Effect of Maternal Diabetes Mellitus on Type 1 Insulin-like Growth Factor Receptor Abundance in Human Umbilical Vein Endothelial Cells

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 806-823-Gestational Diabetes
Basic/Clinical
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-823
Ashwini Mallappa*, April M. Teague and Steven D. Chernausek
University of Oklahoma Health Sciences Center, Oklahoma City, OK
BACKGROUND: Fetal growth is complex and influenced by genotype of the fetus, general maternal health, and intrauterine environment and is coordinated by a variety of regulatory molecules including growth factors.  The insulin-like growth factor (IGF) axis is central in prenatal and postnatal growth control and is responsive to nutritional status. Downstream signaling pathways of IGF-1 such as phosphotidylinositol 3 kinase/protein kinase B pathway, have been shown to be down-regulated in hyperglycemic states. Therefore, we hypothesized that exposure to hyperglycemia would decrease the type 1 IGF receptor (IGF1R) abundance in human umbilical vein endothelial cells (HUVEC) and explain the reduction in IGF-1 signaling.

RESEARCH DESIGN and METHODS:

Study Population: Five pregnant women with Type 2 DM/gestational DM treated with insulin/ glyburide who delivered at term and their offspring.   Six normoglycemic pregnant women with normal pregnancy and delivery at term and their offspring served as controls. Mean HgbA1c in DM mothers: 5.8 % (± 0.6).

Cell Culture: HUVEC were isolated from fresh umbilical cords by collagenase digestion and grown in culture. Cells in passage 3-4 were used for all experiments.

IGF-1R Abundance by Flow Cytometry (FC): Cells were grown to 70-80% confluence in T25 cm2 flasks. HUVECs from DM offspring were maintained in higher glucose concentration (180mg/dL) to mimic intrauterine conditions. Cells were then exposed to media containing normal glucose (100mg/dL) for 72h. HUVEC from control offspring were grown in media with 100mg/dL glucose and then exposed to glucose concentration of 360mg/dL for 72h. Mannitol was used as osmolarity control.

IGF-1R Abundance by Western Blot (WB):HUVECs were cultured under the various glucose exposures as described above in 6 well plates. After overnight serum starvation, cells were lysed and WB analysis was carried out for IGF1R abundance.

RESULTS: No significant differences were seen in the IGF1R abundance in cells derived from offspring of diabetic or control groups. The mean ranks of diabetic and controls groups were 6.6 and 5.5 respectively; U= 18, Z = - 0.46, p= 0.32, r = 0.1 (by Mann–Whitney Utest). Also, there was no influence of exposure to hyperglycemia in vitro

CONCLUSIONS: IGF1R abundance in HUVECs is normal in well-controlled diabetes.  In addition, hyperglycemia does not influence IGF1R abundance, indicating other mechanisms are involved in altering function of the downstream signaling.

Nothing to Disclose: AM, AMT, SDC

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: Support from Children’s Medical Research Institute (CMRI) Diabetes and Metabolic Research Program, University of Oklahoma Health Sciences Center
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