Archaic structure of the gene encoding transcription factor USF

Area of Science:

• Molecular Biology
• Genetics
• Transcription Factors

Background:

• Upstream stimulatory factor (USF) is a helix-loop-helix transcription factor.
• USF interacts with DNA sites recognized by MYC oncoproteins.

Purpose of the Study:

• Isolate and characterize the murine USF2 gene.
• Investigate the USF2 gene's structure, promoter, and alternative splicing.
• Determine the functional impact of alternative splicing on USF2 transcriptional activity.

Main Methods:

• Genomic cloning of the USF2 gene.
• DNA sequencing and analysis of gene structure (exons, introns).
• S1 mapping and transient transfection assays for promoter analysis and transcript origination.
• Analysis of alternative splicing and its correlation with intron features.
• Cotransfection assays to assess the impact of exon 4 on transcription activation.

Main Results:

• The murine USF2 gene spans 13 kb and comprises 10 exons, retaining an archaic structure.
• A GC-rich region (CpG island) surrounds the USF2 translation initiation site, containing a bidirectional promoter.
• USF2 transcripts originate from an initiator element within this GC-rich region.
• Alternative splicing generates USF2 mRNA variants due to the presence or absence of exon 4.
• The inclusion or exclusion of exon 4 significantly alters the transcription activation properties of the USF2 protein.

Conclusions:

• The USF2 gene exhibits conserved structural features and complex transcriptional regulation.
• Alternative splicing of exon 4 is a key mechanism modulating USF2 function.
• Understanding USF2 gene regulation and alternative splicing is crucial for its role in cellular processes.