The effect of human islet amyloid polypeptide on autophagy in murine INS-1 cells and potential mechanisms / 中华内科杂志

Objective The aims of the study were to investigate the effects of human islet amyloid polypeptide (hIAPP) on autophagy in INS-1 cells and its underlying mechanism,and to explore the role of autophagy in hIAPP-induced cytotoxicity and oxidative stress.Methods INS-1 cells were treated with hIAPP (10 μmol/L) for 24 h in the presence or absence of N-acetyl-L-cysteine (NAC),compound C,5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) and 3-methyladenine (3-MA),respectively.Transmission electron microscopy was used to observe the number of autophagosome in cells.Cell viability was determined by methyl thiazolyl tetrazolium (MTT) test.2',7'-dichlorofluorescin diacetate (DCFH-DA) assay was used to measure the relative levels of reactive oxygen species (ROS).Western blot was used to detect expression of adenosine monophosphate-activated protein kinase (AMPK) and autophagic markers p62 and microtubule associated protein 1 light chain3 (LC3).Results Treatment of INS-1 cells with hIAPP resulted in a significant increase in the number of autophagosomes and the expression of LC3-Ⅱ/LC3-Ⅰ (both P＜0.05).Meanwhile,treatment of INS-1 cells with hIAPP enhanced the level of ROS to 1.76 times of control cells (P＜0.01).Co-treatment with NAC,an antioxidant,inhibited hIAPP-induced ROS generation,and the expression of LC3-Ⅱ/LC3-Ⅰ and p-AMPK in the INS-1 cells (all P＜0.05).Pretreatment of INS-1 cells with AMPK inhibitor compound C suppressed hIAPP and AICAR,an activator of AMPK,induced expression of LC3-Ⅱ/LC3-Ⅰ and p-AMPK (all P＜0.05).Autophagic inhibitor 3-MA and compound C aggravated the hIAPP-induced cell death and ROS generation in INS-1 cells (All P＜0.05).The cytotoxic effects of hIAPP were significantly attenuated by co-treatment with AICAR (P＜0.05).Conclusion Autophagy may act as an adaptive mechanism to alleviate hIAPP-induced oxidative damage and toxicity in INS-1 cells.

Novel Molecules Regulating Energy Homeostasis: Physiology and Regulation by Macronutrient Intake and Weight Loss

Excess energy intake, without a compensatory increase of energy expenditure, leads to obesity. Several molecules are involved in energy homeostasis regulation and new ones are being discovered constantly. Appetite regulating hormones such as ghrelin, peptide tyrosine-tyrosine and amylin or incretins such as the gastric inhibitory polypeptide have been studied extensively while other molecules such as fibroblast growth factor 21, chemerin, irisin, secreted frizzle-related protein-4, total bile acids, and heme oxygenase-1 have been linked to energy homeostasis regulation more recently and the specific role of each one of them has not been fully elucidated. This mini review focuses on the above mentioned molecules and discusses them in relation to their regulation by the macronutrient composition of the diet as well as diet-induced weight loss.

Autoantigens in type 1 diabetes / 国际儿科学杂志

Autoimmunity is the main mechanism of type 1 diabetes.The discovery of autoantigens has broadened our understanding of pathogenesis and clinical diagnosis of type 1 diabetes.Insulin,glutamic acid decarboxylase 65,and insulinoma-associated protein 2 have been found to be major autoantigens of type 1 diabetes.In recent years,some autoantigens in type 1 diabetes,such as chromogranin A,islet amyloid polypeptide,zinc transporter 8,and pancreatic duodenal homeobox factor-1,have received some attention in the literature.The purpose of this article is to review the progress of novel autoantigens in type 1 diabetes.

