Foxo1-Expressing Cells in the Gut as a Source of Insulin for Diabetes Treatment

Abstract

The hallmark of type 1 diabetes is the irreversible destruction of insulin-secreting β-cells in the pancreas. Consequently, an attractive therapeutic approach is to trigger the regeneration of functional β-cells elsewhere within a diseased individual. We have previously demonstrated that removal of Foxo1 in Neurogenin3 (Ngn3)-expressing cells creates functional insulin-secreting cells within the intestine. The cells, however, only convert into insulin+ cells at a low frequency, limiting their therapeutic potential. Using a novel knock-in reporter mouse that encodes a Foxo1-Venus fusion protein (FoxV), we have identified a novel population of Foxo1-expressing cells in the glandular epithelium of the stomach. These cells are distinct from other gut FoxV+ cells in that, unlike Foxo1+ cells in the intestine, stomach FoxV+ cells rarely express serotonin. To identify the nature of Foxo1+ stomach cells, we next isolated single cells from stomach and, using flow cytometry and qPCR, analyzed the gene expression of FoxV+ cells. Although Foxo1-positive cells do not express markers of chief, pit, or neck cells, they have increased transcript levels of the parietal cell marker H+/K+ ATPase. We further validated these results by immunofluorescence and FACS. To determine if elimination of Foxo1 can convert stomach cells to insulin-producing cells, we next ablated Foxo1 in either Ngn3+ or parietal cells in mice using cre-mediated recombination. Strikingly, we detected cells positive for insulin and C-peptide in the stomach of mice harboring Foxo1 deletion. Similarly, when we inactivated Foxo1 in primary stomach cultures, we detected markedly increased “β-like” gene expression and insulin+, C-peptide+ cells. Taken together we have identified a new population of Foxo1-expressing cells in the stomach and demonstrated that Foxo1 ablation is sufficient to convert these cells to insulin-producing cells. Disclosure W. McKimpson: None. T. Kuo: None. D. Accili: None.