The expression of natriuretic peptide receptors in developing zebrafish embryos

There are three isoforms of natriuretic peptide (NP) specific cell surface receptor: NP receptor-A (NPRA), receptor-B (NPRB), and receptor-C (NPRC). They are also known as NPR1, NPR2 and NPR3, respectively. NPs and their receptors were revealed to involve in diverse cellular and physiological processes including renal, cardiovascular, neuronal, and immunological aspects. However, the systematic analysis of the expression of these receptors in non-mammalian vertebrates is thus far lacking. In this study, two versions of the npr1 gene (npr1a and npr1b) in zebrafish was identified. Multiple sequences alignment analysis showed that zebrafish NPRs shared high homologies with NPRs of other species and possessed a typical signature domain of NPRs. The results of whole mount in situ hybridization and reverse transcription polymerase chain reaction analysis revealed that at embryonic stages, npr1a was mainly expressed in tectal ventricle, brian, heart and retina, whereas npr1b was broadly present in anterior pronephric duct. Unlike npr1, npr2 mainly expressed in branchial arches and neural tube during embryonic development. However, npr3 was expressed in pronephric ducts and corpuscle of stannius in zebrafish embryos at 72 hpf. In adults, we demonstrated that all the three NP receptors were highly existed in brain and kidney. Overall, these findings will provide an important basis for the functional analysis of NPs and its receptor during embryonic development.