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XB-ART-4248
Development.
January 1, 2004;
131
(2):
Inactivation of mouse Twisted gastrulation reveals its role in promoting Bmp4 activity during forebrain development.
Abstract
Twisted gastrulation (Tsg) is a secreted protein that regulates Bmp signaling in the extracellular space through its direct interaction with Bmp/Dpp and Chordin (Chd)/Short gastrulation (Sog). The ternary complex of Tsg/Chd/Bmp is cleaved by the metalloprotease Tolloid (Tld)/Xolloid (Xld). Studies in Drosophila, Xenopus and zebrafish suggest that Tsg can act both as an anti-Bmp and as a pro-Bmp. We have analyzed Tsg loss-of-function in the mouse. Tsg homozygous mutants are viable but of smaller size and display mild vertebral abnormalities and osteoporosis. We provide evidence that Tsg interacts genetically with Bmp4. When only one copy of Bmp4 is present, a requirement of Tsg for embryonic development is revealed. Tsg-/-;Bmp4+/- compound mutants die at birth and display holoprosencephaly, first branchial arch and eye defects. The results show that Tsg functions to promote Bmp4 signaling during mouse head development.
Pubmed Id:
14681194
Article link:
Development.
Genes referenced:
bmp1
bmp4
chdh
chrd
dspp
hprt1
tll2
twsg1
Antibodies referenced:
Article Images:
[+] show captions
Paper published
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Fig. 1. Genomic organization and expression of the Tsg gene. (A) Schematic representation of the wild-type and targeted alleles of Tsg. The 5′ probe used for the Southern blot is indicated (probe). The oligonucleotides used for PCR genotyping are shown as arrows: Tsg22, Tsg23 and lacZ3. The position of the exons is indicated by black boxes and the recombination arms shown in red. The following restriction sites are indicated: B, BamHI; K, KpnI; N, NsiI; S, SacI. (B) Southern blot analysis of the 5′ genomic region of the Tsg gene. DNAs extracted from wild-type, heterozygous and homozygous Tsg mutant animals were digested with SacI. The 170 bp SacI-NsiI probe fragment detected a wild-type band of 9.2 kb and a knock out (KO) band of 3.7 kb. (C) PCR genotyping of mice carrying the Tsg mutation. The wild-type band of 329 bp was obtained using the Tsg22 and Tsg23 primers. The KO band of 480 bp was obtained using the Tsg22 and lacZ3 primers. (D) RT-PCR analysis of RNAs extracted from E13.5 wild-type and Tsg-/- embryos showing the absence of Tsg mRNA in Tsg-/- embryos. HPRT expression was used as a control. (E-H,E′-H′) Comparison of the expression pattern of Tsg by whole-mount in situ hybridization and β-galactosidase staining. (E) Tsg is expressed in the anterior visceral endoderm and the primitive streak. (F,G) As gastrulation proceeds, Tsg is found in the mesodermal layer. (H) At E8.5 Tsg is present in the endoderm of the gut, the ventral neural tube and the dorsal region of the eye vesicle. (E′-H′) The expression of the lacZ transgene recapitulates the expression of endogenous Tsg. (I) Transverse section through the anterior region of an E8.0 embryo showing Tsg mRNA in the endoderm of the foregut, ventral neuroectoderm and the head mesenchyme. (J) Section of an E8.5 embryo showing the expression of Tsg mRNA in the basal diencephalon. ave, anterior visceral endoderm; bd, basal diencephalon; bm, basal mesencephalon; ev, eye vesicle; en, endoderm; fg, foregut; hg, hindgut; hm, head mesenchyme; mw, mesodermal wings; ne, neuroectoderm; ps, primitive streak; A, anterior; L, left; P, posterior; R, right.
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[2.8.5]
