title: Structural and functional analysis of myostatin-2 promoter alleles from the marine fish Sparus aurata: evidence for strong muscle-specific promoter activity and post-transcriptional regulation.
abstract: Myostatin (MSTN) is a negative regulator of skeletal muscle growth. In contrast to mammals, fish possess at least two paralogs of MSTN: MSTN-1 and MSTN-2. In this study, we analyzed the structural-functional features of the four variants of Sparus aurata MSTN-2 5'-flanking region: saMSTN-2a, saMSTN-2as, saMSTN-2b and saMSTN-2c. In silico analysis revealed numerous putative cis regulatory elements including several E-boxes known as binding sites to myogenic transcription factors. Transient transfection experiments using non-muscle and muscle cell lines showed surprisingly high transcriptional activity in muscle cells, suggesting the presence of regulatory elements unique to differentiated myotubes. These observations were confirmed by in situ intramuscular injections of promoter DNA followed by reporter gene assays. Moreover, high promoter activity was found in differentiated neural cell, in agreement with MSTN-2 expression in brain. Progressive 5'-deletion analysis, using reporter gene assays, showed that the core promoter is located within the first -127 bp upstream of the ATG, and suggested the presence of regulatory elements that either repress or induce transcriptional activity. Transient transgenic zebrafish provided evidence for saMSTN-2 promoter ability to direct GFP expression to myofibers. Finally, our data shows that although no mature saMSTN-2 mRNA is observed in muscle; unspliced forms accumulate, confirming high level of transcription. In conclusion, our study shows for the first time that MSTN-2 promoter is a very robust promoter, especially in muscle cells.
authors.affiliation: Department of Marine Biology & Biotechnology, National Institute of Oceanography, Israel Oceanographic and Limnological Research, Tel-Shikmona, Haifa, Israel.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Nadjar-Boger
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Hinits
authors.forename: Bruria
authors.initials: B
authors.lastname: Funkenstein
mesh_terms: D000483:Alleles; D017398:Alternative Splicing / Q000235:genetics; D000818:Animals; D030801:Animals, Genetically Modified; D059001:Aquatic Organisms / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D017124:Conserved Sequence / Q000235:genetics; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism*; D055435:Myostatin / Q000235:genetics*; D009928:Organ Specificity / Q000235:genetics*; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D051381:Rats; D020218:Response Elements / Q000235:genetics; D021541:Sea Bream / Q000235:genetics*; D017384:Sequence Deletion / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D019076:Transgenes / Q000235:genetics; D015027:Zebrafish
chemical_list: D055435:Myostatin; D014157:Transcription Factors; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins