RNAi reveals the key role of Nervana 1 in cockroach oogenesis and embryo development

Na+, K+-ATPases is a heterodimer protein consisting of α- and β-subunits that control the ion transport through cell membranes. In insects the β-subunit of the Na+, K+-ATPase, known as Nervana, was characterized as a nervous system-specific glycoprotein antigen from adult Drosophila melanogaster heads. Nervana is expressed ubiquitously in all insect tissues, and in epithelial cells appeared located in a basolateral position as part of the septate junctions. Herein we study two Nervana isoforms from Blattella germanica, a cockroach species with panoistic ovaries. The sequencing and the phylogenetic analysis results suggest that these two isoforms are orthologs of D. melanogaster Nervana 1 and Nervana 2, respectively. Nervana 1 is highly expressed in the ovary of B. germanica, and depleting its expression results in changes in oocyte shape that do not impair oviposition. However, the resulting embryos show different defects and never hatch. These findings highlight the importance of this type of membrane pump in insect oogenesis as well as in embryo development, and its possible regulation by juvenile hormone.

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► Two Nervana ortholog isoforms have been described in the cockroach Blattella germanica.
► BgNrv1 was the most represented isoform and was for the first time described in insects ovary.
► BgNrv1 is regulated by juvenile hormone.
► dsBgNrv1 produce sterile females and mis-localized embryos during development.
► dsBgNrv1 affects coracle mRNA expression, probably affecting septate junction.