Pancreatic Beta-cell Apoptosis Research Articles

Sesamol combats diabetogenic effects of atorvastatin through GLUT-4 expression and improved pancreatic viability.

Statin-associated diabetes (SAD) is an issue that has come to light after a series of recent clinical trials that has led to the issue of a black box warning for statins by the US FDA. However, the benefit of statin outweighs its risk. Nevertheless, experiments have been conducted to identify the mechanism by which statins aggravate the risk of diabetes only in a select population who bear the risk factors of obesity, sedentary lifestyle, hypertension, and other associated risk factors of lifestyle disorders. In this study, the possibility of utilization of a phyto-molecule, sesamol, for its ability to combat statin-associated diabetes using atorvastatin as the agent of choice has been explored. MMP assay and western blot was conducted to investigate the effects of atorvastatin on apoptotic cascade with sesamol as a protective agent was conducted in MIN-6 cells. Effect of the combination was tested in L6 cells with 2-NBDG uptake assay and as well as western blot for GLUT-4. A diet-induced hypercholesterolemia model was developed in an in vivo model animals and treated with atorvastatin and sesamol with histopathological analysis being carried out to evaluate the apoptotic markers and GLUT-4 presence. It was found that sesamol can combat pancreatic beta cell apoptosis via the internal apoptotic pathway activated by atorvastatin. With regards to muscle cells, sesamol could improve the GLUT-4 vesical production, but not improve glucose uptake which is inhibited by atorvastatin. These findings are further confirmed by animal studies. These findings indicate that sesamol can serve as a prototype molecule for further development and investigation of similar compounds to tackle SAD.

Lupenone attenuates thapsigargin-induced endoplasmic reticulum stress and apoptosis in pancreatic beta cells possibly through inhibition of protein tyrosine kinase 2 activity

AimsProlonged high levels of cytokines, glucose, or free fatty acids are associated with diabetes, elevation of cytosolic Ca2+ concentration ([Ca2+]C), and depletion of Ca2+ concentration in the endoplasmic reticulum (ER) of pancreatic beta cells. This Ca2+ imbalance induces ER stress and apoptosis. Lupenone, a lupan-type triterpenoid, is beneficial in diabetes; however, its mechanism of action is yet to be clarified. This study evaluated the protective mechanism of lupenone against thapsigargin-induced ER stress and apoptosis in pancreatic beta cells. Materials and methodsMIN6, INS-1, and native mouse islet cells were used. Western blot for protein expressions, measurement of [Ca2+]C, and in vivo glucose tolerance test were mainly performed. Key findingsThapsigargin increased the protein levels of cleaved caspase 3, cleaved PARP, and the phosphorylated form of JNK, ATF4, and CHOP. Thapsigargin increased the interaction between stromal interaction molecule1 (Stim1) and Orai1, enhancing store-operated calcium entry (SOCE). SOCE is further activated by protein tyrosine kinase 2 (Pyk2), which is Ca2+-dependent and phosphorylates the tyrosine residue at Y361 in Stim1. Lupenone inhibited thapsigargin-mediated Pyk2 activation, suppressed [Ca2+]C, ER stress, and apoptosis. Lupenone restored impaired glucose-stimulated insulin secretion effectuated by thapsigargin and glucose intolerance in a low-dose streptozotocin-induced diabetic mouse model. SignificanceThese results suggested that lupenone attenuated thapsigargin-induced ER stress and apoptosis by inhibiting SOCE; this may be due to the hindrance of Pyk2-mediated Stim1 tyrosine phosphorylation. In beta cells that are inevitably exposed to frequent [Ca2+]C elevation, the attenuation of abnormally high SOCE would be beneficial for their survival.

