抗Caspase-12核酶的制备与体外活性鉴定

Preparation and identification of hammerhead ribozyme in vitro against caspase-12 mRNA fragments

目的 设计针对小鼠内质网应激凋亡途径中Caspase-12 mRNA的锤头状核酶(Rz138、Rz218),通过靶基因及核酶的体外转录、切割,进行核酶活性鉴定,评估其应用前景。 方法 小鼠Caspase-12基因的逆转录聚合酶链反应(RT-PCR)扩增片段克隆于PGEM-T载体的T7启动子下游,通过α-32P UTP标记的体外转录物作为靶RNA。设计合成针对小鼠Caspase-12 mRNA的核酶,通过PCR方法扩增核酶的转录模板,采用非同位素标记法行体外转录,核酶与靶RNA进行体外切割实验。 结果 在37℃,Rz138、Rz218均有切割活性,Rz138的切割效率较高,几乎100％。 结论 Rz138在体外具有良好的特异催化切割活性,它有望通过切割Caspase-12 mRNA而抑制内质网应激介导的细胞凋亡发生。

Objective To design and synthesize ribozymes targeting 138 and 218 sites of the mRNA nucleotide of mouse caspase-12, a key intermedium of ER stress mediated apoptosis, and to identify their activities through in vitro transcription and cleavage. Methods The mouse caspase-12 gene fragment was obtained by RT-PCR and cloned into the PGEM-T vector under the control of T7 RNA polymerase promoter. The transcription product of the target was labeled with α-32P UTP, while ribozymes were not labeled. Ribozyme and target RNA were incubated for 90 min at 37℃ in a reaction buffer to perform the cleavage reaction. Results It was found that under a condition of 37℃, pH 7.5 and with Mg2+ in a concentration of 10 mmol/L, Rz138 and Rz218 both cleaved targets at predicted sites, and the cleavage efficiency of Rz138 was 100%, Conclusion Rz138 and Rz218 prepared in vitro possess the perfect specific catalytic cleavage activity. Rz138 has excellent cleavage efficiency. It may be a promising tool to prevent ER stress induced apoptosis through catalytic cleavage of caspase-12 mRNA in vivo. It also can be used to verify whether caspase-12 is necessary in ER stress induced apoptosis.