Excessive secretion of human islet amyloid polypeptide(hIAPP)is an important pathological basis of diabetic encephalopathy(DE).In this study,we aimed to investigate the potential implications of hIAPP in DE pathogenes...Excessive secretion of human islet amyloid polypeptide(hIAPP)is an important pathological basis of diabetic encephalopathy(DE).In this study,we aimed to investigate the potential implications of hIAPP in DE pathogenesis.Brain magnetic resonance imaging and cognitive scales were applied to evaluate white matter damage and cognitive function.We found that the concentration of serum hIAPP was positively correlated with white matter damage but negatively correlated with cognitive scores in patients with type 2 diabetes mellitus.In vitro assays revealed that oligodendrocytes,compared with neurons,were more prone to acidosis under exogenous hIAPP stimulation.Moreover,western blotting and co-immunoprecipitation indicated that hIAPP interfered with the binding process of monocarboxylate transporter(MCT)1 to its accessory protein CD147 but had no effect on the binding of MCT2 to its accessory protein gp70.Proteomic differential analysis of proteins co-immunoprecipitated with CD147 in oligodendrocytes revealed Yeast Rab GTPase-Interacting protein 2(YIPF2,which modulates the transfer of CD147 to the cell membrane)as a significant target.Furthermore,YIPF2 inhibition significantly improved hIAPP-induced acidosis in oligodendrocytes and alleviated cognitive dysfunction in DE model mice.These findings suggest that increased CD147 translocation by inhibition of YIPF2 optimizes MCT1 and CD147 binding,potentially ameliorating hIAPP-induced acidosis and the consequent DE-related demyelination.展开更多
Background:Diabetes is a widespread disease with increasing prevalence.Transplantation of islets of Langerhans is a viable treatment for a selected group of patients with repeated hypoglycemic episodes in type 1 diabe...Background:Diabetes is a widespread disease with increasing prevalence.Transplantation of islets of Langerhans is a viable treatment for a selected group of patients with repeated hypoglycemic episodes in type 1 diabetes.The countries where islet transplantation has not been explored suffer from insufficient knowledge concerning key elements of the isolation process.Donor and organ procurement parameters impact human islet yield,although for research purposes,islet yield may be secondary in importance to islet function.This paper will analyze the feasibility of research-only human islet isolation and signify parameters underlying a successful yield in the Indian population.This eventually can make islet transplantation a clinical reality in India.Method:After receiving the consent for procuring brain-dead pancreas from the first-degree of relatives,samples were collected and transported in a transportation buffer at 4℃.The procedure consists of a mechanically enhanced enzymatic digestion of the pancreas,after which it was taken for purification using Ficoll method,followed by islet quality testing.Results:Through 15 isolations done over a span of approximately 2 years during the COVID pandemic in India,we confirm that ischemic time and glycated hemoglobin,each have a negative impact on isolation purity and yield.Notably,extending cold ischemic tim beyond the typical clinical isolation cutoff of 12 hours(to≥18 h)had a huge impact on islet function and yield.Age had a negative correlation with islet yield;however other biological parameters(specifically body mass index)and isolation variables appear to make a significant contribution to the heterogeneity of human islet yield.Our current work demonstrates the feasibility of extending acceptable cold ischemic time for research-focused human islet isolation and highlights the biological variation in isolation of human islets from donors with and without diabetes.Conclusion:India requires establishment of an islet transplant program using the current standard methods of“islet isolation”and donor program and process.Research should focus on improving standards in the islet preparation process to increase the number of successful preparations,shorten the isolation time,and increase patient safety so that the theoretical risk involved can become a practical reality.展开更多
Curvature is one of the most important features of lipid membranes in living cells,which significantly influences the structure of lipid membranes and their interaction with proteins.Taken the human islet amyloid poly...Curvature is one of the most important features of lipid membranes in living cells,which significantly influences the structure of lipid membranes and their interaction with proteins.Taken the human islet amyloid polypeptide(h IAPP),an important protein related to the pathogenesis of type II diabetes,as an example,we performed molecular dynamics(MD)simulations to study the interaction between the protein and the lipid structures with varied curvatures.We found that the lipids in the high curvature membrane pack loosely with high mobility.The h IAPP initially forms H-bonds with the membrane surface that anchored the protein,and then inserts into the membrane through the hydrophobic interactions between the residues and the hydrophobic tails of the lipids.h IAPP can insert into the membrane more deeply with a larger curvature and with a stronger binding strength.Our result provided important insights into the mechanism of the membrane curvature-dependent property of proteins with molecular details.展开更多
