Expression and DNA-binding activity of C/EBPalpha and C/EBPbeta in human liver and differentiated primary hepatocytes

• Published in: Journal of hepatology Vol. 35; no. 2; pp. 170 - 177
• Main Authors: Ferrini, J B, Rodrigues, E, Dulic, V, Pichard-Garcia, L, Fabr, J M, Blanc, P, Maurel, P
• Format: Journal Article
• Language: English
• Published: Netherlands 01.08.2001
• Subjects: Adult; Aged; Animals; CCAAT-Enhancer-Binding Protein-alpha - genetics; CCAAT-Enhancer-Binding Protein-alpha - metabolism; CCAAT-Enhancer-Binding Protein-beta - genetics; CCAAT-Enhancer-Binding Protein-beta - metabolism; Cell Differentiation; Cells, Cultured; DNA - metabolism; Female; Gene Expression; Hepatocytes - cytology; Hepatocytes - metabolism; Humans; In Vitro Techniques; Liver - metabolism; Macaca; Male; Middle Aged; Protein Binding; Protein Isoforms - genetics; Protein Isoforms - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism
• ISSN: 0168-8278

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