天花粉蛋白诱导的凋亡相关基因(GRETA)的分离

ISOLATION OF A GENE RELATED TO TRICHOSANTHIN- INDUCED APOPTOSIS(GRETA)

天花粉蛋白(Trichosanthin,TCS)制备成免疫毒素后,可抑制肿瘤细胞的生长,已尝试用于治疗恶性肿瘤。在无细胞体系中TCS可通过抑制蛋白质的合成发挥毒性作用。对完整的活细胞,近来发现它可阻断激活信号传递中ZAP-70与CD3ζ链的物理结合,并能诱导人体外周血淋巴细胞发生凋亡。凋亡为一受基因控制的细胞程序性死亡,有关死亡信号传递通路中相关基因的分离是研究和阐明这一细胞自杀事件的有效途径,并有助于了解TCS的作用机理和探索其用于恶性肿瘤治疗的新方式。本文采用mRNA差别显示技术。

Disturbance of the apoptosis-related signaling pathway is regarded as one of the critical factors for tumorigenesis. Isolation of the genes involved in the process of apoptosis would be thereby helpful to explore the mechanism of tumor transformation and to develop novel therapeutic approaches. Here we report a gene fragment GRETA, the gene related to trichosanthin-induced apoptosis, isolated from a leukemia cell line U937 undergoing apoptosis induced by a plant protein Trichosanhin (TCS). A 293bp segment of GRETA was revealed to be 78. 3% homologous to Bruton's tyrosine kinase at nucleic acid level. And Northern blot analysis showed that three mes- sengers of RNA with the size of about 0. 8-kb, 2. 0-kb and 7. 0-kb, respectively, were detected in TCS-untreated U937 cells when probed with GRETA, but there were only 0. 8-kb and 2. 0-kb transcripts appeared in apoptotic U937 cells. In addition, the abundance of each transcript changed apparently. The 0.8-kb transcript, for example, was the main band in Northern analysis in apoptotic U937 cells while was only detected marginally in TCS-untreated cells. These data suggested a possible relationship between the alternative splicing patterns of GRETA and the apoptosis.