Glucose-activated switch regulating insulin analogue secretion enables long-term precise glucose control in type 1 diabetes mice

Genetic modification of non-β cells to produce insulin is a promising therapeutic strategy for type 1 diabetes, however, it is associated with issues including biosafety and precise regulation of insulin supply. In this study, a glucose-activated single-strand insulin analogue (SIA) switch (GAIS) was constructed to achieve repeatable pulse activation of SIA secretion in response to hyperglycemia. In the GAIS system, the CAD-FCS-SIA fusion protein was encoded by the intramuscularly delivered plasmid and temporarily kept in the endoplasmic reticulum (ER) as it binds to the GRP78 protein, then upon hyperglycemia, SIA was released and secreted into the blood. In vitro and in vivo experiments systematically demonstrated the effects of the GAIS system, including glucose-activated and repeatable SIA secretion, long-term precise blood glucose control, recovered HbA1c level, improved glucose tolerance, and ameliorated oxidative stress. Additionally, this system offers sufficient biosafety as evidenced by the assays of immunological and inflammatory safety, ER stress, histological evaluation, etc. Compared with the viral delivery/expression system, the ex vivo implantation of engineered cells, and the exogenous inducer system, the GAIS system combined the advantages of biosafety, effectiveness, persistence, precision, and convenience, providing therapeutic potential for the treatment of type 1 diabetes.