Identification of the positive regulatory and distinct core regions of promoters, and transcriptional regulation in three types of mouse phospholipid hydroperoxide glutathione peroxidase.

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is transcribed into three types of mRNA, mitochondrial, non-mitochondrial and nucleolar types, from one gene by alternative transcription using different first exons, Ia and Ib. We investigated the regulatory mechanisms of the expressions of the three types of PHGPx using promoter analysis with luciferase as the reporter gene and electrophoretical mobility shift analysis. Here we report a draft of the positive regulatory region and the core promoter regions of PHGPx in several cell lines. From promoter deletion analysis we identified the three distinct core regions of mitochondrial PHGPx, non-mitochondrial PHGPx and nucleolar PHGPx. The core promoter activity of non-mitochondrial PHGPx was high in L929 cells, but relatively low for mitochondrial and nucleolar PHGPx. We also identified the positive regulatory region of mitochondrial PHGPx by deletion and mutation analysis of 5'-flanking regions of mitochondrial PHGPx. This region could regulate the promoter activity of non-mitochondrial PHGPx; however, up-regulation by this region was normally suppressed by the upstream region in somatic cells. Electrophoretical mobility shift analysis demonstrated that a specific transcription factor complex bound to this region in adult testis, but not in young testis and different sizes of complexes bound to this region between testis and brain.