Homologues of sox8 and sox10 in the orange-spotted grouper Epinephelus coioides: Sequences, expression patterns, and their effects on cyp19a1a promoter activities in vitro

Sox8 and Sox10 are members of group E Sox proteins involved in a wide range of developmental processes including sex determination and neurogenesis in vertebrates. The orange-spotted grouper sox8a and sox10a homologues were isolated and characterized in the present study. Both sox8a and sox10a genes contain three exons and two introns, and encode putative proteins with typical structures of group E Sox. Sox8a was expressed in diverse tissues including the central nervous system and some peripheral tissues. In contrast, sox10a mRNA was detected primarily in the central nervous system. During embryogenesis, sox8a mRNA seemed to be de novo synthesized in the embryos from otic vesicle stage. However, sox10a mRNA was only detectable in juvenile fish 35 days post hatching and thereafter. The mRNA levels of sox8a in the gonads were not significantly different among ovarian developmental stages but increased in the testis. In vitro transfection assays showed that the Sox10a but not Sox8a up-regulated cyp19a1a promoter activities. Taken together, these results suggested that the sox8a may play roles in diverse tissues and during embryogenesis, whereas sox10a may be mainly involved in the neural regulation of juvenile and adult fish, and that certain Sox homologues may regulate the orange-spotted grouper cyp19a1a promoter.