Drug Repurposing for Thioredoxin Interacting Protein Through Molecular Networking, Pharmacophore Modelling, and Molecular Docking Approaches

Background: Diabetes Mellitus (DM) has emerged as one of the major causes behind global all-cause mortality between the age group of 20-79 years. Thioredoxin Interacting Protein (TXNIP) is a naturally occurring protein that primarily acts by binding to TRX protein, thereby inhibiting its ability to maintain the cellular reduced environment and subsequent oxidative stress, which leads to dysfunctional insulin production and pancreatic islet beta cell apoptosis. Objective: By inhibiting the levels of TXNIP, a search for new molecules was carried out by employing an in-silico approach. Methods: Molecular networking study was carried out using Cytoscape, wherein previously FDA-approved drugs were screened to check their ability to interact with TXNIP. This provided 14 drug molecules, which along with 11 previously obtained drug molecules that inhibit TXNIP, were subjected to pharmacophore generation. A pharmacophore was generated using the PharmaGist web server, which when visualised showed two hydrogen bond acceptors and one aromatic ring. Based on the generated pharmacophore model, we carried out virtual screening using ZINCPharmer. A total of 116 HITs were generated based on this pharmacophore model. We then subjected the 116 molecules to Molecular Docking against TXNIP (PDB: 4GEI) by using PyRx and the standard molecules, metformin and rosiglitazone. Results: Compared to the standard, we found 10 molecules that had a better binding affinity towards TXNIP. These 10 molecules were further taken for ADMET studies. From this, all 10 compounds showed good significant ADMET properties. Conclusion: From the preliminary studies, these 10 molecules showed good activity in the reversal of diabetes mellitus by reducing the levels of TXNIP.

Evaluation of adiponectin and TNF-α expression in diabetic patients and its relationship with cardiovascular diseases.

Diabetes is caused by peripheral insulin resistance and lack of insulin secretion due to the apoptosis of pancreatic beta cells. Tumor necrosis factor alpha (TNF-α), a pro-inflammatory cytokine secreted from the tissue on the insulin signaling pathway, can play a role in causing fat resistance to insulin in type 2 diabetes patients. Adiponectin is a specific protein of adipose tissue. It belongs to the collectin family, which is present in human plasma at a high level and can protect against vascular lesions. Considering the importance of epigenetic changes in the development of multifactorial diseases, this study was conducted to investigate the methylation of TNF-α gene promoter in patients with type diabetes with cardiovascular disease and compare it with diabetic people without cardiovascular disease. Also, the serum concentration of adiponectin was investigated in diabetic patients with and without cardiovascular disease. For this purpose, 95 patients with type 2 diabetes referred to Isfahan Endocrine and Metabolism Research Center were divided into two groups: cardiovascular disease and without cardiovascular disease, based on the angiography results. Serum adiponectin level was measured by the RIA method. In addition to adiponectin, indicators such as FBS, cholesterol, triglycerides, and HDL were also measured in these patients. Then, the promoter region of the TNF-α gene was investigated by bisulfite treatment method, nested PCR, and finally, sequence determination. The results showed that the serum level of adiponectin was higher in diabetic patients without cardiovascular disease than in diabetic patients with cardiovascular disease, but this difference was not statistically significant. Also, no change was observed between men and women in TNF-α gene promoter methylation in diabetic and non-diabetic groups. In general, the decrease in adiponectin concentration in diabetic people can be a factor in causing macroangiopathy, so it can be predicted that the production of recombinant adiponectin can be helpful in the treatment and protection of cardiovascular disease in these patients. Also, it seems that the epigenetic changes of cytokines that play a role in causing insulin resistance in type 2 diabetic patients are not noticeable in the peripheral blood sample. In this regard, other tissues should probably be investigated.

Effect of Verapamil on Pancreatic Beta Cell Function in Newly Diagnosed Pediatric Type 1 Diabetes

