Immunohistochemical Analysis of Cell Cycle for Podocyte
Recently impairment of podocytes has been reported to be continuous with irreversible glomerulosclerosis. We examined the labeling incidences of podocytes (using the puromycin aminonucleoside nephropathy (PAN) and these rats given the fibroblast growth factor 2 (PAN + FGF2) models) and mesangial cells (using the anti-Thyl.l mesangial proliferatied glomerulonephritis (Thy1.1 GN) model) using two markers (Bromodeoxyuridine (BrdU) and proliferating cell nuclear antigen (PCNA), to clarify differences in the cell cycle of podocytes and mesangial cells under pathological conditions. Our results showed no significant differences in BrdU-labeled and PCNA-positive podocytes were found in the PAN group, but BrdU-labeled mesangial cells to be more numerous than PCNA-positive mesangial cells in the Thy1.1 GN group. However, the incidence of PCNA-positive podocytes was higher than that of BrdU-labeled podocytes in the PAN + FGF2 group. These results suggest that no progression took place in the cell cycle of podocytes and that many podocytes appeared in the late G1 phase. The mechanisms of the inhibition of progression from the G1 phase to the S phase are unclear. These findings have led us to consider that the inhibition of progression to the S phase might be taken as a preventive mechanism of podocyte injuries.