Regulation of c-fos expression by static stretch in rat myometrial smooth muscle cells.
OBJECTIVE
We investigated whether mechanical stretch stimulates expression of the immediate early gene c-fos messenger RNA in rat myometrial smooth muscle cells.


METHODS
Freshly isolated myometrial smooth muscle cells (from virgin rats) were plated on flexible culture plates that were coated with either collagen I, laminin, elastin, or pronectin and were subjected to a static stretch with a computerized strain unit. Immunocytochemistry was used to define smooth muscle cell phenotype, and c-fos expression levels were assessed by Northern blotting.


RESULTS
Myometrial smooth muscle cells maintained their phenotype for at least 7 days in culture. Stretch induced a dramatic increase in levels of c-fos messenger RNA, which peaked after 30 minutes. Stimulation of c-fos gene expression was dependent on the degree of stretch (maximum induction at 25% elongation). Interestingly, as little as 1 minute of stretch was sufficient to induce maximal c-fos expression at 30 minutes. The most dramatic induction of c-fos was observed in smooth muscle cells that were stretched on collagen I-coated plates.


CONCLUSIONS
Myometrial smooth muscle cells can directly respond to mechanical stretch with a strength- and matrix component-dependent increase in c-fos messenger RNA. The time delay between the initial stimulus and the cumulative elevation of c-fos messenger RNA suggests a complex regulation from mechanoreception to c-fos gene expression.
Shynlova
Oksana P
OP
Program in Development and Fetal Health, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
Oldenhof
Alexandra D
AD
Liu
Mingyao
M
Langille
Lowell
L
Lye
Stephen J
SJ
D000818:Animals; D002478:Cells, Cultured; D003094:Collagen / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects; D066298:In Vitro Techniques; D009130:Muscle, Smooth / Q000166:cytology / Q000502:physiology*; D009215:Myometrium / Q000166:cytology / Q000502:physiology*; D010641:Phenotype; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013314:Stress, Mechanical; D013997:Time Factors
D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D003094:Collagen