scholarly journals Inhibition of inositol-requiring enzyme 1α RNase activity protects pancreatic beta cell and improves diabetic condition in insulin mutation-induced diabetes

2020 ◽  
Author(s):  
Oana Herlea-Pana ◽  
Venkateswararao Eeda ◽  
Ram Babu Undi ◽  
Iulia Rus ◽  
Hui-Ying Lim ◽  
...  
Keyword(s):  
Er Stress ◽  
Serum Insulin ◽  
Pancreatic Beta Cell ◽  
Cell Mass ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Expression Of Genes ◽  
And Function ◽  
Akita Mice

ABSTRACTProinsulin misfolding in the endoplasmic reticulum (ER) plays an important role in β-cell dysfunction and death and the pathogenesis of mutant INS-gene-induced diabetes of youth (MIDY). There is no effective treatment for MIDY except the insulin administration. Here, we found that the ER stress sensor inositol-requiring enzyme 1α (IRE1α) was activated in the Akita mice, a mouse model of MIDY. Normalization of IRE1α RNase hyperactivity by pharmacological inhibitors significantly ameliorated the hyperglycemic conditions and increased serum insulin levels in Akita mice. These benefits were accompanied by a concomitant protection of functional β-cell mass, as shown by the suppression of β-cell apoptosis, increase in mature insulin production and reduction of proinsulin level. At the molecular level, we observed that the expression of genes associated with β-cell identity and function was significantly up-regulated and ER stress and its associated inflammation and oxidative stress were suppressed in islets from Akita mice treated with IRE1α RNase inhibitors. This study provides the first evidence of the in vivo efficacy of IRE1α RNase inhibition in Akita mice, pointing to the possibility of targeting IRE1α RNase as a therapeutic direction for the treatment of MIDY diabetes.

scholarly journals Pharmacological Inhibition of Inositol-Requiring Enzyme 1α RNase Activity Protects Pancreatic Beta Cell and Improves Diabetic Condition in Insulin Mutation-Induced Diabetes

2021 ◽  
Vol 12 ◽  
Author(s):  
Oana Herlea-Pana ◽  
Venkateswararao Eeda ◽  
Ram Babu Undi ◽  
Hui-Ying Lim ◽  
Weidong Wang
Keyword(s):  
Er Stress ◽  
Serum Insulin ◽  
Pancreatic Beta Cell ◽  
Cell Mass ◽  
Β Cell ◽  
Unfolded Protein ◽  
Expression Of Genes ◽  
And Function ◽  
Akita Mice

β-cell ER stress plays an important role in β-cell dysfunction and death during the pathogenesis of diabetes. Proinsulin misfolding is regarded as one of the primary initiating factors of ER stress and unfolded protein response (UPR) activation in β-cells. Here, we found that the ER stress sensor inositol-requiring enzyme 1α (IRE1α) was activated in the Akita mice, a mouse model of mutant insulin gene-induced diabetes of youth (MIDY), a monogenic diabetes. Normalization of IRE1α RNase hyperactivity by pharmacological inhibitors significantly ameliorated the hyperglycemic conditions and increased serum insulin levels in Akita mice. These benefits were accompanied by a concomitant protection of functional β-cell mass, as shown by the suppression of β-cell apoptosis, increase in mature insulin production and reduction of proinsulin level. At the molecular level, we observed that the expression of genes associated with β-cell identity and function was significantly up-regulated and ER stress and its associated inflammation and oxidative stress were suppressed in islets from Akita mice treated with IRE1α RNase inhibitors. This study provides the evidence of the in vivo efficacy of IRE1α RNase inhibitors in Akita mice, pointing to the possibility of targeting IRE1α RNase as a therapeutic direction for the treatment of diabetes.

scholarly journals Tectorigenin enhances PDX1 expression and protects pancreatic β-cells by activating ERK and reducing ER stress

2020 ◽  
Vol 295 (37) ◽  
pp. 12975-12992 ◽  
Author(s):  
Xinlei Yao ◽  
Kun Li ◽  
Chen Liang ◽  
Zilong Zhou ◽  
Jiao Wang ◽  
...  
Keyword(s):  
Er Stress ◽  
Cell Mass ◽  
Therapeutic Use ◽  
Protective Effects ◽  
Β Cells ◽  
Β Cell ◽  
And Function ◽  
Pdx1 Expression

