Function and
Identification of a Novel Silencer in 5‘ Flanking Distal Region of Human
β Globin Gene
YANG You-Yun, YANG Yu, SUN Xin-Lai, CHEN Hong-Bo and ZHU
Ding-Er
( Research Center of Molecular Biology, Hunan Medical University, Changsha
410078, China )
Abstarct In order to inquire into the
possible function of the sequence in the 5‘ flanking distal region and/or d–b intergene of human b-globin gene, several recombinant
retrovirus vectors containing b-globin gene with different
length of 5‘ flanking sequences were
constructed and transfected into HeLa cells. The levels of b-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 b-globin gene. The silencer
activity was further identified to be possibly located mainly on a 310 bp DNA
restriction fragment by using the competitive gel retardation assay (cGRA), and
many known regulatory elements were found present in it as well. Luciferase
reporter gene expression system was adopted to study the function of this 310
bp fragment, and data showed that the fragment exhibited significant inhibitory
effect on each of the recombinant vectors with a,
b or d
gene promoters. The above results suggest that this silencer may be involved in
a potential regulatory network between d
and b globin genes, and may play an
important role in the regulation of globin gene expression.
Key words Globin gene expression and
regulation; silencer; d–b
intergene regulatory network (d–b
IRN)
Corresponding author:
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