在许多癌症中观察到众所周知的肿瘤抑制因子PTEN的突变。PTEN是一种双特异性磷酸酶,具有脂质和蛋白质磷酸酶活性。秀丽隐杆线虫PTEN直系同源物是daf-18,对dauer形成具有多效性作用,老化,耐饥饿,和发展。3个daf-18点突变体的功能,G174E,D137A,C169S,以前曾在daf-18空背景下使用高拷贝转基因进行过研究。这些等位基因是基于它们的哺乳动物对应物产生的,并且被视为它们特异性破坏脂质或蛋白质磷酸酶活性,或者两者兼而有之,分别。这里,我们使用内源性daf-18的基因组编辑研究了这些等位基因。我们测定了与L1饥饿抗性相关的3个性状,我们表明,每个点突变体基本上与daf-18空突变体一样对饥饿敏感。此外,我们发现G174E和D137A不是互补的,提示对脂质和蛋白磷酸酶活性的重叠作用。我们还表明,每个等位基因对DAF-16/FoxO的核质定位和dauer形成有强烈的影响,两者均受PI3K信号调节,类似于daf-18无效等位基因.此外,每个等位基因在L1饥饿期间也会破坏M细胞的静止,尽管D137A的作用比其他等位基因弱,包括null。我们的结果证实,daf-18/PTEN对于促进饥饿抗性和发育停滞很重要,并且它是PI3K信号传导的有效调节剂,他们强调了使用遗传分析将特定的DAF-18/PTEN酶活性与特定表型联系起来的挑战。
Mutations in the well-known tumor suppressor PTEN are observed in many cancers. PTEN is a dual-specificity phosphatase that harbors lipid and protein-phosphatase activities. The Caenorhabditis elegans PTEN ortholog is daf-18, which has pleiotropic effects on dauer formation, aging, starvation resistance, and development. Function of 3 daf-18 point-mutants, G174E, D137A, and C169S, had previously been investigated using high-copy transgenes in a daf-18 null background. These alleles were generated based on their mammalian counterparts and were treated as though they specifically disrupt lipid or protein-phosphatase activity, or both, respectively. Here, we investigated these alleles using genome editing of endogenous daf-18. We assayed 3 traits relevant to L1 starvation resistance, and we show that each point mutant is essentially as starvation-sensitive as a daf-18 null mutant. Furthermore, we show that G174E and D137A do not complement each other, suggesting overlapping effects on lipid and protein-phosphatase activity. We also show that each allele has strong effects on nucleocytoplasmic localization of DAF-16/FoxO and dauer formation, both of which are regulated by PI3K signaling, similar to a daf-18 null allele. In addition, each allele also disrupts M-cell quiescence during L1 starvation, though D137A has a weaker effect than the other alleles, including the null. Our results confirm that daf-18/PTEN is important for promoting starvation resistance and developmental arrest and that it is a potent regulator of PI3K signaling, and they highlight challenges of using genetic analysis to link specific DAF-18/PTEN enzymatic activities to particular phenotypes.