Cloning of the human RHOB gene promoter: characterization of a VNTR sequence that affects transcriptional activity.

The RHOB gene is an immediate-early gene implicated in cell growth control, cytoskeletal organization, and neoplastic transformation. Although the mouse RHOB gene (Arhb) promoter has been described, the human promoter is unknown. We cloned the human RHOB gene (ARHB) 5'-flanking region from the human genome and characterized its promoter region. Unlike its mouse counterpart, the human gene shows a variable number of tandem repeats (VNTR) sequence with a 34-bp repetitive unit between positions -1124 and -821. We demonstrated that this VNTR sequence significantly decreases the transcriptional activity of ARHB and simian virus-40 (SV40) promoters. PCR amplification of the VNTR sequence using genomic DNA from many cell lines revealed the existence of at least four alleles containing a different number of the repetitive unit. Our data suggest a potential regulatory role for the VNTR sequence in ARHB expression.