Molecular Characterization and Alternative Splicing of a Sodium Channel and DSC1 Ortholog Genes in Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)

Abstract

Alternative splicing greatly contributes to the structural and functional diversity of voltage-gated sodium channels (VGSCs) by generating various isoforms with unique functional and pharmacological properties. Here, we identified a new optional exon 23 located in the linker between domains II and III, and four mutually exclusive exons (exons 27A, 27B, 27C, and 27D) in domains IIIS3 and IIIS4 of the sodium channel of Liposcelis bostrychophila (termed as LbVGSC). This suggested that more alternative splicing phenomena remained to be discovered in VGSCs. Inclusion of exon 27C might lead to generation of non-functional isoforms. Meanwhile, identification of three alternative exons (exons 11, 13A, and 13B), which were located in the linker between domains II and III, indicated that abundant splicing events occurred in the DSC1 ortholog channel of L. bostrychophila (termed as LbSC1). Exons 13A and 13B were generated by intron retention, and the presence of exon 13B relied on the inclusion of exon 13A. Exon 13B was specifically expressed in the embryonic stage and contained an in-frame stop codon, inclusion of which led to generation of truncated proteins with only the first two domains. Additionally, several co-occurring RNA editing events were identified in LbSC1. Furthermore, remarkable similarity between the structure and expression patterns of LbVGSC and LbSC1 were discovered, and a closer evolutionary relationship between VGSCs and DSC1 orthologs was verified. Taken together, the data provided abundant molecular information on VGSC and DSC1 orthologs in L. bostrychophila, a representative Psocoptera storage pest, and insights into the alternative splicing of these two channels.

Molecular characterisation of a sodium channel gene and identification of a Phe1538 to Ile mutation in citrus red mite,Panonychus citri

“…Exclusion of both alt 3‐v1 and v2 results in the third variance v3 , and could also generate a non‐functional channel owing to the absence of IIIS3–S4, which is consistent with the absence of exon 3 in VmNa . In sodium channels of insects, the variances in this splice site that would generate truncated proteins are detected in several spices, such as G3 in BgNa v and 27C in LbVGSC . Although the splicing mechanisms are different, the incomplete protein structure in IIIS4 will cause a loss of partial function.…”

“…20 In sodium channels of insects, the variances in this splice site that would generate truncated proteins are detected in several spices, such as G3 in BgNa v and 27C in LbVGSC. 19,52 Although the splicing mechanisms are different, the incomplete protein structure in IIIS4 will cause a loss of partial function. It was reported that alternative splicing of mutually exclusive exons G1 to G3 generates three splicing variances with different sensitivities to deltamethrin.…”

“…Splicing in this region appears to be of a very ancient origin and is preserved in organisms ranging from arthropods to humans . The first two variances ( alt 3‐v1 and v2 ) correspond to the exons k / l of D. melanogaster para , G1 / G2 of the cockroach BgNa v , exons K / L of Cnaphalocrocis medinalis CmNav and exons 27A / 27B of Liposcelis bostrychophila LbVGSC , which are mostly mutually exclusive in insects. By contrast, the corresponding alternative exons in both VmNa and T. urticae VGSC genes are optional, which may suggest that the splicing type of this position is conserved within mites and different from that of insects.…”