Nuclear localization, DNA binding and restricted expression in neural and germ cells of zebrafish Dmrt3

Abstract

Background information. The DM (doublesex and male aberrant-3) genes implicated in sexual development in diverse metazoan organisms have been proved to be involved in development of non-gonadal tissues. The aim of the present study was to identify and characterize Dmrt3 (DM-related transcription factor 3) of zebrafish.Results. Zebrafish Dmrt3 has a conserved DMA domain, besides a common DM domain, which clustered it into the DMRTA subfamily. During embryogenesis, Dmrt3 expression increases gradually to a high level at pharyngula stage, which is restricted to the olfactory placode and the neural tube. In the juvenile zebrafish, the gene expression is first detected in undifferentiated gonad on 17 dpf (day post-fertilization). In adult, Dmrt3 is expressed only in the developing germ cells of both gonads, mainly in spermatogonia, spermatocytes and developing oocytes. The Dmrt3 has a functional NLS (nuclear localization signal) K 41 GHKR 45 within the DM domain, which ensures that Dmrt3 exerts its role in the nucleus. Moreover, EMSA (electrophoretic mobility-shift assay) indicates that the Dmrt3-derived DM polypeptide binds to similar sites of both targets of DSX (doublesex) and MAB-3 (male aberrant-3).Conclusion. These results suggest that as a DNA-binding protein, zebrafish Dmrt3 may function in the nucleus as a potential transcription factor to exert potential roles in the development of the olfactory placode, the neural tube and germ cells.

Sex dimorphic expression of five dmrt genes identified in the Atlantic cod genome. The fish-specific dmrt2b diverged from dmrt2a before the fish whole-genome duplication

“…The adult cod displayed female-specific dmrt2a expression throughout the reproductive season, while the gonadal expression of cod dmrt3 was restricted to males, except for the upregulated ovarian expression at spawning time. In comparison, medaka and pufferfish displayed male-specific gonad expression of dmrt3, but expressed dmrt2a also in the ovary, whereas zebrafish dmrt2a and dmrt3 were expressed in both male and female gonads (Brunner et al, 2001;Li et al, 2008;Veith et al, 2006;Winkler et al, 2004;Yamaguchi et al, 2006). While the discrepancy might be partly explained by different maturation stage being analysed, a functional switch between the Dmrt factors in different teleost sublineages was suggested by Herpin and Schartl (2011).…”

The Xenopus doublesex-related gene Dmrt5 is required for olfactory placode neurogenesis

“…In zebrafish, mouse and chick, Dmrt3 is also detected in the olfactory placodes and dorsal forebrain. It is also transcribed in spinal cord dorsal interneurons in those species and in the presomitic mesoderm in chicken (Smith et al, 2002;Winkler et al, 2004;Li et al, 2008). Thus, Dmrt3-5 genes have highly overlapping expression patterns.…”

Dmrt1 genes at the crossroads: a widespread and central class of sexual development factors in fish

“…By contrast, in tilapia dmrt4 expression is exclusively detected in the ovary [41]. Finally, both male and female gonadal expression was reported for dmrt2 in medaka [39] and dmrt3 and ‐ 5 in zebrafish [42,43]. This expression discrepancy regarding the dmrt paralogues may indicate a possible functional switch between those in different phylogenetic lineages.…”