Control of proinsulin production by sense-anti-sense regulation in response to glucocorticoids

Abstract

One difficulty involved in gene therapy for diabetes is a control of proinsulin production by the cells transfected with insulin cDNA. The introduction of a feedback mechanism to control the expression of the introduced gene based on the host's need for insulin is one possible treatment approach. To control proinsulin production at a transcriptional level, we introduced a glucocorticoid responsive promoter in the 3' region of insulin cDNA in reverse orientation (pBCMGS-neo-Ins-invMMTV) so that antisense insulin mRNA is produced in response to glucocorticoids. When fibroblasts transfected with pBCMGSneo-Ins-invMMTV were cultured with 1 × 10 −5 M dexainethazone, two of nine clones showed a 10–20% reduction in proinsulin production. On the other hand, all clones of the cells transfected with a control vector containing human insulin cDNA (pBCMGS-neo-Ins) showed an 20–80% increase of proinsulin production when cultured with dexamethazone because of the increase of protein synthesis by glucocorticoids. These data indicated that antisense insulin mRNA effectively suppressed the transcription of insulin cDNA in response to glucocorticoids. This sense-antisense regulation system may make it feasible to induce an feed-back mechanism to control proinsulin production based on the blood glucose concentration.