title: Chaperonin containing T-complex polypeptide subunit eta (CCT-eta) is a specific regulator of fibroblast motility and contractility.
abstract: Integumentary wounds in mammalian fetuses heal without scar; this scarless wound healing is intrinsic to fetal tissues and is notable for absence of the contraction seen in postnatal (adult) wounds. The precise molecular signals determining the scarless phenotype remain unclear. We have previously reported that the eta subunit of the chaperonin containing T-complex polypeptide (CCT-eta) is specifically reduced in healing fetal wounds in a rabbit model. In this study, we examine the role of CCT-eta in fibroblast motility and contractility, properties essential to wound healing and scar formation. We demonstrate that CCT-eta (but not CCT-beta) is underexpressed in fetal fibroblasts compared to adult fibroblasts. An in vitro wound healing assay demonstrated that adult fibroblasts showed increased cell migration in response to epidermal growth factor (EGF) and platelet derived growth factor (PDGF) stimulation, whereas fetal fibroblasts were unresponsive. Downregulation of CCT-eta in adult fibroblasts with short inhibitory RNA (siRNA) reduced cellular motility, both basal and growth factor-induced; in contrast, siRNA against CCT-beta had no such effect. Adult fibroblasts were more inherently contractile than fetal fibroblasts by cellular traction force microscopy; this contractility was increased by treatment with EGF and PDGF. CCT-eta siRNA inhibited the PDGF-induction of adult fibroblast contractility, whereas CCT-beta siRNA had no such effect. In each of these instances, the effect of downregulating CCT-eta was to modulate the behavior of adult fibroblasts so as to more closely approximate the characteristics of fetal fibroblasts. We next examined the effect of CCT-eta modulation on alpha-smooth muscle actin (alpha-SMA) expression, a gene product well known to play a critical role in adult wound healing. Fetal fibroblasts were found to constitutively express less alpha-SMA than adult cells. Reduction of CCT-eta with siRNA had minimal effect on cellular beta-actin but markedly decreased alpha-SMA; in contrast, reduction of CCT-beta had minimal effect on either actin isoform. Direct inhibition of alpha-SMA with siRNA reduced both basal and growth factor-induced fibroblast motility. These results indicate that CCT-eta is a specific regulator of fibroblast motility and contractility and may be a key determinant of the scarless wound healing phenotype by means of its specific regulation of alpha-SMA expression.
authors.affiliation: Center for Genomic Sciences, Allegheny-Singer Research Institute, Allegheny General Hospital, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Latha
authors.initials: L
authors.lastname: Satish
authors.forename: Sandra
authors.initials: S
authors.lastname: Johnson
authors.forename: James H-C
authors.initials: JH
authors.lastname: Wang
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Post
authors.forename: Garth D
authors.initials: GD
authors.lastname: Ehrlich
authors.forename: Sandeep
authors.initials: S
authors.lastname: Kathju
mesh_terms: D000367:Age Factors; D000818:Animals; D002465:Cell Movement; D048429:Cell Size; D056404:Chaperonin Containing TCP-1 / Q000032:analysis / Q000096:biosynthesis / Q000502:physiology*; D002921:Cicatrix; D005333:Fetus; D005347:Fibroblasts / Q000737:chemistry / Q000166:cytology*; D005786:Gene Expression Regulation; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology; D021122:Protein Subunits; D034741:RNA, Small Interfering / Q000494:pharmacology; D011817:Rabbits; D014945:Wound Healing
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D021122:Protein Subunits; D034741:RNA, Small Interfering; D056404:Chaperonin Containing TCP-1