ABSTRACT: Aortic endothelia from mice exposed to dietary model of type II diabetes at 4, 6 and 8 weeks of exposure to Bio-Serv #S3282 diet. Objective: Type II diabetes is associated with endothelial dysfunction, which can contribute to accelerated atherosclerosis and subsequent cardiovascular events. We seek to identify transcripts dysregulated in vivo in response to chronic exposure to high dietary fat that leads to diabetes. Methods: Beginning at 8 weeks of age, male Tie2-GFP mice (transgenically expressing green fluorescent protein exclusively within the endothelia) were fed a 60% fat calorie diet (Bio-Serv #S3282); age-matched mice were fed normal chow. After 4, 6, and 8 weeks on the diet, aortae and skeletal muscles (gastrocnemius, biceps femoris, and plantaris) were excised, minced, and collagenolytically digested. Each tissue digest was then subjected to FACS in order to obtain 10,000 endothelial cells. Transcriptomic analyses were performed with microarrays containing the Operon Murine V4 oligo set, and highly dysregulated genes were confirmed by real-time PCR. Results: By 4 weeks, Tie2-GFP mice receiving a high fat diet exhibited a fasting glucose of 215+17 mg/dL vs. 134+23 mg/dL in controls; by 6 weeks, a high fat diet resulted in lower glucose tolerance vs. control diet. Following 4, 6, and 8 weeks of high-fat regimen, aortic endothelial transcripts up-regulated by greater than 2-fold in biologically replicate experiments included macrophage inflammatory protein 2 (Mip2), chemokine (C-C motif) ligand 9 (CCL9), galectin-3 (Gal-3), and 5-lipoxygenase-activating protein (FLAP). Endothelial transcripts up-regulated in skeletal muscle included Mip2, CCL8 and 9, FLAP, gal-1 and 3, and ferritin light chain 1 (FTL1); transcripts down-regulated in muscle included endothelin-1 (ET-1) and insulin-like growth factor II (IGF II). Discussion: Gal-3 and FTL-1 are known to increase in response to advanced glycation end-products and oxidized LDL, respectively. However, the down-regulation of ET-1 and IGFII was surprising, as the transcription of these genes has previously been thought to exacerbate atherosclerosis. In conclusion, a comprehensive analysis of the endothelial transcript-level response to a dietary model of Type II diabetes has revealed novel regulation of transcripts with roles in inflammation, insulin sensitivity, oxidative stress, and atherosclerosis. Understanding the mechanism of diabetes-associated endothelial dysfunction may lead to improved therapies that lower the risk of cardiovascular complications in diabetic patients.
