Regulation of insulin biosynthesis in non-beta cells by a heat shock promoter

Insulin production under the stringent control is the main issue in gene-based therapeutic strategies directed to type 1 diabetes. As a novel approach, inducible promoters may provide a promising tool for this purpose. In this study, we hypothesize that this control may be achieved via a promoter derived from the heat shock multigene family, Hsp70 A1A, which is inducible at 42°C. To yield mature insulin in transfected fibroblasts (3T3/NIH), a recombinant human insulin gene consisting of sequences corresponding to furin cleavable sites was fused to the promoter. Heat-stimulated cells initiated to release biologically active insulin within 30 min with a ten-fold increase after 24 h. The role of upstream regulatory elements of the promoter on its activity in heat stress conditions was examined. No significant difference between the activity of the minimal and full-length promoters was observed. This promoter exhibited low basal expression in non-inducing conditions. Results indicate that this promoter is responsive to a heat induction after approximately 30 min which causes an efficient insulin production over a relatively short period of time. These potential features of this promoter may provide an insight to control the insulin production in vivo upon an external and physical stimulation.