In preclinical studies, thioredoxin-interacting protein overexpression induces pancreatic beta cell apoptosis and is involved in glucotoxicity-induced beta cell death. Calcium channel blockers reduce these effects and may be beneficial to beta cell preservation in type 1 diabetes. To determine the effect of verapamil on pancreatic beta cell function in children and adolescents with newly diagnosed type 1 diabetes. This double-blind, randomized clinical trial including children and adolescents aged 7 to 17 years with newly diagnosed type 1 diabetes who weighed 30 kg or greater was conducted at 6 centers in the US (randomized participants between July 20, 2020, and October 13, 2021) and follow-up was completed on September 15, 2022. Participants were randomly assigned 1:1 to once-daily oral verapamil (n = 47) or placebo (n = 41) as part of a factorial design in which participants also were assigned to receive either intensive diabetes management or standard diabetes care. The primary outcome was area under the curve values for C-peptide level (a measure of pancreatic beta cell function) stimulated by a mixed-meal tolerance test at 52 weeks from diagnosis of type 1 diabetes. Among 88 participants (mean age, 12.7 [SD, 2.4] years; 36 were female [41%]; and the mean time from diagnosis to randomization was 24 [SD, 4] days), 83 (94%) completed the trial. In the verapamil group, the mean C-peptide area under the curve was 0.66 pmol/mL at baseline and 0.65 pmol/mL at 52 weeks compared with 0.60 pmol/mL at baseline and 0.44 pmol/mL at 52 weeks in the placebo group (adjusted between-group difference, 0.14 pmol/mL [95% CI, 0.01 to 0.27 pmol/mL]; P = .04). This equates to a 30% higher C-peptide level at 52 weeks with verapamil. The percentage of participants with a 52-week peak C-peptide level of 0.2 pmol/mL or greater was 95% (41 of 43 participants) in the verapamil group vs 71% (27 of 38 participants) in the placebo group. At 52 weeks, hemoglobin A1c was 6.6% in the verapamil group vs 6.9% in the placebo group (adjusted between-group difference, -0.3% [95% CI, -1.0% to 0.4%]). Eight participants (17%) in the verapamil group and 8 participants (20%) in the placebo group had a nonserious adverse event considered to be related to treatment. In children and adolescents with newly diagnosed type 1 diabetes, verapamil partially preserved stimulated C-peptide secretion at 52 weeks from diagnosis compared with placebo. Further studies are needed to determine the longitudinal durability of C-peptide improvement and the optimal length of therapy. ClinicalTrials.gov Identifier: NCT04233034.

The Adaptor Protein NumbL Is Involved in the Control of Glucolipotoxicity-Induced Pancreatic Beta Cell Apoptosis.

Avoiding the loss of functional beta cell mass is critical for preventing or treating diabetes. Currently, the molecular mechanisms underlying beta cell death are partially understood, and there is a need to identify new targets for developing novel therapeutics to treat diabetes. Previously, our group established that Mig6, an inhibitor of EGF signaling, mediates beta cell death under diabetogenic conditions. The objective here was to clarify the mechanisms linking diabetogenic stimuli to beta cell death by investigating Mig6-interacting proteins. Using co-immunoprecipitation and mass spectrometry, we evaluated the binding partners of Mig6 under both normal glucose (NG) and glucolipotoxic (GLT) conditions in beta cells. We identified that Mig6 interacted dynamically with NumbL, whereas Mig6 associated with NumbL under NG, and this interaction was disrupted under GLT conditions. Further, we demonstrated that the siRNA-mediated suppression of NumbL expression in beta cells prevented apoptosis under GLT conditions by blocking the activation of NF-κB signaling. Using co-immunoprecipitation experiments, we observed that NumbL's interactions with TRAF6, a key component of NFκB signaling, were increased under GLT conditions. The interactions among Mig6, NumbL, and TRAF6 were dynamic and context-dependent. We proposed a model wherein these interactions activated pro-apoptotic NF-κB signaling while blocking pro-survival EGF signaling under diabetogenic conditions, leading to beta cell apoptosis. These findings indicated that NumbL should be further investigated as a candidate anti-diabetic therapeutic target.

Immune cell-derived extracellular vesicular microRNAs induce pancreatic beta cell apoptosis

BackgroundType 1 diabetes mellitus (T1DM) is an autoimmune disease caused by an autoimmune response against pancreatic islet β cells. Increasing evidence indicates that specific microRNAs (miRNAs) from immune cells extracellular vesicles are involved in islet β cells apoptosis. MethodsIn this study, the microarray datasets GSE27997 and GSE137637 were downloaded from the Gene Expression Omnibus (GEO) database. miRNAs that promote islet β cells apoptosis in T1DM were searched in PubMed. We used the FunRich tool to determine the miRNA expression in extracellular vesicles derived from immune cells associated with islet β cell apoptosis, of which we selected candidate miRNAs based on fold change expression. Potential upstream transcription factors and downstream target genes of candidate miRNAs were predicted using TransmiR V2.0 and starBase database, respectively. ResultsCandidate miRNAs expressed in extracellular vesicles derived from T cells, pro-inflammatory macrophages, B cells, and dendritic cells were analyzed to identify the miRNAs involved in β cells apoptosis. Based on these candidate miRNAs, 25 downstream candidate genes, which positively regulate β cell functions, were predicted and screened; 17 transcription factors that positively regulate the candidate miRNAs were also identified. ConclusionsOur study demonstrated that immune cell-derived extracellular vesicular miRNAs could promote islet β cell dysfunction and apoptosis. Based on these findings, we have constructed a transcription factor-miRNA-gene regulatory network, which provides a theoretical basis for clinical management of T1DM. This study provides novel insights into the mechanism underlying immune cell-derived extracellular vesicle-mediated islet β cell apoptosis.

