Neural and head induction by insulin-like growth factor signals.
Evidence is presented for a new pathway participating in anterior neural development. It was found that IGF binding protein 5 (IGFBP-5), as well as three IGFs expressed in early embryos, promoted anterior development by increasing the head region at the expense of the trunk in mRNA-injected Xenopus embryos. A secreted dominant-negative type I IGF receptor (DN-IGFR) had the opposite effect. IGF mRNAs led to the induction of ectopic eyes and ectopic head-like structures containing brain tissue. In ectodermal explants, IGF signals induced anterior neural markers in the absence of mesoderm formation and DN-IGFR inhibited neural induction by the BMP antagonist Chordin. Thus, active IGF signals appear to be both required and sufficient for anterior neural induction in Xenopus.
Pera
E M
EM
Howard Hughes Medical Institute and Department of Biological Chemistry, University of California, Los Angeles 90095, USA.
Wessely
O
O
Li
S Y
SY
De Robertis
E M
EM
D000595:Amino Acid Sequence; D000818:Animals; D002490:Central Nervous System / Q000196:embryology* / Q000378:metabolism; D002828:Choristoma / Q000378:metabolism; D003001:Cloning, Molecular; D004627:Embryonic Induction; D005123:Eye / Q000196:embryology / Q000378:metabolism; D006257:Head / Q000196:embryology*; D006801:Humans; D017403:In Situ Hybridization; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000737:chemistry / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000235:genetics / Q000378:metabolism; D008648:Mesoderm / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013002:Somatomedins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000254:growth & development
D018975:Insulin-Like Growth Factor Binding Protein 5; D012333:RNA, Messenger; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II