RRC ID 33678
Author Nakayama Y, Kikuta H, Kanai M, Yoshikawa K, Kawamura A, Kobayashi K, Wang Z, Khan A, Kawakami K, Yamasu K.
Title Gbx2 functions as a transcriptional repressor to regulate the specification and morphogenesis of the mid-hindbrain junction in a dosage- and stage-dependent manner.
Journal Mech Dev
Abstract The Gbx subfamily of homeodomain transcription factors is involved in the positioning of the isthmus, which patterns the midbrain and cerebellum in vertebrates. To uncover the details of Gbx functions, we first examined the dose dependency of its effects on brain formation in zebrafish and found that high-dose gbx2 mRNA injection affected the entire forebrain and midbrain, whereas low-dose mRNA specifically disrupted the isthmic folding at the midbrain-hindbrain boundary (MHB) but only weakly affected the expression of genes involved in MHB specification. Thus, isthmus morphogenesis, and not its early specification, is highly sensitive to gbx2. Transient induction of heat-inducible gbx2 using transgenic fish showed that MHB specification is most sensitive to gbx2 at the end of epiboly and further suggested that otx2 is the direct target gene. These together demonstrate that gbx2 regulates both specification and morphogenesis of the MHB/isthmus region. Deletion analyses showed that both the N- and C-terminal regions contribute to the suppressive activity of Gbx2 against the anterior brain and that the N-terminal core region, including the Eh1 and proline-rich sequences, is required for this Gbx2 activity. Comparison of the effects of activated and repressive forms with wild-type Gbx2 suggested that Gbx2 functions as a transcriptional repressor, which was further evidenced by a luciferase assay in which gbx2 repressed the MHB enhancer of fgf8a in mouse P19 cells.
Volume 130(11-12)
Pages 532-52
Published 2013-1-1
DOI 10.1016/j.mod.2013.07.004
PII S0925-4773(13)00059-2
PMID 23933069
MeSH Animals Animals, Genetically Modified Body Patterning / genetics* Cell Line, Tumor Embryo, Nonmammalian Fibroblast Growth Factor 8 / genetics Fibroblast Growth Factor 8 / metabolism Gene Dosage Gene Expression Regulation, Developmental Genes, Reporter Homeodomain Proteins / genetics* Homeodomain Proteins / metabolism Injections, Intraventricular Luciferases / genetics Luciferases / metabolism Mesencephalon / anatomy & histology Mesencephalon / embryology Mesencephalon / metabolism* Mice Prosencephalon / anatomy & histology Prosencephalon / embryology Prosencephalon / metabolism* Protein Structure, Tertiary RNA, Messenger / administration & dosage RNA, Messenger / genetics* RNA, Messenger / metabolism Rhombencephalon / anatomy & histology Rhombencephalon / embryology Rhombencephalon / metabolism* Signal Transduction Transcription, Genetic Zebrafish / anatomy & histology Zebrafish / embryology Zebrafish / genetics* Zebrafish / metabolism Zebrafish Proteins / genetics* Zebrafish Proteins / metabolism
IF 2.126
Times Cited 11
Zebrafish sud12(Tg(hsp70l:gbx2))