Regulatory elements of microfibril-associated glycoprotein-1 gene expression in muscle cells.
The Mfap2 gene encodes the microfibril-associated glycoprotein-1 (MAGP1), an extracellular matrix protein of microfibrillar structures. The gene is transcribed from a major transcription start site embedded in a CpG island. Mapping of transcriptionally active regions in the 5' flanking sequence identified a region, located between nucleotides -339 and -109 as the Mfap2 basal promoter. Site-directed and random mutagenesis demonstrated that a KLF sequence motif at -256/-270, an E-box at -222/-229, and a GC-box at -117/-125, are critical for the promoter function. Using electrophoresis mobility shift assays, we find that the KLF motif mediates the binding of GKLF/KLF4, whereas the E-box is a target for both Upstream Stimulatory Factors 1 and 2, and the GC box at -117/-125 forms complexes with Sp1 and Sp3, but not with Sp4 or AP2alpha. A sequence element spanning position -150 may represent the binding motif of an uncharacterized transcription factor. The basal transcriptional regulation of Mfap2 in muscle cells is discussed.
Segade
Fernando
F
Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA. fsegade@wfubmc.edu
Mecham
Robert P
RP
D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D003285:Contractile Proteins / Q000235:genetics* / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D016326:Extracellular Matrix Proteins / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D051379:Mice; D032342:Muscle Cells / Q000737:chemistry / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D032446:Myoblasts / Q000201:enzymology; D009687:Nuclear Proteins / Q000032:analysis / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology; D000072260:RNA Splicing Factors; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics* / Q000502:physiology; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D051720:Upstream Stimulatory Factors / Q000235:genetics / Q000378:metabolism
D003285:Contractile Proteins; D016326:Extracellular Matrix Proteins; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D009687:Nuclear Proteins; D000072260:RNA Splicing Factors; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D051720:Upstream Stimulatory Factors; C016598:microfibrillar protein