The Pma-PABP4 gene, regulated by Pma-miR-1444, participates in Pinctada fucata gonad development

This study cloned and characterized the full-length cDNA of the Pma-PABP4 gene from Pinctada fucata, which is 3123 bp in length and encodes a 641-amino acid protein. The protein exhibited typical RNA-binding protein characteristics, including four RNA recognition motifs (RRMs) and a poly(A)-binding domain. Bioinformatics analyses revealed that Pma-PABP4 is hydrophobic and contains multiple predicted phosphorylation sites. Phylogenetic analysis showed that Pma-PABP4 is highly homologous to PABP4 from other mollusks and shares evolutionary conservation with human PABP1. Additionally, Pma-PABP4 was widely expressed in many tissues in P. fucata with sex-biased expression, where expression levels varied significantly during early embryonic development and specific stages of gonadal development. It was also localized in the gonadal tissues, and RNA interference experiments confirmed that silencing Pma-PABP4 resulted in abnormal gonadal development and reduced gamete production. This study also showed that Pma-miR-1444 directly targets the coding sequence of Pma-PABP4 at the 1371-bp site, negatively regulating its expression. The spatiotemporal expression patterns of Pma-miR-1444 were also closely associated with gametogenesis and embryonic development. Overexpression of Pma-miR-1444 led to gonadal atrophy and a significant reduction in gamete numbers. In conclusion, Pma-miR-1444 and Pma-PABP4 play crucial regulatory roles in the reproductive development and embryogenesis of P. fucata.