Cloning the promoter for transforming growth factor-beta type III receptor. Basal and conditional expression in fetal rat osteoblasts.
Transforming growth factor-beta binds to three high affinity cell surface molecules that directly or indirectly regulate its biological effects. The type III receptor (TRIII) is a proteoglycan that lacks significant intracellular signaling or enzymatic motifs but may facilitate transforming growth factor-beta binding to other receptors, stabilize multimeric receptor complexes, or segregate growth factor from activating receptors. Because various agents or events that regulate osteoblast function rapidly modulate TRIII expression, we cloned the 5' region of the rat TRIII gene to assess possible control elements. DNA fragments from this region directed high reporter gene expression in osteoblasts. Sequencing showed no consensus TATA or CCAAT boxes, whereas several nuclear factors binding sequences within the 3' region of the promoter co-mapped with multiple transcription initiation sites, DNase I footprints, gel mobility shift analysis, or loss of activity by deletion or mutation. An upstream enhancer was evident 5' proximal to nucleotide -979, and a silencer region occurred between nucleotides -2014 and -2194. Glucocorticoid sensitivity mapped between nucleotides -687 and -253, whereas bone morphogenetic protein 2 sensitivity co-mapped within the silencer region. Thus, the TRIII promoter contains cooperative basal elements and dispersed growth factor- and hormone-sensitive regulatory regions that can control TRIII expression by osteoblasts.
Ji
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C
Plastic Surgery Section, Department of Surgery, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
Chen
Y
Y
McCarthy
T L
TL
Centrella
M
M
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular; D016384:Consensus Sequence; D018983:DNA Footprinting; D017931:DNA Primers; D003850:Deoxyribonuclease I; D005333:Fetus; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D010006:Osteoblasts / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011509:Proteoglycans / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis; D014158:Transcription, Genetic; D014162:Transfection
D017931:DNA Primers; D015345:Oligonucleotide Probes; D011509:Proteoglycans; D018125:Receptors, Transforming Growth Factor beta; D011994:Recombinant Proteins; C071736:betaglycan; D003850:Deoxyribonuclease I