Objective To investigate in vitro heme oxygenase-1 gene (HO-1) delivery to human pancreatic islets by adenovirus vectors. Methods Recombinant adenovirus containing HO-1 or enhanced green fluorescent protein gene(EGFP)...Objective To investigate in vitro heme oxygenase-1 gene (HO-1) delivery to human pancreatic islets by adenovirus vectors. Methods Recombinant adenovirus containing HO-1 or enhanced green fluorescent protein gene(EGFP) was generated by using the AdEasy System. The purified human pancreatic islets were infected with recombinant adenovirus vectors at various multiplicity of infection (MOI). Transduction was confirmed by fluorescence photographs and Western blot. Glucose-stimulated insulin secretion was detected by using Human insulin radioimmunoassay kits and was used to assess the function of human islets infected by recombinant adenovirus.Results Viral titers of Ad-hHO-1 and Ad-EGFP were 1.96×109 and 1.99×109 pfu/mL, respectively. Human pancreatic islets were efficiently infected by recombinant adenovirus vectors in vitro. Transfection of human islets at an MOI of 20 did not inhibit islet function. Recombinant adenovirus mediated HO-1gene transfer significantly improved the islet function of insulin release when simulated by high level glucose. Conclusion Recombinant adenovirus is efficient to deliver exogenous gene into human pancreatic islets in vitro. HO-1 gene transfection can improve human islet function.展开更多
Objective:Exploring the formation and aggregation of human islet amyloid polypeptide(hIAPP)(amylin)fibers is significant for promoting the prevention and treatment of type II diabetes mellitus(T2DM).Flavones in pomelo...Objective:Exploring the formation and aggregation of human islet amyloid polypeptide(hIAPP)(amylin)fibers is significant for promoting the prevention and treatment of type II diabetes mellitus(T2DM).Flavones in pomelo peel have visible biological activity in the anti-diabetes aspect.The present study aimed to investigate the effects of five flavones[naringin(NRG),narirutin(NRR),nobiletin(NOB),sinensetin(SIN),and neohesperidin(NHP)]in pomelo peel on peptide aggregation and explore its possible mechanisms.The cell viability of flavones against peptide aggregation was also evaluated.Methods:The thioflavin T(ThT)assay and transmission electron microscopy(TEM)were used for evaluating the inhibition and disaggregation of flavones on peptide aggregation.The interaction mechanism was analyzed by endogenous fluorescence,molecular dynamics(MD)simulations,ultraviolet spectroscopy(UV)and isothermal titration calorimetry(ITC)experiments.The 3-[4,5-dimethylthiazol-2-y l]-2,5-diphenyl tetrazolium bromide(MTT)and immune assays were performed to characterize the cell viability of flavones against peptide aggregation.Results:The five flavones showed a decrease in fluorescence intensity,fiber number and size under incubation with different molar ratios of hIAPP.The compounds can bind to the aromatic tyrosine(Tyr)residueTyr 37,resulting in the intrinsic fluorescence quenching of the peptides.Five flavones can form hydrogen bonds with hIAPP,which is likely to be based on their phenolic hydroxyl structure.They showed strong binding affinity with peptides.The reaction system of NRG and NRR observed an exothermic reaction,and the others were endothermic reactions.The absorption peaks of the compounds with hIAPP changed and showed hypochromic effects,indicating that there may beπ-πstacking interaction.Flavones noticeably increased the cell viability in the presence of amyloid peptides and reduced the absorption intensity induced by peptide oligomers.Conclusion:A total of five flavones in pomelo peel have inhibitory and depolymerization effects on amyloid fibrils,and can significantly protect cells from the toxic effect of hIAPP and reduce the production of toxic oligomers.展开更多
