Altered Splicing in Stable Cell Strains Expressing Mini-hF9 Gene with Nonsense Mutation / 中国实验血液学杂志

OBJECTIVE@#To investigate the molecular mechanism in stable cell strains expressing Mini-hF9 gene with nonsense mutation.@*METHODS@#Mini-hF9 gene and its nonsense mutants were transfected into HeLa cells independently, and stable cell strains were obtained after G418 resistance screening and monoclonal transformation. The altered splicing and protein expression of mRNA in Mini-hF9 gene in stable cell strains were detected by using RT-PCR and Western blot.@*RESULTS@#The wild type and nonsense mutated human coagulation factor IX stable cell strains were constructed successfully, which were named HeLa-F9-WT, HeLa-F9-M1 and HeLa-F9-M2. Only normal splicing Norm was detected in the wild-type cell strain HeLa-F9-WT; Norm and Alt-S1 splicing were detected in HeLa-F9-M1; while Norm, Alt-S1 and Alt-S2 splicing were detected in HeLa-F9-M2.@*CONCLUSION@#The nonsense associated altered splicing (NAS) pathway, which generated alternately spliced transcripts, might be triggered in coagulation factor IX gene with nonsense mutation.

Construction and significance of recombinant hF9 minigene and its stable nonsense mutant cell lines / 中国实验血液学杂志

This study was purposed to construct the recombinant hF9 minigene and its stable nonsense mutant cell lines, and to investigate its significance. Minigene hF9 was cloned into the mammalian expression vector pCMV-Tag3B; a nonsense mutant containing a premature termination codon (PTC) in the 121(st) amino acid residue was obtained by PCR site-directed mutagenesis; minigene hF9 and nonsense mutant were respectively transfected into HepG2 cells with G418 treatment to get stable HepG2-WT and HepG2-N cell lines. The results confirmed that the minigene hF9 and nonsense mutant were constructed successfully. The gene of interest was amplified by RT-PCR from the stable cell lines, and the minigene hF9 was expressed in the stable cell lines. It is concluded that the recombinant hF9 minigene and its stable nonsense mutant cell lines are constructed successfully. The cell lines can be used to screen the drugs treating the nonsense mutation-caused hemophilia according to PTC read-through approaches.

Construction of nonsense-mutated eukaryotic expression vector of factor IX gene and its expression in COS-7 cells / 中国实验血液学杂志

The purpose of this study was to construct 4 types of nonsense-mutated eukaryotic expression plasmids of fIX gene, using pcDNA3.1 plasmid containing fIX cDNA as template, and to identify, then to perform their expression in COS-7 cells. These stop mutants constructed by site-directed mutagenesis based on PCR, and further confirmed by DNA sequencing. COS-7 cells were transfected with either the wild-type or mutated fIX expression constructs, then the relative expression levels of fIX mRNA were detected by real time fluorescent quantitative PCR. The result showed that except the designed sites, there were no other nucleotide mutation in the sequences of four nonsense mutants. The results of real time PCR proved that the nonsense-mutated vectors can be effectively expressed in COS-7 cells. It is concluded that the nonsense-mutated eukaryotic expression vectors of fIX gene have been successfully constructed and can express in COS-7 cells, which provides the material basis for further researches on mechanism and treatment of FIX deficiency and the function defects caused by nonsense mutation.