Xenopus Smad3 is specifically expressed in the chordoneural hinge, notochord and in the endocardium of the developing heart.
The Smads are intracellular signalling molecules that transduce signals from receptors for members of the TGF-beta superfamily to the nucleus. We have cloned the Xenopus orthologue of Smad3 (XSmad3). It is 94.6% identical to human Smad3 at the amino acid level. It is expressed as a maternal mRNA which disappears after stage 10.5, but reappears at the early tailbud stages. It is much less abundant than XSmad2 at the early developmental stages. From Stage 27 onwards XSmad3 is expressed with XSmad2 throughout the head region and in the somitic region. Strikingly however, XSmad3 alone is specifically expressed in the chordoneural hinge, the notochord and in the developing heart. Closer analysis reveals that XSmad3 is specifically expressed in the endocardium but not in the myocardium or pericardium. The chordoneural hinge staining persists at least until stage 40 whereas the staining in the endocardium peaks at approximately stage 32/33.
Howell
M
M
Laboratory of Developmental Signalling, Imperial Cancer Research Fund, 44 Lincoln's Inn Fields, London WC2A 3PX, UK.
Mohun
T J
TJ
Hill
C S
CS
D000595:Amino Acid Sequence; D000818:Animals; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004699:Endocardium / Q000378:metabolism*; D015723:Gene Library; D006321:Heart / Q000196:embryology*; D008969:Molecular Sequence Data; D009672:Notochord / Q000378:metabolism*; D012260:Ribonucleases / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D051900:Smad3 Protein; D013997:Time Factors; D015534:Trans-Activators / Q000096:biosynthesis*; D014981:Xenopus; D029867:Xenopus Proteins
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051900:Smad3 Protein; D015534:Trans-Activators; D029867:Xenopus Proteins; C497789:madh3 protein, Xenopus; D012260:Ribonucleases