Figure 2.

Glomerular cell types expressed altered gene expression with age. (A) Pnoc mRNA expression was not detectable in young (2-month) glomeruli but was detectable in old (24-month) glomeruli by in situ hybridization. Double-label studies using antibodies to WT1 to identify podocyte nuclei show that the cells that express Pnoc also have WT1-positive nuclei. Therefore, the Pnoc-expressing cells in old glomeruli are podocytes. (B) MMP9-expressing cells identified by immunofluorescence are detectable in young 2-month glomeruli but not in old 24-month glomeruli. Double-label studies using Thy1 as a mesangial cell marker demonstrate that the cells in young glomeruli that express MMP9 protein are mesangial cells. (C) The parietal epithelial cells lining Bowman capsule in old 24-month glomeruli express ceruloplasmin, whereas those of young 2-month glomeruli do not. (D) Western blots of glomerular extracts show that old 24-month glomerular extracts contain higher levels of both VCAM and ICAM than do glomerular extracts from young 2-month glomeruli. Mw, molecular weight; m, month. All photomicrograph images were made at ×200 magnification.