Minimal Promoter Components of the Human Growth/Differentiation Factor-5 Gene

Abstract Growth/differentiation factor-5 (GDF-5) is a new member of the BMP family supposed to be involved in chondrogenesis. We cloned the human GDF-5 gene from lambda phage library and sequenced its 3.5-kb 5′-flanking region. The transcription start site was mapped by 5′-RACE to the sequence that coincides with the initiator element. Electrophoresis mobility shift assays (EMSA) demonstrated a zinc finger transcription factor, YY1, to bind to the sequence surrounding the transcription start site. To localize positive and negative regulatory elements in the GDF-5 5′-upstream region, we constructed a series of progressively deleted promoter–reporter plasmids. The transient transfection assay with human osteoblastic Hos cells indicated that a minimal enhancer element resides within −117 to −27 relative to the transcription initiation site. Since the GDF-5 promoter was active even in fibroblastic L cells, a mechanism governing its chondrocyte-restrictive expression needs to be explored.