title: Tissue-specific DNA methylation profiles regulate liver-specific expression of the APOA1/C3/A4/A5 cluster and can be manipulated with demethylating agents on intestinal cells.
abstract: OBJECTIVE
  The tissue-specific expression profiles of genes within the APOA1/C3/A4/A5 cluster play an important role in lipid metabolism regulation. We hypothesize that the tissue-specific expression of the APOA1/C3/A4/A5 gene cluster will show an inverse pattern with DNA methylation, and that repression in non- or low-expressing tissue, such as the intestine, can be reversed using epigenetic drugs.
  
  
  RESULTS
  We analyzed DNA samples from different human adult tissues (liver, intestine, leukocytes, brain, kidney, pancreas, muscle and sperm) using the Infinium HumanMethyation450 BeadChip array. DNA methylation profiles in APOA1/C3/A4/A5 gene cluster were confirmed by bisulfite PCR and pyrosequencing. To determine whether the observed tissue-specific methylation was associated with the expression profile we exposed intestinal TC7/Caco-2 cells to the demethylating agent 5-Aza-2'-deoxycytidine and monitored intestinal APOA1/C3/A4/A5 transcript re-expression by RT-qPCR. The promoters of APOA1, APOC3 and APOA5 genes were less methylated in liver compared to other tissues, and APOA4 gene was highly methylated in most tissues and partially methylated in liver and intestine. In TC7/Caco-2 cells, 5-Aza-2'-deoxycytidine treatment induced a decrease between 37 and 24% in the methylation levels of APOA1/C3/A4/A5 genes and a concomitant re-expression mainly in APOA1, APOA4 and APOA5 genes ranging from 22 to 600%.
  
  
  CONCLUSIONS
  We have determined the methylation patterns of the APOA1/C3/A4/A5 cluster that may be directly involved in the transcriptional regulation of this cluster. DNA demethylation of intestinal cells increases the RNA levels especially of APOA1, APOA4 and APOA5 genes.
authors.affiliation: Unitat de Recerca en Lípids i Arteriosclerosi, Universitat Rovira i Virgili, IISPV, CIBERDEM, Spain. Electronic address: montse.guardiola@urv.cat.
authors.forename: Montse
authors.initials: M
authors.lastname: Guardiola
authors.affiliation: Unitat de Recerca en Lípids i Arteriosclerosi, Universitat Rovira i Virgili, IISPV, CIBERDEM, Spain. Electronic address: iris.oliva@urv.cat.
authors.forename: Iris
authors.initials: I
authors.lastname: Oliva
authors.affiliation: Imprinting and Cancer Group, Epigenetics and Cancer Biology Program (PEBC), Bellvitge Institute for Biomedical Research (IDIBELL), Barcelona, Spain. Electronic address: aguillaumet@idibell.cat.
authors.forename: Amy
authors.initials: A
authors.lastname: Guillaumet
authors.affiliation: Imprinting and Cancer Group, Epigenetics and Cancer Biology Program (PEBC), Bellvitge Institute for Biomedical Research (IDIBELL), Barcelona, Spain. Electronic address: amartint@idibell.cat.
authors.forename: Álex
authors.initials: Á
authors.lastname: Martín-Trujillo
authors.affiliation: Unitat de Recerca en Lípids i Arteriosclerosi, Universitat Rovira i Virgili, IISPV, CIBERDEM, Spain. Electronic address: roser.rosales@urv.cat.
authors.forename: Roser
authors.initials: R
authors.lastname: Rosales
authors.affiliation: Unitat de Recerca en Lípids i Arteriosclerosi, Universitat Rovira i Virgili, IISPV, CIBERDEM, Spain. Electronic address: jc.vallve@urv.cat.
authors.forename: Joan Carles
authors.initials: JC
authors.lastname: Vallvé
authors.affiliation: Unitat de Recerca en Cirurgia, Universitat Rovira i Virgili, IISPV, Spain. Electronic address: fatima.sabench@urv.cat.
authors.forename: Fàtima
authors.initials: F
authors.lastname: Sabench
authors.affiliation: Unitat de Recerca en Cirurgia, Universitat Rovira i Virgili, IISPV, Spain. Electronic address: danieldel.castillo@urv.cat.
authors.forename: Daniel
authors.initials: D
authors.lastname: Del Castillo
authors.affiliation: Cancer Epigenetics Group, Epigenetics and Cancer Biology Program (PEBC), Bellvitge Institute for Biomedical Research (IDIBELL), Barcelona, Spain; Department of Medical Sciences, Division of Health Sciences, León Campus, University of Guanajuato, Mexico. Electronic address: szaina@ugto.mx.
authors.forename: Silvio
authors.initials: S
authors.lastname: Zaina
authors.affiliation: Imprinting and Cancer Group, Epigenetics and Cancer Biology Program (PEBC), Bellvitge Institute for Biomedical Research (IDIBELL), Barcelona, Spain. Electronic address: dmonk@idibell.cat.
authors.forename: David
authors.initials: D
authors.lastname: Monk
authors.affiliation: Unitat de Recerca en Lípids i Arteriosclerosi, Universitat Rovira i Virgili, IISPV, CIBERDEM, Spain. Electronic address: josep.ribalta@urv.cat.
authors.forename: Josep
authors.initials: J
authors.lastname: Ribalta
mesh_terms: D016632:Apolipoprotein A-I / Q000235:genetics*; D000072040:Apolipoprotein A-V; D053305:Apolipoprotein C-III / Q000235:genetics*; D001054:Apolipoproteins A / Q000235:genetics*; D001706:Biopsy; D001921:Brain / Q000378:metabolism; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D019175:DNA Methylation; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D005810:Multigene Family; D009132:Muscles / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010179:Pancreas / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism
chemical_list: C505693:APOA1 protein, human; C437704:APOA5 protein, human; D016632:Apolipoprotein A-I; D000072040:Apolipoprotein A-V; D053305:Apolipoprotein C-III; D001054:Apolipoproteins A; C022205:apolipoprotein A-IV
keywords: Apolipoproteins; Gene expression; Genetics; Intestine; Lipoproteins/metabolism