title: [The effect of mannose-6-phosphate on adipocyte differentiation and its underlying molecular mechanism].
abstract: OBJECTIVE
  Cathepsin K (CTSK) played an important role in adipocyte differentiation. The activation of CTSK needs to convey by mannose-6-phosphate receptors (M6PR) in osteoclasts. The aim of the present study was to identify the effects of mannose-6-phosphate (M6P) in adipocyte differentiation and its underlying molecular mechanism.
  
  
  METHODS
  Oil red O staining, accumulation of cytoplasmic triglycerides and glycerine release were used to assess its effects on adipocyte differentiation in the 3T3-L1 cell line. The enzyme activity of CTSK was observed by laser confocal microscopy. The proliferation of 3T3-L1 preadipocytes was detected by MTT methods. mRNA expression of M6PR was determined by RT-PCR.
  
  
  RESULTS
  M6P could prevent adipocyte differentiation in a dose-dependent manner as evidenced by absence of triglyceride accumulation and glycerol content. Statistical significance was showed when the concentrations of M6P were 5.0 mmol/L and 8.0 mmol/L respectively (P < 0.05). The mRNA expression of M6PR was detected during the whole process of adipocyte differentiation. With the increase of M6P concentration, enzyme activity of CTSK was inhibited in a concentration-dependent manner. MTT method showed that the absorbance at 570 nm of 3T3-L1 preadipocytes was 0.057 ± 0.091, increased about 62.9% at 10.0 mmol/L compared with the control group (P < 0.05).
  
  
  CONCLUSIONS
  M6P inhibits the terminal differentiation of adipocyte, which may be associated with its effect of blocking CTSK activity by competitive binding with M6PR.
authors.affiliation: Shanghai Institute of Endocrine and Metabolic Disease, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China.
authors.forename: Jun-feng
authors.initials: JF
authors.lastname: Han
authors.forename: Yan-yun
authors.initials: YY
authors.lastname: Gu
authors.forename: Guo
authors.initials: G
authors.lastname: Li
authors.forename: Wei-ping
authors.initials: WP
authors.lastname: Jia
authors.forename: Min
authors.initials: M
authors.lastname: Luo
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D056657:Cathepsin K / Q000378:metabolism*; D002454:Cell Differentiation; D008360:Mannosephosphates / Q000096:biosynthesis*; D051379:Mice
chemical_list: D008360:Mannosephosphates; C027693:mannose-6-phosphate; D056657:Cathepsin K