Sox9 regulates alternative splicing and pancreatic beta cell function [human]
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE245404 | GEO | 2023/10/18
REPOSITORIES: GEO
Similar Datasets
Project description:Type 2 Diabetes Mellitus (T2D), a multifactorial disease, can result from perturbations in numerous pancreatic genes. We describe a previously unanticipated role for Sox9, a transcriptional regulator of embryonic pancreas and endocrine cell development, in mature beta cells. Our data demonstrate that Sox9 has continued function in beta cells as they mature, and elimination of Sox9 compromises beta cell activities. Sox9-depleted rodent beta cells fail to appropriately secrete insulin and exhibit glucose intolerance in aging animals, mimicking the progressive degeneration observed in T2D. Human beta cells lacking SOX9 are functionally impaired with stunted first phase insulin secretion. In both rodent and human, Sox9 loss in beta cells disrupts alternative splicing patterns, with significant implications for maintenance of cellular function. Thus, our data uncover a novel, unprecedented role for a developmental transcription factor in mature beta cell function.
2023-10-18 | GSE245405 | GEO
Project description:The Endoplasmic Reticulum (ER) unfolded protein response (UPRer) pathway plays an important role for pancreatic β cells to adapt their cellular responses to environmental cues and metabolic stress. Although altered UPRer gene expression appears in rodent and human type 2 diabetic (T2D) islets, the underlying molecular mechanisms remain unknown. We show here that germ-line and β-cell specific disruption of the lysine acetyltransferase 2B (Kat2b) gene in mice leads to impaired insulin secretion and glucose intolerance. Genome wide analysis of Kat2b-regulated genes and functional assays revealed a critical role for KAT2B in maintaining UPRer gene expression and subsequent β-cell function. Importantly, Kat2b expression was decreased in db/db and in human T2D islets and correlated with UPRer genes in normal human islets. In conclusion, KAT2B is a crucial transcriptional regulator for adaptive β-cell function during metabolic stress by controlling UPRer and represents a promising target for T2D prevention and treatment
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Project description:Obesity-linked type 2 diabetes (T2D) is a major health problem of global epidemic proportions. The onset of T2D is marked by an eventual failure in pancreatic β-cell function and mass that is no longer able to compensate for the inherent insulin resistance and increased metabolic load intrinsic to obesity. However, β-cells have an inbuilt adaptive flexibility enabling them to effectively adjust insulin production rates relative to the metabolic demand. In a commonly used model of obesity-linked T2D, the db/db mouse, we have recently shown that so-called β-cell dysfunction is symptomatic of a marked increase in insulin production attempting to compensate for increased metabolic load. Pancreatic β-cells from these animals have markedly reduced intracellular insulin stores, yet high rates of (pro)insulin secretion (illustrated by severe chronic hyperinsulinemia), together with a substantial increase in proinsulin biosynthesis highlighted by expanded rough endoplasmic reticulum and Golgi apparatus. However, when the metabolic overload and/or hyperglycemia is normalized, β-cells from db/db mice quickly restore their insulin stores and normalize secretory function. This demonstrates the β-cell’s adaptive flexibility and indicates that therapeutic approaches applied to encourage β-cell rest are capable of restoring endogenous β-cell function. However, mechanisms that regulate β-cell adaptive flexibility are essentially unknown. To gain deeper mechanistic insight into the molecular events underlying β-cell adaptive flexibility in db/db β-cells, we conducted a combined proteomic and post-translational modification specific proteomic (PTMomics) approach on islets from db/db mice and wild-type controls (WT) with or without prior exposure to normal glucose levels. We identified differential modifications of proteins involved in cell redox homeostasis, protein refolding, protein K48-linked deubiquitination, mRNA/protein export along the microtubules, focal adhesion, ERK1/2 signaling, and renin-angiotensin-aldosterone signaling, as well as phosphorylation-regulated sialyltransferase activity, associated with β-cell adaptive flexibility. These proteins are all related to proinsulin biosynthesis and processing, maturation of insulin secretory granules, and vesicular trafficking—core pathways involved in the adaptation of insulin production to meet metabolic demand. Collectively, this study outlines a novel and comprehensive global proteome and PTMome signaling map that highlights important molecular mechanisms related to the adaptive flexibility of β-cell function, providing improved insight into disease pathogenesis of T2D.
