Spector D L
Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, New York, 11724, USA.
Exp Cell Res. 1996 Dec 15;229(2):189-97. doi: 10.1006/excr.1996.0358.
In actively transcribing cells, factors involved in pre-mRNA splicing localize in a speckled pattern at the fluorescence microscopic level. The speckled pattern corresponds to interchromatin granule clusters and perichromatin fibrils at the electron microscopic level. Based upon [3H]uridine incorporation studies transcription is thought to occur at the perichromatin fibrils and not within interchromatin granule clusters. We have shown that upon inhibition of RNA polymerase II transcription or pre-mRNA splicing, splicing factors redistribute and preferentially localize to interchromatin granule clusters, which become larger and more uniform in shape. Introduction of exogenous DNA templates into the cell nucleus results in a recruitment of splicing factors to the new sites of transcription. These data suggest that splicing factors are localized at storage and/or reassembly sites (interchromatin granule clusters) and are recruited to active sites of transcription (perichromatin fibrils). Furthermore, these data demonstrate that the speckled localization of pre-mRNA splicing factors is a reflection of the transcriptional and pre-mRNA splicing activities of the cell.
在活跃转录的细胞中，参与前体mRNA剪接的因子在荧光显微镜水平呈斑点状分布。在电子显微镜水平，斑点状分布对应于染色质间颗粒簇和染色质周纤维。基于[3H]尿苷掺入研究，转录被认为发生在染色质周纤维而非染色质间颗粒簇内。我们已经表明，在抑制RNA聚合酶II转录或前体mRNA剪接后，剪接因子会重新分布并优先定位于染色质间颗粒簇，这些颗粒簇会变得更大且形状更均匀。将外源DNA模板引入细胞核会导致剪接因子被招募到新的转录位点。这些数据表明，剪接因子定位于储存和/或重新组装位点（染色质间颗粒簇），并被招募到转录活性位点（染色质周纤维）。此外，这些数据证明前体mRNA剪接因子的斑点状定位反映了细胞的转录和前体mRNA剪接活性。