ODP251 Thioredoxin-Interacting Protein (Txnip) And Cellular Senescence: Potential Adverse Effects of Txnip Deficiency.

Abstract Thioredoxin-interacting protein (TXNIP) is a ubiquitously expressed protein that belongs to the α-arrestin family of proteins but is unique in that it interacts with and inhibits the function of the endogenous antioxidant, Thioredoxin (Trx). TXNIP is strongly upregulated by hyperglycemia and is associated with increased oxidative stress and promotes pancreatic beta cell apoptosis accelerating the progression of diabetes. Age-dependent dysregulation of the Trx/TXNIP redox system has been implicated in cellular senescence and aging. However, the mechanisms are not fully understood. While Trx overexpression has been reported to protect against aging and age-related diseases, and we found that TXNIP-/- (KO) mice were protected from Diabetic kidney disease, paradoxically, others reported TXNIP KO mice had reduced survival in response to paraquat mediated oxidative stress. To investigate the potential effects of TXNIP in cellular senescence we used primary mouse renal glomerular mesangial cells (MC) from WT and TXNIP KO mice. Passaging of cells leads to replicative senescence. In WT MC this was associated with a significant reduction in TXNIP expression in late passage (LP-passage 25) compared to early passage (EP-passage 5-7) (p<0. 05), and this was accompanied by appearance of the senescence phenotype determined by significant increases in expression of the cellular senescence markers, p53, p16, p21, phosphorylation of histone H2AX (p<0. 05) and senescence associated beta-galactosidase staining (13-fold increase) (p<0. 01). To determine whether TXNIP downregulation played a causal role, primary MC from TXNIP KO were compared to WT at EP 5. TXNIP KO showed significantly higher expression of senescence markers P53 and P16 (p<0. 05), and beta-galactosidase staining (15-fold). AKT activation has been implicated in replicative senescence. Here, increased phosphorylation of AKT and its substrate FOXO were found in LP versus EP WT, and EP KO versus WT MC (p<0. 05). These studies indicate that TXNIP downregulation is a mediator of replicative senescence associated with increased AKT signaling. Thus, while beneficial for diabetes, targeting TXNIP may have long term untoward effects on aging. Presentation: No date and time listed

Evaluation of the Effect of an Advance Diabetes Support Product Targeting the Improved β-Cell Functions and β-Cell Regeneration for the Management of Diabetes Mellitus

Aim: Diabetes support product (ADSP) with phytocompounds was proposed to improve insulin secretion, avoid pancreatic beta cell apoptosis, and moderate beta cell differentiation and proliferation. In this research work, beta cell regenerative potential of ADSP was evaluated with STZ induced diabetes in rodents. Method: Single dose of Streptozotocin (STZ) (70mpk; i.p.) was used to induce diabetes in the Wistar rats. The treatment of vehicle or test or GLB was continued for the next 28 days to assess sub-acute anti-diabetic potential. Fasting blood glucose levels (BGL) was monitored weekly once throughout the experiment. Bodyweight, Feed-water consumption was calculated on every day till end of the experiment. Interleukin-6, Interleukin-1β and Interferon-γ was also analysis from blood serum after 28 days of treatment in rats. Further, animal was humanely sacrifice and organs such as liver, kidney(s) and pancreas were isolated for histopathology analysis. Result: Research showed that Insulin is Increased by 3 times in comparison with the diabetic group by ADSP after 28 days. After 28 days treatment of ADSP to rodents, Interleukin-6 decreased by 52%, Interleukin-1β decreased by 73% and Interferon-γ decreased by 28% in comparison with the diabetic control group. It is also observed in histopathology studies that there was a rise in the quantity of islets after 28 days treatment of ADSP in Streptozotocin carried diabetic rats. Conclusion: Hence in conclusion, advance diabetes support product supposed to be appreciated as synergistic product of encouraging the β-cell regeneration in vivo.

