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      Klf6 protects β-cells against insulin resistance-induced dedifferentiation

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          Abstract

          Objectives

          In the pathogenesis of type 2 diabetes, development of insulin resistance triggers an increase in pancreatic β-cell insulin secretion capacity and β-cell number. Failure of this compensatory mechanism is caused by a dedifferentiation of β-cells, which leads to insufficient insulin secretion and diabetic hyperglycemia. The β-cell factors that normally protect against dedifferentiation remain poorly defined. Here, through a systems biology approach, we identify the transcription factor Klf6 as a regulator of β-cell adaptation to metabolic stress.

          Methods

          We used a β-cell specific Klf6 knockout mouse model to investigate whether Klf6 may be a potential regulator of β-cell adaptation to a metabolic stress.

          Results

          We show that inactivation of Klf6 in β-cells blunts their proliferation induced by the insulin resistance of pregnancy, high-fat high-sucrose feeding, and insulin receptor antagonism. Transcriptomic analysis showed that Klf6 controls the expression of β-cell proliferation genes and, in the presence of insulin resistance, it prevents the down-expression of genes controlling mature β-cell identity and the induction of disallowed genes that impair insulin secretion. Its expression also limits the transdifferentiation of β-cells into α-cells.

          Conclusion

          Our study identifies a new transcription factor that protects β-cells against dedifferentiation, and which may be targeted to prevent diabetes development.

          Highlights

          • Absence of Klf6 in β-cells leads to a reduction in their proliferation and mass during insulin resistance development.

          • Insulin receptor blockade by S961 leads to a greater dedifferentiation state in β-cell-specific Klf6 knockout mice.

          • Insulin receptor antagonism leads to enhanced β-cell to α-cell transdifferentiation in β-cell-specific Klf6 knockout mice.

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          Most cited references50

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          TIGAR, a p53-Inducible Regulator of Glycolysis and Apoptosis

          The p53 tumor-suppressor protein prevents cancer development through various mechanisms, including the induction of cell-cycle arrest, apoptosis, and the maintenance of genome stability. We have identified a p53-inducible gene named TIGAR (TP53-induced glycolysis and apoptosis regulator). TIGAR expression lowered fructose-2,6-bisphosphate levels in cells, resulting in an inhibition of glycolysis and an overall decrease in intracellular reactive oxygen species (ROS) levels. These functions of TIGAR correlated with an ability to protect cells from ROS-associated apoptosis, and consequently, knockdown of endogenous TIGAR expression sensitized cells to p53-induced death. Expression of TIGAR may therefore modulate the apoptotic response to p53, allowing survival in the face of mild or transient stress signals that may be reversed or repaired. The decrease of intracellular ROS levels in response to TIGAR may also play a role in the ability of p53 to protect from the accumulation of genomic damage.
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            Pancreatic β cell dedifferentiation as a mechanism of diabetic β cell failure.

            Diabetes is associated with β cell failure. But it remains unclear whether the latter results from reduced β cell number or function. FoxO1 integrates β cell proliferation with adaptive β cell function. We interrogated the contribution of these two processes to β cell dysfunction, using mice lacking FoxO1 in β cells. FoxO1 ablation caused hyperglycemia with reduced β cell mass following physiologic stress, such as multiparity and aging. Surprisingly, lineage-tracing experiments demonstrated that loss of β cell mass was due to β cell dedifferentiation, not death. Dedifferentiated β cells reverted to progenitor-like cells expressing Neurogenin3, Oct4, Nanog, and L-Myc. A subset of FoxO1-deficient β cells adopted the α cell fate, resulting in hyperglucagonemia. Strikingly, we identify the same sequence of events as a feature of different models of murine diabetes. We propose that dedifferentiation trumps endocrine cell death in the natural history of β cell failure and suggest that treatment of β cell dysfunction should restore differentiation, rather than promoting β cell replication. Copyright © 2012 Elsevier Inc. All rights reserved.
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              Glucolipotoxicity: fuel excess and beta-cell dysfunction.

              Glucotoxicity, lipotoxicity, and glucolipotoxicity are secondary phenomena that are proposed to play a role in all forms of type 2 diabetes. The underlying concept is that once the primary pathogenesis of diabetes is established, probably involving both genetic and environmental forces, hyperglycemia and very commonly hyperlipidemia ensue and thereafter exert additional damaging or toxic effects on the beta-cell. In addition to their contribution to the deterioration of beta-cell function after the onset of the disease, elevations of plasma fatty acid levels that often accompany insulin resistance may, as glucose levels begin to rise outside of the normal range, also play a pathogenic role in the early stages of the disease. Because hyperglycemia is a prerequisite for lipotoxicity to occur, the term glucolipotoxicity, rather than lipotoxicity, is more appropriate to describe deleterious effects of lipids on beta-cell function. In vitro and in vivo evidence supporting the concept of glucotoxicity is presented first, as well as a description of the underlying mechanisms with an emphasis on the role of oxidative stress. Second, we discuss the functional manifestations of glucolipotoxicity on insulin secretion, insulin gene expression, and beta-cell death, and the role of glucose in the mechanisms of glucolipotoxicity. Finally, we attempt to define the role of these phenomena in the natural history of beta-cell compensation, decompensation, and failure during the course of type 2 diabetes.
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                Author and article information

                Contributors
                Journal
                Mol Metab
                Mol Metab
                Molecular Metabolism
                Elsevier
                2212-8778
                2212-8778
                06 February 2020
                May 2020
                06 February 2020
                : 35
                : 100958
                Affiliations
                [1 ]Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
                [2 ]Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
                Author notes
                []Corresponding author. bernard.thorens@ 123456unil.ch
                Article
                S2212-8778(20)30030-2 100958
                10.1016/j.molmet.2020.02.001
                7093812
                32244185
                dac0babd-460a-4b44-bae2-0544d756916b
                © 2020 The Authors

                This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

                History
                : 12 December 2019
                : 30 January 2020
                : 2 February 2020
                Categories
                Original Article

                type 2 diabetes,insulin resistance,β-cell proliferation,dedifferentiation,transdifferentiation,klf6, krüppel-like factor 6,gsis, glucose-stimulated insulin secretion,hfhs, high-fat high sucrose,wgcna, weighted gene co-expression network analysis,rt-pcr, real-time polymerase chain reaction

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