Impairment of the proapoptotic activity of Bax by missense mutations found in gastrointestinal cancers
Autor: | Gil J, Yamamoto H, Jm, Zapata, Jc, Reed, Manuel Perucho |
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Předmět: |
Threonine
Receptors Steroid Receptors Retinoic Acid Recombinant Fusion Proteins DNA Mutational Analysis Mutation Missense bcl-X Protein Apoptosis Kidney Transfection Methionine Proto-Oncogene Proteins Humans Codon Frameshift Mutation Cell Line Transformed Gastrointestinal Neoplasms bcl-2-Associated X Protein Alanine Biological Transport Neoplasm Proteins Ecdysterone Retinoid X Receptors Amino Acid Substitution Proto-Oncogene Proteins c-bcl-2 Protein Multimerization Dimerization Microsatellite Repeats Protein Binding Transcription Factors |
Zdroj: | Europe PubMed Central ResearcherID |
Popis: | We have reported previously that codon 169 of the proapoptotic gene BAX is a mutational hot spot in gastrointestinal cancer. Two different mutations were found in this codon, replacing the wild-type threonine by alanine or methionine. To compare the proapoptotic activity of these Bax mutants with wild-type Bax, we established an ecdysone (muristerone A)-inducible system in cultured human embryonal kidney 293 cells. Addition of muristerone A induced a dose-dependent decrease in the viability of cells transfected with wild-type BAX, but this loss of viability was inhibited in cells transfected with BAX mutants. Furthermore, muristerone A induced morphological changes characteristic of apoptosis, including cell shrinkage, rounding, formation of apoptotic bodies, detachment and nuclear condensation and fragmentation, in cells transfected with wild-type BAX. These hallmarks of apoptosis were clearly diminished in cells transfected with BAX mutants. Mutation of threonine 169 did not affect the binding of Bax to Bax, Bcl-2, or Bcl-X(L). These results demonstrate that missense mutations at codon 169 of BAX are functional because they inhibit its apoptotic activity. This is the first report of the functional significance of missense mutations in BAX, or any other proapoptotic member of the Bcl-2 family, in primary human tumors. |
Databáze: | OpenAIRE |
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