Five ETS Family Members, ELF-1, ETV-4, ETV-3L, ETS-1, and ETS-2 Upregulate Human Leukocyte-Associated Immunoglobulin-Like Receptor-1 Gene Basic Promoter Activity

Human leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1), an immunoinhibitory receptor, is expressed on most types of hematopoietic cells and some tumor cells. LAIR-1 plays an inhibitory role in immune cell maturation, differentiation, and activation. LAIR-1 is also involved in some autoimmune diseases and tumors. However, the mechanism controlling the regulation of the LAIR-1 gene is still unknown. In order to elucidate the molecular mechanisms involved in LAIR-1 regulation, in the present study, we cloned and characterized the promoter region of LAIR-1 gene using a series of truncated promoter plasmids in luciferase reporter assays. Our results show that the basic core promoter of LAIR-1 is located within the region-256/-8 relative to the translational start site. Our further studies indicate that five ETS transcription factors: ELF-1, ETV 4, ETV-3L, ETS-1 and ETS-2, can up-regulate the LAIR-1 basic promoter activity. Of these, ETS-2 is the most effective transcription factor. Moreover, ETS-2 was confirmed to interact directly with the basic promoter of LAIR-1. This study presents the first description of regions/factors capable of up-regulation the promoter activity of LAIR-1. This new knowledge contributes to understanding of the molecular mechanisms involved in LAIR-1 associated immune regulation and diseases.