title: Expression of positive and negative regulators of cell cycle during wound healing.
abstract: OBJECTIVE
  To detect the expression of cell cycle positive regulators cyclin D(1), cyclin E, CDK(2), CDK(4) and negative regulators p21(cip1), p27(kip1), p16(ink4a) and p15(ink4b) during wound healing in rats.
  
  
  METHODS
  Open wounds of full-thickness skin, diameter 1.8 cm, on rat backs were used as the wound model. Wound tissues were harvested on postwounding days 3, 5, 7, 9, 11, 14, 21 and 30. Ki67 expression in granulation tissue was detected by immunohistochemical assay. The patterns of the expression of cyclin D(1), cyclin E, CDK(2), CDK(4) and p21(cip1), p27(kip1), p16(ink4a), p15(ink4b) were detected by Western blot.
  
  
  RESULTS
  Cell proliferation in granulation tissue took place predominantly within the first week after injury, with the proliferation peak occurring at postwounding day 5. There were no dramatic variations in the expression of cyclin D(1), CDK(2) and CDK(4) during wound healing. Up-regulated cyclin E was maintained from day 3 to 11 after injury, and then was down-regulated. No expression of p16(ink4a) and p15(ink4b) was found. p21(cip1) was expressed only from day 7 to 14, with peak expression observed on day 9. Constitutive p27(kip1) was expressed throughout wound healing with low levels in the proliferating period of day 3 to 5 and with increased levels in the post-mitotic and remodeling stage. The expression of p21(cip1) and p27(kip1) showed an inverse gradient to that of Ki67.
  
  
  CONCLUSIONS
  p21(cip1) and p27(kip1) play a supervising role in preventing the hyperproliferative tendency in tissue repair.
authors.affiliation: Research Institute of Surgery, the Third Military Medical University, Chongqing 400042, China.
authors.forename: Xudong
authors.initials: X
authors.lastname: Zhu
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Di
authors.forename: Chengxiang
authors.initials: C
authors.lastname: Hu
authors.forename: Zhengguo
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000096:biosynthesis; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D016213:Cyclins / Q000096:biosynthesis*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012867:Skin / Q000166:cytology / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis / Q000502:physiology; D014945:Wound Healing
chemical_list: C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D016213:Cyclins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases