Expression patterns of SH3BGR family members in zebrafish development

SH3 domain-binding glutamic acid-rich (SH3BGR) gene family is composed of SH3BGR, SH3BGRL, SH3BGRL2, and SH3BGRL3 which encodes a cluster of small thioredoxin-like proteins and shares a Src homology 3 (SH3) domain. However, biological functions of SH3BGR family members are largely elusive. Given that zebrafish (Danio rerio) sh3bgrl, sh3bgrl2, sh3bgrl3, and sh3bgr are evolutionally identical to their corresponding human orthologues, we analyzed the spatiotemporal expression of SH3BGR family members in zebrafish embryonic development stages by in situ hybridization. Our results revealed that except sh3bgrl, other members are all maternally expressed, especially for sh3bgrl3 that is strongly expressed from one-cell stage to juvenile fishes. In situ expression patterns of SH3BGR members are similar in the very early developmental stages, including with commonly strong expression in intestines, olfactory bulbs, and neuromasts for neural system building up. Organ-specific expressions are also demonstrated, of which sh3bgr is uniquely expressed in sarcomere, and sh3bgrl3 in liver. sh3bgrl and sh3bgrl2 are similarly expressed in intestines, notochords, and neuromasts after 12-h post-fertilization of embryos. Eventually, messenger RNAs (mRNAs) of all sh3bgr members are mainly constrained into intestines of juvenile fishes. Collectively, our study clarified the expression patterns of sh3bgr family members in diverse organogenesis in embryonic development and indicates that SH3BGR members may play predominant roles in neural system development and in maintenance of normal function of digestive organs, especially for intestine homeostasis. However, their expression patterns are varied with the development stages and organ types, suggesting that the aberrant expression of these members would result in multiple diseases.