title: Functional characterization of the human biglycan 5'-flanking DNA and binding of the transcription factor c-Krox.
abstract: The transcriptional regulation of human biglycan expression under normal and pathological conditions was studied. The 5'-flanking regions of the human and mouse genes were isolated and analyzed; the two promoter regions share 81% identity. Both promoters are without a TATA and CAT box and contain multiple Sp1 sites. Human dermal fibroblasts were transiently transfected with progressive deletional human biglycan 5'-flanking DNA-CAT constructs, and a significant variation in activity among the individual constructs was found. A small deletion in several cases caused a more than 2-fold increase or decrease in promoter activity, thereby mapping the target sites for repressors or activators. Human biglycan expression is reduced in females with Ullrich-Turner syndrome (45,X) and increased in individuals with supernumerary sex chromosomes, and it has been speculated that biglycan plays a role in the short stature phenotype of Turner syndrome. Analysis of the transcriptional regulation of biglycan in individuals with sex chromosome anomalies showed that a -262 to -218 region of the biglycan promoter was differentially regulated. This region was extensively analyzed by DNAse footprinting and electrophoretic mobility shift assays, and a putative binding site for the transcription factor c-Krox was discovered. The binding of c-Krox to a site located at approximately -248 to -230 in the human biglycan promoter was confirmed by using extracts from COS cells expressing recombinant human c-Krox. The expression of c-Krox in bone was then examined by reverse-transcribed polymerase chain reaction and Northern blotting analysis; an approximately 3.4 kb transcript was detected in primary osteoblastic cells, in MG-63 cells, and in human bone marrow stromal cells. This is the first detection of c-Krox in bone cells, and it suggests that c-Krox, like another member of the Krox family, Krox-20, might play a regulatory role in bone.
authors.affiliation: Center for Clinical and Basic Research, Ballerup, Denmark.
authors.forename: A M
authors.initials: AM
authors.lastname: Heegaard
authors.forename: P
authors.initials: P
authors.lastname: Gehron Robey
authors.forename: W
authors.initials: W
authors.lastname: Vogel
authors.forename: W
authors.initials: W
authors.lastname: Just
authors.forename: R L
authors.initials: RL
authors.lastname: Widom
authors.forename: J
authors.initials: J
authors.lastname: Schøller
authors.forename: L W
authors.initials: LW
authors.lastname: Fisher
authors.forename: M F
authors.initials: MF
authors.lastname: Young
mesh_terms: D000818:Animals; D001483:Base Sequence; D058578:Biglycan; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D016326:Extracellular Matrix Proteins; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D011485:Protein Binding; D011509:Proteoglycans / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D012729:Sex Chromosome Aberrations / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D016335:Zinc Fingers / Q000235:genetics
chemical_list: C546884:BGN protein, human; C546885:Bgn protein, mouse; D058578:Biglycan; D004268:DNA-Binding Proteins; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D012333:RNA, Messenger; D014157:Transcription Factors; C484225:ZBTB7B protein, human; C089581:Zfp67 protein, mouse; D004247:DNA