Notochord signals control the transcriptional cascade of myogenic bHLH genes in somites of quail embryos
| Autor: | Charles P. Emerson, Mary Elizabeth Pownall, Karen E. Strunk |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
medicine.medical_specialty
Mesoderm Transcription Genetic Cell Transplantation Notochord Muscle Proteins Dermomyotome Models Biological Quail Myotome biology.animal Internal medicine Gene expression medicine Animals Molecular Biology In Situ Hybridization MyoD Protein Embryonic Induction biology Muscles Helix-Loop-Helix Motifs Neural tube RNA Probes Cell biology DNA-Binding Proteins Somite medicine.anatomical_structure Endocrinology Myogenic Regulatory Factors embryonic structures Trans-Activators Myogenin Myogenic Regulatory Factor 5 Developmental Biology |
| Zdroj: | Development. 122:1475-1488 |
| ISSN: | 1477-9129 0950-1991 |
| DOI: | 10.1242/dev.122.5.1475 |
| Popis: | Microsurgical, tissue grafting and in situ hybridization techniques have been used to investigate the role of the neural tube and notochord in the control of the myogenic bHLH genes, QmyoD, Qmyf5, Qmyogenin and the cardiac α-actin gene, during somite formation in stage 12 quail embryos. Our results reveal that signals from the axial neural tube/notochord complex control both the activation and the maintenance of expression of QmyoD and Qmyf5 in myotomal progenitor cells during the period immediately following somite formation and prior to myotome differentiation. QmyoD and Qmyf5 expression becomes independent of axial signals during myotome differentiation when somites activate expression of Qmyogenin and α-actin. Ablation studies reveal that the notochord controls QmyoD activation and the initiation of the transcriptional cascade of myogenic bHLH genes as epithelial somites condense from segmental plate mesoderm. The dorsal medial neural tube then contributes to the maintenance of myogenic bHLH gene expression in newly formed somites. Notochord grafts can activate ectopic QmyoD expression during somite formation, establishing that the notochord is a necessary and sufficient source of diffusible signals to initiate QmyoD expression. Myogenic bHLH gene expression is localized to dorsal medial cells of the somite by inhibitory signals produced by the lateral plate and ventral neural tube. Signaling models for the activation and maintenance of myogenic gene expression and the determination of myotomal muscle in somites are discussed. |
| Databáze: | OpenAIRE |
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