Optimal screening of short hairpin and construction of its eukaryotic expression vector for glial fibrillary acidic protein

Mingyong GAO; Zhenyu LI; Hongyin YAN

ABSTRACT

BACKGROUND:

The glial scar formation after spinal cord injury in mammals is the physical and chemical barriers for neural regeneration, and relieving or delaying glial scar formation can provide benefit conditions for the regeneration of injured spinal cord.

OBJECTIVE:

To design and screen short hairpin RNA (shRNA) interfere molecular targeting the gene coding region of glial fibrillary acidic protein (GFAP) in rat, and reconstruct the eukaryotic vector of shRNA.

DESIGN:

An observational animal experiment.

SETTING:

Department of Spine Surgery, Shenzhen Hospital affiliated to Southern Medical University.MATERIALS Twenty-five Wistar rats of clean degree, either male or female, weighing 20-25 g, were used. DMEM/F12,lipofectamine2000, Trizol RNA separating kits); fetal bovine serum (Hyclone); BamH Ⅰ, HindⅢ, Pstl, Sail and T4 ligases;Plasmid mini preparation kit and DNA gel extraction kit.

METHODS:

The experiments were carried out in the Shenzhen Hospital affiliated to Southern Medical University from October 2005 to June 2006. Three pairs of shRNA template which composed of 19 bp reverse repeated motif of GFAP target sequence with 9 bp spacer were designed and synthesized, then they were inserted directionally into plasmid Psilencer 2.1 respectively to generate small interfering RNA (siRNA) eukaryotic expression vector. ShRNA molecules were transfected by liposome via ex vivo expression repressive model of GFAP of rat spinal astrocytes. The effects of expressive suppression were detected with real-time fluorescence quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, and then the optimal shRNA eukaryotic vector of repressive expression of GFAP was screened.MAIN OUTCOME

MEASURES:

① Interfering sequence specific shRNA template synthesis; ② Constructing specific recombinant plasmid eukaryotic expression vector. ③ Culturing rat spinal astrocytes in vitro; ④ Effects of expressive suppression on GFAP in primary astrocytes after RNA interference detected with real-time fluorescence quantitative RT-PCR and Western blot.

RESULTS:

Sequence analysis showed that GFAP-shRNA recombinant plasmid eukaryotic expression vector was successfully constructed, and optimal GFAP-shRNA eukaryotic vector was screened using real-time fluorescence quantitative RT-PCR and Western blot. The GFAP expressions were reduced by 81%, 63% and 56% at the levels of mRNA and protein respectively.

CONCLUSION:

GFAP-shRNA eukaryotic expression vectors were successfully constructed and screened. The gene expression GFAP of primitive rat astrocyte can be suppressed significantly by the GFAP-shRNA eukaryotic expression recombinant optimized via ex vivo cellular expression suppression model, which should pave the way for the following multiple targets of RNAi genetic manipulation in the treatment of suppression of glial scar formation after spinal cord injury.