Bcr-Abl-mediated molecular mechanism for apoptotic suppression in multipotent haemopoietic cells: a role for PKCbetaII.
Bcr-Abl protein tyrosine kinase (PTK) activity is a feature of chronic myeloid leukaemia and confers a survival advantage on haemopoietic progenitor cells. We have expressed conditional mutant of the Bcr-Abl PTK in the FDCP-Mix A4 multipotent haematopoietic cell line in order to examine the molecular mechanisms whereby Bcr-Abl PTK leads to enhanced cell survival under conditions in which normal cells die. Activation of Bcr-Abl PTK does not phosphorylate or activate either ERK-1/2 or JAK-2/STAT-5b, suggesting that these signal transduction pathways are not involved in Abl PTK-mediated suppression of apoptosis in FDCP-Mix cells. However, protein kinase C (PKC) does have a role to play. Inhibition of PKC results in a reversal of Bcr-Abl PTK-mediated survival in the absence of growth factor and Bcr-Abl stimulates translocation of the PKCbetaII isoform to the nucleus. Furthermore, expression of a constitutively activated PKCbetaII in haemopoietic progenitor FDCP-Mix cells stimulates enhanced cell survival when IL-3 is withdrawn. However, expression of this constitutively activated PKC isoform does not suppress cytotoxic drug-induced apoptosis. Thus Bcr-Abl PTK has pleiotropic effects which can suppress cell death induced by a number of stimuli.
Xenaki
Dia
D
Biological Sciences, IENS, Lancaster University, Lancaster LA1 4YQ, UK.
Pierce
Andrew
A
Underhill-Day
Nick
N
Whetton
Anthony D
AD
Owen-Lynch
P Jane
PJ
D017209:Apoptosis / Q000502:physiology*; D002470:Cell Survival / Q000502:physiology*; D018920:Coculture Techniques; D004268:DNA-Binding Proteins / Q000378:metabolism; D016044:Fusion Proteins, bcr-abl; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D007377:Interleukin-3 / Q000172:deficiency / Q000378:metabolism; D053614:Janus Kinase 2; D008894:Milk Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D039902:Multipotent Stem Cells / Q000378:metabolism*; D009154:Mutation; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D064546:Protein Kinase C beta; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D050799:STAT5 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism
D004268:DNA-Binding Proteins; D007377:Interleukin-3; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases