In vitro and computational studies on the effects of ARE deletion and targeted mutations on the expression of interferon beta-1a in HEK293T cells.

Abstract

Interferon beta (IFNβ) is transiently expressed in response to viral infections and widely used to treat relapsing-remitting multiple sclerosis (MS). We introduced mutations in the IFNβ gene (in the 27th and 101st codons and in the Kozak sequence, and also deletion of 3' and 5' unstable, untranslated region, UTR) with the aim of increasing the expression of IFNβ. Computational analyses of mutant and wild-type RNAs and proteins of IFNβ by RNAfold, ASAView, HOPE and Ramachandran plot, and iStable web servers showed that the mutations could decrease RNA stability, protein solvent accessibility, and protein stability but could not change correct folding. Two recombinant IFNβ101 and IFNβ101+27 constructs were designed by site-directed mutagenesis. The wild-type IFNβ gene also was used as a control. In vitro experiments by quantitative real-time PCR, dot blot, SDS-PAGE, and Western blot assays showed an increased expression level of recombinant IFNβs. 79.9-fold, 99.7-fold, and 190-fold elevations in the mRNA expression of IFNβw, IFNβ101, and IFNβ101+27 were seen, respectively, in comparison with the endogenous IFNβ mRNA in untransfected HEK293T cells. The IFNβ mRNA expression was increased 2.38-fold and 1.25-fold for 101+27 and 101 mutated forms, respectively, in comparison with the IFNβ wild-type construct. An elevation in IFNβ protein production was also clearly detected in the transfected HEK293T cell containing recombinant IFNβ101 and IFNβ101+27 constructs. Finally, these directed mutations in the IFNβ gene successfully elevated protein and mRNA production but in silico analyses of mutant mRNAs showed decreased mRNA stability, unlike previous studies, in comparison with the wild-type mRNA.