ROLES OF POLY (ADP-RIBOSE) IN CARCINOGENESIS,CELL DIFFERENTIATION AND PROGRAMMED CELLDEATH

1.发现聚（adp -核糖）合成酶（PARS）抑制剂：我们发现了一种弱到中间的效力，可以抑制PARS活性，在一种常用的溶剂，二甲亚砜，一种强心剂，vesnarinone，以及蛋白质的热解产物，Trp-P-1和PhIP.2中。PARS在癌细胞分化中的功能分析：我们成功地用vesnarinone或PhIP诱导畸形瘤EC细胞分化。我们还发现，在全反式维甲酸诱导分化的EC细胞中，聚腺苷核糖（adp -核糖）的合成会短暂增加，然后显著减少，这些变化是由pars的自修饰和随后的有限蛋白水解所影响的。阐明PARS在细胞生命-死亡程序中的作用：我们发现，暴露于高剂量放射性同位素（如^<35>S或^<32>P）诱导白血病t细胞凋亡后，PARS被磷酸化，然后被蛋白酶caspase-3快速切割，这种切割发生在两部分核定位信号之间，导致PARS的核外丢失。我们确定了dna依赖性蛋白激酶是负责PARS磷酸化的酶。神经退行性变过程中聚adp核糖的变化分析我们发现，在阿尔茨海默病淀粉样β肽诱导的PC-12细胞变性中，PARS活性发生了戏剧性的变化，刺激或减少，这与剂量和时间有关。脑局灶性缺血后聚adp -核糖反应的发现：我们发现人工缺血后大鼠脑区及其周围区域（半暗区）聚adp -核糖合成明显增加。这与延迟神经元死亡的发生相吻合。综上所述，这些发现表明，PARS在基本细胞功能中发挥着核心作用，特别是在DNA损伤后决定细胞的命运（生存与死亡）。

1.Discovery of poly (ADP-ribose) synthetase (PARS) inhibitors : We found a weak to intermediary potency to inhibit the PARS activity in a popular solvent, dimethylsulfoxide, a cardiotonic drug, vesnarinone, and pyrolysis products of protein, Trp-P-1 and PhIP.2.Analysis of PARS functions in cancer cell differentiation : We succeeded in inducing teratocarcinoma EC cell differentiation with vesnarinone or PhIP.We found also that, in the EC cells induced to differentiate by all-trans-retinoic acid, poly (ADP-ribose) synthesis increases transiently and then decreases markedly, and that these changes are effected by automodification and subsequent limited proteolysis of PARS.3.Elucidation of PARS roles in the cell life-deathprogram : We found that, upon induction of apoptosis of leukemic T-cells by exposure to a high-dose of radioisotopes such as ^<35>S or ^<32>P,PARS is phosphorylated and then rapidly cleaved by a protease, caspase-3, and that this cleavageoccurring in-between the bipartite nuclear localization signal leads to an extranuclearloss of PARS.We identified DNA-dependentprotein kinase as the enzyme responsible for the PARS phosphorylation.4.Analysis of poly (ADP-ribose) change during neurodegeneration ; We found a dramatic change, stimuation or reduction, in the PARS activity in PC-12 cells induced to degenerateby Alzheimer's amyloid Abeta peptide dose-and time-dependently.5.Discovery of poly (ADP-ribose) response after focal ischemia in brain : We found a marked increase of poly (ADP-ribose) synthesis in rat brain regions affectedby artificialischemia and later in the surrounding area (penumbra)., which conincided with the occurrence of delayd neuronal death.These findings, taken together, indicate a central role of PARS in the basic cell fubctions, in particular, determination of the fate, survival versus death, of the cell after DNA damage.