THE GENE ENCODING THE MYELOID-RELATED PROTEIN-14 (MRP14), A CALCIUM-BINDING PROTEIN EXPRESSED IN GRANULOCYTES AND MONOCYTES, CONTAINS A POTENT ENHANCER ELEMENT IN THE FIRST INTRON

Myeloid-related proteins 8 and 14 (MRP8 and MRP14) are two Ca2+-bindin g proteins of the S-100 family highly abundant in myelomonocytic cells , The expression is mot only dependent on the developmental status of the cell but also on the inflammatory situation in the tissue. in orde r to identify regulatory elements responsible for the high expression of MRP14 in myeloid cells, reporter gene constructs have been transfec ted into HL-60 cells, Mono Mac 6 cells, and L132 cells, We demonstrate d that a DNA element in the first intron (positions 153-361) enhances the transcriptional activity of the homologous promoter and of the het erologous herpes simplex virus thymidine kinase promoter up to 37-fold . To further identify the functional site, the region between position s 153 and 192 was analyzed functionally using the thymidine kinase pro moter, The region increased the expression in the same magnitude as th e complete intron. This enhancer is highly conserved in time human and murine MRP genes, indicative of its involvement in the transcription of MRPs, Protein binding to the region is demonstrated using EMSA, DNA cross-linking, Southwestern blotting, and affinity purification. Affi nity purification confirms that four proteins bind to the enhancer ele ment.