Effect of Calcium on the Oxidative Phosphorylation Cascade in Skeletal Muscle Mitochondria
Effect of Calcium on the Oxidative Phosphorylation Cascade in Skeletal Muscle Mitochondria
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DOI：
10.1021/bi3015983
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发表时间：
2013-04-23
期刊：
影响因子：
2.9
通讯作者：
Balaban, Robert S.
中科院分区：
文献类型：
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作者：
Glancy, Brian;Willis, Wayne T.;Balaban, Robert S.
钙被认为调节线粒体氧化磷酸化，从而有助于维持细胞能量稳态。骨骼肌的能量转换动态范围高达100倍，是评估ATP生产和消耗的细胞平衡的极端情况。本研究探讨了钙离子在整个氧化磷酸化反应网络中的作用，在分离的骨骼肌线粒体，并试图将这些结果外推回肌肉，在体内。采用动力学分析方法研究了Ca~（2+）对细胞氧化磷酸化最大速率（V-maxO）和ADP亲和力的剂量-反应效应。力流分析评价了能量驱动力和通量之间的相互作用，以确定氧化磷酸化内各个步骤的电导或有效活性。将测量的驱动力[线粒体外磷酸化电位（Δ G（ATP））、膜电位和NADH和细胞色素B（H）、B（1）、c（1）、c和a、a（3）的氧化还原状态]与37 ℃下的通量（耗氧量）进行比较; 840 nM Ca 2+产生了类似于2倍的V-maxO增加，而ADP亲和力没有变化（类似于43 μ M）。力流分析表明，Ca2+激活V-maxO分布在整个氧化磷酸化反应序列。具体地，Ca 2+增加复合物IV（2.3倍）、复合物I和III（2.2倍）、ATP产生/运输（24倍）和燃料运输/脱氢酶（1.7倍）的电导。这些数据支持的概念，钙激活整个肌肉氧化磷酸化级联反应，而这些数据的外推运动肌肉预测的一个显着的作用，钙2+在维持细胞能量稳态。
Calcium is believed to regulate mitochondrial oxidative phosphorylation, thereby contributing to the maintenance of cellular energy homeostasis. Skeletal muscle, with an energy conversion dynamic range of up to 100-fold, is an extreme case for evaluating the cellular balance of ATP production and consumption. This study examined the role of Ca2+ in the entire oxidative phosphorylation reaction network in isolated skeletal muscle mitochondria and attempted to extrapolate these results back to the muscle, in vivo. Kinetic analysis was conducted to evaluate the dose-response effect of Ca2+ on the maximal velocity of oxidative phosphorylation (V-maxO) and the ADP affinity. Force-flow analysis evaluated the interplay between energetic driving forces and flux to determine the conductance, or effective activity, of individual steps within oxidative phosphorylation. Measured driving forces [extramitochondrial phosphorylation potential (Delta G(ATP)), membrane potential, and redox states of NADH and cytochromes b(H), b(1), c(1), c, and a,a(3)] were compared with flux (oxygen consumption) at 37 degrees C; 840 nM Ca2+ generated an similar to 2-fold increase in V-maxO with no change in ADP affinity (similar to 43 mu M). Force flow analysis revealed that Ca2+ activation of V-maxO was distributed throughout the oxidative phosphorylation reaction sequence. Specifically, Ca2+ increased the conductance of Complex IV (2.3-fold), Complexes I and III (2.2-fold), ATP production/transport (24 fold), and fuel transport/dehydrogenases (1.7-fold). These data support the notion that Ca2+ activates the entire muscle oxidative phosphorylation cascade, while extrapolation of these data to the exercising muscle predicts a significant role of Ca2+ in maintaining cellular energy homeostasis.