Divergent effects of intrinsically active MEK variants on developmental Ras signaling.
Divergent effects of intrinsically active MEK variants on developmental Ras signaling.
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DOI：
10.1038/ng.3780
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发表时间：
2017-03
期刊：
影响因子：
30.8
通讯作者：
Shvartsman SY
中科院分区：
文献类型：
--
作者：
Goyal Y;Jindal GA;Pelliccia JL;Yamaya K;Yeung E;Futran AS;Burdine RD;Schüpbach T;Shvartsman SY
Ras通路组分中的种系突变与一大类人类发育异常相关，统称为RASopathies，其特征在于一系列结构和功能表型，包括心脏缺陷和神经认知延迟1，2。虽然人们普遍认为RASopathies是由通路激活水平的改变引起的，但发育组织中信号变化的性质在很大程度上仍然未知3，4。我们在果蝇（果蝇）和斑马鱼（斑马鱼）中使用时空分辨率的测定来量化MEK突变引起的信号变化，MEK是Ras途径的核心组成部分，在RASopathies和癌症中都发生了突变5，6。令人惊讶的是，我们发现MEK的固有活性变体可以增加和减少体内途径激活的水平。该效应的迹象取决于细胞环境，并暗示RASopathies中出现的一些表型可能是由Ras信号传导水平的增加以及减弱引起的MEK是一种普遍表达的激酶，其保持无活性，直到其响应于细胞外信号而磷酸化，例如受体酪氨酸激酶（RTK）的局部分泌配体7。反映RTK激活的模式，MEK的活性在空间和时间上都受到调节，从而对其直接底物细胞外信号调节激酶（ERK）的激活提供严格控制。培养细胞的研究表明，在患有RASopathies和癌症的个体中鉴定的MEK变体即使在没有上游信号的情况下也是活跃的5，6。为了更直接地检验这种可能性，我们重建了包含纯化的ERK 2、MEK 1变体和ATP的生化系统（图1a、B）。我们发现，五分之四的检查疾病相关变体引起强烈的ERK 2磷酸化（dpERK）（图1c，补充图1和补充表1，2）。这一结果确立了这些突变的内在活性，并表明一些突变可能是由基因突变引起的。
Germline mutations in the Ras pathway components are associated with a large class of human developmental abnormalities, collectively known as RASopathies, and characterized by a range of structural and functional phenotypes, including cardiac defects and neurocognitive delays1, 2. While it is generally believed that RASopathies are caused by altered levels of pathway activation, the nature of signaling changes in developing tissues remains largely unknown3, 4. We used assays with spatiotemporal resolution in Drosophila melanogaster (fruit fly) and Danio rerio (zebrafish) to quantify signaling changes caused by mutations in MEK, a core component of the Ras pathway, which is mutated in both RASopathies and cancers5, 6. Surprisingly, we discovered that intrinsically active variants of MEK can both increase and reduce the levels of pathway activation in vivo. The sign of the effect depends on cellular context and implies that some of the emerging phenotypes in RASopathies may be caused by increased, as well as attenuated, levels of Ras signaling.MEK is a ubiquitously expressed kinase that remains inactive until it is phosphorylated in response to extracellular signals, such as locally secreted ligands of receptor tyrosine kinases (RTKs) 7. Reflecting the patterns of RTK activation, the activity of MEK is regulated in both space and time, providing tight control of the activation of its direct substrate, the extracellular signal-regulated kinase (ERK). Studies with cultured cells suggest that MEK variants identified in individuals with RASopathies and cancers are active even without upstream signals5, 6. To examine this possibility more directly, we reconstituted a biochemical system comprising purified ERK2, variants of MEK1, and ATP (Fig. 1a, b). We found that four out of five examined disease-related variants cause strong ERK2 phosphorylation (dpERK)(Fig. 1c, Supplementary Fig. 1 and Supplementary Tables 1, 2). This result establishes the intrinsic activity of these mutations and suggests that some of
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DOI：
10.1002/ajmg.a.36863
发表时间：
2015-03
期刊：
American journal of medical genetics. Part A
影响因子：
--
作者：
Gripp KW;Robbins KM;Sobreira NL;Witmer PD;Bird LM;Avela K;Makitie O;Alves D;Hogue JS;Zackai EH;Doheny KF;Stabley DL;Sol-Church K
通讯作者：
Sol-Church K
影响因子：
64.8
作者：
KLINGLER, M;ERDELYI, M;NUSSLEINVOLHARD, C
通讯作者：
NUSSLEINVOLHARD, C
影响因子：
56.9
作者：
STRECKER, TR;HALSELL, SR;LIPSHITZ, HD
通讯作者：
LIPSHITZ, HD
影响因子：
4.3
作者：
Jindal GA;Goyal Y;Burdine RD;Rauen KA;Shvartsman SY
通讯作者：
Shvartsman SY
影响因子：
30.8
作者：
Tartaglia, M;Mehler, EL;Gelb, BD
通讯作者：
Gelb, BD