positive regulation of snRNA transcription by RNA polymerase II

Definition

Target type: biologicalprocess

Any process that activates or increases the frequency, rate or extent of snRNA transcription mediated by RNA polymerase II. [GO_REF:0000058, GOC:bhm, GOC:TermGenie, PMID:10022900]

Positive regulation of snRNA transcription by RNA polymerase II is a complex process involving a coordinated interplay of factors that influence the activity of RNA polymerase II at snRNA gene promoters. The process is characterized by the following key events:

1. **Chromatin Remodeling:** Prior to transcription, the chromatin structure surrounding snRNA genes must be remodeled to allow access to the DNA by RNA polymerase II. This involves the recruitment of chromatin remodeling complexes like SWI/SNF, which can reposition nucleosomes and expose the promoter region.

2. **Transcription Factor Binding:** Specific transcription factors bind to regulatory elements within the snRNA gene promoters. These factors include:
* **Sp1:** A ubiquitous transcription factor that binds to GC-rich sequences often found in snRNA promoters.
* **Oct-1:** A transcription factor that interacts with the octamer motif present in many snRNA promoters.
* **TFIIH:** A general transcription factor that plays a role in both basal and regulated transcription.

3. **RNA Polymerase II Recruitment:** The transcription factors bound to the promoter, along with other general transcription factors, recruit RNA polymerase II to the transcription start site. RNA polymerase II is the enzyme responsible for synthesizing the snRNA transcript.

4. **Initiation and Elongation:** RNA polymerase II initiates transcription and then progresses along the snRNA gene, creating an RNA copy of the DNA sequence.

5. **Processing and Modification:** During or after transcription, the nascent snRNA transcript undergoes extensive processing and modifications, which are crucial for its function:
* **Capping:** A 5' cap is added to the snRNA transcript.
* **Splicing:** The snRNA transcript undergoes splicing, which removes introns and joins exons.
* **3' end processing:** The snRNA transcript is cleaved at a specific site, and a 3' polyadenylation signal is added.

6. **Nuclear Localization:** The processed and modified snRNA is transported into the nucleus, where it assembles with other snRNAs and proteins to form snRNPs, the core components of the spliceosome.

7. **Spliceosome Assembly:** The snRNPs associate with other proteins and RNA molecules to form the spliceosome, a complex molecular machine that removes introns from precursor messenger RNA (pre-mRNA) during pre-mRNA splicing.

8. **Splicing Regulation:** The positive regulation of snRNA transcription can influence the abundance and activity of snRNPs, thereby affecting the overall efficiency of pre-mRNA splicing. This intricate regulation is essential for maintaining the fidelity of gene expression and the stability of the genome.'
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Proteins (1)

Compounds (1)