Research progress on the mechanism of beta-cell apoptosis in type 2 diabetes mellitus.

Type 2 diabetes mellitus(T2DM) is regarded as one of the most severe chronic metabolic diseases worldwide, which poses a great threat to human safety and health. The main feature of T2DM is the deterioration of pancreatic beta-cell function. More and more studies have shown that the decline of pancreatic beta-cell function in T2DM can be attributable to beta-cell apoptosis, but the exact mechanisms of beta-cell apoptosis in T2DM are not yet fully clarified. Therefore, in this review, we will focus on the current status and progress of research on the mechanism of pancreatic beta-cell apoptosis in T2DM, to provide new ideas for T2DM treatment strategies.

Low concentrations of bisphenol A promote the activation of the mitochondrial apoptotic pathway on Beta-TC-6 cells via the generation of intracellular reactive oxygen species and mitochondrial superoxide.

Τhe natural history of type 2 diabetes mellitus is characterized by a progressive loss of pancreatic beta cell function and insulin resistance. Bisphenol A (BPA) is an endocrine-disrupting chemical that is used widely in industry; people are exposed to BPA and its products daily. Studies have delineated that BPA alters the function of pancreatic beta cells. Herein, we examined the effect of low doses of BPA on pancreatic beta cell viability and apoptosis and we tried to elucidate the mechanisms involved in these processes. Beta-TC-6 (ATCC® CRL-11506™) cells were cultured with a medium containing the following dilutions of BPA: 0.002, 0.02, 0.1, 0.2, 2 μΜ up to 72 h. We examined the viability and adenosine triphosphate (ATP) levels of cells. Then, we measured apoptosis, cell cycle, and insulin levels. We quantified the levels of proteins implicated in the mitochondrial pathway of apoptosis; and finally, we quantified the intracellular reactive oxygen species and mitochondrial superoxide. We found that the exposure of Beta-TC-6 cells to BPA results in a decrease in cell viability, ATP levels, and an increase in insulin levels. We found an increase in apoptosis levels and a decrease in cell cycle levels. In addition, we provide evidence of the levels of apoptotic proteins. Finally, we found an increase in the cellular reactive oxygen species and mitochondrial superoxide production. Exposure to low concentrations of BPA triggers the mitochondrial pathway of apoptosis via the generation of intracellular reactive oxygen species and mitochondrial superoxide on Beta-TC-6 cells in a dose-dependent way.

Deletion of Gdf15 Reduces ER Stress-induced Beta-cell Apoptosis and Diabetes.

Endoplasmic reticulum (ER) stress contributes to pancreatic beta-cell apoptosis in diabetes, but the factors involved are still not fully elucidated. Growth differentiation factor 15 (GDF15) is a stress response gene and has been reported to be increased and play an important role in various diseases. However, the role of GDF15 in beta cells in the context of ER stress and diabetes is still unclear. In this study, we have discovered that GDF15 promotes ER stress-induced beta-cell apoptosis and that downregulation of GDF15 has beneficial effects on beta-cell survival in diabetes. Specifically, we found that GDF15 is induced by ER stress in beta cells and human islets, and that the transcription factor C/EBPβ is involved in this process. Interestingly, ER stress-induced apoptosis was significantly reduced in INS-1 cells with Gdf15 knockdown and in isolated Gdf15 knockout mouse islets. In vivo, we found that Gdf15 deletion attenuates streptozotocin-induced diabetes by preserving beta cells and insulin levels. Moreover, deletion of Gdf15 significantly delayed diabetes development in spontaneous ER stress-prone Akita mice. Thus, our findings suggest that GDF15 contributes to ER stress-induced beta-cell apoptosis and that inhibition of GDF15 may represent a novel strategy to promote beta-cell survival and treat diabetes.

