FOXO transcription factors as critical regulators of intervertebral disc aging

摘要 年龄是椎间盘退变（IDD）的主要危险因素，IDD是慢性腰痛的主要原因。 椎间盘（IVD）细胞，特别是髓核（NP）细胞中的椎间盘相关变化被认为是 损害体内平衡并通过尚不清楚的机制导致组织变性。我们 我建议研究叉头盒O（FOXO）家族转录因子在IVD稳态中的作用 在老化过程中。这一建议的科学前提是：i）衰老是碘缺乏病的主要原因，但分子 IVD衰老的潜在机制仍然没有完全表征，ii）FOXO是IVD衰老的重要调节因子， 寿命和细胞稳态，但其在IVD稳态中的作用尚不清楚，iii）拟议的研究将 阐明FOXO在NP中的功能，并有可能对IVD生物学产生根本性的新见解， 衰老和退化。这一前提得到了我们初步研究的支持，研究显示， FOXO在退化的人IVD和老化过程中的小鼠IVD中的表达，以及条件性FOXO 在小鼠中的缺失导致自发的IVD变性。在本申请中，我们提出测试我们的 假设FOXO 1和FOXO 3是维持细胞内稳态和NP活力的关键因子 细胞在衰老过程中，其衰老相关的减少是IVD衰老的驱动因素，并增加IDD的风险 发展 拟议的研究将确定FOXO 1和FOXO 3在促进组织中NP稳态中的作用， 细胞和转录组水平。在目标1中，我们将研究调节FOXO 1的分子机制。 和FOXO 3表达以及定义人NP细胞中的FOXO信号传导网络，以鉴定 FOXO促进NP细胞功能和存活的精确途径。在第二个目标中，我们将研究年龄- 在具有可诱导的、NP特异性FOXO 1缺失的小鼠脊柱中的相关分子和结构变化， FOXO 3或所有FOXO亚型。在目标3中，我们将测试是否在成熟NP中恢复FOXO功能， 改善转基因小鼠模型中与年龄相关的退行性变化的严重性， 组织特异性FOXO 1或FOXO 3过表达。成功完成拟议项目将建立 FOXO 1和FOXO 3作为衰老过程中IVD稳态的关键调节因子。这些研究的结果将 导致开发旨在保护IVD结构和功能的新药理学干预措施 在老化过程中。

ABSTRACT Aging is a main risk factor for intervertebral disc degeneration (IDD), the main cause of chronic low back pain. Age-related changes in intervertebral disc (IVD) cells, particularly in the nucleus pulposus (NP), are thought to compromise homeostasis and lead to tissue degeneration by mechanisms that are not well understood. We propose to study the role of the Forkhead box O (FOXO) family of transcription factors in IVD homeostasis during aging. The scientific premise of this proposal is that: i) aging is a main cause of IDD but the molecular mechanisms underlying IVD aging remain incompletely characterized, ii) FOXO are important regulators of lifespan and cell homeostasis but their role in IVD homeostasis is unknown, iii) the proposed studies will elucidate the function of FOXO in NP and have potential to generate fundamental new insight into IVD biology, aging and degeneration. This premise is supported by our preliminary studies that revealed a reduction in FOXO expression in degenerated human IVD and in mouse IVD during aging, and that conditional FOXO deletion in mice led to spontaneous IVD degeneration. In the present application we propose to test our hypothesis that FOXO1 and FOXO3 are critical factors in maintaining cellular homeostasis and viability of NP cells during aging and that their aging-related reduction is a driver of IVD aging and increases the risk for IDD development. The proposed studies will define the role of FOXO1 and FOXO3 in promoting NP homeostasis at the tissue, cellular and transcriptomic levels. In Aim 1, we will investigate the molecular mechanisms that regulate FOXO1 and FOXO3 expression as well as define the FOXO signaling network in in human NP cells to identify the precise pathways whereby FOXO promote NP cell function and survival. In Aim 2, we will investigate the age- related molecular and structural changes in the spines of mice with inducible, NP-specific deletion of FOXO1, FOXO3 or all FOXO isoforms. In Aim 3, we will test whether restoring FOXO function in mature NP ameliorates the severity of age-related degenerative changes in a transgenic mouse model with inducible, tissue-specific FOXO1 or FOXO3 overexpression. Successful completion of the proposed project will establish FOXO1 and FOXO3 as critical regulators of IVD homeostasis during aging. Outcomes from these studies will lead to the development of new pharmacological interventions aimed at preserving IVD structure and function during aging.