Linkage of caspase-mediated degradation of paxillin to apoptosis in Ba/F3 murine pro-B lymphocytes.
We have cloned the complete cDNA from mouse paxillin, a 68-kDa adapter protein found in focal adhesions. We found that paxillin was degraded by caspases in Ba/F3 cell apoptosis induced by withdrawal of interleukin-3 (IL-3), a survival factor for this cell, and by ionizing radiation. Also, paxillin was degraded in vitro by incubation with recombinant caspase-3. Western blot analyses of degradation products of overexpressed green fluorescence protein-tagged paxillin and site-specific mutants demonstrated that Asp-102 and Asp-301 were early caspase cleavage sites, and Asp-5, Asp-146, Asp-165, and Asp-222 were late cleavage sites. Overexpression of paxillin delayed apoptosis of Ba/F3 after IL-3 withdrawal. Furthermore, this anti-apoptotic effect of paxillin was augmented by a triple mutation in aspartic acids at caspase cleavage sites. These results suggest that paxillin plays a critical role in cell survival signaling and that the cleavage of paxillin by caspases might be an important event for focal adhesion disassembly during cell apoptosis, contributing to detachment, rounding, and death.
Chay
Kee-Oh
KO
Laboratory of Genetics, NCI, National Institutes of Health, Bethesda, Maryland 20852, USA.
Park
Sung Sup
SS
Mushinski
J Frederic
JF
D000818:Animals; D001483:Base Sequence; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D005720:Gamma Rays; D049452:Green Fluorescent Proteins; D006868:Hydrolysis; D007377:Interleukin-3 / Q000378:metabolism; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D051419:Paxillin; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D003598:Cytoskeletal Proteins; D017931:DNA Primers; D007377:Interleukin-3; D008164:Luminescent Proteins; D051419:Paxillin; D010750:Phosphoproteins; C496062:Pxn protein, mouse; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases