Project E: Does the Arg72Pro polymorphism of p53 have a role in the development of diabetic nephropathy?

Department of Pathology & Medical Biology, Div. Pathology, UMCG
Coordinators: J Moser, H van Goor & JL Hillebrands 

Hyperglycaemia increases oxidative stress and may thereby increase the risk of diabetic complications, including diabetic nephropathy. Despite multiple therapeutic options, the incidence of diabetic nephropathy and renal failure remains worrisome. Classical factors contributing to the pathology of diabetic nephropathy, e.g., hypertension, hyperglycemia, hyperinsulinemia, and hyperlipidemia, are now amenable to treatment. However, current therapies do not fully prevent its renal complications. Genetic factors are also considered to contribute to the development and progression of diabetic nephropathy.

The p53 tumor suppressor protein plays a fundamental role in maintaining genome integrity. The proline rich region of p53 is polymorphic at amino acid 72 since different alleles are found in the general population in relation to different ethnic characteristics. Proline (Pro) and arginine (Arg) polymorphic variants at codon 72 of p53 (Arg72Pro) have different structural characteristics accompanied by different biochemical and functional properties. The Arg allele of the Arg72Pro polymorphism increases p53-mediated apoptosis, whereas the Pro allele effectuates cell cycle arrest in the G1 phase. The p53 Arg72Pro SNP has recently been associated with the development of Type 2 diabetes mellitus and vascular complications. The biological effects of p53 pathway variants at the molecular level in vivo however still need to be determined.

Recently, unique mouse models which mimic the human Arg72Pro variants of p53 have been developed. We plan to use these mice in order to determine if the Arg72Pro polymorphism of p53 has a role in the development of diabetic nephropathy. A diabetic state will be experimentally-induced by treating mice with an intraperitoneal injection of streptozotocin (STZ) for 5 consecutive days. Serum glucose and albumin/creatinine ratios will be closely monitored during the experiment. The mice will be terminated 8 weeks after STZ treatment and renal pathology will be examined. Renal morphology will determine the extent of glomerular, tubular and interstitial damage. Since p53 is a key regulator of cell proliferation, apoptosis and the DNA damage response; these processes including renal oxidative damage will be examined in the kidneys of the various groups of mice.

IRF student(s) will contribute to the characterization of diabetic nephropathy on the histological level (histochemistry, immunofluorescence) as well as the molecular level (PCR analysis) on renal tissue of these recently generated mice.