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Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts
Systemic branched‐chain amino acid (BCAA) metabolism is dysregulated in cardiometabolic diseases. We previously demonstrated that upregulated AMP deaminase 3 (AMPD3) impairs cardiac energetics in a rat model of obese type 2 diabetes, Otsuka Long‐Evans‐Tokushima fatty (OLETF). Here, we hypothesized t...
Autores principales: | , , , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
John Wiley and Sons Inc.
2023
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9938007/ https://www.ncbi.nlm.nih.gov/pubmed/36802195 http://dx.doi.org/10.14814/phy2.15608 |
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author | Ogawa, Toshifumi Kouzu, Hidemichi Osanami, Arata Tatekoshi, Yuki Sato, Tatsuya Kuno, Atsushi Fujita, Yugo Ino, Shoya Shimizu, Masaki Toda, Yuki Ohwada, Wataru Yano, Toshiyuki Tanno, Masaya Miki, Takayuki Miura, Tetsuji |
author_facet | Ogawa, Toshifumi Kouzu, Hidemichi Osanami, Arata Tatekoshi, Yuki Sato, Tatsuya Kuno, Atsushi Fujita, Yugo Ino, Shoya Shimizu, Masaki Toda, Yuki Ohwada, Wataru Yano, Toshiyuki Tanno, Masaya Miki, Takayuki Miura, Tetsuji |
author_sort | Ogawa, Toshifumi |
collection | PubMed |
description | Systemic branched‐chain amino acid (BCAA) metabolism is dysregulated in cardiometabolic diseases. We previously demonstrated that upregulated AMP deaminase 3 (AMPD3) impairs cardiac energetics in a rat model of obese type 2 diabetes, Otsuka Long‐Evans‐Tokushima fatty (OLETF). Here, we hypothesized that the cardiac BCAA levels and the activity of branched‐chain α‐keto acid dehydrogenase (BCKDH), a rate‐limiting enzyme in BCAA metabolism, are altered by type 2 diabetes (T2DM), and that upregulated AMPD3 expression is involved in the alteration. Performing proteomic analysis combined with immunoblotting, we discovered that BCKDH localizes not only to mitochondria but also to the endoplasmic reticulum (ER), where it interacts with AMPD3. Knocking down AMPD3 in neonatal rat cardiomyocytes (NRCMs) increased BCKDH activity, suggesting that AMPD3 negatively regulates BCKDH. Compared with control rats (Long‐Evans Tokushima Otsuka [LETO] rats), OLETF rats exhibited 49% higher cardiac BCAA levels and 49% lower BCKDH activity. In the cardiac ER of the OLETF rats, BCKDH‐E1α subunit expression was downregulated, while AMPD3 expression was upregulated, resulting in an 80% lower AMPD3‐E1α interaction compared to LETO rats. Knocking down E1α expression in NRCMs upregulated AMPD3 expression and recapitulated the imbalanced AMPD3‐BCKDH expressions observed in OLETF rat hearts. E1α knockdown in NRCMs inhibited glucose oxidation in response to insulin, palmitate oxidation, and lipid droplet biogenesis under oleate loading. Collectively, these data revealed previously unrecognized extramitochondrial localization of BCKDH in the heart and its reciprocal regulation with AMPD3 and imbalanced AMPD3‐BCKDH interactions in OLETF. Downregulation of BCKDH in cardiomyocytes induced profound metabolic changes that are observed in OLETF hearts, providing insight into mechanisms contributing to the development of diabetic cardiomyopathy. |
format | Online Article Text |
id | pubmed-9938007 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2023 |
publisher | John Wiley and Sons Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-99380072023-02-19 Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts Ogawa, Toshifumi Kouzu, Hidemichi Osanami, Arata Tatekoshi, Yuki Sato, Tatsuya Kuno, Atsushi Fujita, Yugo Ino, Shoya Shimizu, Masaki Toda, Yuki Ohwada, Wataru Yano, Toshiyuki Tanno, Masaya Miki, Takayuki Miura, Tetsuji Physiol Rep Original Articles Systemic branched‐chain amino acid (BCAA) metabolism is dysregulated in cardiometabolic diseases. We previously demonstrated that upregulated AMP deaminase 3 (AMPD3) impairs cardiac energetics in a rat model of obese type 2 diabetes, Otsuka Long‐Evans‐Tokushima fatty (OLETF). Here, we hypothesized that the cardiac BCAA levels and the activity of branched‐chain α‐keto acid dehydrogenase (BCKDH), a rate‐limiting enzyme in BCAA metabolism, are altered by type 2 diabetes (T2DM), and that upregulated AMPD3 expression is involved in the alteration. Performing proteomic analysis combined with immunoblotting, we discovered that BCKDH localizes not only to mitochondria but also to the endoplasmic reticulum (ER), where it interacts with AMPD3. Knocking down AMPD3 in neonatal rat cardiomyocytes (NRCMs) increased BCKDH activity, suggesting that AMPD3 negatively regulates BCKDH. Compared with control rats (Long‐Evans Tokushima Otsuka [LETO] rats), OLETF rats exhibited 49% higher cardiac BCAA levels and 49% lower BCKDH activity. In the cardiac ER of the OLETF rats, BCKDH‐E1α subunit expression was downregulated, while AMPD3 expression was upregulated, resulting in an 80% lower AMPD3‐E1α interaction compared to LETO rats. Knocking down E1α expression in NRCMs upregulated AMPD3 expression and recapitulated the imbalanced AMPD3‐BCKDH expressions observed in OLETF rat hearts. E1α knockdown in NRCMs inhibited glucose oxidation in response to insulin, palmitate oxidation, and lipid droplet biogenesis under oleate loading. Collectively, these data revealed previously unrecognized extramitochondrial localization of BCKDH in the heart and its reciprocal regulation with AMPD3 and imbalanced AMPD3‐BCKDH interactions in OLETF. Downregulation of BCKDH in cardiomyocytes induced profound metabolic changes that are observed in OLETF hearts, providing insight into mechanisms contributing to the development of diabetic cardiomyopathy. John Wiley and Sons Inc. 2023-02-17 /pmc/articles/PMC9938007/ /pubmed/36802195 http://dx.doi.org/10.14814/phy2.15608 Text en © 2023 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society. https://creativecommons.org/licenses/by/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Original Articles Ogawa, Toshifumi Kouzu, Hidemichi Osanami, Arata Tatekoshi, Yuki Sato, Tatsuya Kuno, Atsushi Fujita, Yugo Ino, Shoya Shimizu, Masaki Toda, Yuki Ohwada, Wataru Yano, Toshiyuki Tanno, Masaya Miki, Takayuki Miura, Tetsuji Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts |
title | Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts |
title_full | Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts |
title_fullStr | Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts |
title_full_unstemmed | Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts |
title_short | Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts |
title_sort | downregulation of extramitochondrial bckdh and its uncoupling from amp deaminase in type 2 diabetic oletf rat hearts |
topic | Original Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9938007/ https://www.ncbi.nlm.nih.gov/pubmed/36802195 http://dx.doi.org/10.14814/phy2.15608 |
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