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Conversion of zebrafish blastomeres to an endodermal fate by TGF-β-related signalling

1998; Elsevier BV; Volume: 8; Issue: 13 Linguagem: Inglês

10.1016/s0960-9822(98)70303-3

1879-0445

Nadine Peyriéras, Uwe Strähle, Frédéric Rosa,

Developmental Biology and Gene Regulation

The endoderm contributes cells to the gut, and participates in the induction and patterning of the vertebrate head and heart. The mechanisms controlling the formation of endoderm are poorly understood. Commitment of endoderm cells occurs at the onset of gastrulation and requires cell interactions [[1]Ho RK Kimmel CB Commitment of cell fate in the early zebrafish embryo.Science. 1993; 261 (93303608): 109-111Crossref PubMed Scopus (147) Google Scholar]; studies in vitro have implicated transforming growth factor β (TGF-β)-related molecules in this process [2Rosa FM Mix.1, a homeobox mRNA inducible by mesoderm Inducers, is expressed mostly in the presumptive endodermal cells of Xenopus embryos.Cell. 1989; 57 (89288302): 965-974Abstract Full Text PDF PubMed Scopus (241) Google Scholar, 3Heasman J Patterning the Xenopus gastrula.Development. 1997; 124 (98043854): 4179-4191PubMed Google Scholar]. TARAM-A is a zebrafish receptor kinase that is related to the type I subunit of the TGF-β receptor, and is expressed in presumptive endomesodermal cells at gastrulation [[4]Renucci A Lemarchandel V Rosa F An activated form of serine/threonine kinase receptor TARAM-A reveals a specific signalling pathway involved in fish head organiser formation.Development. 1996; 122 (97164688): 3735-3743PubMed Google Scholar]. We provide here evidence for its involvement in endoderm formation in vivo. Activation of TARAM-A was found to drive blastomeres towards an endodermal fate. The induced endoderm behaved as endogenous endoderm during gastrulation: it migrated in contact with the yolk and expressed endoderm-specific markers. Loss-of-function mutations in the zebrafish one-eyed-pinhead (oep) gene lead to defects in heart formation, defects of the ventral central nervous system (CNS) and cyclopia [5Stähle U Jesuthasan S Blader P Garcia-Villalba P Hatta K Ingham P One-eyed pinhead is required for development of the ventral midline of the zebrafish neural tube.Gen Function. 1997; 1: 131-148Crossref PubMed Scopus (92) Google Scholar, 6Schier AF Neuhauss SCF Helde KA Talbot WS Driever W The one-eyed pinhead gene functions in mesoderm and endoderm formation in zebrafish and interacts with no tail.Development. 1997; 124 (97178968): 327-342PubMed Google Scholar, 7Zhang J Talbot WS Schier F Positional cloning identifies zebrafish one-eyed pinhead as a permissive EGF-related ligand required during gastrulation.Cell. 1998; 92: 241-251Abstract Full Text Full Text PDF PubMed Scopus (371) Google Scholar]. Mutant embryos also lack endoderm and anterior mesoderm. Endoderm formation in oep mutant embryos was found to be restored by the activation of the TARAM-A signalling pathway. Cardiac and ocular defects, but not midline CNS structures, were rescued non-autonomously, demonstrating that endoderm may provide signals that can pattern the eye anlage, and which are distinct from those specifying the ventral midline of the CNS.