TY - JOUR
T1 - Functional differences between two Tie2 ligands, angiopoietin-1 and -2, in regulation of adult bone marrow hematopoietic stem cells
AU - Gomei, Yumiko
AU - Nakamura, Yuka
AU - Yoshihara, Hiroki
AU - Hosokawa, Kentaro
AU - Iwasaki, Hiroko
AU - Suda, Toshio
AU - Arai, Fumio
N1 - Funding Information:
We thank Dr. Koh GY (Korea Advanced Institute of Science and Technology, Daejeon, Korea) for providing COMP-Ang-1. This work was supported by a Grant-in-Aid for Specially Promoted Research and a Grant-in-Aid for Young Scientists (S) from The Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan (Tokyo, Japan).
PY - 2010/2
Y1 - 2010/2
N2 - Objective: Angiopoietin-1 (Ang-1) plays a critical role in the maintenance of hematopoietic stem cells (HSCs) in the bone marrow (BM) through its binding to the Tie2 receptor. Ang-2, another Tie2 ligand, is known to be an antagonist of Tie2/Ang-1 signaling in angiogenesis; however, its function in regulation of HSCs remains unclear. Here, we investigated the functional differences between Ang-1 and Ang-2 in the maintenance of HSCs. Materials and Methods: We treated mouse BM lineage-Sca-1+c-Kit+ side population+ cells with Ang-1 and/or Ang-2, and evaluated angiopoietin function by gene expression analysis, immunocytochemical staining of phosphorylated Akt, a colony-formation assay, and a long-term BM reconstitution assay. Results: Gene expression analysis and BM transplantation assay revealed that Ang-1 upregulated expression of p57, p18, Itgb1, Alcam, Tie2, Hoxb4, and Bmi1 genes in HSCs, while Ang-2 antagonized the effects of Ang-1. Ang-1 enhanced the phosphorylation of Akt, while Ang-2 again reduced the effect of Ang-1. The colony assay demonstrated that neither Ang-1, nor Ang-2 influenced the colony formation of HSCs. BM transplantation assay, following in vitro cultivation of HSCs with angiopoietins, showed that Ang-1 maintained long-term repopulating activity of HSCs, while the addition of Ang-2 interfered drastically with the effects of Ang-1. Conclusion: Gene expression analysis and BM transplantation assay demonstrated that Ang-1 maintained HSC activity in an in vitro culture. In contrast, Ang-2 reversed the effects of Ang-1/Tie2 signaling in the regulation of long-term HSCs. Our data suggest that Ang-1 is a dominant ligand for the Tie2 receptor in long HSCs in BM.
AB - Objective: Angiopoietin-1 (Ang-1) plays a critical role in the maintenance of hematopoietic stem cells (HSCs) in the bone marrow (BM) through its binding to the Tie2 receptor. Ang-2, another Tie2 ligand, is known to be an antagonist of Tie2/Ang-1 signaling in angiogenesis; however, its function in regulation of HSCs remains unclear. Here, we investigated the functional differences between Ang-1 and Ang-2 in the maintenance of HSCs. Materials and Methods: We treated mouse BM lineage-Sca-1+c-Kit+ side population+ cells with Ang-1 and/or Ang-2, and evaluated angiopoietin function by gene expression analysis, immunocytochemical staining of phosphorylated Akt, a colony-formation assay, and a long-term BM reconstitution assay. Results: Gene expression analysis and BM transplantation assay revealed that Ang-1 upregulated expression of p57, p18, Itgb1, Alcam, Tie2, Hoxb4, and Bmi1 genes in HSCs, while Ang-2 antagonized the effects of Ang-1. Ang-1 enhanced the phosphorylation of Akt, while Ang-2 again reduced the effect of Ang-1. The colony assay demonstrated that neither Ang-1, nor Ang-2 influenced the colony formation of HSCs. BM transplantation assay, following in vitro cultivation of HSCs with angiopoietins, showed that Ang-1 maintained long-term repopulating activity of HSCs, while the addition of Ang-2 interfered drastically with the effects of Ang-1. Conclusion: Gene expression analysis and BM transplantation assay demonstrated that Ang-1 maintained HSC activity in an in vitro culture. In contrast, Ang-2 reversed the effects of Ang-1/Tie2 signaling in the regulation of long-term HSCs. Our data suggest that Ang-1 is a dominant ligand for the Tie2 receptor in long HSCs in BM.
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U2 - 10.1016/j.exphem.2009.11.007
DO - 10.1016/j.exphem.2009.11.007
M3 - Article
C2 - 19945502
AN - SCOPUS:73949131170
SN - 0301-472X
VL - 38
SP - 82-89.e1
JO - Experimental Hematology
JF - Experimental Hematology
IS - 2
ER -
