RT Journal Article
SR Electronic
T1 Molecular and genetic dissection of recursive splicing
JF Life Science Alliance
JO Life Sci. Alliance
FD Life Science Alliance LLC
SP e202101063
DO 10.26508/lsa.202101063
VO 5
IS 1
A1 Brian Joseph
A1 Chaz Scala
A1 Shu Kondo
A1 Eric C Lai
YR 2022
UL https://www.life-science-alliance.org/content/5/1/e202101063.abstract
AB Intronic ratchet points (RPs) are abundant within long introns in the Drosophila genome and consist of juxtaposed splice acceptor and splice donor (SD) sites. Although they appear to encompass zero-nucleotide exons, we recently clarified that intronic recursive splicing (RS) requires a cryptic exon at the RP (an RS-exon), which is subsequently always skipped and thus absent from mRNA. In addition, Drosophila encodes a smaller set of expressed exons bearing features of RS. Here, we investigate mechanisms that regulate the choice between RP and RS-exon SDs. First, analysis of Drosophila RP SD mutants demonstrates that SD competition suppresses inclusion of cryptic exons in endogenous contexts. Second, characterization of RS-exon reporters implicates exonic sequences as influencing choice of RS-exon usage. Using RS-exon swap and mutagenesis assays, we show exonic sequences can determine RS-exon inclusion. Finally, we provide evidence that splicing can suppress utilization of RP SDs to enable RS-exon expression. Overall, multiple factors can influence splicing of Drosophila RS-exons, which usually result in their complete suppression as zero-nucleotide RPs, but occasionally yield translated RS-exons.