scholarly journals A reference map of the human proinsulin biosynthetic interaction network

2019 ◽  
Author(s):  
Duc T. Tran ◽  
Anita Pottekat ◽  
Saiful A. Mir ◽  
Insook Jang ◽  
Salvatore Loguercio ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Beta Cell ◽  
Secretory Pathway ◽  
Cell Function ◽  
Affinity Purification ◽  
Critical Role ◽  
Human Islets ◽  
Cell Protein ◽  
Insulin Biosynthesis ◽  
Human Proinsulin

AbstractThe beta-cell protein synthetic machinery is dedicated to the production of insulin, which plays a critical role in organismal homeostasis. Insulin synthesis requires the proper folding and trafficking of its precursor, proinsulin, yet the precise network of proinsulin protein interactions in the secretory pathway remains poorly defined. In the present study we conducted unbiased profiling of the proinsulin interactome in human islets, utilizing a human proinsulin-specific monoclonal antibody for affinity purification and mass spectrometry. Stringent analysis identified a central node of interactions between human proinsulin and sequential secretory pathway proteins that is remarkably conserved across 3 ethnicities and both genders. Among the most prominent proinsulin interactions was with ER-localized peroxiredoxin-4 (PRDX4). A functional role for PRDX4 in beta-cells was demonstrated by gene silencing that rendered proinsulin susceptible to misfolding, particularly in response to oxidative stress. Conversely, exogenous PRDX4 improved proinsulin folding. Notably, oxidative stress and even high glucose treatment alone induced proinsulin misfolding in human islets and MIN6 cells, and this was accompanied by sulfonylation of PRDX4, a modification known to inactivate peroxiredoxins. This finding prompted PRDX4 analysis in a panel of human islet samples that revealed significantly higher levels of sulfonylated (inactive) PRDX4 in islets from patients with T2D compared to that of healthy individuals. Taken together, these data highlight the importance of elucidating the complete proinsulin interactome in human islets in order to understand critical steps controlling insulin biosynthesis, beta cell function, and T2D.

scholarly journals Unbiased profiling of the human proinsulin biosynthetic interaction network reveals a role for peroxiredoxin 4 in proinsulin folding

2020 ◽  
Author(s):  
Ada Admin ◽  
Duc T. Tran ◽  
Anita Pottekat ◽  
Saiful A. Mir ◽  
Salvatore Loguercio ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Beta Cell ◽  
Secretory Pathway ◽  
Cell Function ◽  
Affinity Purification ◽  
Interaction Network ◽  
Human Islets ◽  
Cell Protein ◽  
Insulin Biosynthesis ◽  
Human Proinsulin

The beta cell protein synthetic machinery is dedicated to the production of mature insulin, which requires the proper folding and trafficking of its precursor, proinsulin. The complete network of proteins that mediate proinsulin folding and advancement through the secretory pathway, however, remains poorly defined. Here we used affinity purification and mass spectrometry to identify for the first time, the proinsulin biosynthetic interaction network in human islets. Stringent analysis established a central node of proinsulin interactions with ER folding factors, including chaperones and oxidoreductases, that is remarkably conserved in both sexes and across three ethnicities. The ER-localized peroxiredoxin PRDX4 was identified as a prominent proinsulin interacting protein. In beta cells, gene silencing of PRDX4 rendered proinsulin susceptible to misfolding, particularly in response to oxidative stress, while exogenous PRDX4 improved proinsulin folding. Moreover, proinsulin misfolding induced by oxidative stress or high glucose was accompanied by sulfonylation of PRDX4, a modification known to inactivate peroxiredoxins. Notably, islets from patients with Type II diabetes (T2D) exhibited significantly higher levels of sulfonylated PRDX4 than islets from healthy individuals. In conclusion, we have generated the first reference map of the human proinsulin interactome to identify critical factors controlling insulin biosynthesis, beta cell function, and T2D.

scholarly journals Unbiased profiling of the human proinsulin biosynthetic interaction network reveals a role for peroxiredoxin 4 in proinsulin folding

