VegT activation of Sox17 at the midblastula transition alters the response to nodal signals in the vegetal endoderm domain

被引:43
作者
Engleka, MJ [1 ]
Craig, EJ [1 ]
Kessler, DS [1 ]
机构
[1] Univ Penn, Sch Med, Dept Cell & Dev Biol, Philadelphia, PA 19104 USA
关键词
endoderm; mesoderm; Mixer; Nodal; Sox17; VegT; Xenopus;
D O I
10.1006/dbio.2001.0366
中图分类号
Q [生物科学];
学科分类号
07 ; 0710 ; 09 ;
摘要
In Xenopas, the prospective endoderm and mesoderm are localized to discrete, adjacent domains at the beginning of gastrulation, and this is made evident by the expression of Sox17 in vegetal blastomeres and Brachyury (Xbra) in marginal blastomeres. Here, we examine the regulation of Sox17 alpha expression and the role of Sox17 alpha in establishing the vegetal endodermal gene expression domain. Injection of specific inhibitors of VegT or Nodal resulted in a loss of Sox17 alpha expression in the gastrula. However, the onset of Sox17 alpha expression at the midblastula transition was dependent on VegT, but not on Nodal function, indicating that Sox17 alpha expression is initiated by VegT and then maintained by Nodal signals. Consistent with these results, VegT, but not Xenopus Nodal-related-1 (Xnr1), can activate Sox17 alpha expression at the midblastula stage in animal explants. In addition, VegT activates Sox17 alpha in the presence of cycloheximide or a Nodal antagonist, suggesting that Sox17 alpha is an immediate-early target of VegT in vegetal blastomeres. Given that Nodal signals are necessary and sufficient for both mesodermal and endodermal gene expression, we propose that VegT activation of Sox17 alpha at the midblastula transition prevents mesodermal gene expression in response to Nodal signals, thus establishing the vegetal endodermal gene expression domain. Supporting this idea, Sox17 alpha misexpression in the marginal zone inhibits the expression of multiple mesodermal genes. Furthermore, in animal explants, Sox17 alpha prevents the induction of Xbra and MyoD, but not Sox17 beta or Mixer, in response to Xnr1. Therefore, VegT activation of Sox17 alpha plays an important role in establishing a region of endoderm-specific gene expression in vegetal blastomeres. (C) 2001 Academic Press.
引用
收藏
页码:159 / 172
页数:14
相关论文
共 64 条
[1]  
Agius E, 2000, DEVELOPMENT, V127, P1173
[2]   A molecular pathway leading to endoderm formation in zebrafish [J].
Alexander, J ;
Stainier, DYR .
CURRENT BIOLOGY, 1999, 9 (20) :1147-1157
[3]   Cerberus is a head-inducing secreted factor expressed in the anterior endoderm of Spemann's organizer [J].
Bouwmeester, T ;
Kim, SH ;
Sasai, Y ;
Lu, B ;
DeRobertis, EM .
NATURE, 1996, 382 (6592) :595-601
[4]  
Casey ES, 1999, DEVELOPMENT, V126, P4193
[5]   A post-mid-blastula transition requirement for TGFβ signaling in early endodermal specification [J].
Chang, CB ;
Hemmati-Brivanlou, A .
MECHANISMS OF DEVELOPMENT, 2000, 90 (02) :227-235
[6]   MOLECULAR NATURE OF SPEMANNS ORGANIZER - THE ROLE OF THE XENOPUS HOMEOBOX GENE GOOSECOID [J].
CHO, KWY ;
BLUMBERG, B ;
STEINBEISSER, H ;
DEROBERTIS, EM .
CELL, 1991, 67 (06) :1111-1120
[7]  
Clements D, 1999, DEVELOPMENT, V126, P4903
[8]  
CONLON FL, 1994, DEVELOPMENT, V120, P1919
[9]   A crucial component of the endoderm formation pathway, CASANOVA, is encoded by a novel sox-related gene [J].
Dickmeis, T ;
Mourrain, P ;
Saint-Etienne, L ;
Fischer, N ;
Aanstad, P ;
Clark, M ;
Strähle, U ;
Rosa, F .
GENES & DEVELOPMENT, 2001, 15 (12) :1487-1492
[10]  
Ecochard V, 1998, DEVELOPMENT, V125, P2577