Type 2 diabetes mellitus patients have a markedly higher risk of developing dementia.While multiple factors contribute to this predisposition,one of these involves the increased secretion of amylin,or islet amyloid po...Type 2 diabetes mellitus patients have a markedly higher risk of developing dementia.While multiple factors contribute to this predisposition,one of these involves the increased secretion of amylin,or islet amyloid polypeptide,that accompanies the pathophysiology of type 2 diabetes mellitus.Islet amyloid polypeptide accumulation has undoubtedly been implicated in various forms of dementia,including Alzheimer’s disease and vascular dementia,but the exact mechanisms underlying islet amyloid polypeptide’s causative role in dementia are unclear.In this review,we have summarized the literature supporting the various mechanisms by which islet amyloid polypeptide accumulation may cause neuronal damage,ultimately leading to the clinical symptoms of dementia.We discuss the evidence for islet amyloid polypeptide deposition in the brain,islet amyloid polypeptide interaction with other amyloids implicated in neurodegeneration,neuroinflammation caused by islet amyloid polypeptide deposition,vascular damage induced by islet amyloid polypeptide accumulation,and islet amyloid polypeptide-induced cytotoxicity.There are very few therapies approved for the treatment of dementia,and of these,clinical responses have been controversial at best.Therefore,investigating new,targetable pathways is vital for identifying novel therapeutic strategies for treating dementia.As such,we conclude this review by discussing islet amyloid polypeptide accumulation as a potential therapeutic target not only in treating type 2 diabetes mellitus but as a future target in treating or even preventing dementia associated with type 2 diabetes mellitus.展开更多
It is crucial to understand the glucose control within our bodies.Bariatric/metabolic surgeries,including laparoscopic sleeve gastrec-tomy(LSG)and Roux-en-Y gastric bypass(RYGB),provide an avenue for exploring the pot...It is crucial to understand the glucose control within our bodies.Bariatric/metabolic surgeries,including laparoscopic sleeve gastrec-tomy(LSG)and Roux-en-Y gastric bypass(RYGB),provide an avenue for exploring the potential key factors involved in maintaining glucose homeostasis since these surgeries have shown promising results in improving glycemic control among patients with severe type 2 diabetes(T2D).For the first time,a markedly altered population of serum proteins in patients after LSG was discovered and analyzed through proteomics.Apolipoprotein A-IV(apoA-IV)was revealed to be increased dramatically in diabetic obese patients following LSG,and a similar effect was observed in patients after RYGB surgery.Moreover,recombinant apoA-IV protein treatment was proven to enhance insulin secretion in isolated human islets.These results showed that apoA-IV may play a crucial role in gly-cemic control in humans,potentially through enhancing insulin secretion in human islets.ApoA-IV was further shown to enhance energy expenditure and improve glucose tolerance in diabetic rodents,through stimulating glucose-dependent insulin secretion in pancreaticβcells,partially via Gαs-coupled GPCR/cAMP(G protein-coupled receptor/cyclic adenosine monophosphate)signaling.Furthermore,T55-121,truncated peptide 55-121 of apoA-IV,was discovered to mediate the function of apoA-IV.These collective findings contribute to our understanding of the relationship between apoA-IV and glycemic control,highlighting its potential as a biomarker or therapeutic target in managing and improving glucose regulation.展开更多
基金supported by the National Natural Science Foundation of China (82100863)Hebei Natural Science Foundation (H2020206643 and H2020206105)+3 种基金Funding project for introducing overseas students of Hebei Province (C20210346)Medical Science Research Project of Hebei Province (20211628)Hebei Province Government-funded Excellent Talents Project in Clinical Medicine (ZF2023029)Spark Scientific Research Project of the First Hospital of Hebei Medical University (XH202004).
文摘Excessive secretion of human islet amyloid polypeptide(hIAPP)is an important pathological basis of diabetic encephalopathy(DE).In this study,we aimed to investigate the potential implications of hIAPP in DE pathogenesis.Brain magnetic resonance imaging and cognitive scales were applied to evaluate white matter damage and cognitive function.We found that the concentration of serum hIAPP was positively correlated with white matter damage but negatively correlated with cognitive scores in patients with type 2 diabetes mellitus.In vitro assays revealed that oligodendrocytes,compared with neurons,were more prone to acidosis under exogenous hIAPP stimulation.Moreover,western blotting and co-immunoprecipitation indicated that hIAPP interfered with the binding process of monocarboxylate transporter(MCT)1 to its accessory protein CD147 but had no effect on the binding of MCT2 to its accessory protein gp70.Proteomic differential analysis of proteins co-immunoprecipitated with CD147 in oligodendrocytes revealed Yeast Rab GTPase-Interacting protein 2(YIPF2,which modulates the transfer of CD147 to the cell membrane)as a significant target.Furthermore,YIPF2 inhibition significantly improved hIAPP-induced acidosis in oligodendrocytes and alleviated cognitive dysfunction in DE model mice.These findings suggest that increased CD147 translocation by inhibition of YIPF2 optimizes MCT1 and CD147 binding,potentially ameliorating hIAPP-induced acidosis and the consequent DE-related demyelination.