2020 ◽  
Author(s):  
Ada Admin ◽  
Duc T. Tran ◽  
Anita Pottekat ◽  
Saiful A. Mir ◽  
Salvatore Loguercio ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Beta Cell ◽  
Secretory Pathway ◽  
Cell Function ◽  
Affinity Purification ◽  
Interaction Network ◽  
Human Islets ◽  
Cell Protein ◽  
Insulin Biosynthesis ◽  
Human Proinsulin

The beta cell protein synthetic machinery is dedicated to the production of mature insulin, which requires the proper folding and trafficking of its precursor, proinsulin. The complete network of proteins that mediate proinsulin folding and advancement through the secretory pathway, however, remains poorly defined. Here we used affinity purification and mass spectrometry to identify for the first time, the proinsulin biosynthetic interaction network in human islets. Stringent analysis established a central node of proinsulin interactions with ER folding factors, including chaperones and oxidoreductases, that is remarkably conserved in both sexes and across three ethnicities. The ER-localized peroxiredoxin PRDX4 was identified as a prominent proinsulin interacting protein. In beta cells, gene silencing of PRDX4 rendered proinsulin susceptible to misfolding, particularly in response to oxidative stress, while exogenous PRDX4 improved proinsulin folding. Moreover, proinsulin misfolding induced by oxidative stress or high glucose was accompanied by sulfonylation of PRDX4, a modification known to inactivate peroxiredoxins. Notably, islets from patients with Type II diabetes (T2D) exhibited significantly higher levels of sulfonylated PRDX4 than islets from healthy individuals. In conclusion, we have generated the first reference map of the human proinsulin interactome to identify critical factors controlling insulin biosynthesis, beta cell function, and T2D.

scholarly journals Oxidative stress in alpha and beta cells as a selection criterion for biocompatible biomaterials

2019 ◽  
Author(s):  
Mireille M.J.P.E. Sthijns ◽  
Marlon J. Jetten ◽  
Sami G. Mohammed ◽  
Sandra M.H. Claessen ◽  
Rick de Vries ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Beta Cell ◽  
Beta Cells ◽  
Cell Function ◽  
Clinical Success ◽  
Selection Criterion ◽  
Cell Encapsulation ◽  
Human Islets ◽  
Acute Ischemia ◽  
Islet Encapsulation

AbstractThe clinical success of islet transplantation is limited by factors including acute ischemia, stress upon transplantation, and delayed vascularization. Islets experience high levels of oxidative stress due to delayed vascularization after transplantation and this can be further aggravated by their encapsulation and undesirable cell-biomaterial interactions. To identify biomaterials that would not further increase oxidative stress levels and that are also suitable for manufacturing a beta cell encapsulation device, we studied five clinically approved polymers for their effect on oxidative stress and islet (alpha and beta cell) function. We found that 300 poly(ethylene oxide terephthalate) 55/poly(butylene terephthalate) 45 (PEOT/PBT300) was more resistant to breakage and more elastic than other biomaterials, which is important for its immunoprotective function. In addition, PEOT/PBT300 did not induce oxidative stress or reduce viability in MIN6 beta cells, and even promoted protective endogenous antioxidant expression over 7 days. Importantly, PEOT/PBT300 is one of the biomaterials we studied that did not interfere with insulin secretion in human islets. These data indicate that PEOT/PBT300 may be a suitable biomaterial for an islet encapsulation device.

scholarly journals Effects of Extra Virgin Olive Oil Polyphenols on Beta-Cell Function and Survival

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 286
Author(s):  
Nicola Marrano ◽  
Rosaria Spagnuolo ◽  
Giuseppina Biondi ◽  
Angelo Cignarelli ◽  
Sebastio Perrini ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Olive Oil ◽  
Beta Cells ◽  
Intracellular Signaling ◽  
Beta Cell Function ◽  
Cell Function ◽  
Virgin Olive Oil ◽  
Extra Virgin Olive Oil ◽  
Insulin Biosynthesis