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Project description:Insufficient insulin release by β-cells is the primary etiology in type 2 diabetes (T2D) and coincides with impaired expression of genes essential to β-cell function, but drivers of gene expression dysregulation are not well resolved. We find that H3K4me3 peak breadth correlates with gene expression dysregulation in T2D. Using an adult β-cell Dpy30-KO mouse model, we show that global reduction of H3K4 methylation causes downregulation of genes also downregulated in T2D. Reduction of H3K4 methylation increases transcriptional entropy and reduces insulin production and glucose-responsiveness. Depletion of H3K4 methylation causes global dilution of epigenetic complexity but does not generally reduce gene expression – instead, genes related to β-cell function and/or in particular chromatin environments are specifically affected. Our data further suggests that promoter-associated H3K4me1 is sufficient to maintain expression in the absence of H3K4me3. These data implicate dysregulation of H3K4 methylation in destabilizing gene expression and contributing to β-cell dysfunction in T2D.
2022-08-11 | GSE181950 | GEO
Project description:Insufficient insulin release by β-cells is the primary etiology in type 2 diabetes (T2D) and coincides with impaired expression of genes essential to β-cell function, but drivers of gene expression dysregulation are not well resolved. We find that H3K4me3 peak breadth correlates with gene expression dysregulation in T2D. Using an adult β-cell Dpy30-KO mouse model, we show that global reduction of H3K4 methylation causes downregulation of genes also downregulated in T2D. Reduction of H3K4 methylation increases transcriptional entropy and reduces insulin production and glucose-responsiveness. Depletion of H3K4 methylation causes global dilution of epigenetic complexity but does not generally reduce gene expression – instead, genes related to β-cell function and/or in particular chromatin environments are specifically affected. Our data further suggests that promoter-associated H3K4me1 is sufficient to maintain expression in the absence of H3K4me3. These data implicate dysregulation of H3K4 methylation in destabilizing gene expression and contributing to β-cell dysfunction in T2D.
2022-08-11 | GSE181949 | GEO
Project description:Dedifferentiation of pancreatic beta cells may reduce islet function in type 2 diabetes (T2D). However, the prevalence, plasticity and functional consequences of this cellular state remain unknown. We employed single-cell RNAseq to detail the maturation program of alpha and beta cells during human ontogeny. We show that although both alpha and beta cells mature in part by repressing non-endocrine genes, alpha-cells retain hallmarks of an immature state, while beta-cells attain a full beta-cell specific gene expression program. In islets from T2D donors, both alpha- and beta-cells return to a less mature expression profile, de-repressing the juvenile genetic program and exocrine genes while increasing expression of exocytosis, inflammation and stress response signaling pathways. These changes support the increased proportion of beta-cells displaying suboptimal function observed in T2D islets. These findings provide new insights into the molecular program underlying islet cell maturation during human ontogeny and the loss of transcriptomic maturity that occurs in islets of type 2 diabetics.
2020-10-01 | GSE154126 | GEO
Project description:Whether amino acids act on cellular insulin signaling remains unclear, given that increased circulating amino acid levels are associated with the onset of type 2 diabetes (T2D). Here, we report that phenylalanine modifies insulin receptor beta (IRβ) and inactivates insulin signaling and glucose uptake. Mice fed phenylalanine-rich chow or phenylalanine-producing aspartame or overexpressing human phenylalanyl-tRNA synthetase (hFARS) developed insulin resistance and T2D symptoms. Mechanistically, FARS phenylalanylated lysine 1057/1079 of IRβ (F-K1057/1079), inactivating IRβ and preventing insulin from promoting glucose uptake by cells. SIRT1 reversed F-K1057/1079 and counteracted the insulin-inactivating effects of hFARS and phenylalanine. F-K1057/1079 and SIRT1 levels in white blood cells from T2D patients wereare positively and negatively correlated with T2D onset, respectively. Blocking F-K1057/1079 with phenylalaninol sensitizeds insulin signaling and relieveds T2D symptoms in hFARS-transgenic and db/db mice. These findings shed light on the activation of insulin signaling and T2D progression through inhibition of phenylalanylation.
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2023-01-09 | GSE218047 | GEO
Project description:Immature β-cells are present in adult islets. However, their contribution to insulin release is not fully understood. Here we show that specific loss of immature β-cells induces failure throughout the β-cell complement. Functional mapping of the β-cell population in rodent and human loss-of-immaturity islets revealed defects in metabolism, ionic fluxes and insulin secretion. At the transcriptomic level, loss of immature β-cells led to dysregulation of gene pathways involved in glucose and carbohydrate-derivative metabolic processes. Using a chemogenetic disruption strategy, immature β-cells were found to depend on the islet signaling network for their phenotype. During metabolic stress, islet function could be restored by redressing the balance between immature and mature β-cells. We thus unveil immature β-cells as a critical component in islet operation. Preserving immature β-cells might be important for islet engineering efforts and more broadly the treatment of type 1 and type 2 diabetes.
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