Preserved C‐peptide in survivors of COVID‐19: Post hoc analysis

Preserved <scp>C</scp>‐peptide in survivors of <scp>COVID</scp>‐19: Post hoc analysis

The Effect of Continuous Aerobic Training on Bax/Bcl2 Ratio in Pancreatic Tissue Diabetic Rats

Objective: Apoptosis of pancreatic beta cells plays an important role in the pathogenesis of type 1 diabetes. the purpose of this study was to investigate the effect of continuous aerobic training on Bax/Bcl-2 ratio in pancreatic tissue of streptozotocin (STZ)-induced diabetic rats.&#x0D; Materials and Methods: A total number of 40 male Wistar rats, were divided into healthy control (HC), healthy trained (HT), diabetic control (DC), and diabetic trained (DT) groups. Diabetes was also induced by a single intraperitoneally injection of STZ (45 mg/kg). the training groups performed the exercise on the treadmill for five consecutive days within six weeks with 10-18 m/min intensity and 10-30 minute duration based on the principle of overload. the pancreatic tissue levels of the Bax and the Bcl-2 proteins were further determined via the ELISA method. The analysis of variance test (ANOVA) with Tukey's post hoc test was used for analyzing the data.&#x0D; Results: The results showed that the induction of diabetes had significantly decreased the levels of Bcl-2 protein and increased the levels of Bax protein and Bax/Bcl-2 ratio in the pancreatic tissue (Pvalue=0.001,Effect Size=0.29). As well, the findings showed that six weeks of aerobic exercise training had significantly increased the levels of Bcl-2 and significantly decreased the levels of Bax and Bax/Bcl-2 ratio in the DT group (P-value=0.012, Effect Size=0.23).&#x0D; Conclusion: According to the results of this study, exercise can be considered an effective strategy to reduce the rate of diabeticinduced apoptosis and control its complications.

The Effect of Verapamil on TXNIP Gene Expression, GLP1R mRNA, FBS, HbA1c, and Lipid Profile in T2DM Patients Receiving Metformin and Sitagliptin.

IntroductionType 2 diabetes mellitus (T2DM) is the most common type of diabetes. A decrease in the number of pancreatic beta cells is a pathological sign of diabetes, and to date there is no drug treatment that targets damage to these cells. Pancreatic beta cells have a weak antioxidant system and are highly sensitive to oxidative stress reactions that occur within cells. Thioredoxin interacting protein (TXNIP) inhibits thioredoxin, which is part of the intracellular antioxidant system, thereby accelerating oxidative stress and apoptosis of pancreatic beta cells. Verapamil is a non-dihydropyridine calcium channel blocker. The efficacy of this drug to improve beta cell survival and glucose homeostasis by inhibiting TXNIP expression has been demonstrated in in vitro studies. Although several retrospective studies have shown a lower incidence of T2DM with verapamil treatment, no prospective intervention studies have determined the efficacy of this drug in patients with T2DM.MethodsThe aim of this randomized, double-blind, placebo-controlled study was to evaluate the efficacy and safety of oral verapamil administration in T2DM patients. In this 90-day study, the effects of verapamil on fasting blood sugar (FBS), hemoglobin A1C (HbA1c), and the lipid profile were evaluated and compared with those of the placebo.ResultsThere was a significant decrease in HbA1c (about 0.5%) in the verapamil group at the end of the intervention period. The effects of verapamil on TXNIP gene expression and glucagon-like peptide-1 receptor (GLP1R) mRNA were compared with those of the placebo (at baseline, after 15 and 30 days, and at the end of the study). During the first month of the study, decreased TXNIP gene expression and increased GLP1R mRNA were associated with the administration of verapamil when compared with the placebo, although the differences were not significant.ConclusionVerapamil can lead to better control of T2DM by reducing TXNIP gene expression and increasing beta cell survival and, possibly, by other mechanisms.Clinical Trial RegistrationIRCT registration no.: IRCT20180417039339N1 (https://www.IRCT.ir).

