Elevated BCAA catabolism reverses the effect of branched-chain ketoacids on glucose transport in mTORC1-dependent manner in L6 myotubes.

IF 2.4 Q3 NUTRITION & DIETETICS
Journal of Nutritional Science Pub Date : 2024-10-18 eCollection Date: 2024-01-01 DOI:10.1017/jns.2024.66
Gagandeep Mann, Olasunkanmi A John Adegoke
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引用次数: 0

Abstract

Plasma levels of branched-chain amino acids (BCAA) and their metabolites, branched-chain ketoacids (BCKA), are increased in insulin resistance. We previously showed that ketoisocaproic acid (KIC) suppressed insulin-stimulated glucose transport in L6 myotubes, especially in myotubes depleted of branched-chain ketoacid dehydrogenase (BCKD), the enzyme that decarboxylates BCKA. This suggests that upregulating BCKD activity might improve insulin sensitivity. We hypothesised that increasing BCAA catabolism would upregulate insulin-stimulated glucose transport and attenuate insulin resistance induced by BCKA. L6 myotubes were either depleted of BCKD kinase (BDK), the enzyme that inhibits BCKD activity, or treated with BT2, a BDK inhibitor. Myotubes were then treated with KIC (200 μM), leucine (150 μM), BCKA (200 μM), or BCAA (400 μM) and then treated with or without insulin (100 nM). BDK depletion/inhibition rescued the suppression of insulin-stimulated glucose transport by KIC/BCKA. This was consistent with the attenuation of IRS-1 (Ser612) and S6K1 (Thr389) phosphorylation but there was no effect on Akt (Ser473) phosphorylation. The effect of leucine or BCAA on these measures was not as pronounced and BT2 did not influence the effect. Induction of the mTORC1/IRS-1 (Ser612) axis abolished the attenuating effect of BT2 treatment on glucose transport in cells treated with KIC. Surprisingly, rapamycin co-treatment with BT2 and KIC further reduced glucose transport. Our data suggests that the suppression of insulin-stimulated glucose transport by KIC/BCKA in muscle is mediated by mTORC1/S6K1 signalling. This was attenuated by upregulating BCAA catabolic flux. Thus, interventions targeting BCAA metabolism may provide benefits against insulin resistance and its sequelae.

在 L6 肌小管中,BCAA 分解代谢的升高会以 mTORC1 依赖性方式逆转支链酮酸对葡萄糖转运的影响。
胰岛素抵抗时,血浆中支链氨基酸(BCAA)及其代谢产物支链酮酸(BCKA)的水平会升高。我们以前的研究表明,酮异己酸(KIC)能抑制 L6 肌管中胰岛素刺激的葡萄糖转运,尤其是在缺乏支链酮酸脱氢酶(BCKD)的肌管中。这表明,上调 BCKD 的活性可能会改善胰岛素敏感性。我们假设,增加 BCAA 分解将上调胰岛素刺激的葡萄糖转运,并减轻 BCKA 诱导的胰岛素抵抗。L6 肌管中的BCKD激酶(BDK)(抑制BCKD活性的酶)或BT2(一种BDK抑制剂)均被去除。然后用 KIC(200 μM)、亮氨酸(150 μM)、BCKA(200 μM)或 BCAA(400 μM)处理肌管,再用或不用胰岛素(100 nM)处理。BDK 的耗竭/抑制挽救了 KIC/BCKA 对胰岛素刺激的葡萄糖转运的抑制。这与 IRS-1(Ser612)和 S6K1(Thr389)磷酸化的减弱一致,但对 Akt(Ser473)磷酸化没有影响。亮氨酸或 BCAA 对这些指标的影响并不明显,而且 BT2 也不影响这种影响。诱导 mTORC1/IRS-1(Ser612)轴可以消除 BT2 处理对 KIC 细胞葡萄糖转运的抑制作用。令人惊讶的是,雷帕霉素与 BT2 和 KIC 联合处理会进一步降低葡萄糖转运。我们的数据表明,肌肉中 KIC/BCKA 对胰岛素刺激的葡萄糖转运的抑制是由 mTORC1/S6K1 信号介导的。上调 BCAA 分解通量可减轻这种抑制作用。因此,针对 BCAA 代谢的干预措施可能对胰岛素抵抗及其后遗症有益。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Nutritional Science
Journal of Nutritional Science NUTRITION & DIETETICS-
CiteScore
3.00
自引率
0.00%
发文量
91
审稿时长
7 weeks
期刊介绍: Journal of Nutritional Science is an international, peer-reviewed, online only, open access journal that welcomes high-quality research articles in all aspects of nutrition. The underlying aim of all work should be, as far as possible, to develop nutritional concepts. JNS encompasses the full spectrum of nutritional science including public health nutrition, epidemiology, dietary surveys, nutritional requirements, metabolic studies, body composition, energetics, appetite, obesity, ageing, endocrinology, immunology, neuroscience, microbiology, genetics, molecular and cellular biology and nutrigenomics. JNS welcomes Primary Research Papers, Brief Reports, Review Articles, Systematic Reviews, Workshop Reports, Letters to the Editor and Obituaries.
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