Abstract
One of the conventional methods to study the effects of gene mutations is that gene mutants are transfected into mammalian cells, and the dominant effects of gene mutants in the cells are examined. However, the result obtained using this method is not always satisfactory due to the interference of endogenous expression. Whether there is a better method to investigate the effects of gene mutations in cells remains to be examined. In the present study, a novel dual expression lentiviral vector was constructed using a shRNA-expressing lentiviral vector and combined techniques. Using this dual expression system, the vectors expressing both transcription factor IIA γ (TFIIAγ) shRNA and HA-TFIIAγ or its mutants were generated, and the effects of TFIIAγ gene mutations on transcription and protein-DNA interaction were investigated. We show that the transfection of the vector expressing TFIIAγ shRNA and HA-TFIIAγ fusion gene was able to silence the expression of endogenous TFIIAγ gene but not affect that of exogenous HA-TFIIAγ fusion gene in either transiently transfected cells or stable cell lines. Mutations in the conservative domain between AA62 and AA69 in TFIIAγ inhibit the activities of promoters and endogenous gene expression, and reduce TFIIAγ binding to AdML core promoter compared with wild-type (WT) TFIIAγ. ChIP-qPCR data suggest that the TFIIAγ N63A mutant inhibits insulin-like growth factor 2 (IGF2) transcription by reducing the recruitments of TFIIAγ, polymerase II (Pol II), TATA box-binding protein (TBP), and TBP associated factor 1 (250 kDa) (TAF1) at its promoter. Our study provides a novel method that is used to investigate the effects of gene mutations at the cellular level.