Cloning of the Human GLI2 Promoter

Abstract

GLI2 (GLI-Kruppel family member 2), a zinc finger transcription factor that mediates Hedgehog signaling, is implicated in the progression of an ever-growing number of human malignancies, including prostate and pancreatic cancer, as well as basal cell carcinoma of the skin. Its expression is up-regulated by transforming growth factor-β (TGF-β) in a variety of cell types, both normal and transformed. We report herein that TGF-β-driven GLI2 expression is transcriptional and does not result from stabilization of GLI2 transcripts. We describe the characterization of the 5′-flanking sequence of human GLI2 mRNA, the identification of a transcription start site, the cloning of ∼1,600 bp of the regulatory promoter region and the identification and functional analysis of a TGF-β-responsive region mapped to a 91-bp sequence between nucleotides −119 and −29 of the promoter. This region harbors SMAD and lymphoid enhancer factor/T cell factor binding sites that allow functional cooperation between SMAD3 and β-catenin, recruited to the promoter in response to TGF-β to drive GLI2 gene transcription. GLI2 (GLI-Kruppel family member 2), a zinc finger transcription factor that mediates Hedgehog signaling, is implicated in the progression of an ever-growing number of human malignancies, including prostate and pancreatic cancer, as well as basal cell carcinoma of the skin. Its expression is up-regulated by transforming growth factor-β (TGF-β) in a variety of cell types, both normal and transformed. We report herein that TGF-β-driven GLI2 expression is transcriptional and does not result from stabilization of GLI2 transcripts. We describe the characterization of the 5′-flanking sequence of human GLI2 mRNA, the identification of a transcription start site, the cloning of ∼1,600 bp of the regulatory promoter region and the identification and functional analysis of a TGF-β-responsive region mapped to a 91-bp sequence between nucleotides −119 and −29 of the promoter. This region harbors SMAD and lymphoid enhancer factor/T cell factor binding sites that allow functional cooperation between SMAD3 and β-catenin, recruited to the promoter in response to TGF-β to drive GLI2 gene transcription.