The 31-kDa caspase-generated cleavage product of p130cas functions as a transcriptional repressor of E2A in apoptotic cells.
In response to integrin receptor binding to the extracellular matrix, the multidomain docking protein p130(cas) (Crk-associated substrate) activates various signaling cascades modulating such cellular processes as proliferation, migration, and apoptosis. During apoptosis, caspase-mediated cleavage of p130(cas) generated a C-terminal 31-kDa fragment (31-kDa) and promoted morphological changes characteristic of apoptosis, including loss of focal adhesions, cell rounding, and nuclear condensation and fragmentation. By contrast, a p130(cas) D748E mutant, which was unable to produce 31-kDa, attenuated the disassembly of focal adhesions at the bottom of the cell. 31-kDa contains a helix-loop-helix (HLH) domain that shows greater sequence homology with Id proteins than with basic HLH proteins, which enabled heterodimerization with E2A. Once coupled to E2A, 31-kDa was translocated to the cell nucleus, where it inhibited E2A-mediated p21(Waf1/Cip1) transcription. Moreover, overexpression of 31-kDa led to cell death that could be inhibited by treatment with the caspase inhibitor ZVAD-fluoromethyl ketone or by ectopic expression of E2A or p21(Waf1/Cip1). These data suggest that during etoposide-induced apoptosis, 31-kDa promotes caspase-mediated cell death by inhibiting E2A-mediated activation of p21(Waf1/Cip1) transcription.
Kim
Wook
W
Department of Life Science, Kwangju Institute of Science and Technology, Kwangju 500-712, Korea.
Kook
Seunghyi
S
Kim
Dae Joong
DJ
Teodorof
Carmen
C
Song
Woo Keun
WK
D033942:Adaptor Proteins, Vesicular Transport / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects*; D051792:Basic Helix-Loop-Helix Proteins; D001692:Biological Transport; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus; D050719:Crk-Associated Substrate Protein; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D019281:Dimerization; D005047:Etoposide / Q000494:pharmacology; D015870:Gene Expression; D006367:HeLa Cells; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D008156:Luciferases / Q000235:genetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D011506:Proteins; D011993:Recombinant Fusion Proteins; D050717:Retinoblastoma-Like Protein p130; D017385:Sequence Homology; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection
D033942:Adaptor Proteins, Vesicular Transport; D051792:Basic Helix-Loop-Helix Proteins; D020169:Caspases; D050719:Crk-Associated Substrate Protein; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; D005047:Etoposide; D008156:Luciferases; D010446:Peptide Fragments; D010750:Phosphoproteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D050717:Retinoblastoma-Like Protein p130; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; C493841:BCAR1 protein, human; C493956:CDKN1A protein, human; C407909:TCF3 protein, human; C544912:TCF7L1 protein, human