The homeodomain transcription factor Prep1 (pKnox1) is required for hematopoietic stem and progenitor cell activity.
Most of the hypomorphic Prep1(i/i) embryos (expressing 3-10% of the Prep1 protein), die between E17.5 and P0, with profound anemia, eye malformations and angiogenic anomalies [Ferretti, E., Villaescusa, J.C., Di Rosa, P., Fernandez-Diaz, L.-C., Longobardi, E., Mazzieri, R., Miccio, A., Micali, N., Selleri, L., Ferrari G., Blasi, F. (2006). Hypomorphic mutation of the TALE gene Prep1 (pKnox1) causes a major reduction of Pbx and Meis proteins and a pleiotropic embryonic phenotype. Mol. Cell. Biol. 26, 5650-5662]. We now report on the hematopoietic phenotype of these embryos. Prep1(i/i) fetal livers (FL) are hypoplastic, produce less common myeloid progenitors colonies (CFU-GEMM) in cytokine-supplemented methylcellulose and have an increased number of B-cells precursors that differentiate poorly. Prep1(i/i) FL is able to protect lethally irradiated mice only at high cell doses but the few protected mice show major anomalies in all hematopoietic lineages in both bone marrow (BM) and peripheral organs. Prep1(i/i) FL cells compete inefficiently with wild type bone marrow in competitive repopulation experiments, suggesting that the major defect lies in long-term repopulating hematopoietic stem cells (LTR-HSC). Indeed, wt embryonic expression of Prep1 in the aorta-gonad-mesonephros (AGM) region, fetal liver (FL), cKit(+)Sca1(+)Lin(-)AA4.1(+) (KSLA) cells and B-lymphocytes precursors agrees with the observed phenotype. We therefore conclude that Prep1 is required for a correct and complete hematopoiesis.
Di Rosa
Patrizia
P
Laboratory of Molecular Genetics, San Raffaele Scientific Institute, via Olgettina 60, 20132 Milano, Italy.
Villaescusa
J Carlos
JC
Longobardi
Elena
E
Iotti
Giorgio
G
Ferretti
Elisabetta
E
Diaz
Victor M
VM
Miccio
Annarita
A
Ferrari
Giuliana
G
Blasi
Francesco
F
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000502:physiology; D015415:Biomarkers / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology / Q000502:physiology; D002454:Cell Differentiation; D019070:Cell Lineage; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology; D006410:Hematopoiesis / Q000502:physiology*; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D015415:Biomarkers; D018398:Homeodomain Proteins; C491412:Pknox1 protein, mouse; D014157:Transcription Factors