title: A microarray search for genes predominantly expressed in human omental adipocytes: adipose tissue as a major production site of serum amyloid A.
abstract: To identify genes predominantly expressed in omental adipocytes, microarray expression profiles from 33 human tissues or cell types were analyzed, using an algorithm developed for identification of transcripts predominantly expressed in a certain tissue. Both known adipocyte-specific and more unexpected genes were among the 28 genes identified. To validate the approach, adipocyte expression of three of these genes, acute-phase serum amyloid A (A-SAA), aquaporin 7, and transport secretion protein-2.2, was compared with 17 other human tissues by real-time PCR. The unexpectedly high expression of A-SAA in adipocytes was further verified by Northern blot and immunohistochemistry. The liver, reported to be the main production site for A-SAA, displayed the second highest expression using microarray and real-time PCR. In obese subjects, adipose tissue mRNA and serum A-SAA levels were down-regulated during an 18-wk diet regime (P < 0.05 and P < 0.0001, respectively). A-SAA serum levels were highly correlated to adipose tissue mRNA levels (P < 0.001) and to the total (P < 0.0001) and sc (P < 0.0001) adipose tissue areas, as analyzed by computed tomography. We show that adipose tissue is a major expression site of A-SAA during the nonacute-phase reaction condition. This provides a direct link between adipose tissue mass and a marker for low-grade inflammation and cardiovascular risk.
authors.affiliation: Research Centre for Endocrinology and Metabolism, Vita Stråket 12, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden. kajsa.sjoholm@medic.gu.se
authors.forename: Kajsa
authors.initials: K
authors.lastname: Sjöholm
authors.forename: Jenny
authors.initials: J
authors.lastname: Palming
authors.forename: Louise E
authors.initials: LE
authors.lastname: Olofsson
authors.forename: Anders
authors.initials: A
authors.lastname: Gummesson
authors.forename: Per-Arne
authors.initials: PA
authors.lastname: Svensson
authors.forename: Theodore C
authors.initials: TC
authors.lastname: Lystig
authors.forename: Eva
authors.initials: E
authors.lastname: Jennische
authors.forename: John
authors.initials: J
authors.lastname: Brandberg
authors.forename: Jarl S
authors.initials: JS
authors.lastname: Torgerson
authors.forename: Björn
authors.initials: B
authors.lastname: Carlsson
authors.forename: Lena M S
authors.initials: LM
authors.lastname: Carlsson
mesh_terms: D017667:Adipocytes / Q000378:metabolism*; D000273:Adipose Tissue / Q000378:metabolism*; D001823:Body Composition; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008075:Lipoproteins, HDL / Q000097:blood; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D009852:Omentum; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000685:Serum Amyloid A Protein / Q000096:biosynthesis* / Q000235:genetics; D015431:Weight Loss
chemical_list: D008075:Lipoproteins, HDL; D012333:RNA, Messenger; D000685:Serum Amyloid A Protein