Expression and DNA-binding activity of C/EBPalpha and C/EBPbeta in human liver and differentiated primary hepatocytes.
OBJECTIVE
Limited information is available on the expression and role of C/EBP factors in human liver and hepatocytes. We investigated the expression and DNA-binding activity of C/EBPalpha and C/EBPbeta in human liver needle biopsies, surgical lobectomies and differentiated cultured hepatocytes derived from lobectomies.


METHODS
RNA and protein extracts were analyzed by RNAse protection, immunoblot and gel shift assays.


RESULTS
C/EBP mRNAs, isoforms and DNA-binding activities were low/undetectable in lobectomies. In contrast, several C/EBPalpha (47, 45, 35 and 33 kDa) and C/EBPbeta isoforms (47, 43, 40, 35 and 21 kDa) were observed in needle biopsies. In cultured hepatocytes, the C/EBP expression pattern dramatically changed with time. C/EBPalpha mRNA and the 45 kDa isoform increased in parallel, reaching a maximum after 3-4 weeks coincident with weak DNA-binding activity. C/EBPbeta mRNA and isoform expression increased rapidly reaching a plateau within 1-2 weeks; all C/EBPbeta isoforms were phosphorylated. C/EBPbeta exhibited greater DNA-binding activity than C/EBPalpha, and this activity paralleled C/EBPbeta isoform expression.


CONCLUSIONS
C/EBP isoforms exhibit markedly different expression patterns in lobectomies, needle biopsies and cultured hepatocytes. Stress stimuli during and/or after surgery for lobectomy resections may account for this difference. The pattern of C/EBP isoform expression in long-term highly differentiated cultured hepatocytes is close to that observed in needle biopsies.
Ferrini
J B
JB
INSERM U128, CNRS IFR24, Montpellier, France.
Rodrigues
E
E
Dulic
V
V
Pichard-Garcia
L
L
Fabr
J M
JM
Blanc
P
P
Maurel
P
P
D000328:Adult; D000368:Aged; D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000235:genetics* / Q000378:metabolism*; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics* / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008251:Macaca; D008297:Male; D008875:Middle Aged; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D022763:CCAAT-Enhancer-Binding Protein-alpha; D022782:CCAAT-Enhancer-Binding Protein-beta; D020033:Protein Isoforms; D012333:RNA, Messenger; D004247:DNA