Newly identified APN splice isoforms suggest novel splicing mechanisms may underlie circRNA circularization in moth

Abstract

Circular RNA (circ RNA ) have long been considered by‐products of splicing errors, but the coordination of RNA transcription and exon circularization events remains poorly understood. Here, we investigated this question using genes encoding aminopeptidases N ( APN s), which are receptors of Bacillus thuringiensis toxins, in the cotton bollworm, Helicoverpa armigera . We cloned and sequenced the cDNA of ten APN genes ( Ha APN 1‐10 ) located in the same APN gene cluster, and detected 20 and 14 novel splicing isoforms with exon skipping in Ha APN 1 and Ha APN 3 , respectively, whereas no or very few variants were found in the remaining genes. Further study identified 14 and 6 circular RNA (circ RNA ) in Ha APN 1 and Ha APN 3, respectively. Neither novel splicing isoforms nor circ RNA were detected in Ha APN 2 and Ha APN 5 . Distinct from the conventional GT / AG splicing signal, short co‐directional repeats were involved in the splicing of the linear and circular isoforms of Ha APN 1 and Ha APN 3 . Identification of the splice sites revealed that the linear isoforms may be related in some way to the circularization. Moreover, phylogenetic analysis and detection of circ RNA of the APN gene of the diamondback moth, Plutella xylostella ( Px APN 3 ), showed that circ RNA formation is relatively conserved during the lepidopteran evolutionary process. These results contribute to an improved understanding of lepidopteran APN s and this novel class of insect circ RNA .

Circular RNA, circ1-3p, is Involved in Cyflumetofen Resistance by Acting as a Competitive RNA against miR-1-3p in Tetranychus cinnabarinus

“…39,40 Currently, the circRNAs of only a few species of insects have been identified, including Drosophila melanogaster, 41 B. mori, 42 Apis mellifera, 12 and Plutella xylostella. 43 Interestingly, a recent study indicated that a circRNA of B. mori, circEgg, could regulate histone epigenetic modification by sponging bmo-miR-3391-5p and encoding circEgg-P122 proteins. Another circRNA, circSfl, also can regulate the lifespan in Drosophila.…”

“…CircRNA is a common ceRNA molecule, which can regulate mRNA expression by sponging miRNA, thereby mediating a variety of physiological changes, such as proliferation, migration, and drug resistance of cancer cells. , Currently, the circRNAs of only a few species of insects have been identified, including Drosophila melanogaster, B. mori, Apis mellifera, and Plutella xylostella . Interestingly, a recent study indicated that a circRNA of B.…”

Circ-Udg Derived from Cyprinid Herpesvirus 2 Promotes Viral Replication

“…Studies have shown that in some organisms, the 5′- and 3′-end split sites of circRNAs tend to have short direct repeats, which are important for circRNA formation, and only one of these repeats is retained in the formed circRNA ( 31 ). Similar short direct repeats were found on the 5′- and 3′-end split sites of circ-udg.…”

Aal-circRNA-407 regulates ovarian development of Aedes albopictus, a major arbovirus vector, via the miR-9a-5p/Foxl axis

“…The genome-wide identification of insect circRNAs was first performed in Drosophila melanogaster in 2014 [ 17 ]. Subsequently, a relatively comprehensive identification of circRNAs was performed in Bombyx mori [ 18 ], Apis mellifera [ 19 ], Dendrolimus punctatus [ 20 ], Helicoverpa armigera [ 21 ] and Culex pipiens pallens [ 22 ]. Nevertheless, only a few circRNAs have been functionally characterized.…”