Reprogramming of enteroendocrine K cells to pancreatic β-cells through the combined expression of Nkx6.1 and Neurogenin3, and reaggregation in suspension culture
Highlights: •K cells were selected from STC-1 cells, a heterogeneous enteroendocrine cell line. •K cells did not express Nkx6.1 and Neurogenin3. •Combined expression of Nkx6.1 and Neurogenin3 reprogrammed K cells to β-cells. •Reprogramming of K cells to β-cells was not complete. -- Abstract: Recent studies have demonstrated that adult cells such as pancreatic exocrine cells can be converted to pancreatic β-cells in a process called cell reprogramming. Enteroendocrine cells and β-cells share similar pathways of differentiation during embryonic development. Notably, enteroendocrine K cells express many of the key proteins found in β-cells. Thus, K cells could be reprogrammed to β-cells under certain conditions. However, there is no clear evidence on whether these cells convert to β-cells. K cells were selected from STC-1 cells, an enteroendocrine cell line expressing multiple hormones. K cells were found to express many genes of transcription factors crucial for islet development and differentiation except for Nkx6.1 and Neurogenin3. A K cell clone stably expressing Nkx6.1 (Nkx6.1{sup +}-K cells) was established. Induction of Neurogenin3 expression in Nkx6.1{sup +}-K cells, by either treatment with a γ-secretase inhibitor or infection with a recombinant adenovirus expressing Neurogenin3, led to a significant increase in Insulin1 mRNA expression. After infection with the adenovirus expressing Neurogenin3 and reaggregation in suspension culture, about 50% of Nkx6.1{sup +}-K cells expressed insulin as determined by immunostaining. The intracellular insulin content was increased markedly. Electron microscopy revealed the presence of insulin granules. However, glucose-stimulated insulin secretion was defective, and there was no glucose lowering effect after transplantation of these cells in diabetic mice. In conclusion, we demonstrated that K cells could be reprogrammed partially to β-cells through the combined expression of Nkx6.1 and Neurogenin3, and reaggregation in suspension culture.