Transition from non-motile behaviour to directed migration during early PGC development in zebrafish.
The migration of zebrafish primordial germ cells (PGCs) is directed by SDF-1a and serves as a model for long-range chemokine-guided cell migration. Whereas the development and migration of zebrafish PGCs have been studied in great detail starting at mid-gastrulation stages when the cells exhibit guided active migration [7-8 hours post fertilization (hpf)], earlier stages have not yet been examined. Here we show that the PGCs acquire competence to respond to the chemokine following discrete maturation steps. Using the promoter of the novel gene askopos and RNA elements of nanos1 to drive GFP expression in PGCs, we found that immediately after their specification (about 3 hpf) PGCs exhibit simple cell shape. This stage is followed by a phase at which the cells assume complex morphology yet they neither change their position nor do they respond to SDF-1a. During the third phase, a transition into a ;migratory stage' occurs as PGCs become responsive to directional cues provided by somatic cells secreting the chemokine SDF-1a. This transition depends on zygotic transcription and on the function of the RNA-binding protein Dead end and is correlated with down regulation of the cell adhesion molecule E-cadherin. These distinctive morphological and molecular alterations could represent a general occurrence in similar processes critical for development and disease.
Blaser
Heiko
H
Germ Cell Development, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
Eisenbeiss
Silke
S
Neumann
Marc
M
Reichman-Fried
Michal
M
Thisse
Bernard
B
Thisse
Christine
C
Raz
Erez
E
D000818:Animals; D030801:Animals, Genetically Modified; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology*; D048430:Cell Shape; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005854:Germ Cells / Q000166:cytology* / Q000502:physiology*; D017403:In Situ Hybridization; D016297:Mutagenesis, Site-Directed; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D029867:Xenopus Proteins / Q000378:metabolism*; D015027:Zebrafish / Q000033:anatomy & histology / Q000196:embryology* / Q000502:physiology; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
C449185:CXCL12 protein, Xenopus; D015820:Cadherins; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D016376:Oligonucleotides, Antisense; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; C506162:kop protein, zebrafish; C440015:nanos3 protein, zebrafish; D020169:Caspases