Scientists have converted human gut cells into insulin producers by turning off a single gene in an experiment that suggests a novel way forward in treating diabetes.
Using a miniature model of the human intestine, only a few millimeters in size and made from stem cells, the scientists deactivated a gene in the cells tied to metabolic regulation called FOXO1. Once disabled, the cells began producing insulin.
The method, described today in the journal Nature Communications, raises the possibility of replacing insulin-making pancreatic beta cells lost in diabetics by using a drug to retrain patients’ existing cells. While progress has been made in generating beta cells from stem cells, the method hasn’t yet produced ones with all the needed functions, said Domenico Accili, the study’s lead author. Plus, such cells would require transplantation.
Forkhead box protein O1 (FOXO1) also known as forkhead in rhabdomyosarcoma is a protein that in humans is encoded by the FOXO1 gene.FOXO1 is a transcription factor that plays important roles in regulation of gluconeogenesis and glycogenolysis by insulin signaling, and is also central to the decision for a preadipocyte to commit to adipogenesis. It is primarily regulated through phosphorylation on multiple residues; its transcriptional activity is dependent on its phosphorylation state.
Recent research has demonstrated that FOXO1 also negatively regulates adipogenesis. Presently, the exact mechanism by which this is accomplished is not entirely understood. In the currently accepted model, FOXO1 negatively regulates adipogenesis by binding to the promoter sites of PPARG and preventing its transcription. Rising levels of PPARG are required to initiate adipogenesis; by preventing its transcription, FOXO1 is preventing the onset of adipogenesis.
During stimulation by insulin, FOXO1 is excluded from the nucleus and is subsequently unable to prevent transcription of PPARG and inhibit adipogenesis. However, there is substantial evidence to suggest that there are other factors that mediate the interaction between FOXO1 and the PPARG promoter, and that inhibition of adipogenesis is not entirely dependent on FOXO1 preventing transcription of PPARG. Other research demonstrates that the failure to commit to adipogenesis is primarily due to active FOXO1 arresting the cell in G0/G1 through activation of yet unknown downstream targets, with a putative target being SOD2