Rfx6 directs islet formation and insulin production in mice and humans

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Insulin from the β-cells of the pancreatic islets of Langerhans controls energy homeostasis in vertebrates, and its deficiency causes diabetes mellitus. During embryonic development, the transcription factor neurogenin 3 (Neurog3) initiates the differentiation of the β-cells and other islet cell types from pancreatic endoderm, but the genetic program that subsequently completes this differentiation remains incompletely understood. Here we show that the transcription factor Rfx6 directs islet cell differentiation downstream of Neurog3. Mice lacking Rfx6 failed to generate any of the normal islet cell types except for pancreatic-polypeptide-producing cells. In human infants with a similar autosomal recessive syndrome of neonatal diabetes, genetic mapping and subsequent sequencing identified mutations in the human RFX6 gene. These studies demonstrate a unique position for Rfx6 in the hierarchy of factors that coordinate pancreatic islet development in both mice and humans. Rfx6 could prove useful in efforts to generate β-cells for patients with diabetes.

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Figure 1: Expression of Rfx6 in mice and human tissues.
Figure 2: Expression of Rfx6 in mice.
Figure 3: Targeting of the Rfx6 gene in mice.
Figure 4: Expression patterns of islet markers in wild-type and Rfx6 eGFPcre/eGFPcre mice at E17.5.
Figure 5: Function of the human Rfx6 protein.


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We thank all the patients and their families for the participation in this study and P. Riley for allowing us access to her clinical data. We thank G. Grodsky, G. Bell, W. Rutter, R. Gasa and members of the German laboratory for discussions, F. Schaufle and the DERC Microscopy Core Laboratory, C. Mrejen and the UCSF DERC Genomics Core, N. Killeen and the UCSF DERC Transgenic Core Laboratory for help with the generation of the Rfx6-targeted mice, R. Koshy for technical assistance, Y. Zhang and S. Zhao for assistance with mouse husbandry and genotyping, the Massively Parallel Sequencing team at the McGill University and Genome Quebec Innovation Center for DNA sequencing and J. Wasserscheid for bioinformatics analyses. This work was supported by grants from the Larry L. Hillblom Foundation (S.B.S. and M.S.G.), the Juvenile Diabetes Research Foundation (S.B.S., F.C.L., T.M., R.W., C.P. and M.S.G.), the American Diabetes Association (M.S.G.), the Nora Eccles Treadwell Foundation (M.S.G.), the Canadian Institutes of Health Research (H.-Q.Q.), and the National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (M.S.G.).

Author Contributions S.B.S., H.-Q.Q., N.T., N.Y.K., D.W.S., F.C.L., K.D., R.W., C.P. and M.S.G. wrote the paper. K.D., C.P. and M.S.G. oversaw the studies. S.B.S., D.W.S., Y.L., J.Wa., T.M., R.W., M.-E.W. and J.D.J. performed mRNA expression analyses. N.Y.K., D.W.S. and J.Wa. performed immunofluorescence studies. S.B.S., F.C.L. and R.S. performed Rfx6 gene targeting studies. S.B.S. performed DNA binding and transcription studies. H.-Q.Q. performed homozygosity mapping. N.T., R.G., K.D. and J.Wa. performed Nimblegen array and sequencing studies. A.-M.P., J.M, J.D, S.V.E., M.A., N.Ka., J.We., M.-E.R., M.G., I.H. and A.T.H. recruited the human subjects and provided phenotypic information. H.-Q.Q. and N.T. contributed equally to this work; N.Y.K. and D.W.S. contributed equally to this work.

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Correspondence to Constantin Polychronakos or Michael S. German.

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Competing interests

Competing interests: M.S.G. is an inventor on patents held by the University of California covering Neurog3 and its use.

Supplementary information

Supplementary Information

This file contains Supplementary Figures S1-S17 with Legends, Supplementary Notes for the Human Mapping and Supplementary Tables S1-S5 and S7-S8. (PDF 7605 kb)

Supplementary Table S6

This table shows the expression of genes in the region of homozygosity by descent. (XLS 396 kb)

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