Extra virgin olive oil (EVOO) is a major component of the Mediterranean diet and is appreciated worldwide because of its nutritional benefits in metabolic diseases, including type 2 diabetes (T2D). EVOO contains significant amounts of secondary metabolites, such as phenolic compounds (PCs), that may positively influence the metabolic status. In this study, we investigated for the first time the effects of several PCs on beta-cell function and survival. To this aim, INS-1E cells were exposed to 10 μM of the main EVOO PCs for up to 24 h. Under these conditions, survival, insulin biosynthesis, glucose-stimulated insulin secretion (GSIS), and intracellular signaling activation (protein kinase B (AKT) and cAMP response element-binding protein (CREB)) were evaluated. Hydroxytyrosol, tyrosol, and apigenin augmented beta-cell proliferation and insulin biosynthesis, and apigenin and luteolin enhanced the GSIS. Conversely, vanillic acid and vanillin were pro-apoptotic for beta-cells, even if they increased the GSIS. In addition, oleuropein, p-coumaric, ferulic and sinapic acids significantly worsened the GSIS. Finally, a mixture of hydroxytyrosol, tyrosol, and apigenin promoted the GSIS in human pancreatic islets. Apigenin was the most effective compound and was also able to activate beneficial intracellular signaling. In conclusion, this study shows that hydroxytyrosol, tyrosol, and apigenin foster beta-cells’ health, suggesting that EVOO or supplements enriched with these compounds may improve insulin secretion and promote glycemic control in T2D patients.

scholarly journals Furin controls β cell function via mTORC1 signaling

2020 ◽  
Author(s):  
Bas Brouwers ◽  
Ilaria Coppola ◽  
Katlijn Vints ◽  
Bastian Dislich ◽  
Nathalie Jouvet ◽  
...  
Keyword(s):  
Secretory Pathway ◽  
Cell Function ◽  
Mammalian Target Of Rapamycin ◽  
Human Islets ◽  
Β Cells ◽  
Β Cell ◽  
Differential Proteomics ◽  
Atpase Subunit ◽  
Proteolytic Activation ◽  
Mtorc1 Signaling

AbstractFurin is a proprotein convertase (PC) responsible for proteolytic activation of a wide array of precursor proteins within the secretory pathway. It maps to the PRC1 locus, a type 2 diabetes susceptibility locus, yet its specific role in pancreatic β cells is largely unknown. The aim of this study was to determine the role of furin in glucose homeostasis. We show that furin is highly expressed in human islets, while PCs that potentially could provide redundancy are expressed at considerably lower levels. β cell-specific furin knockout (βfurKO) mice are glucose intolerant, due to smaller islets with lower insulin content and abnormal dense core secretory granule morphology. RNA expression analysis and differential proteomics on βfurKO islets revealed activation of Activating Transcription Factor 4 (ATF4), which was mediated by mammalian target of rapamycin C1 (mTORC1). βfurKO cells show impaired cleavage of the essential V-ATPase subunit Ac45, and by blocking this pump in β cells the mTORC1 pathway is activated. Furthermore, βfurKO cells show lack of insulin receptor cleavage and impaired response to insulin. Taken together, these results suggest a model of mTORC1-ATF4 hyperactivation in β cells lacking furin, which causes β cell dysfunction.

Prenatal androgen excess impairs beta cell function by decreased Sirtuin3 expression

2021 ◽  
Author(s):  
Yu Zhou ◽  
Min Gong ◽  
Yingfei Lu ◽  
Jianquan Chen ◽  
Rong Ju
Keyword(s):  
Oxidative Stress ◽  
Beta Cell ◽  
Beta Cell Function ◽  
Cell Function ◽  
Pancreatic Beta Cell ◽  
Female Offspring ◽  
Sirtuin 3 ◽  
Prenatal Testosterone ◽  
Pancreatic Beta Cell Function ◽  
Prenatal Androgen

