title: [Effects of PTHrP and Notch signaling on the proliferation of epiphysis stem cells].
abstract: OBJECTIVE
  To study the regulation of the proliferation of epiphysis stem cells by the PTHrP (parathyroid hormone related peptide) and Notch signaling systems.
  
  
  METHODS
  An organ culture system of femurs of SD rat in 24 h after birth was employed. PTHrP (1 - 34) was used as the activator of the PTHrP signaling pathway and PTHrP (7 - 34) as the antagonist of PTH (parathyroid hormone)-receptor. For Notch signaling system, Jagged1/Fc was used as the activator and DAPT as its inhibitor. The femurs were cultured in DMEM (Dulbecco's modified Eagle's medium)/F12 medium while phosphate buffered saline was used for the control groups. Hematoxylin and eosin staining and bromodeoxyuridine analysis were used to analyze the length of the epiphysis stem cells zone and the proliferation of epiphysis stem cells. The expression of NICD (Notch intra-cellular domain) and Jagged1 were analyzed by immunohistochemistry. The epiphysis stem cells were transfected with the lentiviral vectors with rat PTHrP gene overexpression or inhibition properties, the cells transfected with the PGC-GFP-lentivirus or NC-GFP-lentivirus were used as control. Western blot was employed to detect the expression of NICD and Jagged1 genes.
  
  
  RESULTS
  PTHrP (1 - 34) and Jagged1/Fc could dramatically elevate the rate of epiphysis stem cells zone by the whole growth plate length measurement while PTHrP (7 - 34) and DAPT could decrease the rate. Brdu analysis also showed that the number of proliferative epiphysis stem cells could be up-regulated by the PTHrP (1 - 34) or Jagged1/Fc signaling. By contrast, the treatment with PTHrP (7 - 34) or DAPT reduced the number of proliferative epiphysis stem cells. Immunohistochemistry and Western blot showed a significantly elevated expression of NICD and Jagged1 when PTHrP signaling was activated while a reductive expression of NICD and Jagged1 when PTHrP signaling was inactivated.
  
  
  CONCLUSIONS
  Both of PTHrP and Notch signaling system could promote the proliferation of epiphysis stem cells. And the PTHrP signaling can stimulate Notch signaling to promote the proliferation of epiphysis stem cells.
authors.affiliation: Department of Orthopedics, Xiamen University, Xiamen, China.
authors.forename: Fei-tai
authors.initials: FT
authors.lastname: Lin
authors.forename: Chun
authors.initials: C
authors.lastname: Xia
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Jia-gu
authors.initials: JG
authors.lastname: Huang
authors.forename: Xin-peng
authors.initials: XP
authors.lastname: Zheng
authors.forename: Ting-ting
authors.initials: TT
authors.lastname: Yi
authors.forename: Hong-hai
authors.initials: HH
authors.lastname: Zhao
authors.forename: Yi-bei
authors.initials: YB
authors.lastname: Zhang
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D004838:Epiphyses / Q000166:cytology*; D044162:Parathyroid Hormone-Related Protein / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction; D013234:Stem Cells / Q000378:metabolism*
chemical_list: D044162:Parathyroid Hormone-Related Protein; D051880:Receptors, Notch