Pancreas/duodenum homeobox protein 1 (PDX1) is an important transcription factor that regulates islet β-cell proliferation, differentiation, and function. Reduced expression of PDX1 is thought to contribute to β-cell loss and dysfunction in diabetes. Thus, promoting PDX1 expression can be an effective strategy to preserve β-cell mass and function. Previously, we established a PDX1 promoter-dependent luciferase system to screen agents that can promote PDX1 expression. Natural compound tectorigenin (TG) was identified as a promising candidate that could enhance the activity of the promoter for the PDX1 gene. In this study, we first demonstrated that TG could promote the expression of PDX1 in β-cells via activating extracellular signal-related kinase (ERK), as indicated by increased phosphorylation of ERK; this effect was observed under either normal or glucotoxic/lipotoxic conditions. We then found that TG could suppress induced apoptosis and improved the viability of β-cells under glucotoxicity and lipotoxicity by activation of ERK and reduction of reactive oxygen species and endoplasmic reticulum (ER) stress. These effects held true in vivo as well: prophylactic or therapeutic use of TG could obviously inhibit ER stress and decrease islet β-cell apoptosis in the pancreas of mice given a high-fat/high-sucrose diet (HFHSD), thus dramatically maintaining or restoring β-cell mass and islet size, respectively. Accordingly, both prophylactic and therapeutic use of TG improved HFHSD-impaired glucose metabolism in mice, as evidenced by ameliorating hyperglycemia and glucose intolerance. Taken together, TG, as an agent promoting PDX1 expression exhibits strong protective effects on islet β-cells both in vitro and in vivo.

scholarly journals NF-κB activity during pancreas development regulates adult β-cell mass by modulating neonatal β-cell proliferation and apoptosis

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Dror Sever ◽  
Anat Hershko-Moshe ◽  
Rohit Srivastava ◽  
Roy Eldor ◽  
Daniel Hibsher ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Developmental Stages ◽  
Cell Mass ◽  
Diabetes Incidence ◽  
Β Cells ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Regulatory Circuit ◽  
Proliferation And Apoptosis

AbstractNF-κB is a well-characterized transcription factor, widely known for its roles in inflammation and immune responses, as well as in control of cell division and apoptosis. However, its function in β-cells is still being debated, as it appears to depend on the timing and kinetics of its activation. To elucidate the temporal role of NF-κB in vivo, we have generated two transgenic mouse models, the ToIβ and NOD/ToIβ mice, in which NF-κB activation is specifically and conditionally inhibited in β-cells. In this study, we present a novel function of the canonical NF-κB pathway during murine islet β-cell development. Interestingly, inhibiting the NF-κB pathway in β-cells during embryogenesis, but not after birth, in both ToIβ and NOD/ToIβ mice, increased β-cell turnover, ultimately resulting in a reduced β-cell mass. On the NOD background, this was associated with a marked increase in insulitis and diabetes incidence. While a robust nuclear immunoreactivity of the NF-κB p65-subunit was found in neonatal β-cells, significant activation was not detected in β-cells of either adult NOD/ToIβ mice or in the pancreata of recently diagnosed adult T1D patients. Moreover, in NOD/ToIβ mice, inhibiting NF-κB post-weaning had no effect on the development of diabetes or β-cell dysfunction. In conclusion, our data point to NF-κB as an important component of the physiological regulatory circuit that controls the balance of β-cell proliferation and apoptosis in the early developmental stages of insulin-producing cells, thus modulating β-cell mass and the development of diabetes in the mouse model of T1D.

Ameliorating activity of polyphenolic-rich extracts of Basella rubra L. leaves on pancreatic β-cell dysfunction in streptozotocin-induced diabetic rats

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Basiru Olaitan Ajiboye ◽  
Amaka Diayi ◽  
Shedrach Oludare Agunbiade ◽  
Ayodele Jacob Akinyemi ◽  
Olusola Bolaji Adewale ◽  
...  
Keyword(s):  
Bioactive Compounds ◽  
Serum Lipid ◽  
Serum Insulin ◽  
Pancreatic Beta Cell ◽  
Total Phenolic ◽  
Gamma Glutamyl Transferase ◽  
Dependent Manner ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Glutamyl Transferase