Физическая активность как нефармакологическая и эффективная стратегия в контроле симптомов апоптоза у крыс с экспериментальным диабетом

Актуальность. За последние годы сахарный диабет (СД) стал глобальной проблемой здравоохранения. Апоптоз бета-клеток поджелудочной железы играет важную роль в патогенезе СД 1-го типа. Физическая активность как нефармакологическая стратегия для уменьшения частоты осложнений, вызванных диабетом, всегда интересовала исследователей. Поэтому целью данного исследования было установление влияния аэробных упражнений на уровни Bax, Bcl-2 и Bax/Bcl-2 в ткани поджелудочной железы стрептозоцин-индуцированных диабетических крыс. Материалы и методы. Самцы крыс линии Wistar (в возрасте 10 недель, вес 200–250 г), общее количество 40, были рандомизированы на группы здорового контроля (ЗК), здоровых тренированных (ЗТ), с диабетом (контроль, ДК) и с диабетом с физической нагрузкой (ДН). Диабет был индуцирован однократной интраперитонеальной инъекцией стрептозоцина (45 мг/кг). Тренировочные группы выполняли упражнения на беговой дорожке пять дней подряд в течение шести недель. Уровни тканей поджелудочной железы в белках Bax и Bcl-2 дополнительно определяли методом ИФА. Результаты. Индукция диабета существенно снизила уровень белка Bcl-2 и увеличила уровень белка Bax и соотношение Bax/Bcl-2 в ткани поджелудочной железы (p &lt; 0,05). Кроме того, результаты показали, что шесть недель аэробных тренировок значительно повысили уровень белка Bcl-2 и снизили уровень белка Bax в группе ДН. Также соотношение Bax/Bcl-2 существенно снизилось в группе ДН (р &lt; 0,05). Усиление выделения и передачи фактора, индуцирующего апоптоз, который наблюдается в состоянии окислительного стресса, уменьшается в тканях тренированных лиц и указывает на торможение в сигнализации апоптоза. Выводы. Согласно результатам этого исследования, физические упражнения можно рассматривать как эффективную стратегию уменьшения частоты апоптоза, вы­званного диабетом, и контроля его осложнений.

Mechanisms of Beta-Cell Apoptosis in Type 2 Diabetes-Prone Situations and Potential Protection by GLP-1-Based Therapies.

Type 2 diabetes (T2D) is characterized by chronic hyperglycemia secondary to the decline of functional beta-cells and is usually accompanied by a reduced sensitivity to insulin. Whereas altered beta-cell function plays a key role in T2D onset, a decreased beta-cell mass was also reported to contribute to the pathophysiology of this metabolic disease. The decreased beta-cell mass in T2D is, at least in part, attributed to beta-cell apoptosis that is triggered by diabetogenic situations such as amyloid deposits, lipotoxicity and glucotoxicity. In this review, we discussed the molecular mechanisms involved in pancreatic beta-cell apoptosis under such diabetes-prone situations. Finally, we considered the molecular signaling pathways recruited by glucagon-like peptide-1-based therapies to potentially protect beta-cells from death under diabetogenic situations.

Beta cell protective effect of Curcuma longa and Piper nigrum in cytokine cocktail induced apoptosis in Min6 pancreatic beta cells

Background: Type 1 diabetes mellitus is characterized by loss of beta cell mass and insulin insufficiency. Beta cell apoptosis and destruction by cytotoxic T lymphocytes and pro-inflammatory cytokines like IL-1β, TNF-α and IFN-γ appears to represent a key event in pathogenesis of type 1 diabetes mellitus. Purpose: The aim of present study was to evaluate the prophylactic effect of aqueous extract of Curcuma longa and Piper nigrum (CL-PN) in ratio 2:1 on pancreatic beta cell apoptosis and dysfunction induced by cytokine cocktail of IL-1β (50 ng/ml), TNF-α (25 ng/ml) and IFN-γ (25 ng/ml). Methods: We used Min6 beta cell line as an in vitro model and the cells were pre-treated with herbal extract of CL-PN and then exposed to cytokine cocktail for 6 hrs to mimic beta cell destruction as in type 1 diabetes. Beta cell apoptosis and protective activity were assessed by flow cytometer based assay of annexin-V FITC and propidium iodide staining. Results: Aqueous extract of the combination of CL-PN at 1 μg/ml concentration can effectively inhibit apoptosis in Min6 beta cell line by 1.6 fold as compared to cytokine cocktail. It also demonstrated 2.6 fold lesser production of nitric oxide, 1.4 fold reduced ROS and increasing mitochondrial membrane potential which are major markers of beta cell damage. The caspase 3 mRNA expression is also reduced by 4.7 fold despite cytokine challenge. Conclusion: Therefore, the present study paves the way for establishing herbal oral treatment for protection of beta cells in type 1 diabetes mellitus.

