title: Omega-3 fatty acids induce Ca(2+) mobilization responses in human colon epithelial cell lines endogenously expressing FFA4.
abstract: OBJECTIVE
  Free fatty acid receptor 4 (FFA4; formerly known as GPR120) is the G protein-coupled receptor (GPCR) for omega-3 polyunsaturated fatty acids. FFA4 has been found to express in the small intestines and colons of mice and humans. In this study we investigate the effects of omega-3 polyunsaturated fatty acids on FFA4 in human colon epithelial cells in vitro.
  
  
  METHODS
  HCT116 and HT-29 human colon epithelial cell lines endogenously expressing FFA4 were used. Intracellular Ca(2+) concentration ([Ca(2+)]i) was measured in fura 2-AM-loaded cells with fluorescence spectrophotometry. RT-PCR and immunohistochemistry were used to detect FFA4.
  
  
  RESULTS
  Ten to 100 μmol/L of omega-3 polyunsaturated fatty acids α-linolenic acid (αLA) or eicosapentaenoic acid (EPA) induced dose-dependent [Ca(2+)]i increase in HCT116 and HT-29 cells, whereas docosahexaenoic acid (DHA) had no effect. In addition, the omega-6 fatty acids linoleic acid and γ-linoleic acid also dose-dependently increase [Ca(2+)]i, but the mono-unsaturated fatty acid oleic acid and saturated fatty acids such as stearic acid and palmitic acid had no effect. In HCT116 and HT-29 cells, the αLA-induced [Ca(2+)]i increase was partially inhibited by pretreatment with EGTA, phospholipase C inhibitor edelfosine, cADPR inhibitors 8-bro-cADPR or DAB, and abolished by pretreatment with Ca(2+)ATPase inhibitor thapsigargin, but was not affected by Gi/o protein inhibitor PTX or IP3R inhibitor 2-APB.
  
  
  CONCLUSIONS
  Omega-3 and omega-6 long-chain polyunsaturated fatty acids (C18-20) induce Ca(2+) mobilization responses in human colonic epithelial cells in vitro through activation of FFA4 and PTX-insensitive Gi/o protein, followed by Ca(2+) release from thapsigargin-sensitive Ca(2+) stores and Ca(2+) influx across the plasma membrane.
authors.affiliation: Molecular Inflammation Research Center for Aging Intervention (MRCA) and College of Pharmacy, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Jung-min
authors.initials: JM
authors.lastname: Kim
authors.affiliation: Molecular Inflammation Research Center for Aging Intervention (MRCA) and College of Pharmacy, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Kyoung-pil
authors.initials: KP
authors.lastname: Lee
authors.affiliation: Molecular Inflammation Research Center for Aging Intervention (MRCA) and College of Pharmacy, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Soo-jin
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Molecular Inflammation Research Center for Aging Intervention (MRCA) and College of Pharmacy, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Saeromi
authors.initials: S
authors.lastname: Kang
authors.affiliation: Molecular Inflammation Research Center for Aging Intervention (MRCA) and College of Pharmacy, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Jin
authors.initials: J
authors.lastname: Huang
authors.affiliation: Molecular Inflammation Research Center for Aging Intervention (MRCA) and College of Pharmacy, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Jung-min
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Sato
authors.affiliation: Molecular Inflammation Research Center for Aging Intervention (MRCA) and College of Pharmacy, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Hae-young
authors.initials: HY
authors.lastname: Chung
authors.affiliation: Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan.
authors.forename: Fumikazu
authors.initials: F
authors.lastname: Okajima
authors.affiliation: Molecular Inflammation Research Center for Aging Intervention (MRCA) and College of Pharmacy, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Dong-soon
authors.initials: DS
authors.lastname: Im
mesh_terms: D002118:Calcium / Q000378:metabolism*; D003106:Colon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology*; D005786:Gene Expression Regulation; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D043562:Receptors, G-Protein-Coupled / Q000096:biosynthesis*
chemical_list: C519853:FFAR4 protein, human; D015525:Fatty Acids, Omega-3; D043562:Receptors, G-Protein-Coupled; D002118:Calcium