title: PI3K/Akt-dependent Epo-induced signalling and target genes in human early erythroid progenitor cells.
abstract: Erythropoietin (Epo) is the major regulator of differentiation, proliferation and survival of erythroid progenitors, but the Epo-induced changes in gene expression that lead to these effects are not fully understood. The aim of this study was to examine how Epo, via activation of phosphatidylinositol 3-kinase (PI3K)/Akt, exerts its role in the development of erythroid progenitors from CD34+ cells, and to identify early Epo target genes in human erythroid progenitors. In CD34+ progenitor cells, Epo alone was able to induce cell cycle progression as demonstrated by upregulation of cyclin D3, E and A leading to hyperphosphorylation of the retinoblastoma protein (RB). These effects were completely counteracted by the PI3K inhibitor LY294002. Furthermore, enforced expression of an activated form of Akt kinase highly augmented Epo-induced erythropoiesis. Fluorescent-activated cell sorting (FACS)-sorted CD34+CD71+CD45RA-GPA- erythroid progenitors stimulated with Epo in the presence or absence of LY294002 were subjected to gene expression profiling. Several novel target genes of Epo were identified, and the majority were regulated in a PI3K-dependent manner, including KIT (CD117) and CDH1 (E-cadherin). FACS analysis of Epo-stimulated erythroid progenitors showed that the increased mRNA expression of KIT and CDH1 was accompanied by an induction of the corresponding proteins CD117 and E-cadherin.
authors.affiliation: Department of Immunology, Institute of Cancer Research, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway.
authors.forename: Einar Andreas
authors.initials: EA
authors.lastname: Sivertsen
authors.forename: Marit Elise
authors.initials: ME
authors.lastname: Hystad
authors.forename: Kristine Bjerve
authors.initials: KB
authors.lastname: Gutzkow
authors.forename: Guri
authors.initials: G
authors.lastname: Døsen
authors.forename: Erlend Bremertun
authors.initials: EB
authors.lastname: Smeland
authors.forename: Heidi Kiil
authors.initials: HK
authors.lastname: Blomhoff
authors.forename: June Helen
authors.initials: JH
authors.lastname: Myklebust
mesh_terms: D000328:Adult; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D016213:Cyclins / Q000096:biosynthesis / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004920:Erythropoiesis / Q000187:drug effects / Q000502:physiology; D004921:Erythropoietin / Q000494:pharmacology*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011994:Recombinant Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D016213:Cyclins; D011994:Recombinant Proteins; D004921:Erythropoietin; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt