Identification and characterization of PS-GAP as a novel regulator of caspase-activated PAK-2.
p21-activated protein kinase (PAK)-2 is a member of the PAK family of serine/threonine kinases. PAKs are activated by the p21 G-proteins Rac and Cdc42 in response to a variety of extracellular signals and act in pathways controlling cell growth, shape, motility, survival, and death. PAK-2 is unique among the PAK family members because it is also activated through proteolytic cleavage by caspase-3 or similar proteases to generate the constitutively active PAK-2p34 fragment. Activation of full-length PAK-2 by Rac or Cdc42 stimulates cell survival and protects cells from cell death, whereas caspase-activated PAK-2p34 induces a cell death response. Caspase-activated PAK-2p34 is rapidly degraded by the 26 S proteasome, but full-length PAK-2 is not. Stabilization of PAK-2p34 by preventing its polyubiquitination and degradation results in a dramatic stimulation of cell death. Although many proteins have been shown to interact with and regulate full-length PAK-2, little is known about the regulation of caspase-activated PAK-2p34. Here, we identify PS-GAP as a regulator of caspase-activated PAK-2p34. PS-GAP is a GTPase-activating protein for Cdc42 and RhoA that was originally identified by its interaction with the tyrosine kinase PYK-2. PS-GAP interacts specifically with caspase-activated PAK-2p34, but not active or inactive full-length PAK-2, through a region between the GAP and SH3 domains. The interaction with PS-GAP inhibits the protein kinase activity of PAK-2p34 and changes the localization of PAK-2p34 from the nucleus to the perinuclear region. Furthermore, PS-GAP decreases the stimulation of cell death induced by stabilization of PAK-2p34.
Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
Mark A
MA
Koeppel
Corine C
CC
McCarthy
Erin
E
Moertl
Rolf
R
Jakobi
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death; D002460:Cell Line; D002465:Cell Movement; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004789:Enzyme Activation; D004926:Escherichia coli / Q000378:metabolism; D014644:Genetic Variation; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000502:physiology*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014018:Tissue Distribution; D014162:Transfection; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D054462:p21-Activated Kinases
D018076:DNA, Complementary; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D025801:Ubiquitin; D049452:Green Fluorescent Proteins; D005982:Glutathione Transferase; C515907:PAK2 protein, human; C515909:Pak2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D020764:cdc42 GTP-Binding Protein