Interaction of wingless protein (Wnt), transforming growth factor-beta1, and hyaluronan production in fetal and postnatal fibroblasts.
BACKGROUND
Mammalian fetal skin injury heals scarlessly. The intrinsic differences between embryonic and adult fibroblasts that underlie this observation are poorly understood. Several studies have linked Wnt proteins with skin morphogenesis. The authors' study aimed to establish a correlation between beta-catenin-dependent (canonical) Wnt protein, transforming growth factor (TGF)-beta1, and the expression of hyaluronan synthesis enzymes during scarless versus scarring wound healing.


METHODS
Wnt signaling was quantified after 1.5-mm skin wounds were created in BAT-gal fetal (e16.5) and postnatal (p1) mice. Canonical Wnt signals were localized by X-gal staining and quantified with quantitative real-time polymerase chain reaction. Primary embryonic and postnatal mouse dermal fibroblasts were treated with recombinant Wnt3a or TGF-beta1. Proliferation was assayed by bromodeoxyuridine incorporation. Gene expression of enzymes that regulate hyaluronan production and turnover was examined by quantitative real-time polymerase chain reaction (hyaluronan synthases or HAS1-3, hyaluronadase-2), as well as other target genes for Wnt and TGF-beta (Axin2, TGF-beta1, TGF-beta3, type 1 collagen, proliferating cell nuclear antigen).


RESULTS
Canonical Wnt signaling increased following wounding in postnatal, but not fetal, mice. In vitro, rmWnt3a increased postnatal fibroblast proliferation but not in embryonic cells. Both Wnt3a and TGF-beta1 induced HAS2 and HAS3 gene expression in embryonic fibroblasts, while HAS1 and Hyal2 were induced in postnatal fibroblasts. Finally, rmWnt3a significantly increased type I collagen expression, particularly in postnatal fibroblasts, and influenced expression of TGF-beta isoforms.


CONCLUSIONS
Increased canonical Wnt signaling occurs during postnatal but not fetal cutaneous wound repair. Fetal and postnatal fibroblasts have a disparate response to rmWnt3a in vitro. rmWnt3a affects postnatal fibroblasts in a similar fashion to rhTGF-beta1, a known profibrotic cytokine.
Carre
Antoine L
AL
Stanford, Calif. From the Hagey Laboratory for Pediatric Regenerative Medicine, Department of Surgery, Stanford University School of Medicine.
James
Aaron W
AW
MacLeod
Liam
L
Kong
Wuyi
W
Kawai
Kenichiro
K
Longaker
Michael T
MT
Lorenz
H Peter
HP
D000818:Animals; D001973:Bromodeoxyuridine / Q000494:pharmacology; D005333:Fetus / Q000166:cytology*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D014453:Glucuronosyltransferase / Q000378:metabolism; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D015398:Signal Transduction / Q000502:physiology; D053773:Transforming Growth Factor beta1; D051153:Wnt Proteins / Q000378:metabolism*; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D060528:Wnt4 Protein; D014945:Wound Healing / Q000502:physiology*
D053773:Transforming Growth Factor beta1; D051153:Wnt Proteins; D060508:Wnt3 Protein; D060509:Wnt3A Protein; C555511:Wnt3a protein, mouse; D060528:Wnt4 Protein; C555582:Wnt4 protein, mouse; D006820:Hyaluronic Acid; D014453:Glucuronosyltransferase; D000076002:Hyaluronan Synthases; D001973:Bromodeoxyuridine