Inhibition of the growth suppressor gene Necdin results in increased proliferation of primary murine hepatocytes

With microarrays we identified a subset of 44 genes, which were up-regulated in the early mouse fetal vs. adult liver. One of the genes, Necdin, which is described as a cell growth suppressor in postmitotic neurons, was analysed. To study the physiological regulation of Necdin during adult liver regeneration we performed 2/3 hepatectomy and analysed expression at various time points (0–48h). Necdin expression relative to GAPDH peaked at 4 hours and decreased to minimum levels at 24 hour. Subsequently, Necdin mRNA was silenced in cultured primary murine hepatocytes by transfecting a siRNA. Efficacy of silencing 24 hours after transfection was demonstrated by “real-time“ PCR (inhibition ˜ 80%). 72 hours after transfection cell proliferation of the primary murine hepatocytes increased as demonstrated by elevated levels of [3H] Thymidin incorporation. Increased CyclinA expression further supports the hypothesis that Necdin acts as an anti-proliferative factor in the developing fetal and the regenerating adult liver. Conclusions: Necdin mRNA expression was detected in mouse liver and in primary mouse hepatocytes. We were able to show that Necdin is regulated during liver regeneration after hepatectomy. Silencing of the gene in cultured hepatocytes resulted in increased cell proliferation.