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KMID : 0578319940040040511
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Molecules and Cells
1994 Volume.4 No. 4 p.511 ~ p.514
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Cell Growth-Dependent regulation of Lactate Dehydrogenase A-Gene cAMP Response Element Binding Activity of Nuclear protein in Regenerating Rat Liver
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Hwang, Eun Sook
Lee, Mi Young/Lee, Seung Ki
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Abstract
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To explore which types of the cAMP response element (CRE) binding nuclear proteins are responsible for the hepatocyte growth-dependent regulation of lactate dehydrogm" A (LDH A) gene transcription, we performed gel mobility shift assays using the LDH A-CRE and CHAT sequences as probes and also supershift gel mobility assays using the specific antibodies against CRE-binding protein (CREB) and CAAT/Enhancer binding proteins (C/EBPs). The results demonstrate that the CRE . binding activity of nuclear proteins was blocked by 501/o in the presence of 100-fold molar excess of the HSV tk CAAT sequences but was not affected by even 800-fold molar excess of the synthetic CAAT sequences. Conversely, the CAAT binding activity of nuclear proteins was not competed by 800-fold molar excess of the LDH A-CRE sequences. Furthermore, supershift gel mobility assays revealed that the antibody against CREB of 43 kDa did, but the antibody against C/EBPa or R did not supershift the band of the LDH A-CRE binding protein complex. In contrast, the antibody against C/EBP a or 0 did, but the CREB antibody did not supershift the band of the HSV tk CAAT binding protein complex. In addition, the results from Western blot analysis using a specific antibody against CREB of 43 kDa suggest that the increased LDH A-CRE binding activity is not due to the increased level of CREB, but may be due to post-translational modification. From these results, we suggest that the transcriptional activity of the LDH A gene may be regulated by at least two different transcription factors; CREB of 43 kDa and C/EBP via post-translational modification. We speculate that the C/EBP binding to LDH A-CRE may be an isoform of C/EBP which differs from C/EBPa or R.
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KEYWORD
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