Alterations in the cell cycle in the cerebellum of hyperbilirubinemic Gunn rat: a possible link with apoptosis?
Severe hyperbilirubinemia causes neurological damage both in humans and rodents. The hyperbilirubinemic Gunn rat shows a marked cerebellar hypoplasia. More recently bilirubin ability to arrest the cell cycle progression in vascular smooth muscle, tumour cells, and, more importantly, cultured neurons has been demonstrated. However, the involvement of cell cycle perturbation in the development of cerebellar hypoplasia was never investigated before. We explored the effect of sustained spontaneous hyperbilirubinemia on cell cycle progression and apoptosis in whole cerebella dissected from 9 day old Gunn rat by Real Time PCR, Western blot and FACS analysis. The cerebellum of the hyperbilirubinemic Gunn rats exhibits an increased cell cycle arrest in the late G0/G1 phase (p < 0.001), characterized by a decrease in the protein expression of cyclin D1 (15%, p < 0.05), cyclin A/A1 (20 and 30%, p < 0.05 and 0.01, respectively) and cyclin dependent kinases2 (25%, p < 0.001). This was associated with a marked increase in the 18 kDa fragment of cyclin E (67%, p < 0.001) which amplifies the apoptotic pathway. In line with this was the increase of the cleaved form of Poly (ADP-ribose) polymerase (54%, p < 0.01) and active Caspase3 (two fold, p < 0.01). These data indicate that the characteristic cerebellar alteration in this developing brain structure of the hyperbilirubinemic Gunn rat may be partly due to cell cycle perturbation and apoptosis related to the high bilirubin concentration in cerebellar tissue mainly affecting granular cells. These two phenomena might be intimately connected.
Fondazione Italiana Fegato (Italian Liver Foundation, Centro Studi Fegato), Trieste, Italy.
María Celeste
MC
Robert
Giulia
G
Furlan
Natalia
N
Rosso
Sabrina Eliana
SE
Gambaro
Faina
F
Apitsionak
Eleonora
E
Vianello
Claudio
C
Tiribelli
Silvia
S
Gazzin
D000818:Animals; D017209:Apoptosis; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D001663:Bilirubin / Q000097:blood / Q000378:metabolism / Q000494:pharmacology; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D059447:Cell Cycle Checkpoints; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism*; D019925:Cyclin A / Q000235:genetics / Q000378:metabolism; D056750:Cyclin A1 / Q000235:genetics / Q000378:metabolism; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D019927:Cyclin E / Q000235:genetics / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D016193:G1 Phase; D006932:Hyperbilirubinemia / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D008297:Male; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D051381:Rats; D011911:Rats, Gunn; D017208:Rats, Wistar; D016192:Resting Phase, Cell Cycle; D020133:Reverse Transcriptase Polymerase Chain Reaction
D019925:Cyclin A; D056750:Cyclin A1; D019927:Cyclin E; D019938:Cyclin D1; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3; D001663:Bilirubin