Spatiotemporal expression profile of embryonic and adult ankyrin repeat and EF-hand domain containing protein 1-encoding genes ankef1a and ankef1b in zebrafish

Abstract

Recent human next-generation sequencing (NGS) studies indicate a correlation between ANKEF1 (ankyrin repeat and EF-hand domain containing protein 1) expression and cilia formation or function. Additionally, a single study conducted in the African clawed frog (Xenopus laevis) showed ankef1 is down-regulated after pharmacological fibroblast growth factor (FGF) inhibition and plays a role in protocadherin-mediated cell protrusion and adhesion. That study also revealed a critical role for ankef1 in the embryonic development of the frog, with morphants exhibiting phenotypes including spina bifida and a shortened body axis. Interestingly, while little is known about ANKEF1 function in other vertebrate systems, recent proteomic data has shown ANKEF1 enriched in ciliated cells. Likewise, publicly available EST profile databases imply ANKEF1 expression in multiple human tissues, including high levels in the testes. Together, these previous studies suggest an important role for ANKEF1 in ciliated tissues and during embryonic development. Here, we report cloning of zebrafish (Danio rerio) ankef1a, as well as its paralog, ankef1b, and expression analyses by whole-mount in situ hybridization (WISH) and quantitative polymerase chain reaction (qPCR) during embryonic development and in adult tissues. WISH shows both forms are ubiquitously expressed early in development, with more discrete expression of both transcripts in embryonic tissues known to precede or possess motile cilia, including dorsal forerunner cells (DFC) and the otic vesicles, respectively. Additionally, both transcripts are enriched in the developing pharynx and swim bladder. Our qPCR results indicate enhanced expression in the testes, along with increased expression in brain. Certainly, our experiments in the zebrafish model system with ankef1a and ankef1b provide a solid foundation for future studies to uncover the molecular pathways through which Ankef1 acts in both healthy and disease states.

Keywords: Ankef1; Ankrd5; Ankyrin-repeat; Anr5; EF-Hand.