Research article

Transcriptional regulation of human eosinophil RNases by an evolutionary- conserved sequence motif in primate genome

Hsiu-Yu Wang^1* , Hao-Teng Chang^1* , Tun-Wen Pai² , Chung-I Wu³ , Yuan-Hung Lee¹ , Yen-Hsin Chang¹ , Hsiu-Ling Tai¹ , Chuan-Yi Tang⁴ , Wei-Yao Chou^1,4 and Margaret Dah-Tsyr Chang¹

¹  Institute of Molecular and Cellular Biology & Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30013, Republic of China

²  Department of Computer Science and Engineering & Center for Marine Bioscience and Biotechnology, National Taiwan Ocean University, No. 2, Pei Ning Rd., Keelung, Taiwan 20224, Republic of China

³  Department of Ecology and Evolution, University of Chicago, IL, USA

⁴  Department of Computer Science, National Tsing Hua University, Hsinchu, Taiwan 30013, Republic of China

author email corresponding author email* Contributed equally

BMC Molecular Biology 2007, 8:89doi:10.1186/1471-2199-8-89

Published:	11 October 2007

Abstract

Background

Human eosinophil-derived neurotoxin (edn) and eosinophil cationic protein (ecp) are members of a subfamily of primate ribonuclease (rnase) genes. Although they are generated by gene duplication event, distinct edn and ecp expression profile in various tissues have been reported.

Results

In this study, we obtained the upstream promoter sequences of several representative primate eosinophil rnases. Bioinformatic analysis revealed the presence of a shared 34-nucleotide (nt) sequence stretch located at -81 to -48 in all edn promoters and macaque ecp promoter. Such a unique sequence motif constituted a region essential for transactivation of human edn in hepatocellular carcinoma cells. Gel electrophoretic mobility shift assay, transient transfection and scanning mutagenesis experiments allowed us to identify binding sites for two transcription factors, Myc-associated zinc finger protein (MAZ) and SV-40 protein-1 (Sp1), within the 34-nt segment. Subsequent in vitro and in vivo binding assays demonstrated a direct molecular interaction between this 34-nt region and MAZ and Sp1. Interestingly, overexpression of MAZ and Sp1 respectively repressed and enhanced edn promoter activity. The regulatory transactivation motif was mapped to the evolutionarily conserved -74/-65 region of the edn promoter, which was guanidine-rich and critical for recognition by both transcription factors.

Conclusion

Our results provide the first direct evidence that MAZ and Sp1 play important roles on the transcriptional activation of the human edn promoter through specific binding to a 34-nt segment present in representative primate eosinophil rnase promoters.