A Meis family protein caudalizes neural cell fates in Xenopus.
A homologue of the Drosophila homothorax (hth) gene, Xenopus Meis3 (XMeis3), was cloned from Xenopus laevis. XMeis3 is expressed in a single stripe of cells in the early neural plate stage. By late neurula, the gene is expressed predominantly in rhombomeres two, three and four, and in the anterior spinal cord. Ectopic expression of RNA encoding XMeis3 protein causes anterior neural truncations with a concomitant expansion of hindbrain and spinal cord. Ectopic XMeis3 expression inhibits anterior neural induction in neuralized animal cap ectoderm explants without perturbing induction of pan-neural markers. In naive animal cap ectoderm, ectopic XMeis3 expression activates transcription of the posteriorly expressed neural markers, but not pan-neural markers. These results suggest that caudalizing proteins, such as XMeis3, can alter A-P patterning in the nervous system in the absence of neural induction. Regionally expressed proteins like XMeis3 could be required to overcome anterior signals and to specify posterior cell fates along the A-P axis.
Salzberg
A
A
Department of Biochemistry, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
Elias
S
S
Nachaliel
N
N
Bonstein
L
L
Henig
C
C
Frank
D
D
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D019521:Body Patterning; D052004:Bone Morphogenetic Protein Receptors; D002352:Carrier Proteins; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism; D029721:Drosophila Proteins; D051767:Early Growth Response Protein 2; D004627:Embryonic Induction; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009420:Nervous System / Q000196:embryology*; D011506:Proteins / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D017978:Receptors, Growth Factor; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014981:Xenopus / Q000196:embryology*; D029867:Xenopus Proteins; D000099176:Noggin Protein; D000099266:Engrailed 2 Protein
D052004:Bone Morphogenetic Protein Receptors; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D051767:Early Growth Response Protein 2; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D011506:Proteins; D011956:Receptors, Cell Surface; D017978:Receptors, Growth Factor; D014157:Transcription Factors; D029867:Xenopus Proteins; D000099176:Noggin Protein; D000099266:Engrailed 2 Protein; C491174:Meis3 protein, Xenopus; C108704:hth protein, Drosophila