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Mol Metab. 2019 Jun;24:80-97. doi: 10.1016/j.molmet.2019.03.006. Epub 2019 Mar 20.

Point mutations in the PDX1 transactivation domain impair human β-cell development and function.

Author information

1
Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; Institute of Stem Cell Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; Technische Universität München, Ismaningerstraße 22, 81675 München, Germany.
2
Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; Institute of Stem Cell Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany.
3
Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany.
4
Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Zentrum München at the University of Tübingen, 72076 Tübingen, Germany; Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, University of Tübingen, 72076 Tübingen, Germany; German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany.
5
Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Zentrum München at the University of Tübingen, 72076 Tübingen, Germany; Institute of Pharmaceutical Sciences, Department of Pharmacy and Biochemistry, Eberhard Karls University Tübingen, 72076 Tübingen, Germany; German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany.
6
Biomedical Center and Center for Integrated Protein Science Munich, Ludwig-Maximilians-University, 82152 Planegg-Martinsried, Germany.
7
Institute of Experimental Genetics, Helmholtz Zentrum München, 85764 Neuherberg, Germany.
8
German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; Institute of Experimental Genetics, Helmholtz Zentrum München, 85764 Neuherberg, Germany; Chair of Experimental Genetics, School of Life Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany.
9
Vanderbilt University Program in Developmental Biology, Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN 37232, USA.
10
Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; Institute of Stem Cell Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany.
11
Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; Institute of Stem Cell Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; Technische Universität München, Ismaningerstraße 22, 81675 München, Germany; German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany. Electronic address: heiko.lickert@helmholtz-muenchen.de.

Abstract

OBJECTIVE:

Hundreds of missense mutations in the coding region of PDX1 exist; however, if these mutations predispose to diabetes mellitus is unknown.

METHODS:

In this study, we screened a large cohort of subjects with increased risk for diabetes and identified two subjects with impaired glucose tolerance carrying common, heterozygous, missense mutations in the PDX1 coding region leading to single amino acid exchanges (P33T, C18R) in its transactivation domain. We generated iPSCs from patients with heterozygous PDX1P33T/+, PDX1C18R/+ mutations and engineered isogenic cell lines carrying homozygous PDX1P33T/P33T, PDX1C18R/C18R mutations and a heterozygous PDX1 loss-of-function mutation (PDX1+/-).

RESULTS:

Using an in vitro β-cell differentiation protocol, we demonstrated that both, heterozygous PDX1P33T/+, PDX1C18R/+ and homozygous PDX1P33T/P33T, PDX1C18R/C18R mutations impair β-cell differentiation and function. Furthermore, PDX1+/- and PDX1P33T/P33T mutations reduced differentiation efficiency of pancreatic progenitors (PPs), due to downregulation of PDX1-bound genes, including transcription factors MNX1 and PDX1 as well as insulin resistance gene CES1. Additionally, both PDX1P33T/+ and PDX1P33T/P33T mutations in PPs reduced the expression of PDX1-bound genes including the long-noncoding RNA, MEG3 and the imprinted gene NNAT, both involved in insulin synthesis and secretion.

CONCLUSIONS:

Our results reveal mechanistic details of how common coding mutations in PDX1 impair human pancreatic endocrine lineage formation and β-cell function and contribute to the predisposition for diabetes.

KEYWORDS:

Insulin secretion; PDX1; PDX1-Bound genes; Transactivation domain; β-Cell differentiation

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