The latent-TGFbeta-binding-protein-1 (LTBP-1) is expressed in the organizer and regulates nodal and activin signaling.
The latent TGF-beta binding proteins (LTBP) are believed to control the availability of TGF-beta in the extracellular milieu. To gain insight into the potential roles of LTBP in early development, we isolated the Xenopus LTBP-1 (xLTBP-1) cDNA. The cDNA encodes a protein similar to the mammalian LTBP-1 in both size and domain structure. In addition, we found a novel longer splice isoform of xLTBP. The RNAs for both forms of xLTBP displayed temporal regulation and the shorter transcript is expressed maternally. Both transcripts also display spatial regulation and are found in the dorsal mesoderm of the organizer. In animal cap experiments, LTBP-1 potentiates the activity of activin and nodal. The activity of LTBP-1 did not appear to require covalent association with activin as the addition of medium containing activin and LTBP-1 to animal caps enhanced the activin effect. These results indicate that LTBP-1 may be part of the regulatory system that establishes the threshold of morphogen activity for activins and nodals in the dorsal side of the embryo during gastrulation.
Altmann
Curtis R
CR
Laboratory of Molecular Embryology, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Chang
Chenbei
C
Muñoz-Sanjuán
Ignacio
I
Bell
Esther
E
Heke
Michael
M
Rifkin
Daniel B
DB
Brivanlou
Ali H
AH
D028341:Activins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000502:physiology*; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary / Q000378:metabolism; D006801:Humans; D017403:In Situ Hybridization; D047908:Intracellular Signaling Peptides and Proteins; D053779:Latent TGF-beta Binding Proteins; D008648:Mesoderm / Q000378:metabolism; D008969:Molecular Sequence Data; D009697:Nucleolus Organizer Region; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins
D002352:Carrier Proteins; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; C509032:LTBP1 protein, human; D053779:Latent TGF-beta Binding Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; C512833:nodal1 protein, Xenopus; D028341:Activins