Subtotal but not unilateral nephrectomy induces hyperplasia and protooncogene expression

Area of Science:

• Nephrology
• Molecular Biology
• Cellular Biology

Background:

• Renal compensatory growth after unilateral nephrectomy (Uni) is traditionally attributed to hypertrophy, with no protooncogene involvement.
• The cellular mechanisms, including the balance of hypertrophy and hyperplasia, and early-growth-related gene expression following subtotal nephrectomy (Nx) remain uncharacterized.
• Cystic tubular dilatations observed after Nx suggest a potential for excessive cell proliferation in this model.

Purpose of the Study:

• To investigate the cellular events and protooncogene expression following Uni and Nx.
• To compare the roles of hyperplasia and hypertrophy in renal compensatory growth after Uni and Nx.
• To explore the potential link between late protooncogene expression and cystic formation in the Nx model.

Main Methods:

• Rats underwent sham operation, Uni, or Nx.
• Kidney tissues were analyzed for DNA, RNA, and protein content, and nuclei count.
• Expression of protooncogenes (c-fos, c-jun, c-myc, c-H-ras, c-sis, c-erb-B2) was measured at various time points post-surgery.

Main Results:

• Uni induced significant hyperplasia and moderate hypertrophy.
• Nx resulted in greater hyperplasia compared to Uni, with no change in the protein/DNA ratio.
• Protooncogene mRNA and protein expression (c-fos, c-jun) were detected late after Nx but not after Uni or sham operations.

Conclusions:

• Cellular events following Uni and Nx differ significantly.
• Late protooncogene expression observed exclusively in Nx rats may indicate a specific type of cell proliferation.
• This distinct proliferation in Nx could be associated with cystic formation rather than solely compensatory growth.