Boyko Alexandra I, Karlina Irina S, Zavileyskiy Lev G, Aleshin Vasily A, Artiukhov Artem V, Kaehne Thilo, Ksenofontov Alexander L, Ryabov Sergey I, Graf Anastasia V, Tramonti Angela, Bunik Victoria I
Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia.
N.V. Sklifosovsky Institute of Clinical Medicine, Sechenov First Moscow State Medical University, Moscow, Russia.
Front Med (Lausanne). 2022 Jun 1;9:896263. doi: 10.3389/fmed.2022.896263. eCollection 2022.
The -encoded 2-oxoadipate dehydrogenase (OADH) oxidizes 2-oxoadipate-a common intermediate of the lysine and tryptophan catabolism. The mostly low and cell-specific flux through these pathways, and similar activities of OADH and ubiquitously expressed 2-oxoglutarate dehydrogenase (OGDH), agree with often asymptomatic phenotypes of heterozygous mutations in the gene. Nevertheless, OADH/ are linked to impaired insulin sensitivity, cardiovascular disease risks, and Charcot-Marie-Tooth neuropathy. We hypothesize that systemic significance of OADH relies on its generation of glutaryl residues for protein glutarylation. Using pharmacological inhibition of OADH and the animal model of spinal cord injury (SCI), we explore this hypothesis.
The weight-drop model of SCI, a single intranasal administration of an OADH-directed inhibitor trimethyl adipoyl phosphonate (TMAP), and quantification of the associated metabolic changes in the rat brain employ established methods.
The TMAP-induced metabolic changes in the brain of the control, laminectomized (LE) and SCI rats are long-term and (patho)physiology-dependent. Increased glutarylation of the brain proteins, proportional to OADH expression in the control and LE rats, represents a long-term consequence of the OADH inhibition. The proportionality suggests autoglutarylation of OADH, supported by our mass-spectrometric identification of glutarylated K155 and K818 in recombinant human OADH. In SCI rats, TMAP increases glutarylation of the brain proteins more than OADH expression, inducing a strong perturbation in the brain glutathione metabolism. The redox metabolism is not perturbed by TMAP in LE animals, where the inhibition of OADH increases expression of deglutarylase sirtuin 5. The results reveal the glutarylation-imposed control of the brain glutathione metabolism. Glutarylation of the ODP2 subunit of pyruvate dehydrogenase complex at K451 is detected in the rat brain, linking the OADH function to the brain glucose oxidation essential for the redox state. Short-term inhibition of OADH by TMAP administration manifests in increased levels of tryptophan and decreased levels of sirtuins 5 and 3 in the brain.
Pharmacological inhibition of OADH affects acylation system of the brain, causing long-term, (patho)physiology-dependent changes in the expression of OADH and sirtuin 5, protein glutarylation and glutathione metabolism. The identified glutarylation of ODP2 subunit of pyruvate dehydrogenase complex provides a molecular mechanism of the OADH association with diabetes.
α-酮己二酸脱氢酶（OADH）由 基因编码，可氧化α-酮己二酸，它是赖氨酸和色氨酸分解代谢的常见中间产物。这些代谢途径的通量大多较低且具有细胞特异性，同时 OADH 和普遍表达的α-酮戊二酸脱氢酶（OGDH）具有相似的活性，这与该基因杂合突变的常见无症状表型相符。然而，OADH/ 与胰岛素敏感性受损、心血管疾病风险以及夏科 - 马里 - 图斯神经病变有关。我们推测 OADH 的全身重要性依赖于其为蛋白质戊二酰化生成戊二酰基残基。我们使用 OADH 的药理学抑制剂以及脊髓损伤（SCI）动物模型来探究这一假设。
采用 SCI 的重物坠落模型、单次鼻内给予 OADH 定向抑制剂三甲基己二酰膦酸酯（TMAP），并运用既定方法对大鼠脑内相关代谢变化进行定量分析。
TMAP 诱导的对照组、椎板切除术（LE）组和 SCI 组大鼠脑内的代谢变化是长期的且依赖于（病理）生理学状态。脑蛋白戊二酰化增加，在对照组和 LE 组大鼠中与 OADH 表达成比例，这是 OADH 抑制的长期后果。这种比例关系表明 OADH 存在自身戊二酰化，我们通过质谱鉴定重组人 OADH 中的戊二酰化 K155 和 K818 对此提供了支持。在 SCI 大鼠中，TMAP 使脑蛋白戊二酰化增加的幅度超过 OADH 表达增加的幅度，从而在脑谷胱甘肽代谢中引发强烈扰动。在 LE 动物中，氧化还原代谢未受到 TMAP 的干扰，在这些动物中 OADH 的抑制会增加去戊二酰化酶沉默调节蛋白 5 的表达。这些结果揭示了戊二酰化对脑谷胱甘肽代谢的调控作用。在大鼠脑中检测到丙酮酸脱氢酶复合物的 ODP2 亚基在 K451 处发生戊二酰化，这将 OADH 的功能与维持氧化还原状态所必需的脑葡萄糖氧化联系起来。通过给予 TMAP 短期抑制 OADH 表现为脑内色氨酸水平升高以及沉默调节蛋白 5 和 3 的水平降低。
OADH 的药理学抑制会影响脑的酰化系统，导致 OADH 和沉默调节蛋白 5 的表达、蛋白质戊二酰化以及谷胱甘肽代谢发生长期的（病理）生理学依赖性变化。所鉴定的丙酮酸脱氢酶复合物 ODP2 亚基的戊二酰化为 OADH 与糖尿病的关联提供了分子机制。
