scholarly journals Species-Related Differences in the Proteome of Rat and Human Pancreatic Beta Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
G. A. Martens
Keyword(s):  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Redox Regulation ◽  
Radical Scavenging ◽  
Cell Subset ◽  
Glucose Sensing ◽  
Human Cells ◽  
Label Free ◽  
Human Beta Cells ◽  
Shock Proteins

The core proteomes of human and rat pancreatic beta cells were compared by label-free LC-MS/MS: this resulted in quantification of relative molar abundances of 707 proteins belonging to functional pathways of intermediary metabolism, protein synthesis, and cytoskeleton. Relative molar abundances were conserved both within and between pathways enabling the selection of a housekeeping network for geometric normalization and the analysis of potentially relevant differential expressions. Human beta cells differed from rat beta cells in their lower level of enzymes involved in glucose sensing (MDH1, PC, and ACLY) and upregulation of lysosomal enzymes. Human cells also expressed more heat shock proteins and radical scavenging systems: apart from SOD2, they expressed high levels of H2O2-scavenger peroxiredoxin 3 (PRDX3), confirmed by microarray, Western blotting, and microscopy. Besides conferring lower susceptibility to oxidative stress to human cells PRDX3 might also play a role in physiological redox regulation as, in rat, its expression was restricted to a beta cell subset with higher metabolic glucose responsiveness. In conclusion, although their core proteomic architecture is conserved, human and rat beta cells differ in their molar expression of key enzymes involved in glucose sensing and redox control.

scholarly journals Glucose controls co-translation of structurally related mRNAs via the mTOR and eIF2 pathways in human pancreatic beta cells

2021 ◽  
Author(s):  
Manuel Bulfoni ◽  
Costas Bouyioukos ◽  
Albatoul Zakaria ◽  
Fabienne Nigon ◽  
Roberta Rapone ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Beta Cell ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Gene Expression Regulation ◽  
Human Cells ◽  
Rodent Models ◽  
Polysome Profiling ◽  
Acute Increase

ABSTRACTPancreatic beta cell response to glucose is critical for the maintenance of normoglycemia. A strong transcriptional response was classically described in rodent models but, interestingly, not in human cells. In this study, we exposed human pancreatic beta cells to an increased concentration of glucose and analysed at a global level the mRNAs steady state levels and their translationalability. Polysome profiling analysis showed an early acute increase in protein synthesis and a specific translation regulation of more than 400 mRNAs, independently of their transcriptional regulation. We clustered the co-regulated mRNAs according to their behaviour in translation in response to glucose and discovered common structural and sequence mRNA features. Among them mTOR- and eIF2-sensitive elements have a predominant role to increase mostly the translation of mRNAs encoding for proteins of the translational machinery. Furthermore, we show that mTOR and eIF2α pathways are independently regulated in response to glucose, participating to a translational reshaping to adapt beta cell metabolism. The early acute increase in the translation machinery components prepare the beta cell for further protein demand due to glucose-mediated metabolism changes.AUTHOR SUMMARYAdaptation and response to glucose of pancreatic beta cells is critical for the maintenance of normoglycemia. Its deregulation is associated to Diabetic Mellitus (DM), a significant public health concern worldwide with an increased incidence of morbidity and mortality. Despite extensive research in rodent models, gene expression regulation in response to glucose remains largely unexplored in human cells. In our work, we have tackled this question by exposing human EndoC-BH1 cells to high glucose concentration. Using polysome profiling, the gold standard technique to analyse cellular translation activity, we observed a global protein synthesis increase, independent from transcription activity. Among the specific differentially translated mRNAs, we found transcripts coding for ribosomal proteins, allowing the cell machinery to be engaged in a metabolic response to glucose. Therefore, the regulation in response to glucose occurs mainly at the translational level in human cells, and not at the transcriptional level as described in the classically used rodent models.Furthermore, by comparing the features of the differentially translated mRNAs, and classifying them according to their translational response, we show that the early response to glucose occurs through the coupling of mRNA structure and sequence features impacting translation and regulation of specific signalling pathways. Collectively, our results support a new paradigm of gene expression regulation on the translation level in human beta cells.

scholarly journals Disruption of Beta-Cell Mitochondrial Networks by the Orphan Nuclear Receptor Nor1/Nr4a3

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 168 ◽  
Author(s):  
Anne-Françoise Close ◽  
Nidheesh Dadheech ◽  
Hélène Lemieux ◽  
Qian Wang ◽  
Jean Buteau
Keyword(s):  
Beta Cell ◽  
Beta Cells ◽  
Nuclear Receptor ◽  
Pancreatic Beta Cells ◽  
Orphan Nuclear Receptor ◽  
Atp Production ◽  
Human Beta Cells ◽  
Glucose Stimulated Insulin Secretion ◽  
Mitochondrial Networks

