title: Interactive effects of fatty acid and butyrate-induced mitochondrial Ca²⁺ loading and apoptosis in colonocytes.
abstract: BACKGROUND
  The combination of fish oil-derived docosahexaenoic acid (DHA) (22:6; omega 3 [n-3]) and butyrate (4:0), a fiber fermentation product, synergized to enhance colonocyte apoptosis by inducing a p53-independent, oxidation sensitive, mitochondrial Ca(2+) -dependent (intrinsic) pathway.
  
  
  METHODS
  In this study, the authors probed the specificity of n-6 and n-3 polyunsaturated fatty acid induction of Ca(2+) -dependent proapoptotic events in immortalized young adult mouse colonocytes and determined whether combinations of polyunsaturated fatty acid and butyrate could trigger endoplasmic reticulum (ER) stress conditions, thereby promoting mitochondrial Ca(2+) overload. Cultures were treated with 0 μM to 50 μM of DHA (22:6; n-3), EPA (20:5; n-3), arachidoinic acid (AA) (20:4; n-6), linoleic acid (18:2; n-6), or oleic acid (OA) (18:1; n-9) for a total of 72 hours with or without RU-360 (to inhibit the mitochondrial Ca(2+) uniporter) for 30 minutes before cotreatment with butyrate (0 mM or 5 mM).
  
  
  RESULTS
  Combined DHA and butyrate maximally induced apoptosis and mitochondrial-to-cytosolic Ca(2+) levels. By comparison, EPA, a precursor to DHA, was minimally effective. Similarly, AA and OA in combination with butyrate had no effect on mitochondrial Ca(2+) or apoptosis compared with butyrate alone. DHA with or without butyrate cotreatment minimally altered the ER stress-regulated genes DNA damage-inducible transcript 3, the CCAAT enhancer binding protein (C/EBP) homologous protein (CHOP), and eukaryotic initiation factor 2α.
  
  
  CONCLUSIONS
  The current data indicated that butyrate and DHA, but not EPA, worked in a coordinated fashion to trigger an ER-independent, Ca(2+) -dependent, intrinsic mitochondrial-mediated apoptotic pathway in colonocytes.
authors.affiliation: Program in Integrative Nutrition and Complex Diseases, Texas A&M University, College Station, Texas, USA.
authors.forename: Satya
authors.initials: S
authors.lastname: Kolar
authors.forename: Rola
authors.initials: R
authors.lastname: Barhoumi
authors.forename: Chris K
authors.initials: CK
authors.lastname: Jones
authors.forename: Joshua
authors.initials: J
authors.lastname: Wesley
authors.forename: Joanne R
authors.initials: JR
authors.lastname: Lupton
authors.forename: Yang-Yi
authors.initials: YY
authors.lastname: Fan
authors.forename: Robert S
authors.initials: RS
authors.lastname: Chapkin
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002087:Butyrates / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003106:Colon / Q000166:cytology / Q000187:drug effects*; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D017975:Ruthenium Compounds / Q000494:pharmacology
chemical_list: D002087:Butyrates; D015525:Fatty Acids, Omega-3; D005231:Fatty Acids, Unsaturated; C112020:Ru 360; D017975:Ruthenium Compounds; D002118:Calcium