ALTERED EXPRESSION OF TRANSCRIPTION FACTOR FOR CD19 GENE IN HUMAN MYELOMA CELLS

点击翻译按钮获取中文摘要

Myeloma cells do not express CD19 on their surface, while normal plasma cells do. We considered that this loss of CD19 expression is involved in oncogenesis of human myeloma, and performed this project. Our study clarified that loss of CD19 expression on myeloma cells is derived from loss of expression of CD19 gene. Furthermore, it was revealed that loss of CD19 gene expression result from altered expression of Pax-5 gene. It was also confirmed that the functional activity of BSAP encoded by Pax-5 gene was not detected from myeloma cells by gel shift assay. Since expression of Pax-5 gene is altered in human myeloma cells, we tried to clone and analyze regulatory region of human Pax-5 gene in order to clarify the regulatory mechanism of Pax-5 gene expression. We cloned 1,050 bp 5' upstream region of human Pax-5 gene by PCR-mediated gene walking method, and analyzed predicted binding motifs in this DNA fragment. This fragment contained binding motifs of Ikaros-2 (Ik-2), Lyf-1 (Ik-1), bHLH,E-47, Sox-5 et al. In the experiment of deletion mutants of this DNA fragment, the basal promoter activity was located in the region from-70 bp to -820 bp upstream of Pax-5 gene. Therefore, our study showed that the expression of Pax-5 gene is altered in human myeloma cells that do not express CD19, and we cloned and functionally analyzed 1,050 bp 5' upstream region of human Pax-5 gene. The further analysis of this cloned promoter region of human Pax-5 gene will contribute to the understanding of oncogenic mechanism of human myeloma.