, N = 4/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of genotype: # P < 0.05, ## P < 0.01, ### P < 0.001. c, In vivo protein synthesis rate calculated from mixed muscle 3H-phenylalanine incorporation of mice as in B. d, Gastrocnemius complex skeletal muscle (GCM) Gpt isoform mRNA expression in lean C57Bl/6J (Bl6) and age-matched obese/diabetic BKS-db/db mice with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 4/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of genotype: # P < 0.05, ## P < 0.01, ### P < 0.001. e, Ex vivo extensor digitorum longus (EDL) skeletal muscle protein synthesis rate during co-culture and cross-co-culture with liver slices. Tissues were taken from lean C57Bl/6J (Bl6) and age-matched obese/diabetic BKS-db/db mice with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. In one condition, media was collected after culture with db/db liver for 3h after which it was dialyzed (1 KDa cutoff) against normal media to normalize metabolites such as amino acids but retain large molecules such as peptides. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 3/group with 2 technical replicates per treatment condition. Effect of Liver miR: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of muscle genotype: # P < 0.05, ## P < 0.01, ### P < 0.001. f, Serum insulin like growth factor 1 (IGF1) levels of BKS-db/db mice as in D. g, Serum follistatin (FST) levels of BKS-db/db mice as in D. h, Serum fibroblast growth factor 21 (FGF21) levels of BKS-db/db mice as in D. i, Serum insulin levels of BKS-db/db mice as in D. j, Gastrocnemius complex skeletal muscle (GCM) Valine (Val) and Leucine/Isoleucine (Leu/Ile) concentrations in obese/diabetic BKS-db/db mice with hepatocyte selective AAV-miR mediated silencing of glutamic-pyruvic transaminase (Gpt) isoforms. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 6/group. Effect of miR vs. NC miR: * P < 0.05, ** P < 0.01, *** P < 0.001. k, Ex vivo extensor digitorum longus (EDL) skeletal muscle protein synthesis rate during co-culture and cross-co-culture with liver slices with (+5mM Ala) or without (Con) treatment with 5mM alanine in the media. Tissues were taken from lean C57Bl/6J (Bl6) and age-matched obese/diabetic BKS-db/db mice. NC: negative control. miR: micro-RNA. Data are mean ± SEM, N = 3/group with 2 technical replicates per treatment condition. Effect of muscle genotype: * P < 0.05, ** P < 0.01, *** P < 0.001. Effect of 5mM Ala: # P < 0.05, ## P < 0.01, ### P < 0.001. l, Immunoblot images showing phospho-Thr389-p70S6 kinase 1, phospho-Thr37/46-4E binding protein 1, and the loading control vinculin of gastrocnemius skeletal muscle samples from mice as in B. 3 samples per group were analyzed and are shown. Statistical tests: A, B, C, D, J: 2-way ANOVA with Holm-Sidak posthoc hoc tests. E, F, G, H, K: Student’s t-test. I: 1-way ANOVA with Holm-Sidak posthoc hoc tests.

Source data

Supplementary information

Source data

Source Data Fig. 1

Unprocessed western blot images.

Source Data Fig. 2

Unprocessed western blot images.

Source Data Fig. 6

Unprocessed western blot images.

Source Data Extended Data Fig. 2

Unprocessed western blot images.

Source Data Extended Data Fig. 3

Unprocessed western blot images.

Source Data Extended Data Fig. 6

Unprocessed western blot images.

Source Data Extended Data Fig. 7

Unprocessed western blot images.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Okun, J.G., Rusu, P.M., Chan, A.Y. et al. Liver alanine catabolism promotes skeletal muscle atrophy and hyperglycaemia in type 2 diabetes. Nat Metab 3, 394–409 (2021). https://doi.org/10.1038/s42255-021-00369-9

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s42255-021-00369-9

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing