TY - JOUR
T1 - Metabolon formation regulates branched-chain amino acid oxidation and homeostasis
AU - Patrick, McKenzie K.
AU - Gu, Zhimin
AU - Zhang, Gen
AU - Wynn, R. Max
AU - Kaphle, Pranita
AU - Cao, Hui
AU - Vu, Hieu
AU - Cai, Feng
AU - Gao, Xiaofei
AU - Zhang, Yuannyu
AU - Chen, Mingyi
AU - Ni, Min
AU - Chuang, David T.
AU - DeBerardinis, Ralph J.
AU - Xu, Jian
N1 - Funding Information:
The mRNA expression values of human and mouse BCAT1 and BCAT2 across different tissue types were obtained from The Genotype-Tissue Expression (GTEx) Portal on 24 June 2020. The GTeX project was supported by the Common Fund of the Office of the Director of the National Institutes of Health, and by NCI, NHGRI, NHLBI, NIDA, NIMH and NINDS. The mRNA expression of all genes associated with BCAA metabolism in seven human and mouse organs (brain, cerebellum, heart, kidney, liver, ovary and testis) across developmental time points from early organogenesis to adulthood was performed using the database for Evo-devo mammalian organs ( https://apps.kaessmannlab.org/evodevoapp/ ). The expression of Bcat2, Bckdha, Bckdhb, Bckdk and Ppm1k mRNA and protein fractionated liver cell types including hepatocytes, hepatic stellate cells, Kupffer cells and liver sinusoidal endothelial cells were obtained from previous studies by RNA-seq and proteomics, respectively.
Funding Information:
We thank G. Hoxhaj, S. McBrayer and D. Bezwada for discussions, L. Zacharias for assistance with metabolomics and other Xu laboratory members for technical support. We thank the UTSW Metabolic Phenotyping Core for their analysis of AST, ALT and insulin levels, A. Lemoff at the UTSW Proteomics Core, and the UTSW Pre-Clinical MRI Research Core. Figure 2a was created with BioRender.com. J.X. is a Scholar of The Leukaemia & Lymphoma Society (LLS) and an American Society of Haematology (ASH) Scholar. This work was supported by NIH grants (R01CA230631, R01CA259581, R01DK111430 and R21AI158240 to J.X. and R35CA22044901 to R.J.D.), CPRIT grants (RP180504, RP190417, RP220337 and RP220375 to J.X. and RP180778 to R.J.D.), the DoD grant PR191670 (to D.T.C.) and by the Welch Foundation grant I-1942 (to J.X.).
Funding Information:
We thank G. Hoxhaj, S. McBrayer and D. Bezwada for discussions, L. Zacharias for assistance with metabolomics and other Xu laboratory members for technical support. We thank the UTSW Metabolic Phenotyping Core for their analysis of AST, ALT and insulin levels, A. Lemoff at the UTSW Proteomics Core, and the UTSW Pre-Clinical MRI Research Core. Figure was created with BioRender.com. J.X. is a Scholar of The Leukaemia & Lymphoma Society (LLS) and an American Society of Haematology (ASH) Scholar. This work was supported by NIH grants (R01CA230631, R01CA259581, R01DK111430 and R21AI158240 to J.X. and R35CA22044901 to R.J.D.), CPRIT grants (RP180504, RP190417, RP220337 and RP220375 to J.X. and RP180778 to R.J.D.), the DoD grant PR191670 (to D.T.C.) and by the Welch Foundation grant I-1942 (to J.X.).
Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Springer Nature Limited.
PY - 2022/12
Y1 - 2022/12
N2 - The branched-chain aminotransferase isozymes BCAT1 and BCAT2, segregated into distinct subcellular compartments and tissues, initiate the catabolism of branched-chain amino acids (BCAAs). However, whether and how BCAT isozymes cooperate with downstream enzymes to control BCAA homeostasis in an intact organism remains largely unknown. Here, we analyse system-wide metabolomic changes in BCAT1- and BCAT2-deficient mouse models. Loss of BCAT2 but not BCAT1 leads to accumulation of BCAAs and branched-chain α-keto acids (BCKAs), causing morbidity and mortality that can be ameliorated by dietary BCAA restriction. Through proximity labelling, isotope tracing and enzymatic assays, we provide evidence for the formation of a mitochondrial BCAA metabolon involving BCAT2 and branched-chain α-keto acid dehydrogenase. Disabling the metabolon contributes to BCAT2 deficiency-induced phenotypes, which can be reversed by BCAT1-mediated BCKA reamination. These findings establish a role for metabolon formation in BCAA metabolism in vivo and suggest a new strategy to modulate this pathway in diseases involving dysfunctional BCAA metabolism.
AB - The branched-chain aminotransferase isozymes BCAT1 and BCAT2, segregated into distinct subcellular compartments and tissues, initiate the catabolism of branched-chain amino acids (BCAAs). However, whether and how BCAT isozymes cooperate with downstream enzymes to control BCAA homeostasis in an intact organism remains largely unknown. Here, we analyse system-wide metabolomic changes in BCAT1- and BCAT2-deficient mouse models. Loss of BCAT2 but not BCAT1 leads to accumulation of BCAAs and branched-chain α-keto acids (BCKAs), causing morbidity and mortality that can be ameliorated by dietary BCAA restriction. Through proximity labelling, isotope tracing and enzymatic assays, we provide evidence for the formation of a mitochondrial BCAA metabolon involving BCAT2 and branched-chain α-keto acid dehydrogenase. Disabling the metabolon contributes to BCAT2 deficiency-induced phenotypes, which can be reversed by BCAT1-mediated BCKA reamination. These findings establish a role for metabolon formation in BCAA metabolism in vivo and suggest a new strategy to modulate this pathway in diseases involving dysfunctional BCAA metabolism.
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UR - http://www.scopus.com/inward/citedby.url?scp=85142905537&partnerID=8YFLogxK
U2 - 10.1038/s42255-022-00689-4
DO - 10.1038/s42255-022-00689-4
M3 - Article
C2 - 36443523
AN - SCOPUS:85142905537
SN - 2522-5812
VL - 4
SP - 1775
EP - 1791
JO - Nature Metabolism
JF - Nature Metabolism
IS - 12
ER -