Identification of Sp1 and GC-boxes as transcriptional regulators of mouse Dag1 gene promoter.
Dystroglycan is a widely expressed adhesion complex that anchors cells to the basement membrane and is involved in embryonic development and differentiation. Dystroglycan expression is frequently reduced in human dystrophies and malignancies, and its molecular functions are not completely understood. Several posttranslational mechanisms have been identified that regulate dystroglycan expression and/or function, while little is known about how expression of the corresponding Dag1 gene is regulated. This study aimed to clone the Dag1 gene promoter and to characterize its regulatory elements. Analysis of the mouse Dag1 gene 5'-flanking region revealed a TATA and CAAT box-lacking promoter including a GC-rich region. Transfection studies with serially deleted promoter constructs allowed us to identify a minimal promoter region containing three Specificity protein 1 (Sp1) sites and an E-box. Sp1 binding was confirmed by chromatin immunoprecipitation assay, and Sp1 downregulation reduced dystroglycan expression in muscle cells. Treatment with 5-aza-2'-deoxycytidine and/or the histone deacetylase inhibitor trichostatin A increased Dag1 mRNA expression levels in myoblasts, and methylation decreased promoter activity in vitro. Furthermore, Dag1 gene promoter methylation was reduced while its expression increased during differentiation of C(2)C(12) myoblast cells in myotubes. In conclusion, for the first time we have characterized the activity of the mouse Dag1 gene promoter, confirming a complex regulation by Sp1 transcription factor, DNA methylation, and histone acetylation, which might be relevant for a better understanding of the physiopathology of the dystroglycan complex.
Rettino
Alessandro
A
Centro di Ricerche Oncologiche Giovanni XXIII, Università Cattolica del Sacro Cuore, 00168 Rome, Italy.
Rafanelli
Francesca
F
Genovese
Giannicola
G
Goracci
Martina
M
Cifarelli
Rosa Anna
RA
Cittadini
Achille
A
Sgambato
Alessandro
A
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D019175:DNA Methylation; D019852:Diacylglycerol Kinase / Q000235:genetics*; D015870:Gene Expression; D005786:Gene Expression Regulation; D047468:Immunoprecipitation; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor; D014158:Transcription, Genetic
D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D019852:Diacylglycerol Kinase