title: cis-9, trans-11, trans-13-Conjugated linolenic acid induces apoptosis and sustained ERK phosphorylation in 3T3-L1 preadipocytes.
abstract: OBJECTIVE
  The aim of this study was to investigate the adipogenic effect of cis-9, trans-11, trans-13-conjugated linolenic acid (c9,t11,t13-CLN), a fatty acid naturally present in bitter melon.
  
  
  METHODS
  The 3T3-L1 murine preadipocyte cell line was used to test the effect of saponifiables from whole bitter melon and of commercially prepared pure c9,t11,t13-CLN on adipocyte differentiation. The effect of c9,t11,t13-CLN on 3T3-L1 cell viability was also tested at proliferation, mitotic clonal expansion, and terminal differentiation stages.
  
  
  RESULTS
  Compared to the free fatty acid control mixture, the proadipogenic effect on 3T3-L1 was less potent using saponifiables obtained from bitter melon. C9,t11,t13-CLN, unlike its non-conjugated counterpart linolenic acid (LN) or other common fatty acids such as oleic acid or linoleic acid, exerted no proadipogenic effect on 3T3-L1. In contrast to LN displaying no cytotoxic effect at a concentration ≤100 μM, c9,t11,t13-CLN caused a dose-dependent reduction in the viability of pre- and postconfluent preadipocytes associated with apoptosis. Sustained ERK/MAPK activation, accompanied by increased peroxisome proliferator-activated receptor γ phosphorylation, was seen in c9,t11,t13-CLN-treated cells at initiation of differentiation.
  
  
  CONCLUSIONS
  C9,t11,t13-CLN is less adipogenic for 3T3-L1 cells than LN and this is partly due to its apoptotic effect on proliferating preadipocytes and to the sustained ERK phosphorylation seen during mitotic clonal expansion.
authors.affiliation: Institute of Microbiology and Biochemistry, College of Life Science, National Taiwan University, Taipei, Taiwan.
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Chou
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Su
authors.forename: Tzu-Wen
authors.initials: TW
authors.lastname: Lai
authors.forename: Jong-Ho
authors.initials: JH
authors.lastname: Chyuan
authors.forename: Pei-Min
authors.initials: PM
authors.lastname: Chao
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000201:enzymology / Q000502:physiology*; D050156:Adipogenesis; D000818:Animals; D019440:Anti-Obesity Agents / Q000378:metabolism*; D017209:Apoptosis; D049109:Cell Proliferation; D002470:Cell Survival; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005638:Fruit / Q000737:chemistry; D005786:Gene Expression Regulation; D008042:Linolenic Acids / Q000378:metabolism*; D051379:Mice; D029777:Momordica charantia / Q000737:chemistry; D009994:Osmolar Concentration; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000378:metabolism; D014280:Triglycerides / Q000096:biosynthesis
chemical_list: D019440:Anti-Obesity Agents; D008042:Linolenic Acids; D047495:PPAR gamma; D012333:RNA, Messenger; D014280:Triglycerides; C004934:eleostearic acid; D048049:Extracellular Signal-Regulated MAP Kinases