Abstracts / Prostaglandins & other Lipid Mediators 59 (1999) 1-235 159

TRANSCRIPTIONAL REGULATION OF HUMAN LEUKOTRIENE B RECEPTOR

Kazuhiko Kato, Takehiko Yokomizo, Takashi Izumi, and Takao Shimizu

Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan

Leukotriene B is a lipid mediator acting on inflammatory response and host defense against infection. We\solated cDNAs and genes of BLT from various animals. Northem blotting analysis revealed that human BLT mRNA is mainly expressed in leukocytes and to lesser extents in spleen and thymus (1). The upregulation of BLT mRNA was reported in the activated mac- rophages in mice (2). To identify the molecular mechanism of the unique expression of BLT, we isolated BLT gene and analyzed the transcriptional regulation. A human genomic library was screened and one clone containing the S-flanking region of BLT cDNA was isolated. Three transcription initiation sites were detected by 5’-RACE. Sequence analysis revealed that the BLT gene consists of two exons and one intron. The S-flanking region contained high GC rich sequences, no TATA box was observed in the neighbor of the transcription initiation sites. Reporter gene assay revealed that the promoter activity in the S-flanking region was observed both in BLT expressing cells (THP-1 and U937 cells) and in BLT non-expressing cells (HeLa cells). Deletion mutant analysis suggested that the region about 1OObp upstream from the tran- scription initiation site was important as a core promoter for the transcription of BLT gene. Identification of the transcriptional factors involved in the expression of BLT and analysis of the mechanism of cell-specific transcriptional regulation are ongoing.

References 1. Yokomizo, T. et al (1997) Nature 387:620-624. 2. Huang, WW. et al (1998) J. Exp. Med. 188: 1063: 1074.