title: Temporal expression of Pelp1 during proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells.
abstract: BACKGROUND
  Osteogenic induction and bone formation are heavily affected by environmental factors, including estrogen, estrogen receptors, and coregulatory proteins, such as the recently reported proline-, glutamic acid-, and leucine-rich protein 1(Pelp1).
  
  
  OBJECTIVE
  To investigate Pelp1 expression in rat bone mesenchymal stem cells (rBMSCs) during cell proliferation and osteogenic differentiation.
  
  
  METHODS
  rBMSCs were cultured in routine and osteogenic differentiation media. Cell proliferation was assessed at days 1, 3, 5, 7, 9, 11, 14, and 21. Pelp1 protein expression in the nucleus and cytoplasm were detected by immunocytochemical analysis. Real-time RT-PCR and western blot were used to detect mRNA and protein expressions of Pelp1, osteocalcin (OCN), and alkaline phosphatase (ALP).
  
  
  RESULTS
  Over 21 days, rBMSCs in routine culture exhibited a 1-2 day lag phase and exponential growth from day 3 to 9, plateauing at day 9, and correlated with temporal mRNA expression of Pelp1, which almost reached baseline levels at day 21. In osteogenic induction cultures, Pelp1 mRNA levels rose at day 9 and steadily increased until day 21, reaching 6.8-fold greater value compared with day 1. Interestingly, Pelp1 mRNA expression in osteogenic cultures exhibited a trend similar to that of OCN expression. Pelp1 knockdown by siRNA transfection inhibited undifferentiated rBMSC proliferation, and bone markers OCN and ALP expressions in rBMSCs cultured in routine and osteogenic differentiation media.
  
  
  CONCLUSIONS
  Pelp1 may be a key player in BMSCs proliferation and osteogenic differentiation, meriting further consideration as a target for development of therapies for pathological bone loss conditions, such as menopausal bone loss.
authors.affiliation: Department of Orthodontics, College of Stomatology, Forth Military Medical University, Xin Cheng District, Xi'an, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Zhu
authors.initials: Z
authors.lastname: Qiang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhu
authors.forename: Shujun
authors.initials: S
authors.lastname: Song
authors.forename: Liang
authors.initials: L
authors.lastname: Shi
authors.forename: Chuanchuan
authors.initials: C
authors.lastname: Ma
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Tan
authors.forename: Ding
authors.initials: D
authors.lastname: Yin
authors.forename: Yin
authors.initials: Y
authors.lastname: Ding
authors.forename: Zhongying
authors.initials: Z
authors.lastname: Niu
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism*; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D010012:Osteogenesis / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; C506485:PELP1 protein, rat; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D015675:Osteocalcin; D000469:Alkaline Phosphatase