Identification of regulatory elements of human alpha 6 integrin subunit gene.

The integrin alpha 6 subunit associates with either the beta 1 or beta 4 subunit to form receptors for laminin, a major component of the basement membrane. Here, we characterized basal promoter of the human integrin alpha 6 subunit gene. The transcription start site, mapped by primer extension analysis, was 208 bp upstream of the translation start site. The promoter region lacked canonical TATA and GC boxes, but did contain a TATA-like sequence (GATAAA) 23 bp upstream of the major transcription start site. Consensus binding sites for Sp1 and the NF-kappa B complex were also present in the promoter region. A putative glucocorticoid/progesterone receptor responsive element (GRE/PRE), together with the Ap1 and c-myc binding sites located around 350-360 bp upstream of the transcription start site, represented positive regulatory sequences. Our current study showed a molecular model by which progesterone promotes tumor cell invasion through the basement membrane by up-regulating the laminin receptor.