Cell cycle alterations in hyperbilirubinemic Gunn rat cerebella

M. CELESTE ROBERT; SILVIA GAZZIN; CLAUDIO TIRIBELLI

Trieste

Seminario; 7° Seminario SIBBM "Frontiers in Molecular Biology"; 2011

SIBBM- Società Italiana di Biofisica e Biologia Molecolare

Cell cycle alterations in hyperbilirubinemic Gunn rat cerebella M.C. Robert, S. Gazzin, C. Tiribelli. Fondazione Italiana Fegato- Area Science Park Basovizza and Dept of ACADEM University of Trieste, Trieste, Italy. celeste.robert@csf.units.it Neonatal hyperbilirubinemia in jj Gunn rat results from a deficiency of the hepatic bilirubin conjugating enzyme UDP-glucuronosyl transferase 1A1, homologous to human patients with Crigler Najjar type I Syndrome and analogous to the reduced enzyme activity seen in neonates during the first days of life. The high levels of unconjugated bilirubin (UCB) in plasma can lead to the accumulation of bilirubin in the brain. The hyperbilirubinemic jj Gunn rat develop a marked cerebellar hypoplasia, with the greatest damage occurring in brain areas that mature postnatally. Recently, an effect of UCB on cell cycle progression has been described with cell cycle arrest in the late G1 phase. The aim of this study was to investigate if cerebellar hypoplasia in hyperbilirubinemic jj Gunn rat could be due to a cell cycle arrest. Cerebellum from hyperbilirubinemic (jj) and normal (JJ) Gunn rat at 9 days after birth was dissected and divided in two parts. The first was used to evaluated the mRNA relative expression of Cyclin D1, A and Cdk2 genes using Real Time q-PCR (n=11); and the other one to determinate its protein levels by quantitative Western Blot (n=9). At the mRNA level, we observed a slight reduction in Cyclin D1 expression in jj rats (JJ 1.00 ± 0.18 vs. jj 0.80 ± 0.30), whereas the mRNA expression of Cyclin A and Cdk2 was unchanged. However when its protein relative expression were studied a significantly reduction in jj animals was observed (Cyclin D1: 0.813 ± 0.09 vs. 0.69 ± 0.12 p