title: Live imaging of Smad2/3 signaling in mouse skin wound healing.
abstract: Biophotonics and real-time imaging are novel technologies that can greatly enhance the study of complex biological processes. We applied this technology in a transgenic mouse with a luciferase reporter gene fused to a transforming growth factor-beta (TGF-beta) responsive Smad2/3-binding element to study bioluminescence after skin wounding. Two dorsal midline excisional skin wounds were made using a biopsy punch. One wound was randomized to suture closure and the other allowed to heal by secondary intention (n=8 each wound). Bioluminescence was measured at fixed time points following surgery. Phospho-Smad2/3 immunohistochemistry was performed to localize expression in skin wound samples. In vivo bioluminescence increased following skin wounding. Peak activity occurred on day 17 and was fourfold that of baseline (p<0.05). Subgroup analysis of primary and secondary healing showed that primarily sutured wounds had peak activities earlier than those with secondary healing, although this did not reach statistical significance. Intense phospho-Smad2/3 staining was found in the hair follicles. In vivo bioluminescence tracks Smad2/3-dependent TGF-beta signaling in the in vivo wound healing process. Our findings suggest that signaling increases after wound healing, which contrasts with other studies that show raised TGF-beta signaling in the initial days following wounding.
authors.affiliation: Division of Plastic and Reconstructive Surgery, Stanford University Medical Center, Stanford, California 94305, USA.
authors.forename: Alphonsus K S
authors.initials: AK
authors.lastname: Chong
authors.forename: Thomas
authors.initials: T
authors.lastname: Satterwhite
authors.forename: Hung M
authors.initials: HM
authors.lastname: Pham
authors.forename: Melinda A
authors.initials: MA
authors.lastname: Costa
authors.forename: Jian
authors.initials: J
authors.lastname: Luo
authors.forename: Michael T
authors.initials: MT
authors.lastname: Longaker
authors.forename: Tony
authors.initials: T
authors.lastname: Wyss-Coray
authors.forename: James
authors.initials: J
authors.lastname: Chang
mesh_terms: D000818:Animals; D018859:Hair Follicle / Q000378:metabolism; D007150:Immunohistochemistry; D049449:Luminescence; D008163:Luminescent Measurements; D051379:Mice; D008822:Mice, Transgenic; D015398:Signal Transduction / Q000502:physiology*; D012879:Skin Physiological Phenomena; D051899:Smad2 Protein / Q000502:physiology*; D051900:Smad3 Protein / Q000502:physiology*; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000502:physiology*; D014945:Wound Healing / Q000502:physiology*
chemical_list: D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D016212:Transforming Growth Factor beta