The Ste20-like kinase SLK promotes p53 transactivation and apoptosis

• Published in: American journal of physiology. Renal physiology 2009-10, Vol.297 (4), p.F971-F980
• Main Authors: Cybulsky, Andrey V, Takano, Tomoko, Guillemette, Julie, Papillon, Joan, Volpini, Rildo A, Di Battista, John A
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; Biochemistry; Cercopithecus aethiops; COS Cells; Dogs; Epithelial Cells - enzymology; Genes, Reporter; Hypoxia - metabolism; JNK Mitogen-Activated Protein Kinases - metabolism; Kidney - cytology; Kidney - enzymology; Kidneys; Kinases; MAP Kinase Signaling System; Mutation; Nephrology; p38 Mitogen-Activated Protein Kinases - metabolism; Phosphorylation; Protein-Serine-Threonine Kinases - metabolism; Rats; Reperfusion Injury - metabolism; Transcriptional Activation; Tumor Suppressor Protein p53 - metabolism
• ISSN: 1931-857X; 1522-1466
• DOI: 10.1152/ajprenal.00294.2009

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.