Monitoring p21 mRNA expression in living cell based on molecular beacon fluorescence increasing rate

Studying the expression level of mRNA in living cells will offer tremendous opportunities for ad-vancement in cell biology research,disease diagnostics,and drug discovery.In this paper,a molecular beacon(MB)specific for the important tumor suppressor gene p21 has been designed and synthesized.The fluorescence signal was detected in real-time after the MB entered the cytoplasm of nasopharyn-geal carcinoma cells.After injecting the p21MB into nasopharyngeal carcinoma cell and p33-trans-fected nasopharyngeal carcinoma cell,the consistent increase of fluorescent signal intensity was de-tected in both cell lines,and maximum fluorescence intensity achieved in about 15 min.In about 4 min following microinjection,the fluorescence increasing rate was significantly different between these two cell lines,which indicate the different p21 mRNA expression levels.The results obtained in the real-time detection were also validated by RT-PCR.Analysis of the initial fluorescence increasing rate can effi-ciently reduce the side effect of enzyme and improve the accuracy in living cell mRNA detection.