Redefining the mechanisms that promote healthy ageing downstream of HSF1

医学、卫生、社会保健和社会意识方面的进步，使生活到晚年的人数有所增加。虽然这是值得称赞的，但我们未能将健康寿命延长到类似的程度，导致患有与年龄有关的病症或疾病的人数随之增加。这给个人、家庭和社区造成了巨大的情感和经济压力，必须立即予以纠正。已知增加转录因子HSF1的活性，无论是药理学还是遗传学，都可以通过维持蛋白质组的完整性来抑制物种间的衰老。然而，HSF1下游保护老化蛋白质组和促进健康衰老的确切机制尚不清楚。解决这个问题至关重要，因为它将使我们能够开发出增强或模拟HSF1活性特定方面的治疗方法，从而促进健康衰老，而不会产生不必要的副作用。为了实现这一目标，我们使用秀丽隐杆线虫作为模型系统来筛选促进HSF1下游寿命延长的保守基因。通过这种方法，我们发现基因ubql-1（人类中的UBQLN1）对于hsf1介导的蠕虫寿命延长至关重要。Ubql-1编码蛋白泛素-1，泛素-1是通过内质网（ER）相关降解（ERAD）消除细胞中错误折叠蛋白的关键角色。ERAD允许细胞从内质网去除受损或错误折叠的蛋白质，并通过驻留在细胞质和细胞核中的蛋白酶体降解它们。在酵母、蠕虫和人类中，泛素-1已被证明可以通过细胞质转运内质网蛋白，并将它们与蛋白酶体偶联以降解。此外，已知HSF1活性的增加可以上调人类细胞中泛素1的水平，并且在秀丽隐杆线虫和小鼠中发现泛素1的水平随着年龄的增长而下降。这些观察结果提出了HSF1活性增加可能通过ERAD提高泛素-1水平和增强衰老细胞中错误折叠蛋白的消除来保护老化蛋白质组和延长健康组织功能的可能性。为了研究这一点，我们将模拟HSF1活性增加对秀丽隐杆线虫衰老的影响。结合遗传学方法、分子生物学技术和表型分析，我们将确定HSF1通过泛素-1抑制衰老的能力是否在不同的组织类型（肌肉、肠、神经元）中观察到，以及泛素-1水平的增加是否足以概括HSF1活性增加的抗衰老作用。此外，我们将确定hsf1 -泛素轴的促长寿效应是否通过ERAD增加衰老细胞中错误折叠蛋白的降解而介导。最后，我们将通过定义人类细胞中的hsf泛素网络来补充我们基于秀丽隐杆线虫的实验。与秀丽隐杆线虫相比，人类拥有两种广泛表达的hsf （HSF1和HSF2）和三种广泛表达的泛素（ubiquilin-1、2和4）。因此，我们将确定是否需要HSF2才能最大限度地表达泛素-1，并确定人类细胞中是否也受hsf调控泛素-2和泛素-4的表达。此外，我们将利用siRNA单独或联合干扰泛素，并确定ubiquilin-2和ubiquilin-4是否与HSF1-ubiquilin-1轴协同保护人类细胞中老化的蛋白质组。总之，这些实验将极大地扩展我们对蛋白质质量控制途径的理解，并重新定义HSF1与长寿之间关系的现有模型，从而为未来旨在开发促进人类健康衰老的泛素-1激活物或模拟物的工作奠定基础。

Advances in medicine, hygiene, social care and social awareness have resulted in an increase in the number of people living into late-life. While this is laudable, our failure to extend health span to a similar extent has resulted in a concomitant increase in the number of individuals suffering from age-associated morbidities or diseases. This is causing a significant emotional and financial strain on individuals, families, and communities that must be urgently corrected.Increasing the activity of the transcription factor HSF1, either pharmacologically or genetically, is known to suppress ageing across species by maintaining proteome integrity. However, the precise mechanisms that act downstream of HSF1 to protect the ageing proteome and promote healthy ageing are poorly understood. Addressing this is crucial, as it will allow us to develop therapeutics that enhance or mimic specific aspects of HSF1 activity, thereby promoting healthy ageing without causing unwanted side-effects.To realise this goal, we used the nematode worm Caenorhabditis elegans as a model system to screen for conserved genes that promote lifespan extension downstream of HSF1. Through this approach, we have discovered that the gene ubql-1 (UBQLN1 in humans) is crucial for HSF1-mediated lifespan extension in worms. Ubql-1 encodes the protein ubiquilin-1, a key player in the elimination of misfolded proteins from cells through endoplasmic reticulum (ER) associated degradation (ERAD). ERAD allows cells to remove damaged or misfolded proteins from the ER and degrade them via proteasomes, which reside in the cytosol and nucleus. Ubiquilin-1 has been shown to transport ER proteins through the cytosol and couple them with proteasomes for degradation in yeast, worms and humans. Furthermore, increased HSF1 activity is known to up-regulate levels of ubiquilin 1 in human cells, and levels of ubiquilin-1 have been found to decline with age in C. elegans and mice. These observations raise the possibility that increased HSF1 activity may safeguard the ageing proteome and prolong healthy tissue function by elevating ubiquilin-1 levels and enhancing the elimination of misfolded proteins from aged cells through ERAD. To investigate this, we will model the effects of increased HSF1 activity on ageing in C. elegans. Using a combination of genetic approaches, molecular biology techniques, and phenotypic assays, we will establish whether the ability of HSF1 to suppress ageing through ubiquilin-1 is observed in different tissue types (muscles, intestine, neurons), and whether increased ubiquilin-1 levels are sufficient to recapitulate the anti-ageing effects of increased HSF1 activity. In addition, we will determine if the pro-longevity effects of the HSF1-ubiquilin axis are mediated by increasing the degradation of misfolded proteins in aged cells through ERAD. Finally, we will complement our C. elegans-based experiments by defining the HSF-ubiquilin network in human cells. In contrast to C. elegans, humans possess two broadly expressed HSFs (HSF1 and HSF2) and three widely expressed ubiquilins (ubiquilin-1, 2, and 4). Therefore, we will ascertain whether HSF2 is required for maximal expression of ubiquilin-1 and determine if the expression of ubiquilin-2 and ubiquilin-4 is also regulated by HSFs in human cells. In addition, we will use siRNA to perturb ubiquilins, individually or in combination, and establish whether ubiquilin-2 and ubiquilin-4 cooperate with the HSF1-ubiquilin-1 axis to protect the ageing proteome in human cells. Together, these experiments will greatly expand our understanding of protein quality control pathways and redefine existing models of the relationship between HSF1 and longevity, thereby setting the stage for future work aimed at developing ubiquilin-1 activators or mimics that promote healthy ageing in humans.