The role of meis1 in primitive and definitive hematopoiesis during zebrafish development.
BACKGROUND
The Meis1 protein represents an important cofactor for Hox and Pbx1 and is implicated in human and murine leukemias. Though much is known about the role of meis1 in leukemogenesis, its function in normal hematopoiesis remains largely unclear. Here we characterized the role of the proto-oncogene, meis1, during zebrafish primitive and definitive hematopoiesis.


METHODS
Zebrafish embryos were stained with o-dianisidine to detect hemoglobin-containing cells and Sudan black to quantify neutrophils. The numbers of other cells (scl-, gata1- and alas2-positive cells) were also quantified by measuring the corresponding stained areas of the embryos. We used anti-Meis1 antibody and whole mount immunohistochemistry to determine the pattern of expression of Meis1 during zebrafish development and then analyzed the functional role of Meis1 by knocking-down the meis1 gene.


RESULTS
Using antisense morpholino oligomers to interrupt meis1 expression we found that, although primitive macrophage development could occur unhampered, posterior erythroid differentiation required meis1, and its absence resulted in a severe decrease in the number of mature erythrocytes. Furthermore a picture emerged that meis1 exerts important effects on later stages of erythrocyte maturation and that these effects are independent of gata1, but under the control of scl. In addition, meis1 morpholino knock-down led to dramatic single arteriovenous tube formation. We also found that knock-down of pbx1 resulted in a phenotype that was strikingly similar to that of meis1 knock-down zebrafish.


CONCLUSIONS
These results imply that meis1, jointly with pbx1, regulates primitive hematopoiesis as well as vascular development.
Department of Haematology, University of Cambridge, Long Road, Cambridge CB2 0PT, UK.
Ana
A
Cvejic
Jovana
J
Serbanovic-Canic
Derek L
DL
Stemple
Willem H
WH
Ouwehand
D000818:Animals; D002454:Cell Differentiation; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism*; D004912:Erythrocytes / Q000166:cytology* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006410:Hematopoiesis / Q000502:physiology*; D018398:Homeodomain Proteins / Q000502:physiology*; D007124:Immunoenzyme Techniques; D017404:In Situ Hybridization, Fluorescence; D008264:Macrophages / Q000378:metabolism; D000075064:Myeloid Ecotropic Viral Integration Site 1 Protein; D009363:Neoplasm Proteins / Q000502:physiology*; D009504:Neutrophils / Q000378:metabolism; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D000090063:Proto-Oncogene Mas; D014157:Transcription Factors / Q000378:metabolism; D015027:Zebrafish / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029961:Zebrafish Proteins / Q000378:metabolism / Q000502:physiology*
D018398:Homeodomain Proteins; C000715470:MAS1 protein, human; C000616391:MEIS1 protein, human; D000075064:Myeloid Ecotropic Viral Integration Site 1 Protein; D009363:Neoplasm Proteins; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D000090063:Proto-Oncogene Mas; D014157:Transcription Factors; D029961:Zebrafish Proteins; C553464:pbx1a protein, zebrafish