| DMRT/Dmrt (Doublesex and Mab-3 Related Transcription factor) genes encode a family of transcription factors related to Drosophila melanogaster doublesex (Dsx) and Caenorhabditis elegans Mab3, which are characterized by a unique zinc finger like DNA-binding motif known as the DM domain. Dmrt family genes are important genes related to development. Currently, majority of the members are associated with sex differentiation and determination, while some of the members are reported to participate in the process of embryonic development of other organs.Our previous studies show that Dmrt4 plays a key role in the process of the Xenopus olfactory neurogenesis. During the cloning process of Dmrt4, we also cloned two other homologous genes of Dmrt4---Dmrt3 and Dmrt5. And our primarily data also reveal that these three homologues may have overlapping expression regions on olfactory placodes and dorsal telencephalon. Thus, in this study, we focus on their similarities and differences on regulation of downstream genes during embryogenesis by genome wide microarray analysis. Combining with previous study on Xenopus Dmrt4, and through a series of in vitro/in vivo studies, we propose that Dmrt5 is also involving in olfactory neurogenesis. The main findings are as follows:Data from the microarray screen show that 233 genes’expression are raised and 99 genes’ expression are reduced more than 10 times by Dmrt5;337 genes’expression are raised and 361 genes’expression are reduced more than 10 times by Dmrt4; while 201 genes’expression are raised and 289 genes’expression are reduced more than 10 times by Dmrt3. Through profile comparing among Dmrt3,4,5 with each other, we find that they are regulating different profiles of downstream genes, although they are overlapping expressed in forebrain and olfactory placodes. Data from the microarray screen also show that 917 genes’expression are raised and 510 genes’expression are reduced both by Dmrt4 and DmrtS; 117 genes’expression are raised and 105 genes’expression are reduced both by Dmrt3 and Dmrt5\while 124 genes’expression are raised and 228 genes’expression are reduced both by Dmrt3 and Dmrt4. Furthermore 558 genes’ expression are raised and 373 genes’expression are reduced by all of them.These data indicate that Dmrt3、4、5 probably control different downstream gene profiles during embryogenesis, while they may share common characteristics in regulation of olfactory neurogenesis.Further detailed analysis of Dmrt5’s microarray data reveal that Dmrt5 can strongly up-regulate the expression of Dmrt4. Ncam、Neurogenin2 and Ebf2. Since these genes are important genes controlling olfactory neurogenesis in Xenopus tropicalis, we perform a series of in vivo/vitro assays by knockdown, overexpression and rescue to demonstrate that Dmrt5 also paly an important role in olfactory neurogenesis. Most interestingly, our data clearly indicate that Dmrt5 may promote olfactory neurogenesis via inducing Dmrt4’s expression.In addition, we also find Dmrt5 may be a multiple function regulator which participates in different developmental processes. For example Dmrt5 may be involved in embryo gastrulation and anterior cell fate determination by regulating noncanonical Wnt signalling, because over-expression of Dmrt5 could up-regulate some noncanonical Wnt ligands’expression, such as Wnt7a/b, Wntll and Wnt9a/b etc. Furthermore we find some genes like En2、Msx1、Gli3, which are related to ventral mesencephalic neural fate specification, are also up regulated by Dmrt5.In general, our investigation firstly demonstrates that Dmrt5 is essential and critical for olfactory neurogenesis in Xenopus tropicalis. Besides, Dmrt5 could play multiple roles during embryogenesis. And our global gene expression analysis provides a valuable platform for further study. |
PDF Full Text Request