Enhanced insulin secretion from engineered 3T3-L1 preadipocytes by induction of cellular differentiation.

Evidence from laboratory and animal studies provides groundwork for understanding mechanisms and potential before human studies continue.

• Level A · Stronger Clinical Evidence
• Level B · Emerging clinical evidence with positive signals
• Level C · Early human research exploring benefits
• Level D · Scientific groundwork from lab and animal studies
• Emerging · Emerging topic under active research

Abstract (original English)

We have established insulin-secreting cell line, L1-INS/fur cells, by engineering 3T3-L1 murine preadipocytes with human preproinsulin cDNA. Analysis with HPLC, mass spectrometry and immunological assay identified human insulin in the culture medium. Notably, secretion of insulin from L1-INS/fur cell was increased 8.2 times higher after induction of cellular differentiation. The increment of insulin secretion during differentiation was further enhanced by additive treatment with thiazolidinedione, a promoting agent of adipocyte differentiation. This observation strongly suggests that the enhancement of insulin secretion is tightly associated with cellular differentiation process itself. Expression rate of the insulin transgene was not changed after the additional treatment with thiazolidinedione. On the other hand, furin gene expression by Northern analysis showed an increase, and Western analysis revealed even more reduction in cellular content of proinsulin. These results indicate that mechanism of the observed enhancement in insulin secretion during the differentiation is mainly due to increased capacity of the proinsulin processing by induction of furin. Results of our present study will provide important information on cell-based therapy using undifferentiated progenitors and tissue stem cells.

Evidence level

Evidence from laboratory and animal studies provides groundwork for understanding mechanisms and potential before human studies continue.

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