P21waf-1/cip-1/sdi-1 is expressed at G1 phase in primary culture of hepatocytes from old rats, presumably preventing the cells from entering the S phase of the cell cycle.
To elucidate whether p21waf-1/cip-1/sdi-1 expression is associated with loss of growth potential of hepatocytes of old rats, we determined p21waf-1/cip-1/sdi-1 expression of hepatocytes from old (30 months) rats during the cell cycle in primary culture. A high level of expression of p21waf-1/cip-1/sdi-1 was detected at the G1 phase in old-rat hepatocytes, but after the S phase in young-rat hepatocytes. Consistently, the incidence of the cells positive for p21waf-1/cip-1/sdi-1 in nuclei before entering the S phase was significantly higher in old-rat hepatocytes than in young-rat hepatocytes. These results account for the loss of growth potential of old-rat hepatocytes in vitro and the marked retardation of regeneration of liver in old rats in vivo.
Sawada
N
N
Department of Pathology, Sapporo Medical University School of Medicine, Japan. sawadan@sapmed.ac.jp
Kojima
T
T
Obata
H
H
Saitoh
M
M
Isomura
H
H
Kokai
Y
Y
Satoh
M
M
Mori
M
M
D000818:Animals; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics* / Q000378:metabolism; D016193:G1 Phase; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D016196:S Phase
C493958:Cdkn1a protein, rat; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins