Disease relevance of SMTN

• While anti-alpha-SMA staining was generally normal, immunoreactivity for SMMHC, HDAC8 and/or SM was either absent or focally lacking in Hirschsprung's disease (80%), idiopathic megacolon (75%) and slow-transit constipation (70%) [1].

High impact information on SMTN

• Immunohistochemistry and Western blotting revealed synthesis of smoothelin in smooth muscle of species evolutionarily as far apart as human and teleost [2].
• In situ hybridization demonstrated that human smoothelin is encoded by a single copy gene which is located on chromosome 22 [2].
• It is exclusively observed in smooth muscle cells by Northern blotting and immunohistochemical analysis and therefore designated "smoothelin." A human smooth muscle cDNA library was screened with the monoclonal antibody R4A, and a full-size cDNA of the protein was selected [2].
• 1. The estimated linkage-disequilibrium measure rho2 for 36 linked loci of the smoothelin gene when one- and two-subject pool protocols were used suggested that the gross pattern of the distribution of the measure can be reproduced using the two-subject pool data [3].
• These data indicate that the apparent up-regulation of large Galpha(s) species in P is mimicked by elevated smoothelin [4].

Biological context of SMTN

• Assignment of the human gene for smoothelin (SMTN) to chromosome 22q12 by fluorescence in situ hybridization and radiation hybrid mapping [5].
• In addition to the known smoothelin cDNA (c1 isoform) we identified two novel cDNA variants (c2 and c3 isoform) that are generated by alternative splicing within a region, which shows similarity to the spectrin family of F-actin cross-linking proteins [6].
• A novel isoform of the smooth muscle cell differentiation marker smoothelin [7].
• SMMHC and the novel smooth muscle markers SM and HDAC8 often display striking abnormalities linked to the smooth muscle contractile apparatus unnoticed by both routine stainings and alpha-SMA, suggesting specific defects of smooth muscle cells involved in the pathogenesis of gastrointestinal motility disorders [1].
• Transfection studies revealed that smoothelin has an affinity for actin and is either capable of forming filamentous structures or colocalizes with such structures [8].

Anatomical context of SMTN

• These results strongly suggest that the smoothelin gene contains a vascular and a visceral smooth muscle promoter [6].
• Identification and characterization of novel smoothelin isoforms in vascular smooth muscle [6].
• The cell-type-specific expression of smoothelin isoforms that are associated with actin filaments may play a role in the modulation of the contractile properties of different smooth muscle cell types [6].
• Apparent up-regulation of stimulatory G-protein alpha subunits in the pregnant human myometrium is mimicked by elevated smoothelin expression [4].
• In individuals older than 1 year, most smooth muscle cells in the media of all blood vessels contained smoothelin [9].

Associations of SMTN with chemical compounds

• Smoothelin-positive cells were present primarily at the luminal portion of advanced lesions [10].
• Effects of androgen and estrogen on the expressions of basic fibroblast growth factor, transforming growth factor and smoothelin [11].

Co-localisations of SMTN

• Smoothelin was demonstrated to colocalize with actin stress fibers but not with desmin filaments [8].

Regulatory relationships of SMTN

• Smoothelin is a cytoskeletal protein specifically expressed in differentiated smooth muscle cells and has been shown to colocalize with smooth muscle alpha actin [6].
• In stented pig coronary vessels, LPP was expressed in the neointima of cells lacking smoothelin and showed expression patterns identical to those of SM alpha-actin [12].

Other interactions of SMTN

• With few exceptions, smoothelin was more frequently detected than desmin in medial smooth muscle cells [9].
• Smoothelin and vimentin were codistributed in the smooth muscle cells of the media in most vessels [9].
• We used immunochemical and western blotting methods to determine the status of smoothelin and smooth muscle alpha-actin in the valve [13].
• OBJECTIVE: Two major isoforms of smoothelin have been reported, a 59-kDa smoothelin-A in visceral smooth muscle cells and a 110-kDa smoothelin-B in vascular smooth muscle cells [14].
• For calponin-1 and smoothelin, protein levels mirrored respective mRNA levels [15].

Analytical, diagnostic and therapeutic context of SMTN

• The genomic structure and sequence of the smoothelin gene were determined by genomic PCR, RT-PCR and DNA sequencing [6].
• We then generated specific antibodies against the major smoothelin isoforms and could show by Western blotting and immunohistochemistry that the large isoform is specifically expressed in vascular smooth muscle cells, while the small isoform is abundant in visceral smooth muscle [6].
• Smoothelin was not detected in primary or long term smooth muscle cell cultures [2].
• In tissue explants smoothelin mRNA concentration decreases to undetectable levels within 12 hours after dissection as was in general the case in primary cell cultures [8].
• At the protein level smoothelin was investigated by standard and quantitative immunohistochemistry [16].

References