Molecular underpinnings of Prader-Willi syndrome

摘要 Prader-Willi综合征（PWS）是一种神经遗传性疾病， 染色体15 q11-q13上的遗传基因。导致PWS的非典型缺失已经缩小 该疾病的关键遗传区域为包括SNORD 116在内的91 kb基因座。SNORD 116是 30个高度相似的C/D盒小核仁RNA（snoRNA）的簇。典型C/D盒 snoRNA退火并介导核糖体RNA的2 'O-甲基化（2'-OMe），然而， SNORD 116拷贝与rRNA缺乏互补性。相反，他们被假设为修改 mRNA或lncRNA，但尚未鉴定出SNORD 116的直接靶标。因此他们的 神经元的功能尚不清楚。幸运的是，每个患有PWS的人都有一个完整的， PWS关键区域的表观遗传抑制拷贝，包括SNORD 116，在其 母系等位基因我们最近发现，SNORD 116的母体拷贝可以被激活， 在PWS神经元中通过消耗ZNF 274（一种KRAB结构域锌指蛋白）。这不仅 提出了一种有趣的PWS治疗方法，但也提供了一种关键工具， 了解SNORD 116如何在神经元中调节。本提案的总体目标是 更好地了解PWS的分子基础。我们将确定染色质的状态 以及iPSC中活性和非活性15 q11-q13等位基因的长程染色质相互作用， 神经衍生物我们将研究SNORD 116如何通过ZNF 274耗尽而激活 和组蛋白甲基转移酶抑制影响染色质状态和长程相互作用。 最后，我们将确定SNORD 116的直接2 '-O-甲基化靶点，并确定如何 它们影响PWS相关的差异表达基因。

ABSTRACT Prader-Willi syndrome (PWS) is a neurogenetic disorder caused by the loss of paternally inherited genes on chromosome 15q11-q13. Atypical deletions that cause PWS have narrowed the genetic region critical for the disorder to a 91kb locus including SNORD116. SNORD116 is cluster of 30 highly similar C/D box small nucleolar RNAs (snoRNAs). Canonical C/D box snoRNAs anneal to and mediate 2'O-methylation (2'-OMe) of ribosomal RNAs, however, the SNORD116 copies lack complementarity to rRNAs. Instead they are hypothesized to modify mRNAs or lncRNAs, but direct targets for SNORD116 have not been identified. Thus, their function in neurons is not known. Fortunately, every individual with PWS has an intact, but epigenetically repressed copy of the PWS critical region, including SNORD116, on their maternal allele. We have recently shown that the maternal copy of SNORD116 can be activated in PWS neurons by depleting ZNF274, a KRAB domain zinc finger protein. Not only does this suggest an intriguing therapeutic approach to PWS, but also provides a critical tool to help understand how SNORD116 is regulated in neurons. The overall goal of this proposal is to better understand the molecular underpinnings of PWS. We will determine the chromatin states and long-range chromatin interactions of active and inactive 15q11-q13 alleles in iPSCs and neuronal derivatives. We will investigate how activation of SNORD116 via ZNF274 depletion and histone methyltransferase inhibition impact the chromatin state and long-range interactions. Finally, we will identify the direct 2'-O-methylation targets of SNORD116 and determine how they influence PWS-related differentially expressed genes.