Shen Wen, Liang Xue-Hai, Sun Hong, De Hoyos Cheryl L, Crooke Stanley T
Department of Core Antisense Research, IONIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA, United States of America.
PLoS One. 2017 Mar 13;12(3):e0173494. doi: 10.1371/journal.pone.0173494. eCollection 2017.
Altered expression of NEAT1, the architectural long non-coding RNA (lncRNA) of nuclear paraspeckles, has been reported during tumorigenesis, as well as under various cellular stress conditions. Here we report that the depletion of NEAT1 lncRNA alleviates nucleolar stress during RNAP I inhibition through releasing sequestered P54nrb and PSF to facilitate the IRES-dependent translation of c-Myc. RNAP I inhibitor CX5461 disrupts the SL1-rDNA interaction and induces nucleolar disruption, demonstrated by the accumulation of fibrillarin-containing nucleoplasmic foci and nucleolar clearance of ribosomal proteins in HeLa cells. Antisense oligonucleotide-mediated depletion of NEAT1 lncRNA significantly attenuated the RNAP I inhibition and its related nucleolar disruption. Interestingly, induction in the levels of c-Myc protein was observed in NEAT1-depeleted cells under RNAP I inhibition. NEAT1-associated paraspeckle proteins P54nrb and PSF have been reported as positive regulators of c-Myc translation through interaction with c-Myc IRES. Indeed, an increased association of P54nrb and PSF with c-Myc mRNA was observed in NEAT1-depleted cells. Moreover, apoptosis was observed in HeLa cells depleted of P54nrb and PSF, further confirming the positive involvement of P54nrb and PSF in cell proliferation. Together, our results suggest that NEAT1 depletion rescues CX5461-induced nucleolar stress through facilitating c-Myc translation by relocating P54nrb/PSF from nuclear paraspeckles to c-Myc mRNAs.
核旁斑的结构长链非编码RNA（lncRNA）NEAT1的表达改变在肿瘤发生过程以及各种细胞应激条件下均有报道。在此我们报告，NEAT1 lncRNA的缺失通过释放被隔离的P54nrb和PSF以促进c-Myc的内部核糖体进入位点（IRES）依赖性翻译，从而减轻RNA聚合酶I（RNAP I）抑制过程中的核仁应激。RNAP I抑制剂CX5461破坏SL1-rDNA相互作用并诱导核仁破坏，这在HeLa细胞中表现为含纤维蛋白原的核质灶的积累和核糖体蛋白的核仁清除。反义寡核苷酸介导的NEAT1 lncRNA缺失显著减弱了RNAP I抑制及其相关的核仁破坏。有趣的是，在RNAP I抑制条件下，NEAT1缺失的细胞中观察到c-Myc蛋白水平升高。NEAT1相关的旁斑蛋白P54nrb和PSF已被报道为通过与c-Myc IRES相互作用而成为c-Myc翻译的正调控因子。实际上，在NEAT1缺失的细胞中观察到P54nrb和PSF与c-Myc mRNA的结合增加。此外，在P54nrb和PSF缺失的HeLa细胞中观察到细胞凋亡，进一步证实了P54nrb和PSF在细胞增殖中的积极作用。总之，我们的结果表明，NEAT1缺失通过将P54nrb/PSF从核旁斑重新定位到c-Myc mRNA上以促进c-Myc翻译，从而挽救了CX5461诱导的核仁应激。
