Pariat Theisara, Sharan R N
Radiation and Molecular Biology Unit, Department of Biochemistry, North-Eastern Hill University, Shillong 793 022, India.
Indian J Biochem Biophys. 2002 Apr;39(2):130-2.
The role of high mobility group (HMG) proteins and their poly-ADP-ribosylation (PAR) in betel nut induced initiation of carcinogenesis in mice has been studied. A known carcinogen, diethylnitrosamine (DEN) was used as a positive control. Swiss albino mice were chronically exposed to aqueous extract of betel nut (AEBN) or DEN at low doses for up to 4 weeks. The poly-ADP-ribosylation (PAR) of spleen cell HMG proteins was monitored using [32P]-NAD+. Parallel to this, chromatin was subjected to DNase I cleavage and the organizational state of the chromatin was monitored. The PAR of HMG proteins showed a marked progressive reduction at different times following AEBN- or DEN treatment. HMG proteins isolated from the control and carcinogen treated mice were allowed to reassociate with the untreated spleen cells chromatin. The reassociated chromatin showed progressive relaxation in its superstructure. The results suggest that under the influence of potential carcinogens AEBN or DEN, the mouse spleen cell HMG proteins created molecular conditions favourable to initiation of cancer.
高迁移率族（HMG）蛋白及其多聚ADP核糖基化（PAR）在槟榔诱导小鼠致癌起始过程中的作用已得到研究。一种已知的致癌物二乙基亚硝胺（DEN）用作阳性对照。将瑞士白化小鼠长期低剂量暴露于槟榔水提取物（AEBN）或DEN中长达4周。使用[32P]-NAD+监测脾细胞HMG蛋白的多聚ADP核糖基化（PAR）。与此同时，对染色质进行DNase I切割，并监测染色质的组织状态。在AEBN或DEN处理后的不同时间，HMG蛋白的PAR显示出明显的逐渐降低。将从对照和致癌物处理小鼠中分离的HMG蛋白与未处理的脾细胞染色质重新结合。重新结合的染色质在其超结构中显示出逐渐松弛。结果表明，在潜在致癌物AEBN或DEN的影响下，小鼠脾细胞HMG蛋白创造了有利于癌症起始的分子条件。
