• Authors: Vetterkind, S., Illenberger, S., Kubicek, J., Boosen, M., Appel, S., Naim, H. Y., Scheidtmann, K. H., Preuss, U.
  • Year: 2005
  • Journal: Exp Cell Res 305 392-408
  • Applications: in vitro / DNA / jetPEI
  • Cell types:
    1. Name: C6
      Description: Rat glioma cells
    2. Name: HeLa
      Description: Human cervix epitheloid carcinoma cells
    3. Name: NIH/3T3
      Description: Murine embryonic fibroblasts
      Known as: NIH/3T3, 3T3
    4. Name: Rat embryonic fibroblasts
    5. Name: SH-SY5Y
      Description: Human neuroblastoma cells
      Known as:


Prostate apoptosis response-4 (Par-4) is a 38-kDa protein originally identified as a gene product upregulated in prostate cancer cells undergoing apoptosis. Cell death mediated by Par-4 and its interaction partner DAP like kinase (Dlk) is characterized by dramatic changes of the cytoskeleton. To uncover the role of the cytoskeleton in Par-4/Dlk-mediated apoptosis, we analyzed Par-4 for a direct association with cytoskeletal structures. Confocal fluorescence microscopy revealed that endogenous Par-4 is specifically associated with stress fibers in rat fibroblasts. In vitro cosedimentation analyses and in vivo FRET analyses showed that Par-4 directly binds to F-actin. Actin binding is mediated by the N-terminal 266 amino acids, but does not require the C-terminal region of Par-4 containing the leucine zipper and the death domain. Furthermore, the interaction of Par-4 with actin filaments leads to the formation of actin bundles in vitro and in vivo. In rat fibroblasts, this microfilament association is essential for the pro-apoptotic function of Par-4, since both disruption of the actin cytoskeleton by cytochalasin D treatment and overexpression of Par-4 constructs impaired in actin binding result in a significant decrease of apoptosis induction by Par-4 and Dlk. We propose a model, in which Par-4 recruits Dlk to stress fibers, leading to enhanced phosphorylation of the regulatory light chain of myosin II (MLC) and to the induction of apoptosis.