Hematopoietic cells in cultures of the murine embryonic aorta-gonad-mesonephros region are induced by c-Myb.
Definitive hematopoiesis begins in the para-aortic, splanchnopleural (P-Sp) and aorta-gonad-mesonephros (AGM) regions of mouse embryos and then switches to the fetal liver [1] [2] [3]. Gene-targeted mice lacking the c-Myb transcription factor have severe hematopoietic defects in the fetal liver [4]. The role of c-Myb, if any, in P-Sp/AGM hematopoiesis has not been examined, however. Recently, we reported that oncostatin M can effectively expand both hematopoietic and endothelial-like cells from in vitro cultures of the AGM region [5]. Using this cell culture system, we examined the involvement of c-Myb in definitive hematopoiesis in the P-Sp and AGM regions. When primary cultures from the P-Sp or AGM regions of wild-type mouse embryos were probed with an anti-c-Myb antibody, hematopoietic cells but not endothelial-like cells showed positive staining. In contrast, in the P-Sp/AGM culture from c-myb(-/-) embryos, no hematopoietic cells were generated and endothelial-like cells predominated, indicating that the impairment of hematopoiesis in the liver of c-myb(-/-) embryos is actually preceded by a defect in P-Sp/AGM hematopoiesis. Hematogenic precursor cells were, however, still present in an inert but competent form among the endothelial-like, adherent cell population of c-myb(-/-) P-Sp/AGM cultures. When infected with a retrovirus carrying c-myb cDNA, these cultures gave rise to a significant number of hematopoietic cells. The rescued cells, unlike wild-type hematopoietic cells, were negative for c-Kit (a marker of hematopoietic progenitors), but did express other hematopoietic cell surface markers such as Mac-1, Gr-1 (myeloid markers), CD19, B220, Thy-1.2 (Iymphoid markers), and Ter119 (an erythroid marker). Thus, c-Myb plays a role in the generation of hematopoietic cells in the embryonic P-Sp and AGM regions.
Mukouyama
Y s
Ys
Institute of Molecular and Cellular Biosciences The University of Tokyo 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.
Chiba
N
N
Mucenski
M L
ML
Satake
M
M
Miyajima
A
A
Hara
T
T
Watanabe
T
T
D016475:3T3 Cells; D000818:Animals; D001011:Aorta / Q000196:embryology; D003114:Colony-Forming Units Assay; D046508:Culture Techniques; D018507:Gene Expression Regulation, Developmental; D020570:Genes, myb; D005822:Genetic Vectors; D006066:Gonads / Q000196:embryology; D006410:Hematopoiesis / Q000235:genetics / Q000502:physiology; D006413:Hematopoietic System / Q000196:embryology*; D008650:Mesonephros / Q000196:embryology; D051379:Mice; D018345:Mice, Knockout; D020598:Proto-Oncogene Proteins c-myb / Q000502:physiology*; D012190:Retroviridae / Q000235:genetics
D020598:Proto-Oncogene Proteins c-myb