Increased AMP deaminase activity decreases ATP content and slows protein degradation in cultured skeletal muscle
Increased AMP deaminase activity decreases ATP content and slows protein degradation in cultured skeletal muscle
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AMP 脱氨酶活性增加可降低培养骨骼肌中 ATP 含量并减缓蛋白质降解
DOI：
10.1016/j.metabol.2020.154257
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发表时间：
2020-07-01
影响因子：
9.8
通讯作者：
Brault, Jeffrey J.
中科院分区：
文献类型：
--
作者：
Davis, Patrick R.;Miller, Spencer G.;Brault, Jeffrey J.
背景蛋白质降解是一个能量依赖的过程，需要ATP参与多个步骤。然而，关于细胞内能量学与蛋白酶体介导的蛋白质降解速率之间的关系的报道相互矛盾。（ATP + ADP + AMP）影响肌肉细胞中的蛋白质降解，我们过表达AMP降解酶，AMP脱氨酶3（AMPD 3），结果AMPD 3的过表达导致总腺嘌呤核苷酸（ATP、ADP和AMP）的剂量和时间依赖性减少，而ADP/ATP或AMP/ATP比值不增加。在协议中，总腺嘌呤核苷酸浓度的减少并没有导致增加的Thr 172磷酸化的AMP-活化蛋白激酶（AMPK），细胞内能量状态的一个常见指标。此外，未诱导LC 3蛋白积累和ULK 1（Ser 555）磷酸化。然而，总体蛋白质降解和泛素依赖的蛋白质水解减缓过表达的AMPD 3，尽管不变的内容，几个蛋白酶体亚基蛋白和蛋白酶体活性在体外在标准conditions.ConclusionsAltogether，这些研究结果表明，生理相关的减少ATP含量，没有伴随增加ADP或AMP，足以降低肌肉细胞中蛋白质降解速率和遍在蛋白-蛋白酶体系统的活性。这表明，腺嘌呤核苷酸降解酶，如AMPD 3，可能是一个可行的目标，以控制肌肉蛋白质降解和肌肉质量。
BackgroundProtein degradation is an energy-dependent process, requiring ATP at multiple steps. However, reports conflict as to the relationship between intracellular energetics and the rate of proteasome-mediated protein degradation.MethodsTo determine whether the concentration of the adenine nucleotide pool (ATP + ADP + AMP) affects protein degradation in muscle cells, we overexpressed an AMP degrading enzyme, AMP deaminase 3 (AMPD3), via adenovirus in C2C12 myotubes.ResultsOverexpression of AMPD3 resulted in a dose- and time-dependent reduction of total adenine nucleotides (ATP, ADP and AMP) without increasing the ADP/ATP or AMP/ATP ratios. In agreement, the reduction of total adenine nucleotide concentration did not result in increased Thr172 phosphorylation of AMP-activated protein kinase (AMPK), a common indicator of intracellular energetic state. Furthermore, LC3 protein accumulation and ULK1 (Ser 555) phosphorylation were not induced. However, overall protein degradation and ubiquitin-dependent proteolysis were slowed by overexpression of AMPD3, despite unchanged content of several proteasome subunit proteins and proteasome activity in vitro under standard conditions.ConclusionsAltogether, these findings indicate that a physiologically relevant decrease in ATP content, without a concomitant increase in ADP or AMP, is sufficient to decrease the rate of protein degradation and activity of the ubiquitin-proteasome system in muscle cells. This suggests that adenine nucleotide degrading enzymes, such as AMPD3, may be a viable target to control muscle protein degradation and perhaps muscle mass.