Depletion of Bmp2, Bmp4, Bmp7 and Spemann organizer signals induces massive brain formation in Xenopus embryos.
To address the patterning function of the Bmp2, Bmp4 and Bmp7 growth factors, we designed antisense morpholino oligomers (MO) that block their activity in Xenopus laevis. Bmp4 knockdown was sufficient to rescue the ventralizing effects caused by loss of Chordin activity. Double Bmp4 and Bmp7 knockdown inhibited tail development. Triple Bmp2/Bmp4/Bmp7 depletion further compromised trunk development but did not eliminate dorsoventral patterning. Unexpectedly, we found that blocking Spemann organizer formation by UV treatment or beta-Catenin depletion caused BMP inhibition to have much more potent effects, abolishing all ventral development and resulting in embryos having radial central nervous system (CNS) structures. Surprisingly, dorsal signaling molecules such as Chordin, Noggin, Xnr6 and Cerberus were not re-expressed in these embryos. We conclude that BMP inhibition is sufficient for neural induction in vivo, and that in the absence of ventral BMPs, Spemann organizer signals are not required for brain formation.
Howard Hughes Medical Institute and Department of Biological Chemistry, University of California, Los Angeles, CA 90095-1662, USA.
Bruno
B
Reversade
Hiroki
H
Kuroda
Hojoon
H
Lee
Ashley
A
Mays
Edward M
EM
De Robertis
D000818:Animals; D001483:Base Sequence; D019521:Body Patterning / Q000502:physiology; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000172:deficiency / Q000502:physiology*; D001921:Brain / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000502:physiology; D006023:Glycoproteins / Q000172:deficiency / Q000502:physiology; D036341:Intercellular Signaling Peptides and Proteins / Q000172:deficiency / Q000502:physiology; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009025:Morpholines / Q000494:pharmacology; D011506:Proteins / Q000502:physiology*; D015398:Signal Transduction; D013623:Tail / Q000196:embryology*; D016212:Transforming Growth Factor beta / Q000172:deficiency / Q000502:physiology*; D029867:Xenopus Proteins / Q000172:deficiency / Q000502:physiology*; D014982:Xenopus laevis / Q000196:embryology*
C504610:Bmp2 protein, Xenopus; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D009025:Morpholines; D011506:Proteins; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; C525812:bmp4 protein, Xenopus; C525822:bmp7.1 protein, Xenopus; C100866:cer1 protein, Xenopus; C054234:chordin