Language：English   Publishing type：Research paper (scientific journal)   Publisher：Nature Communications  

Transcription is a dynamic process. To detect the dynamic relationship among protein clusters of RNA polymerase II and coactivators, gene loci, and transcriptional activity, we insert an MS2 repeat, a TetO repeat, and inteins with a selection marker just downstream of the transcription start site. By optimizing the individual elements, we develop the Spliced TetO REpeAt, MS2 repeat, and INtein sandwiched reporter Gene tag (STREAMING-tag) system. Clusters of RNA polymerase II and BRD4 are observed proximal to the transcription start site of Nanog when the gene is transcribed in mouse embryonic stem cells. In contrast, clusters of MED19 and MED22 tend to be located near the transcription start site, even without transcription activity. Thus, the STREAMING-tag system reveals the spatiotemporal relationships between transcriptional activity and protein clusters near the gene. This powerful tool is useful for quantitatively understanding transcriptional regulation in living cells.

DOI： 10.1038/s41467-022-35286-2

Web of Science

Scopus

PubMed

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Cell Biology  

In eukaryotic nuclei, most genes are transcribed by RNA polymerase II (RNAP2), whose regulation is a key to understanding the genome and cell function. RNAP2 has a long heptapeptide repeat (Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7), and Ser2 is phosphorylated on an elongation form. To detect RNAP2 Ser2 phosphorylation (RNAP2 Ser2ph) in living cells, we developed a genetically encoded modification-specific intracellular antibody (mintbody) probe. The RNAP2 Ser2ph-mintbody exhibited numerous foci, possibly representing transcription “factories,” and foci were diminished during mitosis and in a Ser2 kinase inhibitor. An in vitro binding assay using phosphopeptides confirmed the mintbody’s specificity. RNAP2 Ser2ph-mintbody foci were colocalized with proteins associated with elongating RNAP2 compared with factors involved in the initiation. These results support the view that mintbody localization represents the sites of RNAP2 Ser2ph in living cells. RNAP2 Ser2phmintbody foci showed constrained diffusional motion like chromatin, but they were more mobile than DNA replication domains and p300-enriched foci, suggesting that the elongating RNAP2 complexes are separated from more confined chromatin domains.

DOI： 10.1083/jcb.202104134

Scopus

PubMed

DOI： 10.64898/2026.02.08.704500

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Molecular Biology  

RNA polymerase II (RNAP2) transcribes most genes in eukaryotic nuclei. During the transition from transcription initiation to productive elongation, and throughout the elongation phase, RNAP2 becomes phosphorylated at the Ser2 residue within the heptapeptide repeats of the carboxyl-terminal domain of its largest subunit. Antibodies specific to RNAP2 Ser2 phosphorylation (Ser2ph) have enabled visualization of active transcription sites in fixed cells and tissues. Here, we report the generation and characterization of knock-in mice ubiquitously expressing a fluorescent protein-tagged, modification-specific intracellular antibody (mintbody) targeting RNAP2 Ser2ph. Using these mice, we successfully visualized transcription elongation foci in mouse tissues and characterized their distribution and dynamics across diverse cell types. RNAP2 Ser2ph-mintbody formed hundreds to thousands of nuclear foci, which were excluded from heterochromatin and transcriptionally repressed domains, such as the XY body in pachytene spermatocytes. Quantitative analysis revealed tissue- and cell type-specific variation in both the number and mobility of transcription elongation foci. The mobility of transcription foci was more restricted in differentiated cells compared to differentiating and proliferating cells, likely reflecting a reduced number of actively transcribed genes and more limited open chromatin regions upon differentiation. These findings suggest that the spatial organization and dynamics of transcription elongation are closely associated with cell identity and differentiation status. The RNAP2 Ser2ph-mintbody knock-in mice provide a valuable tool for future studies of transcription organization and dynamics at the tissue level.

DOI： 10.1016/j.jmb.2025.169395

Web of Science

Scopus

PubMed

Publisher：EMBO Journal  

Eukaryotic genomes replicate in a defined temporal order called the replication timing (RT) program. RT is developmentally regulated with the potential to drive cell fate transitions, but mechanisms controlling RT remain elusive. We previously identified “Early Replication Control Elements” (ERCEs), cis-acting elements necessary for early RT, domain-wide transcription, 3D chromatin architecture and compartmentalization in mouse embryonic stem cells (mESCs), but deletions identifying ERCEs were large and encompassed many putative regulatory elements. Here, we show that ERCEs are compound elements, whose RT activity can largely be accounted for by multiple binding sites for diverse master transcription factors (subERCEs). While deletion of subERCEs had large effects on both transcription and replication timing, deleting transcription start sites eliminated nearly all transcription with only moderate effects on replication timing. Our results suggest a model in which subERCEs are a class of transcriptional enhancers that can also organize chromatin domains structurally to support early replication timing, potentially providing a feed-forward loop to drive robust epigenomic change during cell fate transitions.

DOI： 10.1038/s44318-025-00501-5

Scopus