Comprehensive analysis of the FMR1 locus transcriptional landscape

描述（由申请人提供）：脆性X综合征（FXS）是遗传性精神发育迟滞的最常见形式（Oostra，1996）。它是由FMR 1的5' UTR中的CGG扩增引起的，这导致脆性X智力低下蛋白（FMRP）的缺失。然而，对脆性X染色体患者的纵向临床观察表明，FXS的认知、行为和形态症状的严重程度是高度可变的。因此，我们寻找从FMR 1基因座表达的新的功能性转录物，并鉴定了FMR 4，一种具有强生物（抗凋亡）活性的长非编码RNA。另一个研究小组鉴定了来自FMR 1基因座的第二个长的非编码转录物ASFMR 1，但尚不清楚它是否具有任何生物活性。有趣的是，FMR4和ASFMR1与FMR1相似，在脆性X患者中沉默，在突变前携带者中上调。表达分析表明，FMR 4和ASFMR 1在广泛的成人和胚胎组织中表达。原位杂交研究表明，FMR 4定位于细胞核，表明FMR 4发挥核作用模式。由于FMR 4具有显著的生物学活性并且在FXS中沉默，因此FMR 4是参与FXS和相关疾病的新候选基因。FMR 4、ASFMR 1和尚未表征的FMR 1衍生的非编码RNA的活性是否与FXS中FMR 1的表达和沉默相关尚不清楚。先前已经证明，非编码RNA可以充当染色质修饰复合物的界面，并且短的非编码RNA（例如微小RNA）可以通过与哺乳动物细胞中的启动子相关RNA相互作用来指导表观遗传修饰，从而诱导或抑制基因的转录。因此，它是感兴趣的，以探讨是否存在这样的调节FMR 1启动子，以及是否可以操纵这种调节，以恢复FMR 1在脆性X患者的表达。

DESCRIPTION (provided by applicant): Fragile X syndrome (FXS) is the most common form of inherited mental retardation (Oostra, 1996). It is caused by a CGG expansion in the 5' UTR of FMR1, which leads to the absence of the fragile X mental retardation protein (FMRP). However, longitudinal clinical observations of fragile X patients have shown that the severity of the cognitive, behavioral and morphological symptoms of FXS is highly variable. Therefore we searched for novel functional transcripts expressed from the FMR1 locus and identified FMR4, a long non-coding RNA with a strong biological (anti-apoptotic) activity. Another group identified a second long non-coding transcript originating from the FMR1 locus, ASFMR1, but it is yet unclear if it has any biological activity. Interestingly, both FMR4 and ASFMR1, similar to FMR1, are silenced in fragile X patients and up-regulated in pre-mutation carriers. Expression analyses have shown that FMR4 and ASFMR1 are expressed in a wide range of human adult and embryonic tissues. In situ hybridization studies demonstrated that FMR4 is localized to the nucleus suggesting that FMR4 exerts a nuclear mode of action. Since FMR4 has pronounced biological activity and is silenced in FXS, FMR4 is a new candidate gene for involvement in FXS and related disorders. It is unresolved if the activity of FMR4, ASFMR1, and yet uncharacterized FMR1-derived non-coding RNAs is linked to expression and silencing of FMR1 in FXS. It has been previously demonstrated that non-coding RNAs can serve as an interface for chromatin- modifying complexes and that short non-coding RNAs, e.g. microRNAs, can induce or repress the transcription of genes by directing epigenetic modifications via interaction with promoter-associated RNAs in mammalian cells. It is therefore of interest to explore whether such regulation exists at the FMR1 promoter and whether such regulation can be manipulated to restore FMR1 expression in fragile X patients.