Function and Identification of a Novel Silencer in 5' Flanking Distal Region of Human beta Globin Gene.

In order to inquire into the possible function of the sequence in the 5' flanking distal region and/or delta-beta intergene of human beta-globin gene several recombinant retrovirus vectors containing beta-globin gene with different length of 5' flanking sequences were constructed and transfected into Hela cells. The levels of beta-globin gene expression determined quantitatively by Northern blotting and RT-cPCR revealed that there is a strong silencer activity in a DNA sequence(723 bp) between-2282 bp and -1559 bp upstream from the cap site of beta-globin gene. The silencer activity was further identified to be possibly located mainly on a 310bp DNA restriction fragment by using the competitive gel retardation assay(cGRA) and many known regulatory elements were found present in it as well.

Structure and Function of a Novel Silencer in 5' Flanking Distal Region of Human beta Globin Gene.

A novel silencer fragment(310 bp) was recently discovered and identified to locate between -2 132 bp and -1 822 bp upstream from the cap site of beta-globin gene by gel retardation assay and luciferase reporter gene expression analysis. DNA footprinting assays were performed to determine the interaction between its DNA sequence and binding proteins from the nuclear extract of Hela cells. The results showed that there were two nuclear protein binding sites in thissilencer, one was the -2 017--2 011 bp sequence CTTCCGC" and the other was the -2 006--1 997 bp sequence "CACTTTATTT".