Lipotoxicity induced pancreatic beta cell damage is associated with GPR119/MST1/FoxO1 Pathway

IntroductionG-protein-coupled receptor 119 (GPR119) is emerging as a potential therapeutic target against type 2 diabetes with beneficial effects on glucose homeostasis. However, the function of GRP119 in lipotoxicity induced pancreatic beta cell apoptosis and the molecular mechanism remains largely unknown.Material and methodsImpact of GPR119 on pancreatic islet beta cell apoptosis was evaluated in INS-1 cells treated with palmitate. The subsequent modulation of the MST1-FOXO1-Pdx1 signaling pathway and pro-apoptotic caspase-3 system were determined by measuring the target protein and mRNA expression. Dyslipidemia mice with gain and loss of GPR119 function by the application of specific lenti-viral vector was utilized to evaluate the impact of GPR119 on pancreas function in vivo. Lipid metabolism, glucose and insulin response, morphological changes as well as activation/inhibition of MST1-FOXO1-Pdx1 signaling pathway in pancreas were analyzed systematically.ResultsPalmitate treatment stimulated pro-apoptotic response in INS-1 cells, accompanied by inhibition of GPR119 expression and the subsequent activation of the MST1-FOXO1 combined with inhibition of Pdx1 signaling cascade. Activation of GPR119 by MBX prevents INS-1 cell from lipotoxicity induced apoptosis by targeting the MST1-FOXO1-Pdx1 pathway. Moreover, overexpression of GPR119 significantly attenuates the dyslipidemia and dysfunction of the pancreas. In contrast, inactivation of GPR119 by lentiviral vector in mice results in accelerated pancreas apoptosis and malfunction. The protective effects of GRP119 on lipotoxicity induced pancreas dysfunction are associated with modulating the MST1-FOXO1-Pdx1 signaling cascade.ConclusionsGPR119 alleviates lipotoxicity induced pancreatic beta cell apoptosis and malfunction through regulating MST1-FOXO1-Pdx1 signaling pathway.

CDK11 Promotes Cytokine-Induced Apoptosis in Pancreatic Beta Cells Independently of Glucose Concentration and Is Regulated by Inflammation in the NOD Mouse Model.

BackgroundPancreatic islets are exposed to strong pro-apoptotic stimuli: inflammation and hyperglycemia, during the progression of the autoimmune diabetes (T1D). We found that the Cdk11(Cyclin Dependent Kinase 11) is downregulated by inflammation in the T1D prone NOD (non-obese diabetic) mouse model. The aim of this study is to determine the role of CDK11 in the pathogenesis of T1D and to assess the hierarchical relationship between CDK11 and Cyclin D3 in beta cell viability, since Cyclin D3, a natural ligand for CDK11, promotes beta cell viability and fitness in front of glucose.MethodsWe studied T1D pathogenesis in NOD mice hemideficient for CDK11 (N-HTZ), and, in N-HTZ deficient for Cyclin D3 (K11HTZ-D3KO), in comparison to their respective controls (N-WT and K11WT-D3KO). Moreover, we exposed pancreatic islets to either pro-inflammatory cytokines in the presence of increasing glucose concentrations, or Thapsigargin, an Endoplasmic Reticulum (ER)-stress inducing agent, and assessed apoptotic events. The expression of key ER-stress markers (Chop, Atf4 and Bip) was also determined.ResultsN-HTZ mice were significantly protected against T1D, and NS-HTZ pancreatic islets exhibited an impaired sensitivity to cytokine-induced apoptosis, regardless of glucose concentration. However, thapsigargin-induced apoptosis was not altered. Furthermore, CDK11 hemideficiency did not attenuate the exacerbation of T1D caused by Cyclin D3 deficiency.ConclusionsThis study is the first to report that CDK11 is repressed in T1D as a protection mechanism against inflammation-induced apoptosis and suggests that CDK11 lies upstream Cyclin D3 signaling. We unveil the CDK11/Cyclin D3 tandem as a new potential intervention target in T1D.