DMA-Tudor interaction modules: a novel approach to Survival Motor Neuron protein (SMN) and Cajal body function

存活运动神经元蛋白(SMN)缺乏导致最常见的脊髓性肌萎缩(SMA) 婴儿和幼儿死亡的遗传原因。尽管SMN与转录有关，但RNA 在加工和翻译过程中，运动神经元丢失的分子基础仍然未知。我们最近发现了一种 SMN的新活性：SMN的球状Tudor结构域(SMNTud)引起的生物分子缩合 结合二甲基精氨酸(DMA)修饰的配体。尽管有数百种经DMA修饰的蛋白质 在细胞中，Tudor结构域与其DMA配体之间的对应关系尚不清楚。这 研究不足的翻译后修饰是潜在的动态变化，并在多个方面发挥着新的作用 通过被称为生物分子的细胞隔室的功能改变而引起的神经系统疾病 凝析油(BMC)。我们的中心假设是SMNTud与DMA配体的结合在细胞内起着关键作用 组织，这在神经肌肉系统中特别脆弱。 我们的发现强调了全面确定SMNTud的DMA配体和活性的迫切需要 他们形成的交互模块。SMN弥漫在细胞质中，存在于名为Cajal的核BMCs中 身体，这是胚胎发育所必需的。Cajal小体由一种已知的SMNTud配体作为支架 并在SMA中进行了更改。在应激过程中，SMN在细胞质中形成骨髓细胞。我们的初步结果直接 在SMA中涉及DMA结合和生物分子缩合，因为SMNTud活性被一种 单一氨基酸突变，E134K，阻止与DMA配体的结合并导致SMA。化学缓蚀剂 彻底改变了卡哈尔小体的组成和亚结构，这是我们第一次确定的 与我们的合作者兼合作伙伴Joerg Bewersdorf博士一起。全补DMA配体的恒等式 到目前为止，结合SMNTud的分子和影响Cajal小体的分子还不清楚。我们的初步数据显示 ~70个新颖和特定的SMNTud配体，表明与SMA相关的新见解已在我们掌握之中。 这一新应用的总体目标是：(I)识别SMNTud的DMA配体 生物分子缩合，(Ii)了解不对称(ADMA)和对称(SDMA)的动态性 由精氨酸甲基转移酶安装并由去甲基酶去除的结构和 通过利用DMA-SMNTud交互模块，揭示了SMN的新功能。我们的 理由是，与DMA-SMNTud交互模块有关的目标将最容易为STRICAL 使用小鼠和斑马鱼细胞，通过生物化学和最先进的成像技术相结合进行分析 和组织，包括运动神经元，这是我们的专长。如果实现了，我们的目标将会发现新奇 SMN结合伙伴及SMNTud在生物分子缩合中的作用。监管潜力和 将确定DMA修饰的动态性，这是组织特异性和疾病病因学的来源。 识别DMA-SMNTud相互作用模块将为SMA提供新的治疗方法。

Survival Motor Neuron protein (SMN) deficiencies cause Spinal Muscular Atrophy (SMA), the most common genetic cause of infant and toddler mortality. Although SMN has been implicated in transcription, RNA processing and translation, the molecular basis of motoneuron loss is still unknown. We recently discovered a novel activity of SMN: biomolecular condensation caused by SMN’s globular tudor domain (SMNTud), which binds ligands modified by dimethylarginine (DMA). Although there are hundreds of DMA-modified proteins in cells, the correspondence between tudor domains and their DMA ligands remains unknown. This understudied post-translational modification is potentially dynamic and has emerging roles in multiple neurological diseases through the altered functions of cellular compartments known as biomolecular condensates (BMCs). Our central hypothesis is SMNTud binding to DMA ligands plays critical roles in cellular organization, which are especially vulnerable in the neuromuscular system. Our findings highlight a critical need to comprehensively determine the DMA ligands of SMNTud and the activities of the interaction modules they form. SMN is diffusely cytoplasmic and present in nuclear BMCs called Cajal bodies, which are essential for embryonic development. Cajal bodies are scaffolded by a known SMNTud ligand and altered in SMA. During stress, SMN forms BMCs in the cytoplasm. Our preliminary results directly implicate DMA binding and biomolecular condensation in SMA, because SMNTud activity was blocked by a single amino acid mutation, E134K, that blocks binding to DMA ligands and causes SMA. Chemical inhibitors of DMA drastically altered the composition and substructure of Cajal bodies, which we determined for the first time with our collaborator and co-I, Dr Joerg Bewersdorf. The identities of the full complement of DMA ligands that bind SMNTud and those that affect Cajal bodies have been unknown until now. Our preliminary data reveal ~70 novel and specific SMNTud ligands, indicating that new insights relevant to SMA are within our grasp. The overall objectives of this new application are to (i) identify the DMA ligands of SMNTud that mediate biomolecular condensation, (ii) understand the dynamicity of asymmetric (aDMA) and symmetric (sDMA) installed by arginine methyltransferases and removed by demethylases with respect to the structure and function of BMCs, and (iii) reveal novel SMN functions by leveraging DMA-SMNTud interaction modules. Our rationale is that objectives concerning DMA-SMNTud interaction modules will be most accessible to rigorous analysis through a combination of biochemistry and state-of-the-art imaging, using mouse and zebrafish cells and tissues, including motoneurons, with which we have expertise. If achieved, our aims will discover novel SMN binding partners and functions of SMNTud in biomolecular condensation. The regulatory potential and dynamicity of the DMA modification, a source of tissue specificity and disease etiology, will be determined. Identification of DMA-SMNTud interaction modules will suggest new therapeutic approaches for SMA.