Lmo2 and GATA-3 associated expression in intraembryonic hemogenic sites.
It is now widely accepted that hemopoietic cells born intraembryonically are the best candidates for the seeding of definitive hemopoietic organs. To further understand the mechanisms involved in the generation of definitive hemopoietic stem cells, we analysed the expression of the hemopoietic-related transcription factors Lmo2 and GATA-3 during the early steps of mouse development (7-12 dpc), with a particular emphasis on intraembryonic hemogenic sites. We show here that both Lmo2 and GATA-3 are present in the intraembryonic regions known to give rise to hemopoietic precursors in vitro and in vivo, suggesting that they act together at key points of hemopoietic development. (1) Lmo2 and GATA-3 are expressed in the caudal mesoderm during the phase of intraembryonic precursors determination. (2) A highly transient concomitant expression is observed in the caudal intraembryonic definitive endoderm, suggesting that these factors are involved in the specification of intraembryonic hemopoietic precursors. (3) Lmo2 and GATA-3 are expressed within the hemopoietic clusters located in the aortic floor during fetal liver colonisation. Furthermore, a strong GATA-3 signal allowed us to uncover previously unreported mesodermal aggregates beneath the aorta. A combined in situ and immunocytological analysis strongly suggests that ventral mesodermal GATA-3 patches are involved in the process of intraembryonic stem cell generation.
Manaia
A
A
Institut d'Embryologie Cellulaire et Moléculaire du CNRS et du Collège de France; 49bis, av. de la Belle Gabrielle, France.
Lemarchandel
V
V
Klaine
M
M
Max-Audit
I
I
Romeo
P
P
Dieterlen-Lièvre
F
F
Godin
I
I
D048868:Adaptor Proteins, Signal Transducing; D000482:Allantois / Q000166:cytology / Q000502:physiology; D000818:Animals; D001011:Aorta / Q000196:embryology; D001921:Brain / Q000196:embryology; D004268:DNA-Binding Proteins / Q000235:genetics*; D005314:Embryonic and Fetal Development; D050990:GATA3 Transcription Factor; D005775:Gastrula / Q000166:cytology / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D005854:Germ Cells / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology*; D060588:LIM Domain Proteins; D008648:Mesoderm / Q000502:physiology; D008667:Metalloproteins / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; D050990:GATA3 Transcription Factor; C494748:Gata3 protein, mouse; D060588:LIM Domain Proteins; C513188:Lmo2 protein, mouse; D008667:Metalloproteins; D015534:Trans-Activators; D014157:Transcription Factors