Molecular and genetic dissection of recursive splicing

Area of Science:

• Molecular Biology
• Genetics
• RNA Splicing

Background:

• Intronic ratchet points (RPs) in Drosophila contain juxtaposed splice acceptor and donor sites.
• Recursive splicing (RS) involves cryptic exons (RS-exons) at RPs, typically skipped in mRNA.
• Drosophila also encodes expressed exons with RS features.

Purpose of the Study:

• To investigate regulatory mechanisms governing the choice between RP and RS-exon splice donor sites.
• To understand how exonic sequences influence RS-exon usage.
• To explore how splicing suppresses RP splice donor utilization for RS-exon expression.

Main Methods:

• Analysis of Drosophila RP splice donor mutants.
• Characterization of RS-exon reporter constructs.
• RS-exon swap and mutagenesis assays.
• Investigation of splicing's role in suppressing RP splice donor utilization.

Main Results:

• Splice donor site competition suppresses cryptic exon inclusion in endogenous contexts.
• Exonic sequences play a crucial role in determining RS-exon usage.
• Splicing can suppress RP splice donor utilization, enabling RS-exon expression.

Conclusions:

• Multiple factors regulate Drosophila RS-exon splicing.
• RS-exons are usually suppressed as zero-nucleotide RPs.
• Under certain conditions, translated RS-exons can be produced.