The nutrient-responsive CDK Pho85 primes the Sch9 kinase for its activation by TORC1.
The nutrient-responsive CDK Pho85 primes the Sch9 kinase for its activation by TORC1.
复制标题
DOI：
10.1371/journal.pgen.1010641
复制
发表时间：
2023-02
期刊：
影响因子：
4.5
通讯作者：
中科院分区：
文献类型：
--
作者：
酵母细胞维持着复杂的营养信号通路网络，使它们能够整合有关不同营养物质可用性的信息，并相应地调整其代谢和生长。不再能够整合这些信息或无法进行必要的适应的细胞将停止生长并最终死亡。在这里，我们研究了蛋白激酶 Sch9 的缺失引起的合成致死的分子基础，蛋白激酶 Sch9 是氨基酸信号传导的关键参与者，也是保守的生长调节 TORC1 复合物的近端效应器，当与细胞周期蛋白依赖性激酶 (CDK) Pho85 的缺失或其抑制剂 Pho81 的缺失相结合时，两者都在磷酸盐传感和细胞周期调节中发挥着关键作用。我们证明，当 Sch9 缺失时，CDK 细胞周期蛋白对 Pho85-Pho80 或部分冗余的 CDK 细胞周期蛋白对 Pho85-Pcl6/Pcl7 对生长至关重要。有趣的是，这三个 CDK-细胞周期蛋白对分别调节内体和液泡上磷脂酰肌醇 3 磷酸 5 激酶 Fab1 的活性和分布，在其中生成磷脂酰肌醇 3,5 二磷酸，用于招募 TORC1 及其底物 Sch9。此外，Pho85-Pho80 直接在 Ser726 处磷酸化 Sch9，并在 Thr723 处进行较小程度的磷酸化，从而引发 Sch9 随后被 TORC1 磷酸化和激活。因此，TORC1-Sch9 信号传导分支在不同水平上整合了 Pho85 介导的信息。在这种情况下，我们还发现转录因子 Pho4 的缺失挽救了由 Pho85 和 Sch9 缺失引起的合成致死性，这表明这两条信号通路也汇聚在 Pho4 上，Pho4 似乎连接到一个涉及高亲和力磷酸盐转运蛋白 Pho84 的反馈环路，可微调 Sch9 介导的反应。细胞拥有不同的信号通路来感知和发出营养物质可用性的信号。这些途径之间的串扰对于整合传入信号并使细胞做出适当的适应以维持其新陈代谢和增殖至关重要。在这项研究中，我们破译了酵母中两条众所周知的营养响应途径之间的串扰，即通过细胞周期蛋白依赖性蛋白激酶 Pho85 发出磷酸盐可用性信号的 PHO 信号通路，以及通过其下游效应激酶 Sch9 传达游离氨基酸可用性信息的 TORC1 信号通路。我们发现 Pho85 通过两种不同的机制促进 Sch9 的 TORC1 依赖性激活。通过干扰脂质磷脂酰肌醇-3,5二磷酸的生物合成，Pho85 控制液泡膜上 Sch9 的募集，从而使该效应子与 TORC1 非常接近。此外，Pho85 还直接磷酸化 Sch9，从而为后者随后被 TORC1 磷酸化和激活做好准备。相反，我们提供的证据表明，TORC1-Sch9 轴通过抑制转录因子 Pho4 的核转位向 PHO 通路提供反馈，Pho4 控制维持磷酸盐稳态所需的编码蛋白质的基因表达。
Yeast cells maintain an intricate network of nutrient signaling pathways enabling them to integrate information on the availability of different nutrients and adjust their metabolism and growth accordingly. Cells that are no longer capable of integrating this information, or that are unable to make the necessary adaptations, will cease growth and eventually die. Here, we studied the molecular basis underlying the synthetic lethality caused by loss of the protein kinase Sch9, a key player in amino acid signaling and proximal effector of the conserved growth-regulatory TORC1 complex, when combined with either loss of the cyclin-dependent kinase (CDK) Pho85 or loss of its inhibitor Pho81, which both have pivotal roles in phosphate sensing and cell cycle regulation. We demonstrate that it is specifically the CDK-cyclin pair Pho85-Pho80 or the partially redundant CDK-cyclin pairs Pho85-Pcl6/Pcl7 that become essential for growth when Sch9 is absent. Interestingly, the respective three CDK-cyclin pairs regulate the activity and distribution of the phosphatidylinositol-3 phosphate 5-kinase Fab1 on endosomes and vacuoles, where it generates phosphatidylinositol-3,5 bisphosphate that serves to recruit both TORC1 and its substrate Sch9. In addition, Pho85-Pho80 directly phosphorylates Sch9 at Ser726, and to a lesser extent at Thr723, thereby priming Sch9 for its subsequent phosphorylation and activation by TORC1. The TORC1-Sch9 signaling branch therefore integrates Pho85-mediated information at different levels. In this context, we also discovered that loss of the transcription factor Pho4 rescued the synthetic lethality caused by loss of Pho85 and Sch9, indicating that both signaling pathways also converge on Pho4, which appears to be wired to a feedback loop involving the high-affinity phosphate transporter Pho84 that fine-tunes Sch9-mediated responses. Cells possess different signaling pathways that sense and signal the availability of nutrients. Crosstalk between these pathways is essential to integrate the incoming signals and allow cells to make appropriate adaptations to sustain their metabolism and proliferation. In this study, we deciphered the crosstalk between two well-known nutrient-responsive pathways in yeast, namely the PHO pathway that signals the availability of phosphate via the cyclin-dependent protein kinase Pho85, and the TORC1 signaling pathway that communicates information on the availability of free amino acids via its downstream effector kinase Sch9. We show that Pho85 facilitates the TORC1-dependent activation of Sch9 through two different mechanisms. By interfering with the biosynthesis of the lipid phosphatidylinositol-3,5 bisphosphate, Pho85 controls the recruitment of Sch9 at the vacuolar membrane, thereby bringing this effector in close proximity to TORC1. In addition, Pho85 also directly phosphorylates Sch9, which primes the latter for its subsequent phosphorylation and activation by TORC1. Conversely, we provide evidence that the TORC1-Sch9 axis gives feedback to the PHO pathway by restraining the nuclear translocation of the transcription factor Pho4 that controls the expression of genes encoding proteins required to maintain phosphate homeostasis.
登录
查看更多内容
影响因子：
4.1
作者：
Ghillebert, Ruben;Swinnen, Erwin;Winderickx, Joris
通讯作者：
Winderickx, Joris
DOI：
10.1002/yea.3680
发表时间：
2022-03
期刊：
Yeast (Chichester, England)
影响因子：
--
作者：
通讯作者：
--
影响因子：
16
作者：
Baskaran, Sulochanadevi;Ragusa, Michael J.;Boura, Evzen;Hurley, James H.
通讯作者：
Hurley, James H.
DOI：
10.1083/jcb.143.1.65
发表时间：
1998-10-05
期刊：
The Journal of cell biology
影响因子：
--
作者：
Gary JD;Wurmser AE;Bonangelino CJ;Weisman LS;Emr SD
通讯作者：
Emr SD
影响因子：
56.9
作者：
Fabrizio, P;Pozza, F;Longo, VD
通讯作者：
Longo, VD