Smad Signaling in Skeletal Muscle as a Biomarker of Disease Progression in ALS

 描述（由申请人提供）：肌萎缩侧索硬化症（ALS）是一种运动神经元退行性疾病，可导致进行性虚弱和死亡。这种疾病没有特异性生物标志物，因此通常会延迟诊断一年以上。此外，一旦确定诊断，当前用于跟踪患者的工具对于及时检测疾病改善或恶化不敏感。一种可以促进诊断、跟踪疾病进展或两者兼而有之的生物标志物将填补ALS管理中的巨大临床空白，并加快新疗法的临床试验。ALS研究人员的一个研讨会达成了共识，即这种疾病迫切需要生物标志物，特别是那些可以跟踪疾病进展的生物标志物。在探索性R21资助中，使用RNA测序方法，我们鉴定了Smad家族的成员作为ALS的有希望的肌肉生物标志物（Si et al.，2014）。Smads通过调节基因转录和miRNA成熟介导TGFβ和BMP信号转导。我们发现这些标志物在ALS肌肉样本中显著升高，并且它们从非常早期（临床前）阶段开始跟踪G93 A小鼠模型中的疾病进展。从我们初步的RNA测序和验证数据中，我们发现：1）激活Smads和平行疾病进展的特定TGF配体的早期上调，以及2）作为Smad调节靶点的特定miRNA的上调。这些新的发现构成了我们总体假设的基础，即肌肉中的Smad信号轴是ALS的生物标志物。长期目标是将该轴开发为ALS的生物标志物，以跟踪疾病并在肌肉水平上深入了解疾病机制。我们提出了3个具体的目标来解决这个假设：1）使用人类和小鼠ALS肌肉组织和培养的肌肉细胞表征参与ALS肌肉中Smad轴信号传导的TGF配体。2)将人类和小鼠ALS肌肉样本中的miRNA表达模式（通过miRNA测序确定）与疾病进展相关联。我们将评估Smad诱导/激活对这些模式的影响。3)将Smad信号轴表征为ALS疾病进展的生物传感器。在这个目标中，我们将前瞻性地研究肌萎缩侧索硬化症患者的肌肉中的Smad轴信号传导，并将Smad诱导/激活和miRNA表达的分子模式与疾病进展相关联。这种从实验室到临床的建议代表了一个全新的方向，具有引人注目的转化意义。它垂直整合了基本的 和临床方法，利用UAB的合作精神，以解决我们管理ALS患者能力的主要差距。

 DESCRIPTION (provided by applicant): Amyotrophic lateral sclerosis (ALS) is a degenerative disease of motor neurons that inexorably leads to progressive weakness and death. There is no specific biomarker for this disease, thus often delaying the diagnosis for more than a year. Furthermore, once a diagnosis is established, the current tools to track patients are insensitive for the timely detection of disease improvement or worsening. A biomarker that can facilitate diagnosis, track disease progression, or both, would fill a large clinical gap in ALS management, and expedite clinical trials of novel therapies. A workshop of ALS researchers came to a consensus that biomarkers are critically and urgently needed for this disease, especially those that can track disease progression. In an exploratory R21 grant, using an RNA sequencing approach, we identified members of the Smad family as promising muscle biomarkers of ALS (Si et al., 2014). Smads mediate TGFβ and BMP signal transduction by modulating gene transcription and miRNA maturation. We found these markers to be significantly elevated in ALS muscle samples, and they tracked disease progression in the G93A mouse model starting at very early (preclinical) stages. From our preliminary RNA sequencing and validation data, we have found: 1) early upregulation of specific TGF ligands that activate Smads and parallel disease progression, and 2) upregulation of specific miRNAs that are targets of Smad modulation. These novel findings form the basis of our overarching hypothesis in this proposal that the Smad axis of signaling in muscle is a biomarker of ALS. The long term goal is to develop this axis as a biomarker of ALS to track the disease and to provide insight into disease mechanisms at the level of muscle. We propose 3 specific aims to address this hypothesis: 1) Characterize the TGF ligands involved in the Smad axis of signaling in ALS muscle using human and mouse ALS muscle tissues and cultured muscle cells. 2) Correlate miRNA expression patterns in human and mouse ALS muscle samples (as determined by miRNA sequencing) to disease progression. We will assess the impact of Smad induction/activation on these patterns. 3) Characterize the Smad axis of signaling as a biosensor of ALS disease progression. In this aim we will prospectively study the Smad axis of signaling in muscle from a cohort of ALS patients and correlate the molecular patterns of Smad induction/activation and miRNA expression with disease progression. This bench-to-bedside proposal represents an entirely novel direction with compelling translational implications. It vertically integrates basic and clinical approaches, capitalizing on the collaborative spirit at UAB, to address a major gap in our ability to manage patients with ALS.