1. To characterise the physical and biochemical characteristics of both the OST-48 transgenic knock-in models.
2. To investigate if changes in OST-48 expression in mice affects kidney function and insulin sensitivity in the presence or absence of diabetic kidney disease.
Kidney disease leading to heart attacks and strokes affects up to one third of Australian individuals with diabetes and is one of the most deadly and poorly understood chronic complications1. There is recent evidence that changes leading to the accumulation of inappropriately folded proteins severely impacts kidney function2, 3. This project investigates the role of N-glycosylation, which is controlled by a subunit called oligosaccharyltransferase-48 (OST-48) in mammals and is necessary for the correct folding and trafficking of many proteins.
Male heterozygous global OST-48 transgenic knock-in mice C57Bl/6-Tg(Ubi-Cre, DDOST) (OST-48Tg), podocyte specific C57Bl/6-Tg(Pod-Cre, DDOST) (OST-48Tg Pod) and littermate controls (WT) (N=8/group) were randomised to diabetes by low dose streptozotocin (55mg/kg/day for 5 days) or no diabetes and followed for 24 weeks (OST-48Tg) or 12 weeks (OST-48Tg Pod). Physical characteristics were measured throughout the study and biochemical properties were identified through metabolic caging. We then examined kidney function through the rate of albumin excretion measured by ELISA and the ratio of creatinine clearance by HPLC. Finally we investigated the insulin sensitivity of these mice through IPGTT and IPITT.
Global OST-48Tg mice had a decrease in insulin sensitivity by the study completion. Moreover kidney function and health in both transgenic models was severely exacerbated by diabetes developing into end-stage kidney disease.
This preliminary investigation has demonstrated that functional OST-48 may play a role in normal kidney function and insulin sensitivity, particularly when exacerbated by diabetes. Therefore, we suggest that the alteration of functional OST-48 may play a role in kidney function which is further exacerbated by diabetes.