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Transcriptional analysis of the endothelial response to diabetes reveals a role for galectin-3.

ABSTRACT: To characterize the endothelial dysfunction associated with Type II diabetes, we surveyed transcriptional responses in the vascular endothelia of mice receiving a diabetogenic, high-fat diet. Tie2-GFP mice were fed a diet containing 60% fat calories (HFD); controls were littermates fed normal chow. Following 4, 6, and 8 wk, aortic and leg muscle tissues were enzymatically dispersed, and endothelial cells were obtained by fluorescence-activated cell sorting. Relative mRNA abundance in HFD vs. control endothelia was measured with long-oligo microarrays; highly dysregulated genes were confirmed by real-time PCR and protein quantification. HFD mice were hyperglycemic by 2 wk and displayed vascular insulin resistance and decreased glucose tolerance by 5 and 6 wk, respectively. Endothelial transcripts upregulated by HFD included galectin-3 (Lgals3), 5-lipoxygenase-activating protein, and chemokine ligands 8 and 9. Increased LGALS3 protein was detected in muscle endothelium by immunohistology accompanied by elevated LGALS3 in the serum of HFD mice. Our comprehensive analysis of the endothelial transcriptional response in a model of Type II diabetes reveals novel regulation of transcripts with roles in inflammation, insulin sensitivity, oxidative stress, and atherosclerosis. Increased endothelial expression and elevated humoral levels of LGALS3 supports a role for this molecule in the vascular response to diabetes, and its potential as a direct biomarker for the inflammatory state in diabetes.

SUBMITTER: Darrow AL

PROVIDER: S-EPMC3217326 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature

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Transcriptional analysis of the endothelial response to diabetes reveals a role for galectin-3.

Darrow April L AL Shohet Ralph V RV Maresh J Gregory JG

Physiological genomics 20110726 20

To characterize the endothelial dysfunction associated with Type II diabetes, we surveyed transcriptional responses in the vascular endothelia of mice receiving a diabetogenic, high-fat diet. Tie2-GFP mice were fed a diet containing 60% fat calories (HFD); controls were littermates fed normal chow. Following 4, 6, and 8 wk, aortic and leg muscle tissues were enzymatically dispersed, and endothelial cells were obtained by fluorescence-activated cell sorting. Relative mRNA abundance in HFD vs. con ...[more]

PMID: 21791638

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Project description:Diabetes promotes maladaptive changes in the endothelium that lead to its dysfunction and contribute to the vascular pathology of diabetes. We have previously reported the up-regulation of galectin-3, a ?-galactoside-binding lectin, in the endothelium and sera of diabetic mice, implicating this molecule in diabetic vasculopathy and suggesting its potential as a biomarker of the disease. Therefore, we sought to assess the role of galectin-3 in the vascular pathology of diabetes.Galectin-3 knockout mice (KO) and wild-type mice (WT) were fed either a high-fat diet (HFD) (60 % fat calories) to produce insulin resistant diabetes, or standard chow (12 % fat calories), and their metabolic and endothelial responses were measured. After 8 weeks, the aortic and skeletal muscle endothelia were isolated by fluorescence sorting of CD105(+)/CD45(-) cells and comprehensive transcriptional analyses were performed. Transcripts differentially dysregulated by HFD in KO endothelium compared to WT were confirmed by semi-quantitative RT-PCR, and protein expression was determined by immunofluorescence of aortic and muscle tissue. Ingenuity® Pathway Analysis was used to identify pathways up-regulated by HFD in the KO, such as the coagulation cascade, and measurements of blood clotting activity were performed to confirm these results.KO mice demonstrate greater hyperglycemia and impaired glucose tolerance but lower insulin levels on HFD compared to WT. KO mice demonstrate a more robust transcriptional response to HFD in the vascular endothelium compared to WT. Transcripts dysregulated in the KO endothelium after HFD are involved in glucose uptake and insulin signaling, vasoregulation, coagulation, and atherogenesis. One of the most down-regulated transcripts in the endothelium of the KO after HFD was the glucose transporter, Glut4/Slc2a4. GLUT4 immunofluorescence confirmed lower protein abundance in the endothelium and muscle of the HFD-fed KO. Prothrombin time was decreased in the diabetic KO indicating increased coagulation activity.Galectin-3 deficiency leads to exacerbated metabolic derangement and endothelial dysfunction. The impaired tissue uptake of glucose in KO mice can be attributed to the reduced expression of GLUT4. Enhanced coagulation activity in the diabetic KO suggests a protective role for galectin-3 against thrombosis. These studies demonstrate that galectin-3 deficiency contributes both to the pathogenesis of diabetes and the associated vasculopathy.

Project description:Heparan sulfate (HS) is a linear, abundant, highly sulfated polysaccharide that expresses in the vasculature. Recent genetic studies documented that HS critically modulates various endothelial cell functions. However, elucidation of the underlying molecular mechanism has been challenging because of the presence of a large number of HS-binding ligands found in the examined experimental conditions. In this report, we used quantitative phosphoproteomics to examine the global HS-dependent signaling by comparing wild type and HS-deficient endothelial cells that were cultured in a serum-containing medium. A total of 7222 phosphopeptides, corresponding to 1179 proteins, were identified. Functional correlation analysis identified 25 HS-dependent functional networks, and the top five are related to cell morphology, cellular assembly and organization, cellular function and maintenance, cell-to-cell communication, inflammatory response and disorder, cell growth and proliferation, cell movement, and cellular survival and death. This is consistent with cell function studies showing that HS deficiency altered endothelial cell growth and mobility. Mining for the underlying molecular mechanisms further revealed that HS modulates signaling pathways critically related to cell adhesion, migration, and coagulation, including ILK, integrin, actin cytoskeleton organization, tight junction and thrombin signaling. Intriguingly, this analysis unexpectedly determined that the top HS-dependent signaling is the IGF-1 signaling pathway, which has not been known to be modulated by HS. In-depth analysis of growth factor signaling identified 22 HS-dependent growth factor/cytokine/growth hormone signaling pathways, including those both previously known, such as HGF and VEGF, and those unknown, such as IGF-1, erythropoietin, angiopoietin/Tie, IL-17A and growth hormones. Twelve of the identified 22 growth factor/cytokine/growth hormone signaling pathways, including IGF-1 and angiopoietin/Tie signaling, were alternatively confirmed in phospho-receptor tyrosine kinase array analysis. In summary, our SILAC-based quantitative phosphoproteomic analysis confirmed previous findings and also uncovered novel HS-dependent functional networks and signaling, revealing a much broader regulatory role of HS on endothelial signaling.

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Transcriptional analysis of the endothelial response to diabetes reveals a role for galectin-3.

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Transcriptional analysis of the endothelial response to diabetes reveals a role for galectin-3.

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