SoxE factors function equivalently during neural crest and inner ear development and their activity is regulated by SUMOylation

Sox9 and the closely related factor Sox10 are essential for the formation of neural crest precursor cells, and play divergent roles in the process by which these cells are subsequently directed to form specific derivatives. These group E Sox factors have also been implicated in the development of the vertebrate inner ear. Despite their importance, however, the mechanisms that allow SoxE proteins to regulate such a diverse range of cell types have remained poorly understood. Here we demonstrate that during vertebrate development, the activities of individual SoxE factors are well conserved and are regulated by SUMOylation. We show that SoxE mutants that cannot be SUMOylated, or that mimic constitutive SUMOylation, are each able to mediate a subset of the diverse activities characteristic of wild-type SoxE proteins. These findings provide important mechanistic insight into how the activity of widely deployed developmental regulatory proteins can be directed to specific developmental events.     

Impact of transcription factor Sox8 on oligodendrocyte specification in the mouse embryonic spinal cord

The myelin-forming oligodendrocytes of the mouse embryonic spinal cord express the three group E Sox proteins Sox8, Sox9, and Sox10. They require Sox9 for their specification from neuroepithelial cells of the ventricular zone and Sox10 for their terminal differentiation and myelination. Here, we show that during oligodendrocyte development, Sox8 is expressed after Sox9, but before Sox10. Loss of Sox8 did not impair oligodendrocyte specification by itself, but enhanced the Sox9-dependent defect. Oligodendrocyte progenitors were still generated in the Sox9-deficient spinal cord, albeit at 20-fold lower rates than in the wildtype. Combined loss of Sox8 and Sox9, in contrast, led to a near complete loss of oligodendrocytes. Other cell types such as ventricular zone cells and radial glia remained unaffected in their numbers as well as their rates of proliferation and apoptosis. Oligodendrocyte development thus relies on the differential contribution of all three group E Sox proteins at various phases.     

野生中国大鲵Sox基因的克隆与序列分析

Sox基因家族是一类编码转录因子的基因家族,其产物具有一个HMG-box基序保守区,调节动物的性别决定与分化过程,并参与多种器官的发育。参照人SRY基因HMG-box保守区序列及有关文献,设计一对简并引物,PCR扩增了野生雌性中国大鲵（Andrias davidianus）基因组DNA,结果得到了一条长约220 bp的产物片段;菌落PCR扩增结果表明,克隆后的白色菌落中90%以上都是阳性克隆;通过SSCP技术筛选到3种有差异的阳性克隆,进行测序,获得了3个Sox基因：Sox4a、Sox4b与Sox14。对所得序列进行序列比对和聚类分析,结果显示该基因在分子进化上具有高度的保守性。对中国大鲵Sox基因的研究,目前国内外尚未见报道。为研究中国大鲵性别决定机制以及Sox基因进化提供了分子遗传学资料。     

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.