The biological effects of C/EBPalpha in K562 cells depend on the potency of the N-terminal regulatory region, not on specificity of the DNA binding domain.
The transcription factor C/EBPα is more potent than C/EBPβ in inducing granulocitic differentiation and inhibiting BCR/ABL-expressing cells. We took a "domain swapping" approach to assess biological effects, modulation of gene expression, and binding to C/EBPα-regulated promoters by wild-type and chimeric C/EBPα/C/EBPβ proteins. Wild-type and N-C/EBPα+ C/EBPβ-DBD induced transcription of the granulocyte-colony stimulating factor receptor (G-CSFR) gene, promoted differentiation, and suppressed proliferation of K562 cells vigorously; instead, wild-type C/EBPβ and N-C/EBPβ+C/EBPα-DBD had modest effects, although they bound the G-CSFR promoter like wild-type C/EBPα and N-C/EBPα+C/EBPβ-DBD. Chimeric proteins consisting of the TAD of VP16 and the DBD of C/EBPα or C/EBPβ inhibited proliferation and induced differentiation of K562 cells as effectively as wild-type C/EBPα. Gene expression profiles induced by C/EBPα resembled those modulated by N-C/EBPα+C/EBPβ-DBD, whereas C/EBPβ induced a pattern similar to that of N-C/EBPβ+C/EBPα-DBD. C/EBPα activation induced changes in the expression of more cell cycle- and apoptosis-related genes than the other proteins and enhanced Imatinib-induced apoptosis of K562 cells. Expression of FOXO3a, a novel C/EBPα-regulated gene, was required for apoptosis but not for differentiation induction or proliferation inhibition of K562 cells.
Ferrari-Amorotti
Giovanna
G
Department of Biological Sciences, University of Modena and Reggio Emilia, 41100 Modena, Italy.
Mariani
Samanta Antonella
SA
Novi
Chiara
C
Cattelani
Sara
S
Pecorari
Luisa
L
Corradini
Francesca
F
Soliera
Angela Rachele
AR
Manzotti
Gloria
G
Fragliasso
Valentina
V
Zhang
Ying
Y
Martinez
Robert V
RV
Lam
Eric W-F
EW
Guerzoni
Clara
C
Calabretta
Bruno
B
D017209:Apoptosis / Q000235:genetics; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle; D002454:Cell Differentiation / Q000235:genetics; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation; D016179:Granulocyte Colony-Stimulating Factor / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D020014:K562 Cells; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D022782:CCAAT-Enhancer-Binding Protein-beta; D022762:CCAAT-Enhancer-Binding Proteins; C515848:CEBPA protein, human; C545012:CEBPB protein, human; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D011993:Recombinant Fusion Proteins; D016179:Granulocyte Colony-Stimulating Factor