Human β-interferon is used extensively as a therapeuticagent in a wide variety of diseases, ranging from multi-ple sclerosis to viral infections. At present, the mostcommon source of interferon-β is derived from CHO(Chinese-hamster ovary) cells. Interestingly, however,the IFNB gene is characterized by a lack of intronicsequences and therefore does not undergo splicingduring its expression pathway. As nuclear processing ofpre-mRNA molecules has often been demonstrated toimprove production yields of recombinant molecules,we have inserted a heterologous intronic sequence atdifferent positions within the IFNB gene and analysedits effects on protein production. The results obtainedin the present study show that the position of introninsertion has profound effects on the expressionlevels of the IFNB gene and on the nuclear/cytoplasmdistribution levels of its mRNA as determined by FISH(fluorescent in situ hybridization) analysis of stablytransfected clones. In conclusion, our results provideadditional evidence that insertion of intronic sequencesmay be used to improve protein expression efficiencyalso in molecules that do not normally undergo anysplicing process.
