Functional Screening of Candidate Causal Genes for Insulin Resistance in Human Preadipocytes and Adipocytes

The key pathological link between obesity and type 2 diabetes is insulin resistance, but the molecular mechanisms are not entirely identified. micro-RNAs (miRNA) are dysregulated in obesity and may contribute to insulin resistance. Our objective was to detect and functionally investigate miRNAs linked to insulin sensitivity in human subcutaneous white adipose tissue (scWAT). Subjects were selected based on the insulin-stimulated lipogenesis response of subcutaneous adipocytes. Global miRNA profiling was performed in abdominal scWAT of 18 obese insulin-resistance (OIR), 21 obese insulin-sensitive (OIS), and 9 lean women. miRNAs demonstrating differential expression between OIR and OIS women were overexpressed in human in vitro-differentiated adipocytes followed by assessment of lipogenesis and identification of miRNA targets by measuring mRNA/protein expression and 3′-untranslated region analysis. Eleven miRNAs displayed differential expression between OIR and OIS states. Overexpression of miR-143-3p and miR-652-3p increased insulin-stimulated lipogenesis in human in vitro differentiated adipocytes and directly or indirectly affected several genes/proteins involved in insulin signaling at transcriptional or posttranscriptional levels. Adipose expression of miR-143-3p and miR-652-3p was positively associated with insulin-stimulated lipogenesis in scWAT independent of body mass index. In conclusion, miR-143-3p and miR-652-3p are linked to scWAT insulin resistance independent of obesity and influence insulin-stimulated lipogenesis by interacting at different steps with insulin-signaling pathways.

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Circulating Pigment Epithelium-Derived Factor Levels Are Associated with Insulin Resistance and Decrease after Weight Loss

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2010-0630 ◽

2010 ◽

Vol 95 (10) ◽

pp. 4720-4728 ◽

Cited By ~ 69

Author(s):

Mònica Sabater ◽

Jose M. Moreno-Navarrete ◽

Francisco José Ortega ◽

Gerard Pardo ◽

Javier Salvador ◽

...

Keyword(s):

Gene Expression ◽

Insulin Resistance ◽

Blood Pressure ◽

Body Mass Index ◽

Weight Loss ◽

Insulin Sensitivity ◽

Body Mass ◽

Pigment Epithelium ◽

Pigment Epithelium Derived Factor ◽

Human Preadipocytes

Objective: We aimed to study circulating pigment epithelium-derived factor (PEDF) in vivo in association with insulin resistance and in vitro in human adipocytes. Methods: Circulating PEDF (ELISA) and metabolic profile were assessed in 125 Caucasian men. PEDF levels were also assessed in an independent cohort of subjects (n = 33) to study the effects of changing insulin action. PEDF gene expression and secretion were measured during differentiation of human preadipocytes. Results: In all subjects, PEDF was positively associated with body mass index (r = 0.326; P < 0.0001), waist-to-hip ratio (r = 0.380; P < 0.0001), HbA1c, and fasting triglycerides and negatively with insulin sensitivity (r = −0.320; P < 0.0001). PEDF levels were significantly increased in subjects with altered glucose tolerance and type 2 diabetes. Of the inflammatory markers measured, PEDF levels were positively associated with serum soluble TNF-α receptor 1 and IL-10 in obese subjects. Interestingly, weight loss led to significantly decreased PEDF concentration from 34.8 ± 19.3 to 22.5 ± 14.2 μg/ml (P < 0.0001). Multiple linear regression analyses revealed that insulin sensitivity contributed independently to explain 14% of the variance in PEDF levels after controlling for the effects of body mass index, age, and log fasting triglycerides. Differences in PEDF observed after weight loss were related to changes in obesity, insulin resistance, and blood pressure measures. PEDF gene expression and secretion increased during differentiation of human preadipocytes. Conclusion: Circulating PEDF is associated with insulin sensitivity. The findings show, for the first time in humans, that PEDF concentrations decrease significantly after weight loss in association with blood pressure. PEDF seems to be involved in human adipocyte biology.

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