Hematopoiesis following disruption of the Pitx2 homeodomain gene.
OBJECTIVE
Study the effect of loss of expression of Pitx2, a homeodomain gene preferentially expressed in murine hematopoietic stem/progenitor cells, on hematopoietic stem cells (HSCs).


METHODS
We examined the fetal livers of mouse embryos with homozygous disruption of the Pitx2 gene, using flow cytometry immunophenotyping analysis, as well as immunohistochemistry techniques. We further investigated the role of Pitx2 in HSCs using a chimeric mouse model system. Pitx2 null embryonic stem (ES) cell clones were generated from embryonic day 3.5 blastocysts of Pitx2 null embryos. The Pitx2 null donor ES cell contribution to the adult hematopoietic system was confirmed by identifying donor-specific glucose-phosphate isomerase isotype in the erythrocytes using cellulose acetate eletrophoresis, and by demonstrating donor-specific major histocompatibility complex antigen allotype on the granulocytes/monocytes and T and B lymphocytes of the chimeric mice using flow cytometry analysis.


RESULTS
Pitx2 homozygous null fetal livers are decreased in size and overall cellularity. The erythroid cell component of these livers is further reduced as compared to that of their wild-type and heterozygous littermates. Detailed quantitative analysis of the chimeric mice revealed contribution of Pitx2 null ES cells to erythroid, myeloid, lymphoid, and megakaryocytic lineages. The quantitative level of ES cell contribution to the peripheral hematopoietic cells was proportional to the level of general chimerism as determined by coat color.


CONCLUSIONS
Although the fetal livers of Pitx2 null embryos displayed signs of impaired erythropoiesis, Pitx2 gene disrupted HSCs can contribute to hematopoiesis under physiological conditions.
Zhang
Hui Z
HZ
Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520-8021, USA.
Degar
Barbara A
BA
Rogoulina
Svetlana
S
Resor
Charles
C
Booth
Carmen J
CJ
Sinning
Joseph
J
Gage
Philip J
PJ
Forget
Bernard G
BG
D000818:Animals; D002478:Cells, Cultured; D002999:Clone Cells; D004195:Disease Models, Animal; D041905:Erythroid Cells / Q000378:metabolism; D005434:Flow Cytometry; D006410:Hematopoiesis / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics* / Q000502:physiology; D006720:Homozygote; D007150:Immunohistochemistry; D008099:Liver / Q000196:embryology / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008817:Mice, Mutant Strains; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics* / Q000502:physiology; D000097577:Homeobox Protein PITX2
D018398:Homeodomain Proteins; D014157:Transcription Factors; D000097577:Homeobox Protein PITX2