MicroRNAs (short non-coding RNAs that post-transcriptionally silence target mRNAs) are essential for early pancreas development. But how specific microRNAs are intertwined into the transcriptional network that controls endocrine differentiation is poorly understood. On , Eran Hornstein and colleagues investigate the involvement of miR-7, which is highly expressed in the endocrine pancreas of several vertebrates, during mouse endocrine cell differentiation. They show that miR-7 is expressed in mouse endocrine precursors and mature endocrine cells, and that the transcription factor Pax6, which is required for endocrine cell differentiation, is an important miR-7 target. The overexpression of miR-7 in developing pancreas explants or in transgenic mice downregulates Pax6 and inhibits α- and β-cell differentiation, they report, whereas miR-7 knockdown has opposite effects. Notably, Pax6 downregulation reverses the effects of miR-7 knockdown on insulin promoter activity. These findings, which suggest that miR-7 and Pax6 are wired into a transcriptional network that ensures the precise control of endocrine cell differentiation, may help in the development of cell-based therapies for diabetes.
