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Journal of Lipid Research, Vol. 49, 308-323, February 2008
Copyright © 2008 by American Society for Biochemistry and Molecular Biology





* Experimental Medicine, McGill University Health Centre, Montreal, Canada
Centre de Recherche Hôpital Laval, Laval University, Quebec, Canada
The online version of this article (available at http://www.jlr.org) contains supplementary data in the form of two tables.
Published, JLR Papers in Press, November 6, 2007.
1 To whom correspondence should be addressed. e-mail: katherine.cianflone{at}crhl.ulaval.ca
Obesity and insulin resistance are independent risk factors for metabolic syndrome, diabetes, and cardiovascular disease. Adipose tissue samples from nonobese (NO), insulin-sensitive obese (ISO), and insulin-resistant obese (IRO) subjects from subcutaneous (SC) and omental (OM) adipose tissue (n = 28) were analyzed by microarray and confirmed by real-time PCR. Insulin signaling gene expression changes were greater in OM than in SC tissue and were related to insulin resistance rather than to obesity; few genes correlated with body mass index. Insulin receptor and insulin receptor substrate 1 (IRS-1) increased in the IRO versus pooled insulin-sensitive (NO+ISO) subjects. In glucose transport, PI3K
and PDK2 decreased in IRO subjects, whereas PI3K
, Akt2, GLUT4, and GLUT1 increased. IRS-1 regulators Jnk and IKK increased in IRO (P < 0.01 and P < 0.001 respectively). In protein synthesis, most genes examined were downregulated in IRO subjects, including mTor, Rheb, and 4EBP and eIF members (all P < 0.05). In proliferation, SHC, SOS, and Raf1 (P < 0.05) were increased, whereas Ras and MEK1/2 kinase 1 (P < 0.05) were decreased, in IRO subjects. Finally, in differentiation, PPAR
, CEBP
, and CEBPβ decreased, whereas PPAR
, CEBP
, and CEBP
increased, in IRO subjects (P < 0.05). Together, microarray and real-time PCR data demonstrate that insulin resistance rather than obesity is associated with altered gene expression of insulin signaling genes, especially in OM adipose tissue.
Supplementary key words differentiation glucose proliferation protein synthesis insulin-sensitive obese insulin-resistant obese
Abbreviations: BMI, body mass index; cRNA, complimentary RNA; FDR, false discovery rate; HOMA-IR, homeostasis model assessment insulin resistance; InsR, insulin receptor; IRO, insulin-resistant obese; IRS-1, insulin receptor substrate 1; ISO, insulin-sensitive obese; NIDDM, non-insulin-dependent diabetes mellitus; NO, nonobese; OM, omental; SAM, Significant Analysis of Microarrays; SC, subcutaneous
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