[HP8: the partial cDNA clone of a novel member of C/EBP gene family].

OBJECTIVE

To explore the human C/EBP related genes.

METHODS

Screening human placenta cDNA library with rat C/EBP cDNA probe.

RESULTS

One positive clone, HP8 was obtained. This clone contained 1975 base pairs which include 604 coding base pairs. The matched DNA sequence was not found in the gene database (EMBL 95.6). The 201 amino acids encoded by this gene had the leucine zipper structure and demonstrated the highest homology (97%) with C/EBP throughout the DNA-binding domain and leucine repeat region (C-terminal 60 amino acids). Beyond this region, only low homology was detected in HP8 protein and C/EBP or C/EBP related proteins. Herewith, HP8 was defined as a novel member of C/EBP gene family. Genomic Southern blot analysis confirmed that HP8 was a single copy gene. Northern blot analysis in 14 different fetus tissues showed that high level of HP8 mRNA was expressed in small intestine and skin, middle level in adrenal gland, low level in liver, lung, kidney, thyroid gland and gallbladder. In 3 human adult liver tissues, only one low level HP8 mRNA, whereas of 5 hepatomas and one of their surrounding nontumorous hepatic tissues had, high level HP8 mRNA.

CONCLUSION

These results suggested that HP8 gene might be a transactivator related to cell growth. As Northern blot analysis indicated, HP8 gene has about 2.7 Kb full length cDNA.