The alternative splice variant of DAPK-1, s-DAPK-1, induces proteasome-independent DAPK-1 destabilization.
Death-associated protein kinase 1 (DAPK-1) is a Ca(2+)/CaM-regulated kinase involved in multiple cellular signalling pathways that trigger cell survival, apoptosis, and autophagy. An alternatively spliced product expressed from the dapk1 locus, named s-DAPK-1, does not contain the kinase domain but has part of the DAPK-1 ankyrin-repeat and a novel polypeptide tail extension which is processed proteolytically in vivo. Cleavage of this polypeptide tail from s-DAPK-1 can regulate the ability of the protein to mimic one of the biological functions of DAPK-1 in promoting membrane blebbing. The full-length DAPK-1 protein is a relatively long-lived protein whose half-life is regulated by stress-activated signals from TNFR1 or HSP90 that can promote DAPK-1 protein degradation. Transfection of s-DAPK-1 into cells can also have a direct effect on DAPK-1 protein itself by promoting DAPK-1 de-stabilization. This effect does not require the novel polypeptide tail-extension of s-DAPK-1, as the core ankyrin-repeat containing region of s-DAPK-1 is sufficient to promote DAPK-1 protein de-stabilization. Conversely, the minimal domain on full-length DAPK-1 that responds to the effect of s-DAPK-1 is not the ankyrin-repeat domain but the core kinase domain of DAPK-1. The de-stabilization of DAPK-1 by s-DAPK-1 is not dependent upon the proteasome. However, s-DAPK-1 itself is a very short-lived protein which is regulated by a proteasomal-dependent pathway. Together, these data identify a novel function of s-DAPK-1 in controlling the half-life of DAPK-1 protein itself and indicate that the degradation of each gene product is controlled by two distinct degradation pathways.
Lin
Yao
Y
Institute of Genetics and Molecular Medicine, University of Edinburgh, UK.
Stevens
Craig
C
Harrison
Ben
B
Pathuri
Suresh
S
Amin
Eliana
E
Hupp
Ted R
TR
D017398:Alternative Splicing; D017089:Ankyrin Repeat; D051017:Apoptosis Regulatory Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D064550:Death-Associated Protein Kinases; D006207:Half-Life; D006801:Humans; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D020033:Protein Isoforms / Q000502:physiology; D055550:Protein Stability
D051017:Apoptosis Regulatory Proteins; D020033:Protein Isoforms; C579096:DAPK1 protein, human; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D046988:Proteasome Endopeptidase Complex