Clem R J, Miller L K
Department of Genetics, University of Georgia, Athens 30602-2603.
Mol Cell Biol. 1994 Aug;14(8):5212-22. doi: 10.1128/mcb.14.8.5212-5222.1994.
The SF-21 insect cell line undergoes rapid and widespread apoptosis when treated with actinomycin D or when infected with a mutant of the baculovirus Autographa californica nuclear polyhedrosis virus lacking a p35 gene or a functionally active iap (inhibitor of apoptosis) gene. Here we provide evidence that the basis for the induction of apoptosis by these two different stimuli is the cessation of RNA synthesis. We also show that expression of either p35 or two different functional iap homologs blocks apoptosis independently of other viral genes, indicating that these gene products act directly on the cellular apoptotic pathway. The iap genes encode a C3HC4 (or RING) finger motif found in a number of transcriptional regulatory proteins, as well as two additional Cys/His motifs (baculovirus iap repeats). We show that specific amino acids within both the C3HC4 finger and the N-terminal baculovirus iap repeat are critical for anti-apoptosis function. Overexpression of either mammalian bcl-2 or adenovirus E1B-19K, genes which block apoptosis when overexpressed in a number of mammalian cells, does not block actinomycin D-induced apoptosis in SF-21 cells.
用放线菌素D处理或感染缺乏p35基因或功能活性iap（凋亡抑制因子）基因的苜蓿银纹夜蛾核型多角体病毒突变体时，SF - 21昆虫细胞系会经历快速且广泛的凋亡。在此我们提供证据表明，这两种不同刺激诱导凋亡的基础是RNA合成的停止。我们还表明，p35或两种不同功能的iap同源物的表达可独立于其他病毒基因阻断凋亡，这表明这些基因产物直接作用于细胞凋亡途径。iap基因编码在许多转录调节蛋白中发现的C3HC4（或RING）指基序，以及另外两个Cys/His基序（杆状病毒iap重复序列）。我们表明，C3HC4指基序和N端杆状病毒iap重复序列中的特定氨基酸对于抗凋亡功能至关重要。在许多哺乳动物细胞中过表达时可阻断凋亡的哺乳动物bcl - 2或腺病毒E1B - 19K基因的过表达，并不会阻断SF - 21细胞中放线菌素D诱导的凋亡。