Nor1, the third member of the Nr4a subfamily of nuclear receptor, is garnering increased interest in view of its role in the regulation of glucose homeostasis. Our previous study highlighted a proapoptotic role of Nor1 in pancreatic beta cells and showed that Nor1 expression was increased in islets isolated from type 2 diabetic individuals, suggesting that Nor1 could mediate the deterioration of islet function in type 2 diabetes. However, the mechanism remains incompletely understood. We herein investigated the subcellular localization of Nor1 in INS832/13 cells and dispersed human beta cells. We also examined the consequences of Nor1 overexpression on mitochondrial function and morphology. Our results show that, surprisingly, Nor1 is mostly cytoplasmic in beta cells and undergoes mitochondrial translocation upon activation by proinflammatory cytokines. Mitochondrial localization of Nor1 reduced glucose oxidation, lowered ATP production rates, and inhibited glucose-stimulated insulin secretion. Western blot and microscopy images revealed that Nor1 could provoke mitochondrial fragmentation via mitophagy. Our study unveils a new mode of action for Nor1, which affects beta-cell viability and function by disrupting mitochondrial networks.

scholarly journals Deletion of ARNT/HIF1β in pancreatic beta cells does not impair glucose homeostasis in mice, but is associated with defective glucose sensing ex vivo

Diabetologia ◽  
2015 ◽  
Vol 58 (12) ◽  
pp. 2832-2842 ◽  
Author(s):  
Renjitha Pillai ◽  
Sabina Paglialunga ◽  
Monica Hoang ◽  
Katelyn Cousteils ◽  
Kacey J. Prentice ◽  
...  
Keyword(s):  
Beta Cells ◽  
Glucose Homeostasis ◽  
Pancreatic Beta Cells ◽  
Ex Vivo ◽  
Glucose Sensing

scholarly journals Tankyrase interacts with the allosteric site of glucokinase and inhibits its glucose-sensing function in the beta cell

2021 ◽  
Author(s):  
Nai-Wen Chi ◽  
Travis Eisemann ◽  
Tsung-Yin J Yeh ◽  
Swati Roy ◽  
Tyler J Chi ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Glucose Sensor ◽  
Pancreatic Beta Cell ◽  
Glucose Sensing ◽  
Binding Motif ◽  
Allosteric Site

Insulin secretion in the pancreatic beta cell is rate-limited by glucokinase (GCK), the glucose sensor that catalyzes the first step of glucose metabolism. GCK consists of two lobes connected by a flexible hinge that allows the kinase to sample a spectrum of conformations ranging from the active, closed form to several inactive, less-compact forms. Activating GCK mutations can cause hyperinsulinemia and hypoglycemia in infants. A similar phenotype is exhibited in mice deficient in tankyrase (TNKS), prompting us to investigate whether TNKS might modulate the glucose-sensing function of GCK. We found that TNKS colocalizes and directly interacts with GCK. Their interaction is mediated by two ankyrin-repeat clusters (ARC-2 and -5) in TNKS and a tankyrase-binding motif (TBM, aa 63-68) in the GCK hinge. This interaction is conformation sensitive: human GCK variants that cause hyperglycemia (V62M) or hypoglycemia (S64Y) enhance or diminish the interaction respectively, even though they have no impact on TNKS interaction in the context of a GCK peptide (V62M) or a peptide library (S64Y). Moreover, the TNKS-GCK interaction is inhibited by high concentrations of glucose, which are known to stabilize GCK in the active (closed, glucose-avid) conformation. Conversely, glucose phosphorylation by GCK in vitro is inhibited by TNKS. To validate this in vitro inhibitory effect in the MIN6 beta cells, we showed that glucose-stimulated insulin secretion is suppressed upon stabilization of the TNKS protein and conversely is enhanced upon TNKS knockdown. Based on these findings as well as by contrasting with hexokinase-2, we propose that TNKS is a physiological GCK inhibitor in pancreatic beta cells that acts by trapping the kinase in an open (inactive) conformation.

2120-P: The Protein Phosphatase M1K Connects Glucose Sensing to Protein Translation in Pancreatic Beta Cells

Diabetes ◽  
2020 ◽  
Vol 69 (Supplement 1) ◽  
pp. 2120-P
Author(s):  
YANN DELEYE ◽  
JACOB HERRING ◽  
KAVAN H. HESS ◽  
BRENNAN LEININGER ◽  
ROBERT W. MCGARRAH ◽  
...  
Keyword(s):  
Beta Cells ◽  
Protein Phosphatase ◽  
Pancreatic Beta Cells ◽  
Protein Translation ◽  
Glucose Sensing

scholarly journals Human Islets Contain a Beta Cell Type That Expresses Proinsulin But Not the Enzyme That Converts the Precursor to Insulin

2020 ◽  
Vol 68 (10) ◽  
pp. 691-702
Author(s):  
Gladys Teitelman
Keyword(s):  
Beta Cell ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Cell Types ◽  
Human Islets ◽  
Cell Type ◽  
Human Beta Cells ◽  
Human Beta Cell ◽  
Cell Phenotypes

