Involvement of ice family proteases in apoptosis induced by
reoxygenation of hypoxic hepatocytes.
Shimizu, Shigeomi, Yutaka Eguchi, Wataru Kamiike, Yukihiro Akao,
Hiroaki Kosaka, Jun-Ichi Hasegawa, Hikaru Matsuda, Yoshihide
Tsujimoto.
The First Department of Surgery, Department of Medical Genetics,
Biomedical Research Center, The First Department of Physiology, Osaka
University Medical School, 2-2 Yamadaoka, Suita 565, Japan.
Department of Anatomy and Biology, Osaka Medical College, 2-7,
Daigakumachi, Takatsuki, 569, Japan
APStracts 3:0122G, 1996.
Cell death due to reoxygenation after hypoxia was characterized in
primary cultured hepatocytes. Fluorescence and electron microscopic
analyses of reoxygenated hepatocytes revealed morphological
characteristics of apoptosis, including chromatin condensation,
nuclear fragmentation, and formation of apoptotic bodies. Few
necrotic hepatocytes, defined by loss of plasma membrane integrity,
mitochondrial swelling and formation of large vacuoles, were
observed. Activation of ICE(-like) and CPP32/Yama(-like) proteases,
which are known to drive apoptosis, was observed during
reoxygenation, and the addition of their respective inhibitors
inhibited the induction of apoptosis, indicating the involvement of
ICE family proteases in apoptosis by reoxygenation. Production of
oxygen radicals was enhanced by reoxygenation of hypoxic cells, and
reoxygenation-induced apoptosis was inhibited by oxygen radical
scavengers, suggesting a role for reactive oxygen species (ROS) as a
triggering factor in the cell death. Electrophoretic analysis
revealed the presence of 50-kb DNA fragments but not oligonucleosomal
DNA fragments in reoxygenation-induced apoptotic hepatocytes.
Received 22 March 1996; accepted in final form 29 May 1996.
APS Manuscript Number G103-6.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 June 96