TNF-related apoptosis-inducing ligand (TRAIL) and erythropoiesis: a role for PKC epsilon.
The regulation of the hematopoietic stem cell pool size and the processes of cell differentiation along the hematopoietic lineages involve apoptosis. Among the different factors with a recognized activity on blood progenitor cells, TRAIL - a member of the TNF family of cytokines - has an emerging role in the modulation of normal hematopoiesis.PKC(epsilon) levels are regulated by EPO in differentiating erythroid progenitors and control the protection against the apoptogenic effect of TRAIL. EPO-induced erythroid CD34 cells are insensitive to the apoptogenic effect of TRAIL between day 0 and day 3, due to the lack of specific surface receptors expression. Death receptors appear after day 3 of differentiation and consequently erythroid cells become sensitive to TRAIL up to day 9/10, when the EPO-driven up-regulation of PKC epsilon intracellular levels inhibits the TRAIL-mediated apoptosis, via Bcl-2. In the time interval between day 3 and 9, therefore, the number of erythroid progenitors can be limited by the presence of soluble or membrane-bound TRAIL present in the bone marrow microenvironment.
Department of Anatomy, Pharmacology & Forensic Medicine, University of Parma, Ospedale Maggiore, Via Gramsci, 14, I-43100 Parma, Italy. marco.vitale@unipr.it
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D000818:Animals; D017209:Apoptosis / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology; D019070:Cell Lineage; D004920:Erythropoiesis / Q000502:physiology*; D004921:Erythropoietin / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology; D006801:Humans; D008562:Membrane Glycoproteins / Q000502:physiology*; D051744:Protein Kinase C-epsilon / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D053221:TNF-Related Apoptosis-Inducing Ligand; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D004921:Erythropoietin; D051744:Protein Kinase C-epsilon