title: Mapping and functional characterization of the murine smoothelin-like 1 promoter.
abstract: BACKGROUND
  Smoothelin-like 1 (SMTNL1, also known as CHASM) plays a role in promoting relaxation as well as adaptive responses to exercise, pregnancy and sexual development in smooth and skeletal muscle. Investigations of Smtnl1 transcriptional regulation are still lacking. Thus, in this study, we identify and characterize key regulatory elements of the mouse Smtnl1 gene.
  
  
  RESULTS
  We mapped the key regulatory elements of the Smtnl1 promoter region: the transcriptional start site (TSS) lays -44 bp from the translational start codon and a TATA-box motif at -75 bp was conserved amongst all mammalian Smtnl1 promoters investigated. The Smtnl1 proximal promoter enhances expression up to 8-fold in smooth muscle cells and a second activating region lays 500 bp further upstream. Two repressing motifs were present (-118 to -218 bp and -1637 to -1869 bp). The proximal promoter is highly conserved in mammals and contains a mirror repeat sequence. In silico analysis suggests many transcription factors (notably MyoD) could potentially bind within the Smtnl1 proximal promoter sequence.
  
  
  CONCLUSIONS
  Smtnl1 transcript was identified in all smooth muscle tissues examined to date, albeit at much lower levels than found in skeletal muscle. It is unlikely that multiple SMTNL1 isoforms exist since a single Smtnl1 transcription start site was identified in both skeletal and intestinal smooth muscle. Promoter studies suggest restrictive control of Smtnl1 expression in non-muscle cells.
authors.affiliation: Smooth Muscle Research Group, Department of Biochemistry & Molecular Biology, University of Calgary, Alberta, Canada.
authors.forename: Annegret
authors.initials: A
authors.lastname: Ulke-Lemée
authors.forename: Sara R
authors.initials: SR
authors.lastname: Turner
authors.forename: Saad H
authors.initials: SH
authors.lastname: Mughal
authors.forename: Meredith A
authors.initials: MA
authors.lastname: Borman
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Winkfein
authors.forename: Justin A
authors.initials: JA
authors.lastname: MacDonald
mesh_terms: D000818:Animals; D051379:Mice; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism; D009130:Muscle, Smooth / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000378:metabolism; D024363:Transcription Initiation Site; D000096985:Calponins
chemical_list: D009124:Muscle Proteins; D010750:Phosphoproteins; D014157:Transcription Factors; C543629:SMTNL1 protein, human; D000096985:Calponins; C491838:SMTNL1 protein, mouse