Prenatal androgen exposure induces metabolic disorders in female offspring. However, the long-term effect of maternal testosterone excess on glucose metabolism, especially on pancreatic beta cell function, is rarely investigated. Our current study mainly focused on the effects of prenatal testosterone exposure on glucose metabolism and pancreatic beta cell function in aged female offspring. By using maternal mice and their female offspring as animal models, we found that prenatal androgen treatment induced obesity and glucose intolerance in aged offspring. These influences were accompanied by decreased fasting serum insulin concentration, elevated serum triglyceride and testosterone concentrations. Glucose stimulated insulin secretion in pancreatic beta cells of aged female offspring was also affected by prenatal testosterone exposure. We further confirmed that increased serum testosterone contributed to down regulation of Sirtuin 3 expression, activated oxidative stress and impaired pancreatic beta cell function in aged female offspring. Moreover, over-expression of Sirtuin 3 in islets isolated from female offspring treated with prenatal testosterone normalized the oxidative stress level, restored cyclic adenosine monophosphate and adenosine triphosphate generation, which finally improved glucose stimulated insulin secretion in beta cells. Taken together, these results demonstrated that prenatal testosterone exposure caused metabolic disturbance in aged female offspring via suppression of Sirtuin 3 expression and activation of oxidative stress in pancreatic beta cells.

scholarly journals Quantification and Mechanisms of Oxidative Stress in Chronic Disease

Proceedings ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 18 ◽  
Author(s):  
Davies
Keyword(s):  
Oxidative Stress ◽  
Chronic Disease ◽  
Defense Mechanisms ◽  
Antioxidant Defense ◽  
Cell Function ◽  
Critical Role ◽  
Extracellular Proteins ◽  
Oxidation Chemistry ◽  
Redox Equilibria

There is now strong evidence that the redox environment inside cells is very different to that outside the cell, and that many extracellular environments are both more oxidizing and also subject to extensive oxidation. This difference in redox environments results in significant changes in oxidation chemistry and biology, altered redox equilibria, and antioxidant defense mechanisms. It is also increasingly apparent that oxidation events both inside and outside cells (extracellular oxidation) play a critical role in driving many diseases. Many extracellular proteins are highly abundant, long-lived and relatively poorly protected against damage. They can therefore accumulate high levels of modification during ageing and chronic disease, resulting in their use as biomarkers of long-term oxidative stress. Furthermore, increasing evidence supports the hypothesis that oxidized extracellular matrix materials play a key role in determining cell function and fate.

Critical role of c-Kit in beta cell function: increased insulin secretion and protection against diabetes in a mouse model

Diabetologia ◽  
2012 ◽  
Vol 55 (8) ◽  
pp. 2214-2225 ◽  
Author(s):  
Z. C. Feng ◽  
J. Li ◽  
B. A. Turco ◽  
M. Riopel ◽  
S. P. Yee ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Mouse Model ◽  
Beta Cell ◽  
Beta Cell Function ◽  
Cell Function ◽  
Critical Role

Glucagon-like peptide-1: a major regulator of pancreatic beta-cell function

2000 ◽  
pp. 717-725 ◽  
Author(s):  
R Perfetti ◽  
P Merkel
Keyword(s):  
Beta Cell ◽  
Cell Function ◽  
Pancreatic Beta Cell ◽  
Cell Mass ◽  
Beta Cell Mass ◽  
Glucagon Secretion ◽  
Insulin Biosynthesis ◽  
Gut Hormone ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Glucagon-like peptide-1 (GLP-1) is a gut hormone synthesized by post-translational processing in intestinal L-cells, and it is released in response to food ingestion. GLP-1 stimulates insulin secretion during hyperglycemia, suppresses glucagon secretion, stimulates (pro)-insulin biosynthesis and decreases the rate of gastric emptying and acid secretion. GLP-1 has also been shown to have a pro-satiety effect. In addition, it has been demonstrated that a long-term infusion with GLP-1, or exendin-4, a long-acting analog of human GLP-1, increases beta-cell mass in rats. In conclusion, GLP-1 appears to regulate plasma glucose levels via various and independent mechanisms. GLP-1 is an excellent candidate option for the treatment of patients with type 2 diabetes mellitus.

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