Abstract Objectives To assess the ameliorative activity of polyphenolic-rich extracts of Basella rubra leaves on β-cell dysfunction in type-II diabetes (T2DM). Methods Total phenolic and flavonoid contents; α-amylase and α-glucosidase inhibitory actions and qualitative analysis of the bioactive compounds of the polyphenolic-rich extract of B. rubra leaves were investigated using gas chromatography-mass spectroscopy (GC-MS). Diabetes mellitus (DM) was induced by single intraperitoneal injection of streptozotocin (60 mg/kg body weight) and the rats were orally given bound phenolic (BPE) and free phenolic extracts (FPE) of B. rubra (B.R) leaves at 200 and 400 mg/kg b.w once daily for 14 days. Biochemical analyses were executed for evaluation of serum insulin, serum lipid profile concentrations, liver enzymes activities. Results The extracts demonstrated antioxidant potentials and enzymes inhibitory activities in dose dependent manner; and several bioactive compounds as revealed by GC-MS. BPE and FPE considerably (p<0.05) reduced hyperglycemia, improved serum insulin levels, ameliorated the concentration of serum lipid profiles and improved liver antioxidant activities. Additionally, BPE and FPE expressively decreased alanine aminotransferases (ALT), aspartate aminotransferases (AST), gamma-glutamyl transferase (GGT) activities along with levels of bilirubin and urea when compare to diabetic control rats. Conclusions Data acquired exhibited the ability of BPE and FPE to improve pancreatic beta-cell in streptozotocin-induced rats.

scholarly journals Quercetin Preservesβ-Cell Mass and Function in Fructose-Induced Hyperinsulinemia through Modulating Pancreatic Akt/FoxO1 Activation

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Jian-Mei Li ◽  
Wei Wang ◽  
Chen-Yu Fan ◽  
Ming-Xing Wang ◽  
Xian Zhang ◽  
...  
Keyword(s):  
Serum Insulin ◽  
Cell Mass ◽  
Janus Kinase ◽  
Cytokine Signaling ◽  
Akt Phosphorylation ◽  
High Fructose ◽  
Stat3 Phosphorylation ◽  
And Function

Fructose-induced hyperinsulinemia is associated with insulin compensative secretion and predicts the onset of type 2 diabetes. In this study, we investigated the preservation of dietary flavonoid quercetin on pancreaticβ-cell mass and function in fructose-treated rats and INS-1β-cells. Quercetin was confirmed to reduce serum insulin and leptin levels and blockade islet hyperplasia in fructose-fed rats. It also prevented fructose-inducedβ-cell proliferation and insulin hypersecretion in INS-1β-cells. High fructose increased forkhead box protein O1 (FoxO1) expressionsin vivoandin vitro, which were reversed by quercetin. Quercetin downregulated Akt and FoxO1 phosphorylation in fructose-fed rat islets and increased the nuclear FoxO1 levels in fructose-treated INS-1β-cells. The elevated Akt phosphorylation in fructose-treated INS-1β-cells was also restored by quercetin. Additionally, quercetin suppressed the expression of pancreatic and duodenal homeobox 1 (Pdx1) and insulin gene (Ins1 and Ins2)in vivoandin vitro. In fructose-treated INS-1β-cells, quercetin elevated the reduced janus kinase 2/signal transducers and activators of transcription 3 (Jak2/Stat3) phosphorylation and suppressed the increased suppressor of cytokine signaling 3 (Socs3) expression. These results demonstrate that quercetin protectsβ-cell mass and function under high-fructose induction through improving leptin signaling and preserving pancreatic Akt/FoxO1 activation.

scholarly journals Imeglimin Ameliorates β-cell Apoptosis by Modulating the Endoplasmic Reticulum Homeostasis Pathway

2021 ◽  
Author(s):  
Jinghe Li ◽  
Ryota Inoue ◽  
Yu Togashi ◽  
Tomoko Okuyama ◽  
Aoi Satoh ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Cell Survival ◽  
Cell Apoptosis ◽  
Cell Function ◽  
Cell Mass ◽  
Β Cells ◽  
Β Cell ◽  
Akita Mice ◽  
The Impact

The effects of imeglimin, a novel anti-diabetes agent, on β-cell function remain unclear. Here, we unveiled the impact of imeglimin on β-cell survival. Treatment with imeglimin augmented mitochondrial function, enhanced insulin secretion, promoted β-cell proliferation, and improved β-cell survival in mouse islets. Imeglimin upregulated the expression of endoplasmic reticulum (ER)-related molecules including <i>Chop (Ddit3),</i> <i>Gadd34</i> (<i>Ppp1r15a</i>), <i>Atf3</i>, and <i>Sdf2l1</i>, and decreased eIF2α phosphorylation, after treatment with thapsigargin, and restored global protein synthesis in β-cells under ER stress. Imeglimin failed to protect ER stress-induced β-cell apoptosis in CHOP-deficient islets or in the presence of GADD34 inhibitor. Treatment with imeglimin showed a significant decrease in the number of apoptotic β-cells and increased β-cell mass in Akita mice. Imeglimin also protected against β-cell apoptosis in both human islets and human pluripotent stem cell (<a>hPSC)-derived β-like cells</a>. <a>Taken together, imeglimin modulates ER homeostasis pathway, which results in the prevention of β-cell apoptosis both <i>in vitro</i> and <i>in vivo</i>.</a>

scholarly journals PET/MRI enables simultaneous in vivo quantification of β-cell mass and function

