Zyxin is a critical regulator of the apoptotic HIPK2-p53 signaling axis.
HIPK2 activates the apoptotic arm of the DNA damage response by phosphorylating tumor suppressor p53 at serine 46. Unstressed cells keep HIPK2 levels low through targeted polyubiquitination and subsequent proteasomal degradation. Here we identify the LIM domain protein Zyxin as a novel regulator of the HIPK2-p53 signaling axis in response to DNA damage. Remarkably, depletion of endogenous Zyxin, which colocalizes with HIPK2 at the cytoskeleton and in the cell nucleus, stimulates proteasome-dependent HIPK2 degradation. In contrast, ectopic expression of Zyxin stabilizes HIPK2, even upon enforced expression of its ubiquitin ligase Siah-1. Consistently, Zyxin physically interacts with Siah-1, and knock-down of Siah-1 rescues HIPK2 expression in Zyxin-depleted cancer cells. Mechanistically, our data suggest that Zyxin regulates Siah-1 activity through interference with Siah-1 dimerization. Furthermore, we show that endogenous Zyxin coaccumulates with HIPK2 in response to DNA damage in cancer cells, and that depletion of endogenous Zyxin results in reduced HIPK2 protein levels and compromises DNA damage-induced p53 Ser46 phosphorylation and caspase activation. These findings suggest an unforeseen role for Zyxin in DNA damage-induced cell fate control through modulating the HIPK2-p53 signaling axis.
Cellular Senescence Group, Cell & Tumor Biology Program, Deutsches Krebsforschungszentrum (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany.
Johanna
J
Crone
Carolina
C
Glas
Kathrin
K
Schultheiss
Jutta
J
Moehlenbrink
Eva
E
Krieghoff-Henning
Thomas G
TG
Hofmann
D000595:Amino Acid Sequence; D017209:Apoptosis; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004789:Enzyme Activation; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D055503:Protein Multimerization; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012694:Serine / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D060589:Zyxin; D000098563:Seven in Absentia Proteins
D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D006023:Glycoproteins; D009687:Nuclear Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C092842:ZYX protein, human; D060589:Zyxin; D012694:Serine; D044767:Ubiquitin-Protein Ligases; D000098563:Seven in Absentia Proteins; C115114:HIPK2 protein, human; D017346:Protein Serine-Threonine Kinases; D020169:Caspases