IDENTIFICATION OF A TRANSFORMING GROWTH FACTOR-BETA-1 BONE MORPHOGENETIC PROTEIN-4 (TGF-BETA-1/BMP4) RESPONSE ELEMENT WITHIN THE MOUSE-TISSUE TRANSGLUTAMINASE GENE PROMOTER/

Tissue transglutaminase is a calcium-dependent, protein cross-linking enzyme that is highly expressed in cells undergoing apoptosis, The exp ression of tissue transglutaminase is regulated by a variety of molecu les including retinoids, interleukin-6, and transforming growth factor -beta 1 (TGF-beta 1). Retinoid and interleukin-6 inductions of tissue transglutaminase expression are mediated by specific cis-regulatory el ements located within the first 4.0 kilobase pairs of the promoter of the gene. The present studies were designed to identify the molecular mechanisms mediating the regulation of tissue transglutaminase gene ex pression by TGF-beta family members. Transient transfection of Mv1Lu c ells with transglutaminase promoter constructs demonstrated that 0.2 n ar TGF-beta 1 maximally induced the activation of the promoter through a 10-base pair TGF-beta 1 response element (TRE; GAGTTGGTGC) located 868 base pairs upstream of the transcription start site. This same ele ment mediated an inhibitory activity of TGF-beta 1 on the transglutami nase promoter in MC3T3 El cells. The TRE through which TGF-beta 1-regu lated the activity of the transglutaminase promoter was necessary and sufficient for bone morphogenetic protein 2-(BMP) and BMP4-dependent i nhibition of the tissue transglutaminase promoter. The TGF-beta 1, BMP 2, and BMP4 regulation of the transglutaminase promoter activity was s imilar to the responses we observed for the endogenous transglutaminas e activity of Mv1Lu and MC3T3 El cells. For BMP2 and BMP4, this regula tion was paralleled by a decrease in tissue transglutaminase mRNA in M C3T3 El cells. The results of these experiments suggest that TGF-beta 1, BMP2, and BMP4 regulation of mouse tissue transglutaminase gene exp ression requires a composite TRE located in the 5'-flanking DNA.