Transcription (biology)

About: Transcription (biology) is a research topic. Over the lifetime, 56532 publications have been published within this topic receiving 2952782 citations. The topic is also known as: genetic transcription & transcription, genetic.

Higher level organization of individual gene transcription and RNA splicing

Abstract: Visualization of fibronectin and neurotensin messenger RNAs within mammalian interphase nuclei was achieved by fluorescence hybridization with genomic, complementary DNA, and intron-specific probes. Unspliced transcripts accumulated in one or two sites per nucleus. Fibronectin RNA frequently accumulated in elongated tracks that overlapped and extended well beyond the site of transcription. Splicing appears to occur directly within this RNA track, as evidenced by an unambiguous spatial separation of intron-containing and spliced transcripts. Excised introns for neurotensin RNA appear free to diffuse. The transcription and processing site of the fibronectin gene localized to the nuclear interior and was associated with larger transcript domains in over 88 percent of the cells. These results support a view of nuclear function closely integrated with structure.

Pol II phosphorylation regulates a switch between transcriptional and splicing condensates

Abstract: The synthesis of pre-mRNA by RNA polymerase II (Pol II) involves the formation of a transcription initiation complex, and a transition to an elongation complex1–4. The large subunit of Pol II contains an intrinsically disordered C-terminal domain that is phosphorylated by cyclin-dependent kinases during the transition from initiation to elongation, thus influencing the interaction of the C-terminal domain with different components of the initiation or the RNA-splicing apparatus5,6. Recent observations suggest that this model provides only a partial picture of the effects of phosphorylation of the C-terminal domain7–12. Both the transcription-initiation machinery and the splicing machinery can form phase-separated condensates that contain large numbers of component molecules: hundreds of molecules of Pol II and mediator are concentrated in condensates at super-enhancers7,8, and large numbers of splicing factors are concentrated in nuclear speckles, some of which occur at highly active transcription sites9–12. Here we investigate whether the phosphorylation of the Pol II C-terminal domain regulates the incorporation of Pol II into phase-separated condensates that are associated with transcription initiation and splicing. We find that the hypophosphorylated C-terminal domain of Pol II is incorporated into mediator condensates and that phosphorylation by regulatory cyclin-dependent kinases reduces this incorporation. We also find that the hyperphosphorylated C-terminal domain is preferentially incorporated into condensates that are formed by splicing factors. These results suggest that phosphorylation of the Pol II C-terminal domain drives an exchange from condensates that are involved in transcription initiation to those that are involved in RNA processing, and implicates phosphorylation as a mechanism that regulates condensate preference. RNA polymerase II with a hypophosphorylated C-terminal domain preferentially incorporates into mediator condensates, and with a hyperphosphorylated C-terminal domain into splicing-factor condensates, revealing phosphorylation as a regulatory mechanism in condensate preference.

Suppression of interleukin-3-induced gene expression by a C-terminal truncated Stat5: role of Stat5 in proliferation.

Abstract: Interleukin-3 (IL3) was shown recently to utilize the transcription factor Stat5, but the genes regulated by this pathway and the biological consequence of Stat5 activation remained to be determined. In order to study the role of Stat5 in IL3 signalling, we constructed a dominant-negative Stat5 protein by C-terminal truncation, and inducibly expressed it in an IL3-dependent cell line. The effect of dominant-negative Stat5 induction on expression of IL3 early response genes was examined, and expression of several genes, including cis, osm and pim-1 was inhibited profoundly. The expression of c-fos was also reduced, but to a lesser extent. While activated Ras alone (though not Stat5 alone) could induce c-fos, maximal expression required the action of both Ras and Stat5. Interestingly, although the membrane-proximal region of the IL3 receptor beta-chain is responsible for both Jak2-Stat5 activation and c-myc induction, c-myc levels were not affected by the dominant-negative Stat5. Thus, the signals directed by this membrane-proximal domain, which is essential for transducing a DNA synthesis signal, can be separated further into Stat5 or c-myc pathways. The net effect of dominant-negative Stat5 expression was partial inhibition of IL3-dependent growth. This provides the first direct evidence that Stat5 is involved in regulation of cell proliferation.