拟南芥热激因子AtHsfA1a对渗透胁迫中Caspase-3酶的调控

Regulation of Heat Shock Factor At Hsf A1a on Caspase-3 Enzyme Activity under Osmotic Stress in Arabidopsis Thaliana

以热激因子At Hsf A1a不同基因型(野生型、基因突变型)的拟南芥为材料,PEG处理后采用分光光度法测定Caspase-3酶活性,结果发现渗透胁迫处理后拟南芥Caspase-3酶活性明显增强,而At Hsf A1a基因突变型拟南芥类Caspase-3酶活性比野生型拟南芥的高,说明渗透胁迫下拟南芥At Hsf A1a能够抑制Caspase-3蛋白酶的活性.为了从分子水平进一步鉴定At Hsf A1a与Caspase-3蛋白酶的关系,采用染色质免疫沉淀技术和凝胶阻滞电泳体内外分析At Hsf A1a与Caspase-3酶的关系,结果显示At Hsf A1a在体内外与Caspase-3蛋白酶的启动子片段均有结合.研究结果初步表明,渗透胁迫下拟南芥热激因子At Hsf A1a通过对Caspase-3蛋白酶表达的调控而对细胞程序性死亡有一定的抑制作用,这对揭示植物耐逆境反应机理具有重要意义.

The different gene type of Arabidopsis thaliana heat shock factor AtHsfA1a （ the wild type and AtHsfA1a gene mutant type） were used as materials. After PEG treatment, activity of Caspase-3 enzyme was determinated by using spectrophotometric method. The results found that activity of Caspase-3 enzyme significantly enhanced after PEG treatment, and caspase-3 enzyme activity of Arabidopsis thaliana in gene mutant type was higher than that of the wild type Arabidopsis under osmotic stress, showing Arabidopsis AtHsfA1a can inhibit the activity of Caspase-3 under osmotic stress. In order to reveal regulatory effect of AtHsfAla on Caspase-3 at molecular level, the binding of AtHsfA1a to the promoter region of Caspase-3 was investigated by using chromatin immunoprecipitation and electrophoretic mobility shift assay. The results showed that the binding of AtHsfAla to the promoter regions of Caspase-3 at different degrees existed in vivo or in vitro. These indicated that AtHsfAla inhibited programmed cell death by inhibiting the expression of Caspase-3 , which was important and useful for revealing the mechanism of stress resistance in plant.