Lactate oxidative phosphorylation by annulus fibrosus cells: evidence for lactate-dependent metabolic symbiosis in intervertebral discs.
Lactate oxidative phosphorylation by annulus fibrosus cells: evidence for lactate-dependent metabolic symbiosis in intervertebral discs.
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纤维环细胞的乳酸氧化磷酸化：椎间盘中乳酸依赖性代谢共生的证据。
DOI：
10.1186/s13075-021-02501-2
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发表时间：
2021-05-21
影响因子：
4.9
通讯作者：
Vo N
中科院分区：
文献类型：
--
作者：
Wang D;Hartman R;Han C;Zhou CM;Couch B;Malkamaki M;Roginskaya V;Van Houten B;Mullett SJ;Wendell SG;Jurczak MJ;Kang J;Lee J;Sowa G;Vo N
椎间盘退变导致腰痛。无血管椎间盘由中央缺氧髓核（NP）和含氧较多的纤维环（AF）所包围。乳酸是NP糖酵解的一种丰富的最终产物，长期以来被认为是一种有害的废物，它会使椎间盘组织酸化，降低细胞活力和功能。由于乳酸在椎间盘组织中很容易转化为乳酸，本研究的目的是确定乳酸是否可以被AF细胞用作碳源，而不是作为废物副产品从椎间盘组织中清除。采用质谱法重同位素（13c -乳酸）示踪实验，测定兔房颤细胞中乳酸向三羧酸（TCA）循环中间体和氨基酸的输入和转化。Western blots检测NP和AF组织中乳酸转化酶、乳酸输入酶和乳酸输出酶的蛋白表达水平。采用海马XFe96细胞外通量分析仪（Extracellular Flux Analyzer）测定乳酸对AF细胞中蛋白聚糖（35s -硫酸盐）和胶原（3h -脯氨酸）基质蛋白合成和氧化磷酸化的影响。重同位素示踪实验表明，体外细胞培养和体内模型显示AF细胞导入乳酸并将乳酸转化为TCA循环中间体和氨基酸。在生理氧（2-5% O2）和葡萄糖浓度（1-5mM）下培养的AF细胞中，在培养基中添加外源性乳酸（4mM）诱导了乳酸输入基因MCT1的表达，使耗氧量提高了50%，线粒体atp相关呼吸提高了30%，胶原合成提高了50%。AF组织高度表达MCT1、LDH-H（一种优先将乳酸转化为丙酮酸的酶）和PDH（一种将丙酮酸转化为乙酰辅酶a的酶）。相反，NP组织高度表达MCT4（一种乳酸出口者）和LDH-M（一种优先将丙酮酸转化为乳酸的酶）。这些发现支持了盘状乳酸依赖的代谢共生关系，在这种共生关系中，缺氧糖酵解NP细胞产生的乳酸通过氧化磷酸化被更富氧的AF细胞利用，以产生能量和基质，从而改变了目前将盘状乳酸视为废物的研究范式，将其视为重要的生物燃料。这些具有科学影响的结果为椎间盘代谢和退变提供了新的治疗靶点。在线版本包含补充材料，可在10.1186/s13075-021-02501-2获得。
Intervertebral disc degeneration contributes to low back pain. The avascular intervertebral disc consists of a central hypoxic nucleus pulpous (NP) surrounded by the more oxygenated annulus fibrosus (AF). Lactic acid, an abundant end-product of NP glycolysis, has long been viewed as a harmful waste that acidifies disc tissue and decreases cell viability and function. As lactic acid is readily converted into lactate in disc tissue, the objective of this study was to determine whether lactate could be used by AF cells as a carbon source rather than being removed from disc tissue as a waste byproduct. Import and conversion of lactate to tricarboxylic acid (TCA) cycle intermediates and amino acids in rabbit AF cells were measured by heavy-isotope (13C-lactate) tracing experiments using mass spectrometry. Levels of protein expression of lactate converting enzymes, lactate importer and exporter in NP and AF tissues were quantified by Western blots. Effects of lactate on proteoglycan (35S-sulfate) and collagen (3H-proline) matrix protein synthesis and oxidative phosphorylation (Seahorse XFe96 Extracellular Flux Analyzer) in AF cells were assessed. Heavy-isotope tracing experiments revealed that AF cells imported and converted lactate into TCA cycle intermediates and amino acids using in vitro cell culture and in vivo models. Addition of exogenous lactate (4mM) in culture media induced expression of the lactate importer MCT1 and increased oxygen consumption rate by 50%, mitochondrial ATP-linked respiration by 30%, and collagen synthesis by 50% in AF cell cultures grown under physiologic oxygen (2-5% O2) and glucose concentration (1-5mM). AF tissue highly expresses MCT1, LDH-H, an enzyme that preferentially converts lactate to pyruvate, and PDH, an enzyme that converts pyruvate to acetyl-coA. In contrast, NP tissue highly expresses MCT4, a lactate exporter, and LDH-M, an enzyme that preferentially converts pyruvate to lactate. These findings support disc lactate-dependent metabolic symbiosis in which lactate produced by the hypoxic, glycolytic NP cells is utilized by the more oxygenated AF cells via oxidative phosphorylation for energy and matrix production, thus shifting the current research paradigm of viewing disc lactate as a waste product to considering it as an important biofuel. These scientifically impactful results suggest novel therapeutic targets in disc metabolism and degeneration. The online version contains supplementary material available at 10.1186/s13075-021-02501-2.
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影响因子：
4.3
作者：
Draoui N;Feron O
通讯作者：
Feron O
影响因子：
2.8
作者：
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4.1
作者：
Dimmer, KS;Friedrich, B;Bröer, S
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Alves TC;Pongratz RL;Zhao X;Yarborough O;Sereda S;Shirihai O;Cline GW;Mason G;Kibbey RG
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影响因子：
2.8
作者：
Gruber, Helen E.;Watts, John A.;Hanley, Edward N., Jr.
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