Advanced Glycation End Products Upregulate Insulin Receptor Substrate-1 (IRS-1) in Human Cumulus Granulosa Cells

Area of Science:

• Reproductive Endocrinology
• Metabolic Research
• Cellular Biology

Background:

• Polycystic ovary syndrome (PCOS) and insulin resistance (IR) are linked to elevated advanced glycation end-products (AGEs) in the ovaries.
• AGEs can disrupt insulin signaling in granulosa cells (GCs) by affecting glucose transporter translocation.
• PCOS is associated with altered insulin receptor substrate-1 (IRS-1) expression in GCs.

Purpose of the Study:

• To investigate the hypothesis that AGEs contribute to ovarian IR by altering IRS-1 in human GCs.
• To examine the molecular effects of AGEs on key components of insulin signaling pathways in GCs.

Main Methods:

• Human cumulus granulosa cells (GCs) from IVF patients were cultured with or without human glycated albumin (HGA) as a source of AGEs.
• Quantitative RT-PCR was used to measure mRNA expression of RAGE, IRS-1, IRS-2, GLUT-1, and NF-κB.
• Immunofluorescence was employed to assess IRS-1 protein intensity and GLUT-4 localization.

Main Results:

• HGA treatment significantly upregulated RAGE mRNA (314%) and IRS-1 mRNA (423%) in GCs.
• Immunofluorescence revealed increased IRS-1 protein intensity and a significant reduction in cytoplasmic GLUT-4 signal in HGA-treated GCs.
• No significant changes were observed in IRS-2 or NF-κB mRNA levels; GLUT-1 mRNA increase was not statistically significant.

Conclusions:

• AGE exposure induces upregulation of IRS-1 and alters GLUT-4 localization in human GCs, suggesting a potential role in early molecular changes related to ovarian insulin resistance.
• These findings indicate that AGEs may initiate molecular alterations contributing to impaired insulin signaling in the ovarian microenvironment.