Role of the Fas system in liver regeneration after a partial hepatectomy in rats.
Apoptosis is involved in the homeostatic control of organs. The aim of this study was to define the in vivo role of apoptosis-related proteins including the Fas system and Bcl-2 in liver regeneration following a partial hepatectomy (PH). We used 70% hepatectomized rats which were serially sacrificed from 12 h to 28 days. The expressions of Fas, Fas ligand, and Bcl-2 were examined by semiquantitative RT-PCR and immunohistochemistry. Liver regeneration, as examined by PCNA staining, peaked from 24 h to day 3, and declined from day 5. On the other hand, hepatocyte apoptosis, as examined by TUNEL staining, was seldom observed until 24 h, but increased from 1 week after PH. In the RT-PCR study, Fas showed an early decline by 24 h, followed by a later peak from days 3 to 5, and then a constant expression thereafter. Meanwhile, the Fas ligand was also low until day 3, but showed a remarkable increase from days 5 to 7, followed by a gradual decrease. On the other hand, Bcl-2 showed an early peak until 24 h, followed by a decline from day 5. In an immunohistochemical study, the time courses of these protein expressions were almost synchronous with their mRNAs in the RT-PCR study. We thus conclude that the coordinated interplay between these apoptosis-related proteins and hepatocyte apoptosis suggests the possible involvement of these proteins in the course of liver regeneration.
Taira
K
K
First Department of Surgery, University of the Ryukyus, School of Medicine, Okinawa, Japan. ka-ru@ka3.so-net.ne.jp
Hiroyasu
S
S
Shiraishi
M
M
Muto
Y
Y
Koji
T
T
D000818:Animals; D017209:Apoptosis; D053222:Fas Ligand Protein; D006498:Hepatectomy / Q000379:methods*; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008099:Liver / Q000503:physiopathology*; D008115:Liver Regeneration / Q000502:physiology*; D008297:Male; D008562:Membrane Glycoproteins / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019014:fas Receptor / Q000502:physiology*
D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D019014:fas Receptor