Phosphatidylinositol 3-kinase is essential for kit ligand-mediated survival, whereas interleukin-3 and flt3 ligand induce expression of antiapoptotic Bcl-2 family genes

Journal of Leukocyte Biology

Maria Engström¹  Jan-Ingvar Jönsson¹  Cornelis J.H. Pronk¹  Johan Richter²  Peter Karlberg¹  Maria Jönsson¹  Richard Karlsson¹ 

[1] Division of Molecular Medicine, Department of Laboratory Medicine, Lund University, University Hospital MAS, Malmö, and Division of Molecular Medicine, Department of Laboratory Medicine, Lund University, University Hospital MAS, Malmö, and Division of Molecular Medicine, Department of Laboratory Medicine, Lund University, University Hospital MAS, Malmö, and;Department of Molecular Medicine and Gene Therapy, Lund University, Lund, Sweden Department of Molecular Medicine and Gene Therapy, Lund University, Lund, Sweden Department of Molecular Medicine and Gene Therapy, Lund University, Lund, Sweden

关键词: Hematopoiesis;    Progenitor;    Cytokines;    Apoptosis;    PKB;    Bcl-2;   

DOI  :  10.1189/jlb.0403142

学科分类：生理学

来源: Federation of American Societies for Experimental Biology

【 摘 要 】

Cytokines such as interleukin 3 (IL-3), kit ligand (KL), and flt3 ligand (FL) promote survival of hematopoietic stem cells and myeloid progenitor cells. In many cell types, members of the Bcl-2 gene family are major regulators of survival, but the mediating mechanisms are not fully understood. Using two myeloid progenitor cell lines, FDCP-mix and FDC-P1, as well as primary mouse bone marrow progenitors, we demonstrate that KL-mediated survival is dependent on the activation of phosphatidylinositol-3 (PI-3) kinase. The inhibitor LY294002 was able to completely abolish survival mediated by KL, whereas IL-3 and FL were only partially affected. Although all three cytokines induced phosphorylation of protein kinase B (PKB), only KL required PI-3 kinase activity to elicit survival in hematopoietic progenitors. In contrast, pretreatment of cells with inhibitors to the MAP kinase pathway did not affect the survival. We next established if IL-3 and FL activated antiapoptotic Bcl-2 and the related genes Bcl-XL and Mcl-1. By RNA protection assay and Western blot analysis, we show that all three genes are induced by IL-3, whereas FL induces Bcl-2 and to some extent Bcl-XL. Importantly, KL could not sustain their expression. Moreover, use of inhibitors implied that IL-3 was mainly exerting its effect on Bcl-2 at the level of transcription. The addition of LY294002 did not affect the expression of Bcl-2 and Bcl-XL, and thus, we conclude that expression of antiapoptotic Bcl-2 family member genes is not dependent on PI-3 kinase activity. Our results indicate that cytokines exert distinct survival effects and that FL and IL-3 are capable of sustaining progenitor survival by up-regulating the expression of Bcl-2 and related genes.

【 授权许可】

Unknown