文摘Background:Diabetes is a widespread disease with increasing prevalence.Transplantation of islets of Langerhans is a viable treatment for a selected group of patients with repeated hypoglycemic episodes in type 1 diabetes.The countries where islet transplantation has not been explored suffer from insufficient knowledge concerning key elements of the isolation process.Donor and organ procurement parameters impact human islet yield,although for research purposes,islet yield may be secondary in importance to islet function.This paper will analyze the feasibility of research-only human islet isolation and signify parameters underlying a successful yield in the Indian population.This eventually can make islet transplantation a clinical reality in India.Method:After receiving the consent for procuring brain-dead pancreas from the first-degree of relatives,samples were collected and transported in a transportation buffer at 4℃.The procedure consists of a mechanically enhanced enzymatic digestion of the pancreas,after which it was taken for purification using Ficoll method,followed by islet quality testing.Results:Through 15 isolations done over a span of approximately 2 years during the COVID pandemic in India,we confirm that ischemic time and glycated hemoglobin,each have a negative impact on isolation purity and yield.Notably,extending cold ischemic tim beyond the typical clinical isolation cutoff of 12 hours(to≥18 h)had a huge impact on islet function and yield.Age had a negative correlation with islet yield;however other biological parameters(specifically body mass index)and isolation variables appear to make a significant contribution to the heterogeneity of human islet yield.Our current work demonstrates the feasibility of extending acceptable cold ischemic time for research-focused human islet isolation and highlights the biological variation in isolation of human islets from donors with and without diabetes.Conclusion:India requires establishment of an islet transplant program using the current standard methods of“islet isolation”and donor program and process.Research should focus on improving standards in the islet preparation process to increase the number of successful preparations,shorten the isolation time,and increase patient safety so that the theoretical risk involved can become a practical reality.
基金supported by funds from the National Natural Science Foundation of China(Grants 11932017,11772054,11772055,and 11532009)supported by the Fundamental Research Funds for the Central Universities(Grant 2019QNA4060)。
文摘Curvature is one of the most important features of lipid membranes in living cells,which significantly influences the structure of lipid membranes and their interaction with proteins.Taken the human islet amyloid polypeptide(h IAPP),an important protein related to the pathogenesis of type II diabetes,as an example,we performed molecular dynamics(MD)simulations to study the interaction between the protein and the lipid structures with varied curvatures.We found that the lipids in the high curvature membrane pack loosely with high mobility.The h IAPP initially forms H-bonds with the membrane surface that anchored the protein,and then inserts into the membrane through the hydrophobic interactions between the residues and the hydrophobic tails of the lipids.h IAPP can insert into the membrane more deeply with a larger curvature and with a stronger binding strength.Our result provided important insights into the mechanism of the membrane curvature-dependent property of proteins with molecular details.
基金Supported by the National Natural Science Foundation of China (30571759).
文摘Objective To investigate in vitro heme oxygenase-1 gene (HO-1) delivery to human pancreatic islets by adenovirus vectors. Methods Recombinant adenovirus containing HO-1 or enhanced green fluorescent protein gene(EGFP) was generated by using the AdEasy System. The purified human pancreatic islets were infected with recombinant adenovirus vectors at various multiplicity of infection (MOI). Transduction was confirmed by fluorescence photographs and Western blot. Glucose-stimulated insulin secretion was detected by using Human insulin radioimmunoassay kits and was used to assess the function of human islets infected by recombinant adenovirus.Results Viral titers of Ad-hHO-1 and Ad-EGFP were 1.96×109 and 1.99×109 pfu/mL, respectively. Human pancreatic islets were efficiently infected by recombinant adenovirus vectors in vitro. Transfection of human islets at an MOI of 20 did not inhibit islet function. Recombinant adenovirus mediated HO-1gene transfer significantly improved the islet function of insulin release when simulated by high level glucose. Conclusion Recombinant adenovirus is efficient to deliver exogenous gene into human pancreatic islets in vitro. HO-1 gene transfection can improve human islet function.
