Endogenous Multiple Exon Skipping and Back-Splicing at the DMD Mutation Hotspot.

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Duchenne muscular dystrophy (DMD) is a severe genetic disorder.
• Multiple exon skipping (MES) targeting the DMD gene (exons 45-55) is a potential therapeutic strategy.
• Mild symptoms in patients with natural deletions of these exons support MES approaches.

Purpose of the Study:

• To investigate the mechanisms of endogenous multiple exon skipping (MES) in the DMD gene.
• To identify novel splice sites involved in DMD exon skipping.
• To explore the relationship between DMD circular RNA (circRNA) generation and MES.

Main Methods:

• Reverse transcription polymerase chain reaction (RT-PCR) on human skeletal muscle total RNA.
• Analysis of endogenous DMD mRNA transcripts spanning exons 44-56.
• Investigation of exon combinations for DMD circRNA formation.

Main Results:

• Identified eight types of endogenous MES products in the DMD gene.
• Discovered that 5' splice sites of post-transcriptional introns function as donor sites for MES.
• Confirmed that preferential back-splicing sites are involved in both circRNA generation and MES.
• Results align with current circRNA generation models.

Conclusions:

• Post-transcriptional introns play a critical role in triggering MES and circRNA production in the DMD gene.
• Understanding these splicing mechanisms may advance therapeutic strategies for Duchenne muscular dystrophy.
• The findings provide insights into the regulation of splicing and circRNA biogenesis.