Decreased Phosphorylation of Y14Caveolin-1 in Endometrial Tissue of Polycystic Ovary Syndrome Patients may be Related with an Insulin Resistant State in this Tissue

P. Ormazabal; C. Romero; F. Gabler; A.F. G. Quest; M. Vega

doi:10.1055/s-0032-1329972

Hormone and Metabolic Research, Table of Contents

Horm Metab Res 2013; 45(04): 291-296
DOI: 10.1055/s-0032-1329972

Original Basic

Decreased Phosphorylation of Y¹⁴Caveolin-1 in Endometrial Tissue of Polycystic Ovary Syndrome Patients may be Related with an Insulin Resistant State in this Tissue

P. Ormazabal

¹Department of Preclinical Sciences, School of Medicine, Catholic University of Maule, Talca, Chile

,

C. Romero

²Laboratory of Endocrinology and Biology of Reproduction, University of Chile Clinical Hospital (HCUCH), Independencia, Santiago, Chile

³Obstetrics and Gynecology Department, Faculty of Medicine, HCUCH, Independencia, Santiago, Chile

,

F. Gabler

⁴Department of Pathology, Faculty of Medicine, University of Chile, Santiago, Chile

,

A.F. G. Quest

⁵Laboratory of Cellular Communication, Center for Molecular Studies of the Cell (CEMC). Faculty of Medicine, University of Chile, Independencia, Santiago, Chile

,

M. Vega

²Laboratory of Endocrinology and Biology of Reproduction, University of Chile Clinical Hospital (HCUCH), Independencia, Santiago, Chile

³Obstetrics and Gynecology Department, Faculty of Medicine, HCUCH, Independencia, Santiago, Chile

› Author Affiliations

Abstract

Endometrial tissue of patients with polycystic ovary syndrome (PCOS) shows an impaired expression of insulin signaling molecules. Tyrosine phosphorylation of the insulin receptor (IR) by insulin promotes glucose uptake by activating the PI3K/Akt pathway. IR stability and function depend on the presence of the protein caveolin-1. Activation of IR increases phosphorylation of Y¹⁴caveolin-1. Since the endometrium of PCOS patients is proposed to be insulin resistant, we evaluated the phosphorylation of IR and caveolin-1 in endometria of patients with insulin resistance (PCOSE-IR) compared to controls (CE). To explore the mechanism associated with this condition, cultured endometrial cells (T-HESC) were exposed to high glucose (25 mM, 24 h), an experimental condition that leads to insulin resistance in other cell types. Endometrial protein levels of phospho-Y⁹⁷²IR, phospho-Y¹⁴caveolin-1 and caveolin-1 were determined by Western blotting. In cultured cells, protein levels of caveolin-1, IR, and Akt were evaluated by Western blotting. After acute insulin stimulation, phospho-S⁴⁷³Akt, phospho-Y¹⁴caveolin-1, and 2-deoxyglucose (2-DOG) uptake were determined. PCOSE-IR samples showed high protein levels of caveolin-1, but reduced phospho-Y¹⁴caveolin-1 compared to CE. No differences were observed for phospho-Y⁹⁷²IR between both groups. Cells pretreated with glucose showed a reduction in protein levels of IR and caveolin-1 and were unable to increase 2-DOG uptake, phospho-S⁴⁷³Akt and phospho-Y¹⁴caveolin-1 after insulin stimulation. In conclusion, in PCOSE-IR the impaired phosphorylation of IR downstream molecules such as phospho-Y¹⁴caveolin-1 suggests a diminished insulin sensitivity in endometria, condition that could be supported in vitro by the ability of T-HESCs to become insulin resistant when they are exposed to high glucose.

Key words

endometrial cells - high glucose - PCOS - caveolin-1

Full Text

References

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