基金supported by the National Natural Science Foundation of China(No.82174074,81873092)。
文摘Objective:Exploring the formation and aggregation of human islet amyloid polypeptide(hIAPP)(amylin)fibers is significant for promoting the prevention and treatment of type II diabetes mellitus(T2DM).Flavones in pomelo peel have visible biological activity in the anti-diabetes aspect.The present study aimed to investigate the effects of five flavones[naringin(NRG),narirutin(NRR),nobiletin(NOB),sinensetin(SIN),and neohesperidin(NHP)]in pomelo peel on peptide aggregation and explore its possible mechanisms.The cell viability of flavones against peptide aggregation was also evaluated.Methods:The thioflavin T(ThT)assay and transmission electron microscopy(TEM)were used for evaluating the inhibition and disaggregation of flavones on peptide aggregation.The interaction mechanism was analyzed by endogenous fluorescence,molecular dynamics(MD)simulations,ultraviolet spectroscopy(UV)and isothermal titration calorimetry(ITC)experiments.The 3-[4,5-dimethylthiazol-2-y l]-2,5-diphenyl tetrazolium bromide(MTT)and immune assays were performed to characterize the cell viability of flavones against peptide aggregation.Results:The five flavones showed a decrease in fluorescence intensity,fiber number and size under incubation with different molar ratios of hIAPP.The compounds can bind to the aromatic tyrosine(Tyr)residueTyr 37,resulting in the intrinsic fluorescence quenching of the peptides.Five flavones can form hydrogen bonds with hIAPP,which is likely to be based on their phenolic hydroxyl structure.They showed strong binding affinity with peptides.The reaction system of NRG and NRR observed an exothermic reaction,and the others were endothermic reactions.The absorption peaks of the compounds with hIAPP changed and showed hypochromic effects,indicating that there may beπ-πstacking interaction.Flavones noticeably increased the cell viability in the presence of amyloid peptides and reduced the absorption intensity induced by peptide oligomers.Conclusion:A total of five flavones in pomelo peel have inhibitory and depolymerization effects on amyloid fibrils,and can significantly protect cells from the toxic effect of hIAPP and reduce the production of toxic oligomers.
基金supported by The Mike Hogg FundBaylor College of Medicine Medical Scientist Training Program,NICHD R01HD099252(to RJP)and R01HD098131(to RJP)the NHLBI T32 HL092332(to ASB)。
文摘Type 2 diabetes mellitus patients have a markedly higher risk of developing dementia.While multiple factors contribute to this predisposition,one of these involves the increased secretion of amylin,or islet amyloid polypeptide,that accompanies the pathophysiology of type 2 diabetes mellitus.Islet amyloid polypeptide accumulation has undoubtedly been implicated in various forms of dementia,including Alzheimer’s disease and vascular dementia,but the exact mechanisms underlying islet amyloid polypeptide’s causative role in dementia are unclear.In this review,we have summarized the literature supporting the various mechanisms by which islet amyloid polypeptide accumulation may cause neuronal damage,ultimately leading to the clinical symptoms of dementia.We discuss the evidence for islet amyloid polypeptide deposition in the brain,islet amyloid polypeptide interaction with other amyloids implicated in neurodegeneration,neuroinflammation caused by islet amyloid polypeptide deposition,vascular damage induced by islet amyloid polypeptide accumulation,and islet amyloid polypeptide-induced cytotoxicity.There are very few therapies approved for the treatment of dementia,and of these,clinical responses have been controversial at best.Therefore,investigating new,targetable pathways is vital for identifying novel therapeutic strategies for treating dementia.As such,we conclude this review by discussing islet amyloid polypeptide accumulation as a potential therapeutic target not only in treating type 2 diabetes mellitus but as a future target in treating or even preventing dementia associated with type 2 diabetes mellitus.
基金supported by the National Natural Science Foundation of China(92357302,32170787,and 32100557)the National Key Research and Development Program of China(2018YFA0800700,2023YFA1801103,and 2018YFA0800900)Researches on human islets were supported by the National Natural Science Foundation of Tianjin Municipal Human Resources and Social Security Bureau(XB202011).
文摘It is crucial to understand the glucose control within our bodies.Bariatric/metabolic surgeries,including laparoscopic sleeve gastrec-tomy(LSG)and Roux-en-Y gastric bypass(RYGB),provide an avenue for exploring the potential key factors involved in maintaining glucose homeostasis since these surgeries have shown promising results in improving glycemic control among patients with severe type 2 diabetes(T2D).For the first time,a markedly altered population of serum proteins in patients after LSG was discovered and analyzed through proteomics.Apolipoprotein A-IV(apoA-IV)was revealed to be increased dramatically in diabetic obese patients following LSG,and a similar effect was observed in patients after RYGB surgery.Moreover,recombinant apoA-IV protein treatment was proven to enhance insulin secretion in isolated human islets.These results showed that apoA-IV may play a crucial role in gly-cemic control in humans,potentially through enhancing insulin secretion in human islets.ApoA-IV was further shown to enhance energy expenditure and improve glucose tolerance in diabetic rodents,through stimulating glucose-dependent insulin secretion in pancreaticβcells,partially via Gαs-coupled GPCR/cAMP(G protein-coupled receptor/cyclic adenosine monophosphate)signaling.Furthermore,T55-121,truncated peptide 55-121 of apoA-IV,was discovered to mediate the function of apoA-IV.These collective findings contribute to our understanding of the relationship between apoA-IV and glycemic control,highlighting its potential as a biomarker or therapeutic target in managing and improving glucose regulation.
