Gene expression of growth-related proteins and ECM constituents in response to unilateral nephrectomy

To identify the specific regulatory mechanism associated with the events following unilateral nephrectomy, we measured the levels of mRNA encoding for extracellular matrix (ECM) constituents, for protooncogenes, and for proliferating cell nuclear antigen (PCNA) in renal cortex and glomeruli. One hour after left nephrectomy, c-jun and c-fos mRNA levels in renal cortex increased rapidly and then decreased rapidly to the control level, whereas c-myc and PCNA mRNA levels showed a slower and more sustained increase, with a peak at 6 h after nephrectomy, and then decreased to the control level after 7 days. mRNA levels for basement membrane components including alpha 1-chain of type IV collagen, laminin B1 and B2 chains, and heparan sulfate proteoglycan core protein were significantly increased in renal cortex at 12 h after nephrectomy, whereas those for interstitial collagens including alpha 1-chains of type I and type III collagen were unchanged following nephrectomy. On the other hand, the glomerular expression of all genes examined in this study showed little change during the experimental period. These results suggest that the time course of mRNA expression of ECM constituents is different from that of growth-related proteins in renal cortex and that glomerular mRNA levels for these components may not be associated with renal hypertrophy in the early stages following unilateral nephrectomy.