Stumpf Miriam, den Hertog Jeroen
Hubrecht Institute, Koninklijke Nederlandse Akademie van Wetenschappen (KNAW) and University Medical Center Utrecht, Utrecht, the Netherlands.
Institute of Biology Leiden, Leiden University, Leiden, the Netherlands.
PLoS One. 2016 Feb 5;11(2):e0148508. doi: 10.1371/journal.pone.0148508. eCollection 2016.
The lipid- and protein phosphatase PTEN is one of the most frequently mutated tumor suppressor genes in human cancers and many mutations found in tumor samples directly affect PTEN phosphatase activity. In order to understand the functional consequences of these mutations in vivo, the aim of our study was to dissect the role of Pten phosphatase activities during zebrafish embryonic development. As in other model organisms, zebrafish mutants lacking functional Pten are embryonically lethal. Zebrafish have two pten genes and pten double homozygous zebrafish embryos develop a severe pleiotropic phenotype around 4 days post fertilization, which can be largely rescued by re-introduction of pten mRNA at the one-cell stage. We used this assay to characterize the rescue-capacity of Pten and variants with mutations that disrupt lipid, protein or both phosphatase activities. The pleiotropic phenotype at 4dpf could only be rescued by wild type Pten, indicating that both phosphatase activities are required for normal zebrafish embryonic development. An earlier aspect of the phenotype, hyperbranching of intersegmental vessels, however, was rescued by Pten that retained lipid phosphatase activity, independent of protein phosphatase activity. Lipid phosphatase activity was also required for moderating pAkt levels at 4 dpf. We propose that the role of Pten during angiogenesis mainly consists of suppressing PI3K signaling via its lipid phosphatase activity, whereas the complex process of embryonic development requires lipid and protein phosphatase of Pten.
脂质和蛋白质磷酸酶PTEN是人类癌症中最常发生突变的肿瘤抑制基因之一，在肿瘤样本中发现的许多突变直接影响PTEN磷酸酶活性。为了了解这些突变在体内的功能后果，我们研究的目的是剖析Pten磷酸酶活性在斑马鱼胚胎发育过程中的作用。与其他模式生物一样，缺乏功能性Pten的斑马鱼突变体在胚胎期致死。斑马鱼有两个pten基因，pten双纯合子斑马鱼胚胎在受精后约4天会出现严重的多效性表型，在单细胞阶段重新引入pten mRNA可在很大程度上挽救这种表型。我们利用这个实验来表征Pten和具有破坏脂质、蛋白质或两者磷酸酶活性突变的变体的挽救能力。4dpf时的多效性表型只能由野生型Pten挽救，这表明正常斑马鱼胚胎发育需要两种磷酸酶活性。然而，表型的一个早期方面，即节间血管的过度分支，可由保留脂质磷酸酶活性的Pten挽救，而与蛋白质磷酸酶活性无关。在4dpf时调节pAkt水平也需要脂质磷酸酶活性。我们提出，Pten在血管生成过程中的作用主要包括通过其脂质磷酸酶活性抑制PI3K信号传导，而胚胎发育的复杂过程需要Pten的脂质和蛋白质磷酸酶。
