Abstract 438: Global Gene Expression Analysis of Human Perivascular Adipocytes Reveals Reduced Expression of Insulin and Wnt Signaling Genes: Implications for Inflammatory Crosstalk

Abstract

Inflammatory crosstalk between PV adipose tissue and the blood vessel wall has been proposed to contribute to the pathogenesis of atherosclerosis. We reported that PV adipocytes exhibit a pro-inflammatory phenotype, reduced state of differentiation, and altered expression of developmental genes as compared with subcutaneous (SQ) adipocytes derived from the same human subjects. To define global differences in gene expression patterns between PV and SQ adipocytes, genome-wide microarray studies were performed in three sets of in vitro differentiated SQ and PV adipocytes derived from unrelated human subjects. Insulin-regulated and Wnt signaling genes were markedly down-regulated in PV adipocytes. Validation of microarray data by qPCR demonstrated reductions in expression of C/EBPα, PPARγ, FABP4, adiponectin, lipoprotein lipase, hormone sensitive lipase and perilipin in PV compared to SQ adipocytes. We further observed that insulin-induced Akt ser-473 phosphorylation and glucose uptake were markedly reduced (∼ 3 fold and 4 fold, respectively) in differentiated PV adipocytes compared to SQ adipocytes. The mRNA levels of insulin and insulin-like growth factor receptors, however, were similar in adipocytes differentiated from these two depots. Regarding the Wnt pathway, PV adipocytes exhibited dramatically elevated expression of Wnt inhibitor DKK1 (2864%) and reduced expression of Wnt 5A (50%), FDZ4 (38%), and LRP5 (38%). Further evaluation revealed that these Wnt signaling pathway genes, like those of the insulin signaling pathway, correlated with the extent of adipogenic differentiation. We propose that dysregulation of Wnt 5A/FDZ4 and insulin signaling pathways contributes to impaired adipogenic differentiation and insulin resistance in PV adipocytes. This, in turn, may contribute to heightened inflammatory crosstalk between PV adipose tissue and the vascular wall in the setting of atherosclerosis.