Identification of distinct molecular phenotypes in cultured gastrointestinal smooth muscle cells.
OBJECTIVE
Cultured gastrointestinal smooth muscle cells have been shown to dedifferentiate and reinitiate their myogenic program in vitro. The aim of this study was to determine whether the cellular phenotypes observed in vitro were similar to those previously characterized in vivo.


METHODS
Differential isoactin expression was examined in primary cultures of intestinal smooth muscle cells (ISMCs) by Northern blot and immunohistochemical analysis. Cellular phenotype was determined for cultured ISMCs grown at high density, at low density, in the presence and absence of serum supplementation, and on several distinct substrates including collagen type IV, laminin, fibronectin, and plastic.


RESULTS
The unique patterns of isoactin protein and gene expression observed in cultured ISMCs indicate that distinct cellular phenotypes were present in vitro. The production and maintenance of these distinct smooth muscle cell phenotypes was dependent on cell density, serum supplementation, and substrate used.


CONCLUSIONS
Cultured ISMCs appear to recapitulate a portion of their in vivo myogenic program in vitro, providing a unique opportunity for the molecular mechanisms controlling gastrointestinal smooth muscle myogenesis and pathogenesis to begin to be identified.
Department of Biochemistry, University of Iowa, Iowa City, Iowa, USA.
J
J
Brittingham
C
C
Phiel
W C
WC
Trzyna
V
V
Gabbeta
K M
KM
McHugh
D000199:Actins / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn; D018929:Cell Culture Techniques / Q000379:methods; D002455:Cell Division; D002478:Cells, Cultured; D003094:Collagen; D016895:Culture Media, Serum-Free; D005314:Embryonic and Fetal Development; D005353:Fibronectins; D007421:Intestine, Small / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D007700:Kinetics; D007797:Laminin; D009130:Muscle, Smooth / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D010641:Phenotype; D010969:Plastics; D014176:Protein Biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D014158:Transcription, Genetic
D000199:Actins; D016895:Culture Media, Serum-Free; D005353:Fibronectins; D007797:Laminin; D010969:Plastics; D003094:Collagen