Dlk/ZIP kinase-induced apoptosis in human medulloblastoma cells: requirement of the mitochondrial apoptosis pathway.
Dlk/ZIP kinase is a member of the Death Associated Protein (DAP) kinase family of pro-apoptotic serine/threonine kinases that have been implicated in regulation of apoptosis and tumour suppression. Expression of both Dlk/ZIP kinase and its interaction partner Par-4 is maintained in four medulloblastoma cell lines investigated, whereas three of seven neuroblastoma cell lines have lost expression of Par-4. Overexpression of a constitutively pro-apoptotic deletion mutant of Dlk/ZIP kinase induced significant apoptosis in D283 medulloblastoma cells. Cell death was characterized by apoptotic membrane blebbing, and a late stage during which the cells had ceased blebbing and were drastically shrunken or disrupted into apoptotic bodies. Over-expression of the anti-apoptotic Bcl-xL protein had no effect on Dlk/ZIP kinase-induced membrane blebbing, but potently inhibited Dlk/ZIP kinase-induced cytochrome c release and transition of cells to late stage apoptosis. Treatment with caspase inhibitors delayed, but did not prevent entry into late stage apoptosis. These results demonstrate that Dlk/ZIP kinase-triggered apoptosis involves the mitochondrial apoptosis pathway. However, cell death proceeded in the presence of caspase inhibitors, suggesting that Dlk/ZIP kinase is able to activate alternative cell death pathways. Alterations of signal transduction pathways leading to Dlk/ZIP kinase induced apoptosis or loss of expression of upstream activators could play important roles in tumour progression and metastasis of neural tumours.
Kögel
D
D
Interdisciplinary Center for Clinical Research (IZKF), Research Group 'Apoptosis and Cell Death', University of Bonn, Germany.
Reimertz
C
C
Mech
P
P
Poppe
M
M
Frühwald
M C
MC
Engemann
H
H
Scheidtmann
K H
KH
Prehn
J H
JH
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism; D064550:Death-Associated Protein Kinases; D015972:Gene Expression Regulation, Neoplastic; D049452:Green Fluorescent Proteins; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008527:Medulloblastoma / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D009154:Mutation; D009447:Neuroblastoma / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D009842:Oligopeptides / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D014407:Tumor Cells, Cultured; D051020:bcl-X Protein
D000590:Amino Acid Chloromethyl Ketones; D051017:Apoptosis Regulatory Proteins; C494811:BCL2L1 protein, human; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D003574:Cytochrome c Group; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins; D009842:Oligopeptides; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; C099158:acetyl-aspartyl-glutamyl-valyl-aspartal; D051020:bcl-X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C101296:prostate apoptosis response-4 protein; C096429:L 709049; D049452:Green Fluorescent Proteins; D064550:Death-Associated Protein Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases