[An expression element of a new controlling insulin growth factors binding protein-3(IGFBP-3)in senescent cells]

To study the influencing factors of the increased expression of the controlling insulin growth factors binding protein-3(IGFBP-3)in the senescent cells.

Northern blot was used to show of the differential expression of the IGFBP-3 gene in the young and senescent 2BS cells; The size of 2 kb human IGFBP-3 upstream sequence including the series of the 5'-UTR area was amplified by PCR, and four groups of IGFBP-3 promoter fragments of different lengths were obtained by enzyme digestion. The Effectene Transfection Reagent (Qiagen) kit was used to transfect the fragments into the young and senescent cells. The promoting activity of several groups of constructing gene fragments were evaluated. The area of the controlling transfection activity was determined. The enhancer element in the activity area was ascertained by superimposing the oligonucleotide gel blocking experiment.

Compared with the young 2BS cells, the expression of the IGFBP-3 gene in the senescent 2BS cells was enhanced. There was a protein binding in the fragment site from site +59 to -58 of the IGFBP-3 enhancer. 5'-ccagcctgccaagcagcgtgccccggttgc-3' was the enhancer element of IGFBP-3.

In the 30 bp fragment from site -37 to -8 of the IGFBP-3 gene upstream, there is a new IGFBP-3 enhancer element IEE, which plays a controlling role in the expression of IGFBP-3.