Aims/hypothesis. Altered glucose transporter expression has been implicated in the pathogenesis of diabetic nephropathy. There is increasing evidence that genetic factors convey risk of, or protection from, diabetic nephropathy and that the behaviour of cultured skin fibroblasts from Type 1 diabetic patients may reflect these genetic influences. This study aimed to compare GLUT1 mRNA expression levels in skin fibroblasts from Type 1 diabetic patients with either rapid ("fast-track", n=25) or slow ("slow-track", n=25) development of diabetic nephropathy and from non-diabetic normal control subjects (controls, n=25). Methods. Skin fibroblasts were cultured in Dulbecco's Modified Eagle's Medium with 25 mmol/1 glucose for 36 h. Total RNA was isolated, and GLUT1 mRNA levels were estimated by microarray analysis and RT-PCR. Results. Levels of GLUT1 mRNA expression in skin fibroblasts from "slow-track" patients were greater than those from "fast-track" patients (p=0.02), as initially detected by microarray. GLUT1 inRNA expression levels were confirmed by RT-PCR to be higher in skin fibroblasts from "slow-track" patients (4.59± 2.04) than in those from "fast-track" patients (3.34± 1.2, p=0.02), and were also higher than in skin fibroblasts from control subjects (3.52±1.66, p=0.03). There was no statistically significant difference between levels of expression in the "fast-track" patients and the control subjects. Conclusions/interpretation. This finding is consistent with the presence of cellular protection factors against diabetic nephropathy in the "slow-track" patients. These factors could be associated with the regulation of the GLUT1 pathway and may be genetically determined.
Bibliographical noteFunding Information:
Acknowledgements. C. Huang was supported by a mentor-based research fellowship from the American Diabetes Association. M. L. Caramori was initially supported by the Foundation for the Coordination of Higher Education and Graduate Training (CAPES) from the Brazilian Government and subsequently by a research fellowship grant from Juvenile Diabetes Foundation International. This work was supported by grants from the National Institutes of Health (DK 13083 and DK 54638), the National Center for Research Resources (M01-RR00400) and the Viking Children’s Fund (Eden Prairie, Minn., USA). We are especially grateful to P. Walker for his help with the RT-PCR. We also thank J. Basgen and T. Groppoli for performing the morphometric studies, K. Pinkham for the cell culture, M. Watrin for patient recruitment and S. Kupcho-Sandberg for AER measurements.
- Cellular marker
- Diabetic nephropathy
- Skin fibroblasts
- mRNA expression