Divergent Expression Patterns and Function Implications of Four nanos Genes in a Hermaphroditic Fish, Epinephelus coioides.

Zhi-Hui Sun,Yang Wang,Jian-Fang Gui,Li Zhou,Xiao-Chun Liu,Zhi Li,Shui-Sheng Li,Wei-Jia Lu

doi:10.3390/ijms18040685

Abstract

Multiple nanos genes have been characterized in several fishes, but the functional implications of their various expression patterns remain unclear. In this study, we identified and characterized four nanos genes from a hermaphroditic fish orange-spotted grouper, Epinephelus coioides. Ecnanos1a and Ecnanos1b show divergent expression patterns, and the dynamic expression change of Ecnanos1a in pituitaries during sex change is associated with testis differentiation and spermatogenesis. Ecnanos2 and Ecnanos3 might be germline stem cells (GSCs) and primordial germ cells (PGCs)-specific markers, respectively. Significantly, Ecnanos3 3′-untranslated region (UTR) is necessary for PGC specific expression, where a non-canonical “GCACGTTT” sequence is required for miR-430-mediated repression of Ecnanos3 RNA. Furthermore, grouper Dead end (Dnd) can relieve miR-430 repression in PGCs by associating with a 23 bp U-rich region (URR) in Ecnanos3 3′-UTR. The current study revealed the functional association of multiple nanos genes with PGC formation and germ cell development in orange-spotted grouper, and opened up new possibilities for developing biotechnologies through utilizing the associations between Ecnanos3 and PGCs or between Ecnanos2 and GSCs in the hermaphroditic fish.

Highlights

Germ-line cells, including primordial germ cells (PGCs), germline stem cells (GSCs) and gametes, have been attracting more and more attention
Nanos1 was observed to be expressed in the central nervous system [15], NANOS3 was detected in the PGCs as early as Embryonic Day 9.5 (E9.5) and expressed in ovary and testis at a later stage of development, whereas NANOS2 was found to be restricted in the developing male PGCs at E13.5 and to be expressed predominantly in male germ cells [10]
We revealed that a non-canonical “GCACGTTT” sequence and a 23 bp U-rich element with Ecnanos3 3 -untranslated region (UTR) are required for Ecnanos3 PGC specific expression through interacting with miR-430 and Dead end (Dnd) protein

Summary

Introduction

Germ-line cells, including primordial germ cells (PGCs), germline stem cells (GSCs) and gametes, have been attracting more and more attention. Only one nanos gene was found in Drosophila, multiple nanos genes, including nanos, nanos, and nanos, have been cloned in diverse organisms They show varied expression patterns, functions and regulatory mechanisms among different species. Nanos was observed to be expressed in the central nervous system [15], NANOS3 was detected in the PGCs as early as Embryonic Day 9.5 (E9.5) and expressed in ovary and testis at a later stage of development, whereas NANOS2 was found to be restricted in the developing male PGCs at E13.5 and to be expressed predominantly in male germ cells [10]. Multiple nanos genes and their diverse expression patterns have been identified and characterized in several species. The various expression patterns and function implications of nanos genes should be further investigated in diverse fishes

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Conclusion