Elsevier

Developmental Biology

Volume 225, Issue 2, 15 September 2000, Pages 447-458
Developmental Biology

Regular Article
csal1 Is Controlled by a Combination of FGF and Wnt Signals in Developing Limb Buds

https://doi.org/10.1006/dbio.2000.9852Get rights and content
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Abstract

While some of the signaling molecules that govern establishment of the limb axis have been characterized, little is known about the downstream effector genes that interpret these signals. In Drosophila, the spalt gene is involved in cell fate determination and pattern formation in different tissues. We have cloned a chick homologue of Drosophila spalt, which we have termed csal1, and this study focuses on the regulation of csal1 expression in the limb bud. csal1 is expressed in limb buds from HH 17 to 26, in both the apical ectodermal ridge and the distal mesenchyme. Signals from the apical ridge are essential for csal1 expression, while the dorsal ectoderm is required for csal1 expression at a distance from the ridge. Our data indicate that both FGF and Wnt signals are required for the regulation of csal1 expression in the limb. Mutations in the human homologue of csal1, termed Hsal1/SALL1, result in a condition known as Townes–Brocks syndrome (TBS), which is characterized by preaxial polydactyly. The developmental expression of csal1 together with the digit phenotype in TBS patients suggests that csal1 may play a role in some aspects of distal patterning.

Keywords

spalt
sal
Townes–Brocks syndrome
limb
FGF
Wnt
Shh
BMP

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Sequence data from this article have been deposited with the EMBL/GenBank Data Libraries under Accession No. AF 288697.

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