Mouse Lefty2 and Zebrafish Antivin Are Feedback Inhibitors of Nodal Signaling during Vertebrate Gastrulation

Abstract

Mammalian lefty and zebrafish antivin form a subgroup of the TGF beta superfamily. We report that mouse mutants for lefty2 have an expanded primitive streak and form excess mesoderm, a phenotype opposite to that of mutants for the TGF beta gene nodal. Analogously, overexpression of Antivin or Lefty2 in zebrafish embryos blocks head and trunk mesoderm formation, a phenotype identical to that of mutants caused by loss of Nodal signaling. The lefty2 mutant phenotype is partially suppressed by heterozygosity for nodal. Similarly, the effects of Antivin and Lefty2 can be suppressed by overexpression of the nodal-related genes cyclops and squint or the extracellular domain of ActRIIB. Expression of antivin is dependent on Nodal signaling, revealing a feedback loop wherein Nodal signals induce their antagonists Lefty2 and Antivin to restrict Nodal signaling during gastrulation.

Identification of nodal signaling targets by array analysis of induced complex probes

“…This finding suggests that Wnt signaling in the germ ring may be tightly balanced by agonistic and antagonistic interactions under the control of Nodal signals. Activation of inhibitors has also been reported in the Nodal signal transduction pathway (Bisgrove et al, 1999;Meno et al, 1999). In agreement, the Nodal inhibitors lefty1 (by sequencing of probe subclones, Table 1) and lefty2 (Bisgrove et al, 1999) (by macro-array hybridization, Table 2) were enriched in the Tar* probe.…”

“…The identified clones include 15 genes that have previously been identified to be inducible by Nodal/Tar signaling (e.g., lefty2 [Meno et al, 1999], bhikhari [Vogel and Gerster, 1999], foxA2 [axial; Strahle et al, 1993;Peyrieras et al, 1998], casanova [Dickmeis et al, 2001a;Kikuchi et al, 2001]), or to be expressed in the germ ring/organizer (e.g., spadetail [Griffin et al, 1998], otx3 [Mori et al, 1994], forkhead2, [Odenthal and Nusslein-Volhard, 1998], chordin [Schulte-Merker et al, 1997]). Forty-three genes were either related to hypothetical proteins (16), previously identified ESTs (19), or had no obvious sequence homology (8) ( Table 2, and additional data in Table 4 in supplementary material on the Web).…”

21st Century neontology and the comparative development of the vertebrate skull

“…This asymmetry is mirrored by the underlying hypoblast (visceral endoderm;e.g., Otx2, Lim1, Hesx1, Hex, HNF3␤, Lefty1, Nodal (Acampora et al, 1995;Thomas and Beddington, 1996;Belo et al, 1997;Filosa et al, 1997;Varlet et al, 1997;Thomas et al, 1998;Meno et al, 1999;Shimono and Berhinger, 1999;Kimura et al, 2001). …”

Xenopus Lefty requires proprotein cleavage but not N‐linked glycosylation to inhibit nodal signaling

“…For FGF8, endocytosis regulates the amount of extracellular protein available for signaling, and the distance the protein can travel from the source of production (Scholpp and Brand, 2004). Receptor availability and extracellular antagonists are powerful dynamic regulators of morphogen gradients (Smith and Harland, 1992;Sasai et al, 1994;Bouwmeester et al, 1996;Goodrich et al, 1996;Meno et al, 1996Meno et al, , 1999Thisse and Thisse, 1999;Cheng et al, 2000;Tanegashima et al, 2000;Larrain et al, 2001;Branford and Yost, 2002;Chang et al, 2003;Harms and Chang, 2003;Zhang et al, 2004). In addition, the preferential degradation of a particular mRNA can contribute to formation of a morphogen gradient.…”

“…Lefty, a divergent member of the TGF␤ family whose transcription is directly regulated by Nodal signaling, is one of the principal extracellular feedback inhibitors of Nodal signaling (Meno et al, 1996(Meno et al, , 1999Thisse and Thisse, 1999;Cheng et al, 2000;Tanegashima et al, 2000;Branford and Yost, 2002;Cha et al, 2006). The current understanding is that Lefty antagonizes Nodal signaling by binding to either the EGF-CFC cofactor directly, or by physically interacting with the Nodal ligand, thereby blocking Nodal-receptor interaction and inhibiting downstream signal transduction (Chen and Shen, 2004;Cheng et al, 2004;Tanegashima et al, 2004).…”