A microarray search for genes predominantly expressed in human omental adipocytes: adipose tissue as a major production site of serum amyloid A.
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.
Sjöholm
Kajsa
K
Research Centre for Endocrinology and Metabolism, Vita Stråket 12, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden. kajsa.sjoholm@medic.gu.se
Palming
Jenny
J
Olofsson
Louise E
LE
Gummesson
Anders
A
Svensson
Per-Arne
PA
Lystig
Theodore C
TC
Jennische
Eva
E
Brandberg
John
J
Torgerson
Jarl S
JS
Carlsson
Björn
B
Carlsson
Lena M S
LM
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
D008075:Lipoproteins, HDL; D012333:RNA, Messenger; D000685:Serum Amyloid A Protein