Background: Intrauterine growth restriction (IUGR) leads to low nephron number and higher incidence of renal disease. We hypothesized that IUGR induces early podocyte alterations based on a dysregulation of Wilms' tumour suppressor gene 1 (WT1), a key player of nephrogenesis and mediator of podocyte integrity.
Methods: IUGR was induced in rats by maternal protein restriction during pregnancy. Kidneys were harvested from male offspring at Days 1 and 70 of life. qRT-PCR, immunohistochemistry and electron microscopy were performed in renal tissue. Albuminuria was assessed by enzyme-linked immunosorbent assay.
Results: At Day 70 of life, higher albuminuria and overt alterations of podocyte ultrastructure were detected in IUGR animals in spite of normal blood pressure. Moreover, we found increased glomerular immunoreactivity and expression of desmin, while synaptopodin and nephrin were decreased. Glomerular immunoreactivity and expression of WT1 were increased in IUGR animals at this time point with an altered expressional ratio of WT1 +KTS and -KTS isoforms. These changes of WT1 expression were already present at the time of birth.
Conclusions: IUGR results in early podocyte damage possibly due to a dysregulation of WT1. We suggest that an imbalance of WT1 isoforms to the disadvantage of -KTS affects nephrogenesis in IUGR rats and that persistent dysregulation of WT1 results in a reduced ability to maintain podocyte integrity, rendering IUGR rats more susceptible for renal disease.
Keywords: WTI KTS isoforms; intrauterine growth restriction; maternal protein restriction; nephron reduction; podocyte damage.