In pancreatic beta cells, proinsulin (ProIN) undergoes folding in endoplasmic reticulum/Golgi system and is translocated to secretory vesicles for processing into insulin and C-peptide by the proprotein convertases (PC)1/3 and PC2, and carboxypeptidase E. Human beta cells show significant variation in the level of expression of PC1/3, the critical proconvertase involved in proinsulin processing. To ascertain whether this heterogeneity is correlated with the level of expression of the prohormone and mature hormone, the expression of proinsulin, insulin, and PC1/3 in human beta cells was examined. This analysis identified a human beta cell type that expressed proinsulin but lacked PC1/3 (ProIN+PC1/3−). This beta cell type is absent in rodent islets and is abundant in human islets of adults but scarce in islets from postnatal donors. Human islets also contained a beta cell type that expressed both proinsulin and variable levels of PC1/3 (ProIN+PC1/3+) and a less abundant cell type that lacked proinsulin but expressed the convertase (ProIN−PC1/3+). These cell phenotypes were altered by type 2 diabetes. These data suggest that these three cell types represent different stages of a dynamic process with proinsulin folding in ProIN+PC1/3− cells, proinsulin conversion into insulin in ProIN+PC1/3+cells, and replenishment of the proinsulin content in ProIN−PC1/3+ cells:

scholarly journals Long-RNA Sequencing and Ribosome Profiling of Inflamed Beta-Cells Reveal an Extensive Translatome Landscape

2021 ◽  
Author(s):  
Sofia Thomaidou ◽  
Roderick C. Slieker ◽  
Arno R. van der Slik ◽  
Jasper Boom ◽  
Flip Mulder ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Beta Cell ◽  
Beta Cells ◽  
Translation Initiation ◽  
Pancreatic Beta Cells ◽  
Ribosome Profiling ◽  
Central Tolerance ◽  
Autoreactive T Cell ◽  
Human Beta Cells

Type 1 diabetes is an autoimmune disease characterized by autoreactive T-cell mediated destruction of the insulin-producing pancreatic beta-cells. Increasing evidence suggest that the beta-cells themselves contribute to their own destruction by generating neo-antigens through the production of aberrant or modified proteins that escape central tolerance. We have recently demonstrated that ribosomal infidelity amplified by stress could lead to the generation of neoantigens in human beta-cells, emphasizing the participation of nonconventional translation events to autoimmunity, as occurring in cancer or virus-infected tissues. Using a transcriptome-wide profiling approach to map translation initiation start sites in human beta-cells under standard and inflammatory conditions, we identify a completely new set of polypeptides derived from non-canonical start sites and translation initiation within lncRNA. Our data underline the extreme diversity of the beta-cell translatome and may reveal new functional biomarkers for beta-cell distress, disease prediction and progression and therapeutic intervention in type 1 diabetes.

The loss of Sirt1 in mouse pancreatic beta cells impairs insulin secretion by disrupting glucose sensing

Diabetologia ◽  
2013 ◽  
Vol 56 (9) ◽  
pp. 2010-2020 ◽  
Author(s):  
L. Luu ◽  
F. F. Dai ◽  
K. J. Prentice ◽  
X. Huang ◽  
A. B. Hardy ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Glucose Sensing

scholarly journals Long-RNA Sequencing and Ribosome Profiling of Inflamed Beta-Cells Reveal an Extensive Translatome Landscape

2021 ◽  
Author(s):  
Sofia Thomaidou ◽  
Roderick C. Slieker ◽  
Arno R. van der Slik ◽  
Jasper Boom ◽  
Flip Mulder ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Beta Cell ◽  
Beta Cells ◽  
Translation Initiation ◽  
Pancreatic Beta Cells ◽  
Ribosome Profiling ◽  
Central Tolerance ◽  
Autoreactive T Cell ◽  
Human Beta Cells

Type 1 diabetes is an autoimmune disease characterized by autoreactive T-cell mediated destruction of the insulin-producing pancreatic beta-cells. Increasing evidence suggest that the beta-cells themselves contribute to their own destruction by generating neo-antigens through the production of aberrant or modified proteins that escape central tolerance. We have recently demonstrated that ribosomal infidelity amplified by stress could lead to the generation of neoantigens in human beta-cells, emphasizing the participation of nonconventional translation events to autoimmunity, as occurring in cancer or virus-infected tissues. Using a transcriptome-wide profiling approach to map translation initiation start sites in human beta-cells under standard and inflammatory conditions, we identify a completely new set of polypeptides derived from non-canonical start sites and translation initiation within lncRNA. Our data underline the extreme diversity of the beta-cell translatome and may reveal new functional biomarkers for beta-cell distress, disease prediction and progression and therapeutic intervention in type 1 diabetes.

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