Hully J R, Chang L, Schwall R H, Widmer H R, Terrell T G, Gillett N A
Department of Safety Evaluation, Genentech, Inc., South San Francisco, California 94080.
Hepatology. 1994 Oct;20(4 Pt 1):854-62. doi: 10.1002/hep.1840200413.
Recombinant human activin A, a member of the transforming growth factor-beta superfamily, induced significant cell loss in rodent livers and in primary hepatocyte cultures. Histologically and biochemically the hepatocyte death was mediated by apoptosis, a form of programmed cell death. Male mice were treated with 200 or 500 micrograms recombinant human activin A/kg body wt/day for up to 3 days by means of a subcutaneously implanted minipump. Livers were taken for light and electron microscopy, DNA isolation and in situ nick end-labeling. Primary cultures of rat hepatocytes were treated with 10 ng/ml recombinant human activin A for 24 hr before being harvested for electron microscopy and DNA isolation. Infusion of activin A evoked dose-dependent loss of liver mass due to the atrophy and death of hepatocytes around the central vein. Morphologically, the dying cells demonstrated all the characteristic nuclear and cytoplasmic features of apoptosis. Low molecular weight DNA isolated activin A-treated intact livers and primary cultures exhibited the typical oligosomal ladder. Nick end-labeling of DNA in situ confirmed that virtually all topographical apoptotic hepatocytes had fragmented DNA. The currently accepted criteria for apoptosis (i.e., specific morphological alterations and internucleosomal clipping of DNA) were evident in activin A-treated hepatocytes both in vitro and in vivo, leading to the conclusion that cell loss occurs mainly through apoptosis. These observations suggest that activin A may be important in hepatic homeostasis.
重组人激活素A是转化生长因子-β超家族的一员，可导致啮齿动物肝脏和原代肝细胞培养物中出现明显的细胞损失。从组织学和生物化学角度来看，肝细胞死亡是由凋亡介导的，凋亡是一种程序性细胞死亡形式。雄性小鼠通过皮下植入微型泵，以200或500微克重组人激活素A/千克体重/天的剂量治疗长达3天。取出肝脏进行光镜和电镜检查、DNA分离以及原位缺口末端标记。大鼠肝细胞原代培养物在收获用于电镜检查和DNA分离之前，用10纳克/毫升重组人激活素A处理24小时。激活素A的输注导致肝质量出现剂量依赖性损失，这是由于中央静脉周围肝细胞的萎缩和死亡所致。从形态学上看，濒死细胞表现出凋亡的所有典型核和细胞质特征。从经激活素A处理的完整肝脏和原代培养物中分离出的低分子量DNA呈现出典型的寡核苷酸梯带。DNA原位缺口末端标记证实，几乎所有形态学上凋亡的肝细胞都有DNA片段化。目前公认的凋亡标准（即特定的形态学改变和DNA的核小体间剪切）在体外和体内经激活素A处理的肝细胞中均很明显，从而得出细胞损失主要通过凋亡发生的结论。这些观察结果表明，激活素A可能在肝脏内环境稳定中起重要作用。
