Phosphoproteomic mapping reveals distinct signaling actions and activation of muscle protein synthesis by Isthmin-1.
Phosphoproteomic mapping reveals distinct signaling actions and activation of muscle protein synthesis by Isthmin-1.
复制标题
磷蛋白组学图谱揭示了Isthmin-1不同的信号作用和肌肉蛋白合成的激活。
DOI：
10.7554/elife.80014
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发表时间：
2022-09-28
期刊：
影响因子：
7.7
通讯作者：
Svensson KJ
中科院分区：
文献类型：
--
作者：
Zhao M;Banhos Danneskiold-Samsøe N;Ulicna L;Nguyen Q;Voilquin L;Lee DE;White JP;Jiang Z;Cuthbert N;Paramasivam S;Bielczyk-Maczynska E;Van Rechem C;Svensson KJ
分泌的蛋白质isthmin-1（Ism1）通过激活PI3K-Akt通路增加脂肪细胞和骨骼肌葡萄糖摄取来减轻糖尿病。然而，虽然Ism1和胰岛素都集中在这些共同的靶点上，但Ism1具有不同的细胞作用，表明下游细胞内信号传导途径存在分歧。为了了解Ism1信号传导的生物学复杂性，我们在急性暴露后进行了磷酸蛋白质组学分析，揭示了Ism1和胰岛素的重叠和不同的途径。我们确定了Ism1和胰岛素信号传导之间的53%重叠，以及Ism1介导的约450种蛋白质中不与胰岛素共享的磷酸化蛋白质组改变。有趣的是，我们发现了几个未知的磷酸化位点的蛋白质相关的蛋白质翻译，mTOR通路，并出乎意料地，肌肉功能的Ism1信号网络。在生理学上，小鼠中的Ism1消融导致蛋白质稳态改变，包括进食和禁食条件下肌肉蛋白质水平降低，蛋白质中氨基酸掺入减少，以及关键蛋白质合成效应物Akt和下游mTORC 1靶标的磷酸化减少。由于代谢紊乱如糖尿病与骨骼肌蛋白含量的加速损失有关，这些研究定义了这种抗糖尿病循环蛋白控制肌肉生物学的非经典机制。细胞需要能量来生存并在体内发挥作用。它们通过将糖等分子分解成可以促进蛋白质或脂质等新化合物产生的物质来实现这一点。这个过程，称为新陈代谢，涉及一系列相互联系的化学反应，这些反应被组织成途径。代谢途径包含催化每个顺序反应的蛋白质。激素可以通过添加一种称为磷酸盐的化学基团来改变这些蛋白质的活性。这种可逆的修饰可以主要影响细胞的代谢，导致身体组织的变化。例如，激素胰岛素改变了一个众所周知的代谢途径，触发骨骼肌细胞产生更多的蛋白质，导致肌肉更强壮，更大。2021年，一组科学家发现了一种由脂肪细胞产生的分子，称为Isthmin-1，也激活了这一途径中的成分。与胰岛素类似，Isthmin-1鼓励肌肉和脂肪细胞摄取糖。然而，它也可以防止肝脏积累多余的脂肪，这表明Isthmin-1可能会引发不同的分子级联反应。为了研究这种可能性，Zhao等人-包括参与2021年研究的一些研究人员-将实验室中生长的细胞暴露于Isthmin-1或胰岛素，并寻找其所有蛋白质上的磷酸盐。这表明只有53%的Isthmin-1修饰的蛋白质也被胰岛素改变。在Isthmin-1所特有的蛋白质中，有几种已知在肌肉细胞中制造和维持蛋白质的作用。为了更多地了解这种新发现的通路的作用，Zhao等人对小鼠进行了基因工程改造，使其缺乏编码Isthmin-1的基因。这降低了小鼠肌肉纤维的大小和强度，并减少了通常导致骨骼肌生长的信号。这些发现表明，Isthmin-1通过与胰岛素激活的代谢途径略有不同的代谢途径调节骨骼肌大小。许多代谢紊乱与肌肉损失有关，如糖尿病，这种新发现的蛋白质网络可以进一步了解如何预防和治疗这些疾病。
The secreted protein isthmin-1 (Ism1) mitigates diabetes by increasing adipocyte and skeletal muscle glucose uptake by activating the PI3K-Akt pathway. However, while both Ism1 and insulin converge on these common targets, Ism1 has distinct cellular actions suggesting divergence in downstream intracellular signaling pathways. To understand the biological complexity of Ism1 signaling, we performed phosphoproteomic analysis after acute exposure, revealing overlapping and distinct pathways of Ism1 and insulin. We identify a 53% overlap between Ism1 and insulin signaling and Ism1-mediated phosphoproteome-wide alterations in ~450 proteins that are not shared with insulin. Interestingly, we find several unknown phosphorylation sites on proteins related to protein translation, mTOR pathway, and, unexpectedly, muscle function in the Ism1 signaling network. Physiologically, Ism1 ablation in mice results in altered proteostasis, including lower muscle protein levels under fed and fasted conditions, reduced amino acid incorporation into proteins, and reduced phosphorylation of the key protein synthesis effectors Akt and downstream mTORC1 targets. As metabolic disorders such as diabetes are associated with accelerated loss of skeletal muscle protein content, these studies define a non-canonical mechanism by which this antidiabetic circulating protein controls muscle biology. Cells need energy to survive and carry out their role in the body. They do this by breaking down molecules, like sugar, into substances that can fuel the creation of new compounds, like proteins or lipids. This process, known as metabolism, involves a series of interconnecting chemical reactions which are organized into pathways. Metabolic pathways contain proteins that catalyze each sequential reaction. Hormones can change the activity of these proteins by adding a chemical group called a phosphate. This reversible modification can majorly impact the metabolism of cells, resulting in changes to the body’s tissues. The hormone insulin, for instance, alters a well-known metabolic pathway that triggers skeletal muscle cells to produce more proteins, leading to stronger and larger muscles. In 2021, a group of scientists discovered a molecule made by fat cells, called Isthmin-1, also activates components in this pathway. Similar to insulin, Isthmin-1 encourages muscle and fat cells to take up sugar. However, it also prevents the liver from accumulating excess fat, suggesting Isthmin-1 may trigger a different cascade of molecules to insulin. To investigate this possibility, Zhao et al. – including some of the researchers involved in the 2021 study – exposed cells grown in the laboratory to Isthmin-1 or insulin and looked for phosphates on all their proteins. This revealed that only 53% of the proteins Isthmin-1 modifies are also altered by insulin. Of the proteins unique to Isthmin-1, several had known roles in making and maintaining proteins in muscle cells. To understand more about the role of this newly discovered pathway, Zhao et al. genetically engineered mice to lack the gene that codes for Isthmin-1. This decreased the size and strength of the mice’s muscle fibers and reduced the signals that normally lead to skeletal muscle growth. These findings suggest that Isthmin-1 regulates skeletal muscle size via a metabolic pathway that is slightly different to the one activated by insulin. Many metabolic disorders are associated with muscle loss, like diabetes, and this newly discovered network of proteins could further our understanding of how to prevent and treat these diseases.