Theranostics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 398-410 ◽  
Author(s):  
Filippo C. Michelotti ◽  
Gregory Bowden ◽  
Astrid Küppers ◽  
Lieke Joosten ◽  
Jonas Maczewsky ◽  
...  
Keyword(s):  
Cell Mass ◽  
Β Cell ◽  
And Function

scholarly journals Imeglimin Ameliorates β-cell Apoptosis by Modulating the Endoplasmic Reticulum Homeostasis Pathway

2021 ◽  
Author(s):  
Jinghe Li ◽  
Ryota Inoue ◽  
Yu Togashi ◽  
Tomoko Okuyama ◽  
Aoi Satoh ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Cell Survival ◽  
Cell Apoptosis ◽  
Cell Function ◽  
Cell Mass ◽  
Β Cells ◽  
Β Cell ◽  
Akita Mice ◽  
The Impact

The effects of imeglimin, a novel anti-diabetes agent, on β-cell function remain unclear. Here, we unveiled the impact of imeglimin on β-cell survival. Treatment with imeglimin augmented mitochondrial function, enhanced insulin secretion, promoted β-cell proliferation, and improved β-cell survival in mouse islets. Imeglimin upregulated the expression of endoplasmic reticulum (ER)-related molecules including <i>Chop (Ddit3),</i> <i>Gadd34</i> (<i>Ppp1r15a</i>), <i>Atf3</i>, and <i>Sdf2l1</i>, and decreased eIF2α phosphorylation, after treatment with thapsigargin, and restored global protein synthesis in β-cells under ER stress. Imeglimin failed to protect ER stress-induced β-cell apoptosis in CHOP-deficient islets or in the presence of GADD34 inhibitor. Treatment with imeglimin showed a significant decrease in the number of apoptotic β-cells and increased β-cell mass in Akita mice. Imeglimin also protected against β-cell apoptosis in both human islets and human pluripotent stem cell (<a>hPSC)-derived β-like cells</a>. <a>Taken together, imeglimin modulates ER homeostasis pathway, which results in the prevention of β-cell apoptosis both <i>in vitro</i> and <i>in vivo</i>.</a>

scholarly journals Regulation of islet function and gene expression by prolactin during pregnancy

2019 ◽  
Author(s):  
Vipul Shrivastava ◽  
Megan Lee ◽  
Marle Pretorius ◽  
Guneet Makkar ◽  
Carol Huang
Keyword(s):  
Gene Expression ◽  
Insulin Secretion ◽  
Serum Insulin ◽  
Prolactin Receptor ◽  
Cell Mass ◽  
Insulin Level ◽  
Β Cells ◽  
Β Cell

AbstractPancreatic islets adapt to insulin resistance of pregnancy by up regulating β-cell proliferation and increase insulin secretion. Previously, we found that prolactin receptor (Prlr) signaling is important for this process, as heterozygous prolactin receptor-null (Prlr+/−) mice are glucose intolerant, had a lower number of β cells and lower serum insulin levels than wild type mice during pregnancy. However, since Prlr expression is ubiquitous, to determine its β-cell specific effects, we generated a transgenic mouse with a floxed Prlr allele under the control of an inducible promoter, allowing conditional deletion of Prlr from β cells in adult mice. In this study, we found that β-cell-specific Prlr reduction resulted in elevated blood glucose during pregnancy. Similar to our previous finding in mouse with global Prlr reduction, β-cell-specific Prlr loss led to a lower β-cell mass and a lower in vivo insulin level during pregnancy. However, these islets do not have an intrinsic insulin secretion defect when tested in vitro. Interestingly, when we compared the islet gene expression profile, using islets isolated from mice with global versus β-cell-specific Prlr reduction, we found some important differences in genes that regulate apoptosis and insulin secretion. This suggests that Prlr has both cell-autonomous and non-cell-autonomous effect on β cells, beyond its regulation of pro-proliferative genes.

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