Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

Binding of two nuclear complexes to a novel regulatory element within the human S100A9 promoter drives the S100A9 gene expression

Abstract

S100A9, also refered to as MRP14, is a calcium-binding protein, whose expression is tightly regulated during differentiation of myeloid cells. The present study was performed in order to study the cell type- and differentiation-specific transcriptional regulation of the S100A9 gene. Analysis of the S100A9 promoter in MonoMac-6 cells revealed evidence for a novel regulatory region at position -400 to -374 bp, termed MRP regulatory element (MRE). MRE deletion resulted into a 5.2-fold reduction of promoter activity. By electrophoretic mobility shift analysis two nuclear complexes binding to this region were identified and referred to as MRE-binding complex A (MbcA) and MbcB. By mutagenesis the MRE binding motif could be narrowed to a 12 bp region. The relevance of MRE is deduced from the observations that the formation of either MbcA or MbcB strongly correlated with S100A9 gene expression in a cell type-specific, activation- and differentiation-dependent manner. Moreover, DNA affinity chromatography and Western blot studies indicate that a Kruppel-related zinc finger protein and the transcriptional intermediary factor 1beta (TIF1beta) are involved in as MRE-binding complex, thereby regulating the S100A9 gene expression.