Rovozzo René, Korza George, Baker Mei W, Li Meng, Bhattacharyya Anita, Barbarese Elisa, Carson John H
Center for Cell Analysis and Modeling, UConn Health, Farmington, Connecticut, United States of America.
Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, United States of America.
PLoS One. 2016 Dec 22;11(12):e0168204. doi: 10.1371/journal.pone.0168204. eCollection 2016.
CGG repeats in the 5'UTR of Fragile X Mental Retardation 1 (FMR1) RNA mediate RNA localization and translation in granules. Large expansions of CGG repeats (> 200 repeats) in FMR1, referred to as full mutations, are associated with fragile X syndrome (FXS). Smaller expansions (55-200 repeats), referred to as premutations, are associated with fragile X tremor ataxia syndrome (FXTAS) and fragile X premature ovarian insufficiency (FXPOI). TMPyP4 is a porphyrin ring compound that destabilizes CGG repeat RNA secondary structure. Here we show that exogenous CGG repeat RNA by itself, lacking the FMRP ORF, microinjected into hippocampal neurons is localized in RNA granules and inhibits translation of ARC RNA, which is localized in the same granules. TMPyP4 rescues translation of ARC RNA in granules. We also show that in human premutation fibroblasts with endogenous CGG repeat expansions in the FMR1 gene, translation of ARC RNA is inhibited and calcium homeostasis is disrupted and both phenotypes are rescued by TMPyP4. Inhibition of granule translation by expanded CGG repeats and rescue of granule translation by TMPy4, represent potential pathogenic mechanism and therapeutic strategy, respectively, for FXTAS and FXPOI.
脆性X智力低下1（FMR1）RNA 5'非翻译区（UTR）中的CGG重复序列介导RNA在颗粒中的定位和翻译。FMR1中CGG重复序列的大量扩增（>200次重复），称为完全突变，与脆性X综合征（FXS）相关。较小的扩增（55 - 200次重复），称为前突变，与脆性X震颤共济失调综合征（FXTAS）和脆性X早发性卵巢功能不全（FXPOI）相关。TMPyP4是一种卟啉环化合物，可使CGG重复RNA二级结构不稳定。在这里，我们表明，缺乏FMRP开放阅读框（ORF）的外源性CGG重复RNA微注射到海马神经元中后，会定位在RNA颗粒中，并抑制同样定位在这些颗粒中的ARC RNA的翻译。TMPyP4可挽救颗粒中ARC RNA的翻译。我们还表明，在FMR1基因中具有内源性CGG重复扩增的人类前突变成纤维细胞中，ARC RNA的翻译受到抑制，钙稳态被破坏，而这两种表型均被TMPyP4挽救。CGG重复序列扩增对颗粒翻译的抑制以及TMPy4对颗粒翻译的挽救，分别代表了FXTAS和FXPOI的潜在致病机制和治疗策略。
