Par-4-mediated recruitment of Amida to the actin cytoskeleton leads to the induction of apoptosis.
Par-4 (prostate apoptosis response-4) sensitizes cells to apoptotic stimuli, but the exact mechanisms are still poorly understood. Using Par-4 as bait in a yeast two-hybrid screen, we identified Amida as a novel interaction partner, a ubiquitously expressed protein which has been suggested to be involved in apoptotic processes. Complex formation of Par-4 and Amida occurs in vitro and in vivo and is mediated via the C-termini of both proteins, involving the leucine zipper of Par-4. Amida resides mainly in the nucleus but displays nucleo-cytoplasmic shuttling in heterokaryons. Upon coexpression with Par-4 in REF52.2 cells, Amida translocates to the cytoplasm and is recruited to actin filaments by Par-4, resulting in enhanced induction of apoptosis. The synergistic effect of Amida/Par-4 complexes on the induction of apoptosis is abrogated when either Amida/Par-4 complex formation or association of these complexes with the actin cytoskeleton is impaired, indicating that the Par-4-mediated relocation of Amida to the actin cytoskeleton is crucial for the pro-apoptotic function of Par-4/Amida complexes in REF52.2 cells. The latter results in enhanced phosphorylation of the regulatory light chain of myosin II (MLC) as has previously been shown for Par-4-mediated recruitment of DAP-like kinase (Dlk), suggesting that the recruitment of nuclear proteins involved in the regulation of apoptotic processes to the actin filament system by Par-4 represents a potent mechanism how Par-4 can trigger apoptosis.
Boosen
Meike
M
Institute of Genetics, University of Bonn, Römerstr. 164, D-53117 Bonn, Germany.
Vetterkind
Susanne
S
Koplin
Ansgar
A
Illenberger
Susanne
S
Preuss
Ute
U
D008841:Actin Cytoskeleton / Q000737:chemistry / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000032:analysis / Q000378:metabolism*; D002467:Cell Nucleus / Q000737:chemistry; D002478:Cells, Cultured; D003593:Cytoplasm / Q000737:chemistry; D006801:Humans; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D018994:Myosin Light Chains / Q000378:metabolism; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D020798:Two-Hybrid System Techniques
D000199:Actins; D051017:Apoptosis Regulatory Proteins; D008840:Microfilament Proteins; D018994:Myosin Light Chains; D009687:Nuclear Proteins; C404187:Tfpt protein, rat; C101296:prostate apoptosis response-4 protein