The Ste20-like kinase SLK promotes p53 transactivation and apoptosis.
Expression and activity of the germinal center kinase [corrected] SLK are increased during kidney development and recovery from renal ischemia-reperfusion injury. SLK promotes apoptosis, in part, via pathway(s) involving apoptosis signal-regulating kinase-1 and p38 mitogen-activated protein kinase. This study addresses the role of p53 as a potential effector of SLK. p53 transactivation was measured after transient transfection of a luciferase reporter plasmid that contains a p53 cis-acting enhancer element. Overexpression of SLK in COS-1 cells and cotransfection of SLK and p53-wild type (wt) cDNAs in glomerular epithelial cells (GECs) stimulated p53 transactivational activity, as measured by a p53 response element-driven luciferase reporter. In GECs, chemical anoxia followed by glucose reexposure (in vitro ischemia-reperfusion) increased p53 reporter activity, and this increase was amplified by overexpression of SLK. Expression of SLK induced p53 phosphorylation on serine (S)-33 and S315. In GECs, cotransfection of SLK with p53-wt, p53-S33A, p53-S315A, or p53-S33A+S315A mutants showed that only the double mutation abolished the SLK-induced increase in p53 reporter activity. SLK-induced stimulation of p53 reporter activity was attenuated by inhibition of JNK. Overexpression of SLK amplified apoptosis induced by subjecting cells to in vitro ischemia-reperfusion injury, while ectopic expression of a dominant negative SLK mutant attenuated the ischemia-reperfusion-induced apoptosis. The p53 transactivation inhibitor pifithrin-alpha significantly attenuated the amount of apoptosis after ischemia-reperfusion and SLK overexpression. Thus SLK induces p53 phosphorylation and transactivation, which enhances apoptosis after in vitro ischemia-reperfusion injury.
Cybulsky
Andrey V
AV
Div. of Nephrology, Royal Victoria Hospital, 687 Pine Ave. West, Montreal, Quebec H3A1A1, Canada. andrey.cybulsky@mcgill.ca
Takano
Tomoko
T
Guillemette
Julie
J
Papillon
Joan
J
Volpini
Rildo A
RA
Di Battista
John A
JA
D000818:Animals; D017209:Apoptosis; D019556:COS Cells; D002522:Chlorocebus aethiops; D004285:Dogs; D004847:Epithelial Cells / Q000201:enzymology; D017930:Genes, Reporter; D000081410:Germinal Center Kinases; D000860:Hypoxia / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000201:enzymology*; D020935:MAP Kinase Signaling System; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D015427:Reperfusion Injury / Q000378:metabolism; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D000081410:Germinal Center Kinases; D016159:Tumor Suppressor Protein p53; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases