title: [Serine residues at position 63-84 are important for CITED1 nuclear translocation and osteoblast differentiation].
abstract: OBJECTIVE
  To determine the role of serine residues at position 63-84 of CITED1 in the nuclear translocation of CITED1 and osteoblast differentiation.
  
  
  METHODS
  We engineered all the 9 phosphorylated serine residues of CITED1 with a serine-to-alanine mutation at position 63-84. MC3T3E1 cells transfected with pCDNA3-CFP-CITED1 63-84 (9S>A), pCDNA3-CFP-CITED1, and vehicle plasmid were examined with confocal laser scanning microscopy before and after treatment with 100 nmol/L parathyroid hormone [PTH(1-34)] to observe the changes in the intracellular localization of CITED1. The transfected cells were induced for osteoblastic differentiation with mineralized solution in the absence or presence of 10 nmol/L PTH(1-34), and the changes in ALP activity and Ca(2+) concentration were measured; RT-PCR was used to detect the changes in ALP2, RUNX2, and OC gene expressions after the treatments.
  
  
  RESULTS
  s PTH(1-34) promoted the nuclear translocation of CITED1 in MC3T3-E1 cells. The (63-84) 9S>A mutation of CITED1 obviously suppressed its translocation and increased ALP activity and Ca(2+) levels in the cells, which led to enhanced mineralization in the cells with also increased expressions of ALP2, RUNX2, and OC.
  
  
  CONCLUSIONS
  The serine residues at position 63-84 of CITED1 play a vital role in the nuclear translocation of CITED1 and osteoblast differentiation.
authors.affiliation: Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. nflinzhen@163.com
authors.forename: Zhen
authors.initials: Z
authors.lastname: Lin
authors.forename: Liang
authors.initials: L
authors.lastname: Yuan
authors.forename: Yue
authors.initials: Y
authors.lastname: Meng
authors.forename: Ruiqiang
authors.initials: R
authors.lastname: Feng
authors.forename: Zhaozong
authors.initials: Z
authors.lastname: Fu
authors.forename: Dehong
authors.initials: D
authors.lastname: Yang
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology*; D010957:Plasmids; D012694:Serine / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; C102208:Cited1 protein, mouse; D009687:Nuclear Proteins; D015534:Trans-Activators; D012694:Serine