title: Identification and characterization of regulatory elements in the promoter of ACVR1, the gene mutated in Fibrodysplasia Ossificans Progressiva.
abstract: BACKGROUND
  The ACVR1 gene encodes a type I receptor for bone morphogenetic proteins (BMPs). Mutations in the ACVR1 gene are associated with Fibrodysplasia Ossificans Progressiva (FOP), a rare and extremely disabling disorder characterized by congenital malformation of the great toes and progressive heterotopic endochondral ossification in muscles and other non-skeletal tissues. Several aspects of FOP pathophysiology are still poorly understood, including mechanisms regulating ACVR1 expression. This work aimed to identify regulatory elements that control ACVR1 gene transcription.
  
  
  RESULTS
  We first characterized the structure and composition of human ACVR1 gene transcripts by identifying the transcription start site, and then characterized a 2.9 kb upstream region. This region showed strong activating activity when tested by reporter gene assays in transfected cells. We identified specific elements within the 2.9 kb region that are important for transcription factor binding using deletion constructs, co-transfection experiments with plasmids expressing selected transcription factors, site-directed mutagenesis of consensus binding-site sequences, and by protein/DNA binding assays. We also characterized a GC-rich minimal promoter region containing binding sites for the Sp1 transcription factor.
  
  
  CONCLUSIONS
  Our results showed that several transcription factors such as Egr-1, Egr-2, ZBTB7A/LRF, and Hey1, regulate the ACVR1 promoter by binding to the -762/-308 region, which is essential to confer maximal transcriptional activity. The Sp1 transcription factor acts at the most proximal promoter segment upstream of the transcription start site. We observed significant differences in different cell types suggesting tissue specificity of transcriptional regulation. These findings provide novel insights into the molecular mechanisms that regulate expression of the ACVR1 gene and that could be targets of new strategies for future therapeutic treatments.
authors.affiliation: Department of Neurosciences, Rehabilitation, Ophthalmogy, Genetics, Maternal and Child Health and CEBR, Università degli Studi di Genova, Genova, Italy. bocciardi@unige.it.
authors.forename: Francesca
authors.initials: F
authors.lastname: Giacopelli
authors.forename: Serena
authors.initials: S
authors.lastname: Cappato
authors.forename: Laura
authors.initials: L
authors.lastname: Tonachini
authors.forename: Marzia
authors.initials: M
authors.lastname: Mura
authors.forename: Simona
authors.initials: S
authors.lastname: Di Lascio
authors.forename: Diego
authors.initials: D
authors.lastname: Fornasari
authors.forename: Roberto
authors.initials: R
authors.lastname: Ravazzolo
authors.forename: Renata
authors.initials: R
authors.lastname: Bocciardi
mesh_terms: D030201:Activin Receptors, Type I / Q000235:genetics*; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics; D045744:Cell Line, Tumor; D019295:Computational Biology; D024202:Electrophoretic Mobility Shift Assay; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D009221:Myositis Ossificans / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; C425423:ACVR1 protein, human; D030201:Activin Receptors, Type I
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