Background: A protocol of differentiation form induced pluripotent stem cells (iPSCs) to hepatocytes has been previously reported, and such iPSCs-derived hepatocytes possessed morphological and biochemical characteristics similar to authentic hepatocytes. It is however unknown whether iPSCs-derived hepatocytes normally respond to metabolic regulatory hormones including insulin. Mutations in the gene for p85α subunit of PI3K (PIK3R1), an essential element of insulin action, give rise to severe insulin resistance in human. Such cases are very rare, and only ∼30 families with PIK3R1 mutations have been reported as of today.
Methods and Results: We established a protocol of differentiation from iPSCs to hepatocytes that respond to insulin. In hepatocytes differentiated from iPSCs derived from healthy subject with this protocol, phosphorylation of AKT and the expression of the lipogenic genes FASN as well as SREBF1c were induced by insulin. Furthermore, the expression of the gluconeogenic gene G6PC was upregulated by a combination of cAMP and dexamethasone, which was markedly impaired by the addition of insulin. We then generated iPSCs from a severe insulin resistant diabetic patient with the PIK3R1 c.1945C>T mutation, a hot-spot mutation in this gene. Insulin-induced gene expression along with phosphorylation of AKT was impaired in hepatocytes differentiated from the patient-derived iPSCs. We also repaired the mutation of PIK3R1 in the patient-derived iPSCs by the CRISPR/Cas9 genome editing. Insulin responsiveness was recovered in hepatocytes differentiated from the resultant iPSCs in which the mutation was repaired.
Conclusion: We established a differentiation protocol of hepatocytes in which insulin’s metabolic actions can be evaluated. The usefulness of this protocol was validated with the use of iPSCs derived from a severe insulin-resistant patient with PIK3R1 mutation.
T. Hamaguchi: None. Y. Hirota: Other Relationship; Self; Sanofi. T. Takeuchi: None. M. Koyanagi-Aoi: None. T. Aoi: None. W. Ogawa: Research Support; Self; Astellas Pharma Inc., Boehringer Ingelheim Pharma GmbH & Co.KG, Eli Lilly Japan K.K., Kowa Company, Ltd., Nippon Boehringer Ingelheim Co. Ltd., Novo Nordisk Inc., Ono Pharmaceutical Co., Ltd., Sumitomo Dainippon Pharma Co., Ltd. Other Relationship; Self; Sumitomo Dainippon Pharma Co., Ltd., Takeda Pharmaceutical Company Limited.