title: Effect of age and hypoxia on TGFbeta1 receptor expression and signal transduction in human dermal fibroblasts: impact on cell migration.
abstract: Wound healing is critically affected by age, ischemia, and growth factors such as TGFbeta1. The combined effect of these factors on fibroblast migration, an essential component of wound healing, is poorly understood. To address this deficiency, we examined expression of TGFbeta receptor type I and II (TGFbetaRI and RII) under normoxia or hypoxia (1% O(2)) in cultured human dermal fibroblasts (HDFs) from young (ages 24-33) and aged (ages 61-73) adults. TGFbetaRI and RII expression was similar in both groups under normoxia. Hypoxia did not alter receptor levels in young HDFs but significantly decreased TGFbetaRI in aged cells (12 and 43%, respectively). Additionally, young cells displayed a 50% increase in activation of p42/p44 mitogen-activated kinase by TGFbeta1 (2-200 pg/ml) under hypoxia while aged cell levels of active p42/p44 decreased up to 24%. To determine functional outcomes of these findings, we measured the migratory capacity of the cells on type I collagen using a gold salt migration assay. Hypoxia increased the migratory index (MI) of young HDFs over normoxia by 30% but had no effect on aged cells. Under normoxia, TGFbeta1 (1-1000 pg/ml) increased young HDF migration in a concentration-dependent manner up to 109% over controls but minimally increased aged HDF migration (37%). Under hypoxia, TGFbeta1 significantly increased young cell MI at all concentrations but was without effect on the aged HDF response. These data demonstrate that aged fibroblasts have an impaired migratory capacity with complete loss of responsiveness to hypoxia and deficits in the migratory and signal transduction responsiveness to TGFbeta1 that may partly explain diminished healing capabilities often observed in aged patients.
authors.affiliation: Wound Healing Research Laboratory, Division of Plastic and Reconstructive Surgery, Northwestern University, Chicago, Illinois 60611, USA.
authors.forename: Jon E
authors.initials: JE
authors.lastname: Mogford
authors.forename: Nabil
authors.initials: N
authors.lastname: Tawil
authors.forename: Alexandria
authors.initials: A
authors.lastname: Chen
authors.forename: David
authors.initials: D
authors.lastname: Gies
authors.forename: Yuping
authors.initials: Y
authors.lastname: Xia
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Mustoe
mesh_terms: D030201:Activin Receptors, Type I / Q000378:metabolism; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D015687:Cell Hypoxia / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D012016:Reference Values; D015398:Signal Transduction / Q000502:physiology*; D012867:Skin / Q000166:cytology*; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000494:pharmacology; D053773:Transforming Growth Factor beta1
chemical_list: D018125:Receptors, Transforming Growth Factor beta; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II