AUTHOR=Liu Bing-Zheng , Cong Jing-Jing , Su Wei-Yi , Hao Zhen-Lin , Sun Zhi-Hui , Chang Ya-Qing 

TITLE=Identification and functional analysis of Dmrt1 gene and the SoxE gene in the sexual development of sea cucumber, Apostichopus japonicus

JOURNAL=Frontiers in Genetics

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2023.1097825

DOI=10.3389/fgene.2023.1097825

ISSN=1664-8021

ABSTRACT=<p>Members of the Doublesex and Mab-3-related transcription factor (<italic>Dmrt</italic>) gene family handle various vital functions in several biological processes, including sex determination/differentiation and gonad development. <italic>Dmrt1</italic> and <italic>Sox9</italic> (<italic>SoxE</italic> in invertebrates) exhibit a very conserved interaction function during testis formation in vertebrates. However, the dynamic expression pattern and functional roles of the <italic>Dmrt</italic> gene family and <italic>SoxE</italic> have not yet been identified in any echinoderm species. Herein, five members of the <italic>Dmrt</italic> gene family (<italic>Dmrt1</italic>, <italic>2</italic>, <italic>3a</italic>, <italic>3b</italic> and <italic>5</italic>) and the ancestor <italic>SoxE</italic> gene were identified from the genome of <italic>Apostichopus japonicus</italic>. Expression studies of <italic>Dmrt</italic> family genes and <italic>SoxE</italic> in different tissues of adult males and females revealed different expression patterns of each gene. Transcription of <italic>Dmrt2</italic>, <italic>Dmrt3a</italic> and <italic>Dmrt3b</italic> was higher expressed in the tube feet and coelomocytes instead of in gonadal tissues. The expression of <italic>Dmrt1</italic> was found to be sustained throughout spermatogenesis. Knocking-down of <italic>Dmrt1</italic> by means of RNA interference (RNAi) led to the downregulation of <italic>SoxE</italic> and upregulation of the ovarian regulator <italic>foxl2</italic> in the testes. This indicates that <italic>Dmrt1</italic> may be a positive regulator of <italic>SoxE</italic> and may play a role in the development of the testes in the sea cucumber. The expression level of <italic>SoxE</italic> was higher in the ovaries than in the testes, and knocking down of <italic>SoxE</italic> by RNAi reduced <italic>SoxE</italic> and <italic>Dmrt1</italic> expression but conversely increased the expression of <italic>foxl2</italic> in the testes. In summary, this study indicates that <italic>Dmrt1</italic> and <italic>SoxE</italic> are indispensable for testicular differentiation, and <italic>SoxE</italic> might play a functional role during ovary differentiation in the sea cucumber.</p>