Lariatdriven

Lariat-driven, sometimes written as lariat-driven or lariatdriven, is a term used in molecular biology to describe a mechanism of circular RNA biogenesis, also called lariat-driven circularization. In this model, exon-containing lariat intermediates formed during pre-mRNA splicing serve as substrates for generating circular RNAs (circRNAs). This mechanism contrasts with intron-pairing-driven circularization, which relies on base-pairing between complementary intronic sequences to promote back-splicing.

Mechanism: During splicing, introns are removed via lariat formation. In some transcripts, skipping of exons produces a lariat that includes exonic sequences. Following intron removal and debranching, exon junctions can undergo back-splicing, yielding a circRNA composed mainly of exons derived from the original transcript. The lariat stage is thus considered a driving intermediate in the production of certain circRNAs.

Evidence and scope: Lariat-driven circularization is one of several models proposed for circRNA biogenesis. It has been supported by observations that the production of some circRNAs correlates with exon skipping and with the presence of lariat-like intermediates. The relative contribution of this route appears to be gene- and context-dependent, and not all circRNAs are explained by this mechanism.

Implications: Understanding lariat-driven circularization enhances knowledge of the regulatory potential of circRNAs, including roles in gene expression regulation, miRNA sequestration, and potential translation. Experimental manipulation of splicing factors or debranching enzymes has been used to probe its involvement in specific transcripts.

See also: circular RNA, RNA splicing, lariat intron, back-splicing.