title: Post-transcriptional regulation of alpha-smooth muscle actin determines the contractile phenotype of Dupuytren's nodular cells.
abstract: The objective was to study Dupuytren's myofibroblast cells in constrained collagen matrices in order to more closely emulate their in vivo environment and, to correlate their contractility with alpha-smooth muscle actin (alpha-SMA) expression and determine if dermal fibroblasts regulate Dupuytren's myofibroblast phenotype. Isotonic and isometric force contraction by cells isolated from Dupuytren's nodules, palmar and non-palmar skin fibroblasts was measured in collagen matrices. The effect of co-culturing nodule cells with dermal fibroblasts on isometric contraction was examined. Isometric contraction was correlated with levels of alpha-SMA mRNA by pcr and protein by Western blotting, and alpha-SMA distribution assessed by immunofluorescence. Dupuytren's nodule cells exhibited similar levels of isotonic contraction to both palmar and non-palmar dermal fibroblasts. However, nodule cells generated high levels of isometric force (mean: 3.5 dynes/h), which continued to increase over 24 h to a maximum of 173 dynes. In contrast, dermal fibroblasts initially exhibited low levels of contraction (mean: 0.5 dynes/h) and reached tensional homeostasis on average after 15 h (range: 4-20 h), with a maximum force of 52 dynes. Although all three cell types had similar alpha-SMA mRNA levels, increased levels of alpha-SMA protein were observed in nodule cells compared to dermal fibroblasts. alpha-SMA localised to stress fibres in 35% (range: 26-50%) of nodule cells compared to only 3% (range:0-6%) of dermal fibroblasts. Co-cultures of Dupuytren's cells and dermal fibroblasts showed no contractile differences. The contractile phenotype of Dupuytren's myofibroblasts is determined by increased alpha-SMA protein distributed in stress fibres, not by cellular mRNA levels. Dupuytren's cell contractility is not influenced by dermal fibroblasts.
authors.affiliation: Kennedy Institute of Rheumatology, Imperial College London, London, UK. l.suleman-verjee@imperial.ac.uk
authors.forename: Liaquat Suleman
authors.initials: LS
authors.lastname: Verjee
authors.forename: Kim
authors.initials: K
authors.lastname: Midwood
authors.forename: Dominique
authors.initials: D
authors.lastname: Davidson
authors.forename: Mark
authors.initials: M
authors.lastname: Eastwood
authors.forename: Jagdeep
authors.initials: J
authors.lastname: Nanchahal
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000818:Animals; D002478:Cells, Cultured; D018920:Coculture Techniques; D004387:Dupuytren Contracture / Q000378:metabolism / Q000473:pathology; D005205:Fascia / Q000166:cytology / Q000473:pathology; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D013314:Stress, Mechanical; D014158:Transcription, Genetic; D014159:Transducers
chemical_list: D000199:Actins