X-linked Dyskeratosis Congenita and ribosomal frameshifting

描述（由申请人提供）：与人类先天性和获得性骨髓衰竭综合征有关的核糖体功能缺失被归类于核糖体病的大保护伞下。最近我们两个实验室之间的合作已经启动了一个全新的研究途径，通过建立一个进化上保守的作用，核糖体修饰介导的假尿苷合酶dyskerin在翻译控制的特定方面。假尿苷修饰的功能作用具有重要的医学意义，因为DKC 1（编码dyskerin的基因）的突变在许多疾病中发现，包括X连锁先天性角化不良（X-DC），Hoyeraal-Hreidarsson综合征和许多癌症。重要的是，我们已发表的工作已经确定，rRNA缺陷型核糖体对tRNA的亲和力降低，导致程序性-1核糖体移码（-1 PRF）的速率增加，这是一种正在成为基因表达重要调节因子的分子机制。该提议试图检验以下假设：-1PRF的整体变化影响编码关键造血因子的mRNA的特定子集的表达，这可能导致与X-DC相关的一些病理学特征。从我们广泛的已发表和未发表的研究结果中可以明显看出对这一假设的支持，这些研究结果表明，-1 PRF的速率增加通过无义介导的mRNA衰变（NMD）途径促进特定mRNA的快速降解。此外，我们已经证明，在来自携带不同DKC 1突变的X-DC患者的造血细胞中，rRNA水平受损。重要的是，我们的初步和已发表的数据还表明，参与端粒维持的一类重要功能性mRNA在酵母和人类细胞中都受到这种机制的调节，并在X-DC患者中被破坏，从而将rRNA缺陷和端粒缩短联系起来。通过利用X-DC作为疾病范例并结合三种模型系统，酵母，小鼠和人类，在该提议中，我们将扩展我们的新发现并鉴定与核糖体功能障碍相关的骨髓衰竭的mRNA库，并确定抑制X-DC中NMD和-1 PRF的治疗潜力。本提案的目的1旨在使用两种互补方法鉴定酵母、小鼠和人类细胞中表达受rRNA缺陷影响的mRNA库。目的2将确定受损的rRNA β改变含-1 PRF的mRNA表达的机制。目的3旨在确定X-DC中靶向NMD和-1 PRF的治疗潜力。在拟议的研究结束时，我们将1）建立一个理解核糖体病的新范式，2）确定可用作生物标志物和治疗干预靶向的特定基因，3）探索治疗这类疾病的新方法。

DESCRIPTION (provided by applicant): Abnormalities in ribosome function that are implicated in both congenital and acquired bone marrow failure syndromes in humans are classified under the broad umbrella of ribosomopathies. A recent collaboration between our two laboratories has initiated a completely new avenue of research by establishing an evolutionarily conserved role for ribosome modifications mediated by the pseudouridine synthase dyskerin in specific aspects of translation control. The functional role of pseudouridine (�) modifications is of great medical importance as mutations in DKC1, the gene encoding for dyskerin, are found in a number of diseases including X-linked dyskeratosis congenita (X-DC), Hoyeraal-Hreidarsson syndrome, and numerous cancers. Importantly, our published work has identified that the decreased affinity of rRNA � defective ribosomes for tRNAs results in increased rates of programmed -1 ribosomal frameshifting (-1 PRF), a molecular mechanism that is emerging as an important regulator of gene expression. This proposal seeks to test the hypothesis that global changes in -1 PRF affect the expression of specific subsets of mRNAs encoding key hematopoietic factors, that may contributing to some of the pathological features associated with X- DC. Support for this hypothesis is evident from our extensive published and unpublished findings showing that increased rates of -1 PRF promotes rapid degradation of specific mRNAs through the Nonsense-Mediated mRNA Decay (NMD) pathway. Furthermore, we have demonstrated that rRNA � levels are impaired in hematopoietic cells from X-DC patients harboring distinct DKC1 mutations. Importantly, our preliminary and published data also suggest that one important functional class of mRNAs involved in telomere maintenance is regulated by this mechanism in both yeast and human cells and is disrupted in X-DC patients, thus linking rRNA � defects and telomere shortening. By utilizing X-DC as a disease paradigm and combining three model systems, yeast, mouse and humans, in this proposal we will extend our novel findings and identify the repertoire of mRNAs that underlie bone marrow failure associated with ribosome dysfunction and determine the therapeutic potential of inhibiting NMD and -1 PRF in X-DC. Aim 1 of this proposal seeks to identify the repertoire of mRNAs whose expression is affected by rRNA � defects in yeast, mouse and human cells using two complementary approaches. Aim 2 will determine the mechanisms through which impaired rRNA � alters expression of -1 PRF containing mRNAs. Aim 3 is oriented towards determining the therapeutic potential of targeting NMD and -1 PRF in X-DC. By the end of the proposed studies, we will have 1) established a new paradigm for understanding ribosomopathies, 2) identified specific genes that can be used as biomarkers and targeted for therapeutic intervention, and 3) explored novel approaches to treat this class of diseases.