Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555, Japan.
Laboratory of Disease Biology, Institute of Microbial Chemistry, Shinagawa-ku, Tokyo 141-0021, Japan.
Biochem Biophys Res Commun. 2014 Mar 28;446(1):119-24. doi: 10.1016/j.bbrc.2014.02.060. Epub 2014 Feb 22.
Nuclear speckles are subnuclear structures enriched with RNA processing factors and poly (A)(+) RNAs comprising mRNAs and poly (A)(+) non-coding RNAs (ncRNAs). Nuclear speckles are thought to be involved in post-transcriptional regulation of gene expression, such as pre-mRNA splicing. By screening 3585 culture extracts of actinomycetes with in situ hybridization using an oligo dT probe, we identified tubercidin, an analogue of adenosine, as an inhibitor of speckle formation, which induces the delocalization of poly (A)(+) RNA and dispersion of splicing factor SRSF1/SF2 from nuclear speckles in HeLa cells. Treatment with tubercidin also decreased steady-state MALAT1 long ncRNA, thought to be involved in the retention of SRSF1/SF2 in nuclear speckles. In addition, we found that tubercidin treatment promoted exon skipping in the alternative splicing of Clk1 pre-mRNA. These results suggest that nuclear speckles play a role in modulating the concentration of splicing factors in the nucleoplasm to regulate alternative pre-mRNA splicing.
核斑点是富含 RNA 处理因子和多聚 A（+）RNA 的亚核结构，其中包括 mRNA 和多聚 A（+）非编码 RNA（ncRNA）。核斑点被认为参与基因表达的转录后调控，如前体 mRNA 的剪接。通过使用寡聚 dT 探针进行原位杂交筛选 3585 株放线菌的培养物提取物，我们鉴定出结核菌素（一种腺苷类似物）是一种斑点形成抑制剂，它可诱导多聚 A（+）RNA 去定位和剪接因子 SRSF1/SF2 从 HeLa 细胞的核斑点中弥散。结核菌素处理还降低了 MALAT1 长 ncRNA 的稳态水平，该 RNA 被认为参与了 SRSF1/SF2 在核斑点中的保留。此外，我们发现结核菌素处理促进了 Clk1 前体 mRNA 可变剪接中的外显子跳跃。这些结果表明，核斑点在调节核质中剪接因子的浓度以调节可变前体 mRNA 剪接方面发挥作用。
