Differential GATA factor stabilities: implications for chromatin occupancy by structurally similar transcription factors.
Whereas the transcription factors GATA-1 and GATA-2 function both uniquely and redundantly to control blood cell development, the process termed hematopoiesis, mechanisms underlying their unique versus common functions are poorly understood. We used two independent assays to demonstrate that GATA-1 is considerably more stable than GATA-2 in multiple cellular contexts, even though both factors are subject to degradation via the ubiquitin-proteasome system. Studies with GATA factor mutants and novel chimeric GATA factors provided evidence that both GATA-1 and GATA-2 have highly unstable zinc finger core modules. The GATA-1 and GATA-2 N-termini both confer stabilization to their respective zinc finger core modules. In contrast, the GATA-1 and GATA-2 C-termini confer stabilization and destabilization, respectively. As GATA-2 stabilization via proteasome inhibition impairs the capacity of GATA-1 to displace GATA-2 from endogenous chromatin sites, we propose that differential GATA factor stability is an important determinant of chromatin target site occupancy and therefore the establishment of genetic networks that control hematopoiesis.
D000818:Animals; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D050982:GATA1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D050989:GATA2 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D020014:K562 Cells; D007976:Leupeptins / Q000494:pharmacology; D051379:Mice; D009154:Mutation / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D014176:Protein Biosynthesis / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013629:Tamoxifen / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D002843:Chromatin; D015853:Cysteine Proteinase Inhibitors; D050982:GATA1 Transcription Factor; D050989:GATA2 Transcription Factor; D007976:Leupeptins; D009687:Nuclear Proteins; D061988:Proteasome Inhibitors; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C107310:Zfpm1 protein, mouse; D013629:Tamoxifen; D003513:Cycloheximide; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde