Identification of herpes simplex virus type 1 latency-associated transcript sequences that both inhibit apoptosis and enhance the spontaneous reactivation phenotype
Identification of herpes simplex virus type 1 latency-associated transcript sequences that both inhibit apoptosis and enhance the spontaneous reactivation phenotype
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DOI：
10.1128/jvi.77.11.6556-6561.2003
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发表时间：
2003-06-01
影响因子：
5.4
通讯作者：
Wechsler, SL
中科院分区：
文献类型：
--
作者：
Jin, L;Peng, WP;Wechsler, SL
单纯疱疹病毒1型（HSV-1）潜伏相关转录本（LAT）基因是兔眼模型中HSV-1高自发和诱导再活化表型以及小鼠眼模型中高诱导再活化表型所必需的。最近，我们发现，LAT具有抗凋亡的功能，我们假设，LAT的能力，抑制细胞凋亡发挥了重要作用，LAT的能力，以提高再激活表型。仅表达8.3-kb LAT基因的前1.5 kb就足以在体外瞬时转染测定中抑制细胞凋亡和在体内抑制高自发再活化表型。在这里，我们展示了更复杂的映射研究的结果，其中抑制细胞凋亡和增强的自发再激活表型也似乎是相关的。HSV-1突变体病毒dLAT 371在兔中具有高自发再活化表型，表明该突变体中缺失的LAT区域（LAT核苷酸76至447）对于该表型不是必需的。LAT3.3A病毒突变体（表达LAT核苷酸1至1499）也具有高自发再活化表型，表明该突变体不表达的LAT区域（LAT核苷酸1500至LAT末端）也不是该表型所需的。令人惊讶的是，作为dLAT 371和LAT 3.3A的组合的LAT 2.9A（即，它表达LAT核苷酸1至76和447至1499），具有与LAT无效突变体的自发再活化表型难以区分的低自发再活化表型。我们在这里报告说，与低自发再活化表型的LAT2.9A，质粒表达相同的LAT RNA不抑制caspase 9诱导的细胞凋亡。相反，含有相同缺失但能够转录至LAT核苷酸2850或超过LAT核苷酸2850（而不是仅至LAT核苷酸1499）的质粒抑制胱天蛋白酶9诱导的细胞凋亡，这与dLAT 371的高自发再活化表型一致。因此，LAT2.9A可能具有低自发再活化表型，因为所制备的LAT RNA不能阻断细胞凋亡，而dLAT 371显然具有高自发再活化表型，因为所制备的LAT RNA具有显著的抗细胞凋亡活性。此外，LAT似乎有至少两个区域能够干扰caspase 9诱导的细胞凋亡。一个区域部分重叠LAT核苷酸76至447。第二区域部分（或完全）位于LAT核苷酸1499的下游。
The herpes simplex virus type 1 (HSV-1) latency-associated transcript (LAT) gene is essential for the high spontaneous and induced reactivation phenotype of HSV-1 in the rabbit ocular model and for the high induced reactivation phenotype in the mouse ocular model. Recently we showed that LAT has an antiapoptosis function, and we hypothesized that LAT's ability to inhibit apoptosis played an important role in LAT's ability to enhance the reactivation phenotype. Expression of just the first 1.5 kb of the 8.3-kb LAT gene is sufficient for both inhibition of apoptosis in an in vitro transient-transfection assay and the high spontaneous reactivation phenotype in vivo. Here we show the results of more complex mapping studies in which inhibition of apoptosis and the enhanced spontaneous reactivation phenotype also appear to be linked. The HSV-1 mutant virus dLAT371 has a high spontaneous reactivation phenotype in rabbits, suggesting that the LAT region deleted in this mutant (LAT nucleotides 76 to 447) is not required for this phenotype. The LAT3.3A viral mutant (which expresses LAT nucleotides 1 to 1499) also has a high spontaneous reactivation phenotype, suggesting that the region of LAT not expressed by this mutant (LAT nucleotide 1500 to the end of LAT) is also not required for this phenotype. Surprisingly, LAT2.9A, which is a combination of dLAT371 and LAT3.3A (i.e., it expresses LAT nucleotides 1 to 76 and 447 to 1499), has a low spontaneous reactivation phenotype indistinguishable from that of LAT null mutants. We report here that consistent with the low spontaneous reactivation phenotype of LAT2.9A, a plasmid expressing the identical LAT RNA did not inhibit caspase 9-induced apoptosis. In contrast, plasmids containing the same deletion but able to transcribe up to or past LAT nucleotide 2850 (rather than just up to LAT nucleotide 1499) inhibited caspase 9-induced apoptosis, consistent with the high spontaneous reactivation phenotype of dLAT371. Thus, LAT2.9A may have a low spontaneous reactivation phenotype because the LAT RNA that is made cannot block apoptosis, and dLAT371 apparently has a high spontaneous reactivation phenotype because the LAT RNA made has significant antiapoptosis activity. Furthermore, LAT appeared to have at least two regions capable of interfering with caspase 9-induced apoptosis. One region partially overlaps LAT nucleotides 76 to 447. The second region is partially (or completely) downstream of LAT nucleotide 1499.