Figure 6

Comparison of hiPSC-derived insulin-producing cells and human islets suggesting missing molecular landscape involved in β-cell fate. For the differentiation of patient-specific S7 insulin-producing cells, we reprogrammed skin fibroblasts from four donors from the same family (n = 4), including a parental diabetic mutation carrier, and three offspring; one diabetic mutation carrier, one non-diabetic mutation carrier, and non-diabetic non-mutation carrier (family control). We found that positive HNF4A mutation status does not prevent the formation of insulin positive S7 cells. However, in agreement with previous reports, these S7 cells are immature and require further maturation to become fully functional β-like cells. Specifically addressing this absent maturation of S7 cells, we show that the careful assessment of the proteome of these differentiating cells compared to the human islet proteome can be exploited to detect factors that are deficient or overexpressed, factors that might enable the in vitro maturation towards fully functional β-cells. The human islets specific proteome landscape predicted HNF1α and PPARγ as upstream regulators important for β-cell identity and function. A similar analysis of the S7-cells-specific proteome landscape predicted TP53 and MYC as upstream regulators transcription factors involved in cell cycle progression. These results suggest that the S7 cells contain a significant fraction of proliferating cells. Moreover, as indicated by the human islets specific proteome landscape analysis, the S7 cells are also missing critical networks required for β-cell identity and function.