A novel cilium-to-nucleus axis promotes cellular senescence

项目摘要 细胞衰老是一种程序性的生长停滞，由不可修复的外在或内在应激激活。 衰老在某些情况下是有益的，例如胚胎发育期间的组织稳态。 发展或肿瘤抑制。然而，如果由衰老细胞持续分泌， 细胞因子、趋化因子、蛋白酶和生长因子实际上是衰老和年龄相关性疾病的主要驱动因素。 疾病，矛盾的是，促进肿瘤发生。衰老细胞的遗传或药理学清除 有效地提高了啮齿动物模型的寿命和健康寿命。因此，针对衰老已经成为 预防或治疗衰老合并症和癌症的有希望的治疗策略。然而， 在应激细胞中诱导和维持不可逆的衰老程序仍然知之甚少。 细胞利用初级纤毛将环境信号转化为不同的细胞信号， 增殖、分化和组织稳态。纤毛功能障碍导致广泛的综合征 统称为纤毛病的疾病。通过辐射，我们发现， 成纤维细胞或上皮细胞表现出短暂的纤毛生物发生。引人注目的是，FBF 1，一种过渡纤维的成分， (TFs)在睫状体基部，意外地易位到早幼粒细胞白血病核小体（PML-NB）， 应激细胞PML-NBs是高度动态的蛋白质核结构，在细胞内具有工具性作用。 调节应激诱导的反应，包括衰老和凋亡。FBF 1有效耗竭 消除应激诱导的PML-NB上调和相关的衰老起始，而FBF 1 过表达显示出相反的效果。我们的初步研究表明，应激诱导的PML-NB FBF 1的易位受不同纤毛模块调节，所述纤毛模块包括Joubert综合征蛋白ARL 3和 ARL 13 B和SUMO缀合酶UBC 9。进一步的蛋白质组学研究揭示了新的FBF 1 在PML-NB生物发生和/或功能中涉及的相互作用物（PML、53 BP 1和BRD 4）。值得注意的是， Fbf 1 tm 1a/tm 1a小鼠在整个生命过程中表现出显著降低的衰老负担，并且可以进一步 防止辐射引起的脆弱。因此，我们的初步数据提出了一个令人兴奋的范例， 应激诱导睫状蛋白FBF 1 TF-到-PML-NB易位是衰老所必需的 在哺乳动物细胞中的起始。在这里，我们建议使用互补的方法来解决机械 问题，包括纤毛ARL 3-ARL 13 B-UBC 9模块如何调节FBF 1 SUMO化和PML-NB 易位（Aim 1），以及PML-NB相关的FBF 1如何促进应激细胞的衰老（Aim 2）。 结合FBF 1通路在体内衰老中的生理重要性的扩展分析， 小鼠模型（Aim 3），该项目将有可能将基本发现与下一代 用于预防或治疗衰老相关病理的治疗策略。

Project Summary Cellular senescence is a programmed growth arrest activated by irreparable extrinsic or intrinsic stresses. Senescence can be beneficial in certain circumstances, such as tissue homeostasis during embryonic development or tumor suppression. However, if persistently secreted by senescent cells, the proinflammatory cytokines, chemokines, proteases, and growth factors are actually major drivers for aging and age-associated diseases and, paradoxically, promote tumorigenesis. Genetic or pharmacological clearance of senescent cells effectively improves lifespan and healthspan in rodent models. As such, targeting senescence has emerged as a promising therapeutic strategy to prevent or treat aging comorbidities and cancer. However, how the irreversible senescence program is induced and maintained in stressed cells remains poorly understood. Cells utilize primary cilia to convert environmental cues into diverse cellular signalings that govern proliferation, differentiation, and tissue homeostasis. Cilia dysfunction leads to a wide spectrum of syndromic disorders that are collectively termed ciliopathies. Using irradiation, we discovered that stressed human fibroblasts or epithelial cells exhibit transient cilia biogenesis. Strikingly, FBF1, a component of transition fibers (TFs) at the ciliary base, unexpectedly translocates to promyelocytic leukaemia nuclear bodies (PML-NBs) in stressed cells. PML-NBs are highly dynamic proteinaceous nuclear structures with instrumental roles in regulating stress-induced responses, including senescence and apoptosis. FBF1 depletion effectively abolishes stress-induced PML-NB upregulation and associated senescence initiation, whereas FBF1 overexpression shows the opposite effects. Our initial studies indicated that the stress-induced PML-NB translocation of FBF1 is regulated by a distinct cilia module comprising Joubert syndrome proteins ARL3 and ARL13B and the SUMO-conjugating enzyme UBC9. Further proteomic studies revealed novel FBF1 interactors (PML, 53BP1, and BRD4) implicated in PML-NB biogenesis and/or function. Remarkably, Fbf1tm1a/tm1a mice exhibit a significantly reduced senescence burden throughout life and could be further protected against irradiation-induced frailty. Our preliminary data thus suggest an exciting paradigm that a stress-induced TF-to-PML-NB translocation of ciliary protein FBF1 is essential for senescence initiation in mammalian cells. Here, we propose to use complementary approaches to address mechanistic questions, including how the ciliary ARL3-ARL13B-UBC9 module regulates FBF1 SUMOylation and PML-NB translocation (Aim 1), and how PML-NB-associated FBF1 promotes senescence in stressed cells (Aim 2). Together with the extended analysis of the physiological importance of FBF1 pathway in in vivo senescence mouse models (Aim 3), this project will potentially bridge the fundamental discovery to the next generation of therapeutic strategies for preventing or treating senescence-associated pathologies.