Pax5 is a key transcription factor for B-lineage commitment and differentiation. Clarifying the regulatory system of the Pax5 gene will increase our knowledge of the mechanism controlling differentiation from multipotent progenitors to B-lineage specific cells. Functional dissection of the 5'-flanking region of human Pax5 gene by luciferase reporter assays indicated a cluster of regulatory elements acting as a strong represser between +320 and +453. Insertion of this segment between the heterologous simian virus 40 promoter and the luciferase gene in both the sense and reverse orientation sharply inhibited the luciferase activity, but insertion to the upstream of the promoter did not, suggesting that this segment must be located in the 5'UTR to function effectively. Electrophoretic gel mobility shift assay indicated that unknown DNA binding factors bound to the fragment +408 to +429 with the nuclear extract of B cells as well as T cells. Insertion of only this fragment between the promoter and the reporter gene suppressed the luciferase activity to almost background level. Competitive assay indicated that the region between nucleotides +413 and +427 encompassed the binding site of the DNA binding factors and was regarded as a represser element. Mutagenesis in this element significantly recovered the reporter gene activity. However, known DNA binding factor was not searched out through several databases around this element, suggesting that this element may be a novel repressor. Thus, the segment +320 to +453, especially the represser element +413 to + 427, may be important for B-cell differentiation and proliferation through the regulation of Pax5 gene expression.
|Issue number||11 PART II|
|Publication status||Published - 2000|
ASJC Scopus subject areas
- Cell Biology