Expression changes of islet amyloid polypeptide, somatostatin positive cells of pancreatic islet in type 1 diabetes mellitus mice / 解剖学报

Objective To explore the changes of the expression of islet amylodi polypeptide ( IAPP ) and somatostatin( SS) of islet in type 1 diabetes mice, and the mechanism of the expression changes .Methods We established the diabetes model in C57BL/6J mice by low-dose streptozotocin ( STZ) injection.The excisions of the pancreas tails removed on the 3th, 7th, 10th, 14th, 21th and 28th day.Tissues were assessed by immunohistochemical SABC, immunofluorescence in the study .Results 1.Numerical density on area ( NA ) of IAPP positive cells in experimental group (EG) decreased since the 3th day, but average absorbance increased since the 7th day.2.NA of SS-IR cells in EG increased since the 3th day, and average absorbance increased since the 7th day.3.The results of immunofluorescence double staining showed that , IAPP and SS could coexpression in part of cells in islets .Conclusion The number of IAPP positive cells in type 1 diabetes is decreased , but the immunoreaction increased .Immunoreaction and number of SS positive cells increase .Both of them are involved in the pathogenesis of type 1 diabetes.

Detecting the research trend of islet amyloid polypeptide with text mining technique / 中华医学科研管理杂志

Islet amyloid polypeptide (IAPP) is an important etiologic factor for the type 2 diabetes mellitus.To investigate the biological functions and the applications of IAPP,we used text mining to explore the development of the research about IAPP biochemical reagents and test kits in this study.

Computational Approach for Protein Structure Prediction / 대한의료정보학회지

OBJECTIVES: To predict the structure of protein, which dictates the function it performs, a newly designed algorithm is developed which blends the concept of self-organization and the genetic algorithm. METHODS: Among many other approaches, genetic algorithm is found to be a promising cooperative computational method to solve protein structure prediction in a reasonable time. To automate the right choice of parameter values the influence of self-organization is adopted to design a new genetic operator to optimize the process of prediction. Torsion angles, the local structural parameters which define the backbone of protein are considered to encode the chromosome that enhances the quality of the confirmation. Newly designed self-configured genetic operators are used to develop self-organizing genetic algorithm to facilitate the accurate structure prediction. RESULTS: Peptides are used to gauge the validity of the proposed algorithm. As a result, the structure predicted shows clear improvements in the root mean square deviation on overlapping the native indicates the overall performance of the algorithm. In addition, the Ramachandran plot results implies that the conformations of phi-psi angles in the predicted structure are better as compared to native and also free from steric hindrances. CONCLUSIONS: The proposed algorithm is promising which contributes to the prediction of a native-like structure by eliminating the time constraint and effort demand. In addition, the energy of the predicted structure is minimized to a greater extent, which proves the stability of protein.

Leptin, Neuropeptide Y and Islet Amyloid Polypeptide Levels in Obese Children / 대한소아소화기영양학회지

PURPOSE: The aim of this study was to compare serum leptin, neuropeptide Y (NPY), and islet amyloid polypeptide (amylin) levels in obese and normal weight children, and to investigate their correlations with anthropometric parameters and metabolic bio-marker levels. METHODS: Body mass index (BMI), waist and hip circumference, blood pressure (systolic/diastolic), lipid profile, fasting glucose, and serum insulin, leptin, NPY, and amylin levels were measured in 56 children (24 obese children and 32 non-obese controls). Homeostatic model assessment-insulin resistance (HOMA-IR) values were calculated and the relationships between anthropometric variables, metabolic biomarkers, and diet-regulating factors (leptin, NPY, and amylin levels) were examined. RESULTS: BMI, hip circumference, waist circumference, and systolic and diastolic pressure were significantly higher in the obese group than in the non-obese group (p<0.0001). Total cholesterol, triglyceride, low-density lipoprotein-cholesterol, glucose, and insulin levels were also significantly higher in the obese group (p<0.05). On the other hand, high-density lipoprotein-cholesterol levels were higher in the non-obese group , but this was not significant. Serum leptin, NPY, and amylin levels were significantly higher in the obese group (p<0.05). Furthermore, in the obese group, leptin levels were found to be significantly correlated with BMI (r=0.379, p=0.043), and NPY levels (r=0.377, p=0.044), and amylin levels were found to be significantly correlated with insulin levels (r=0.400, p=0.048), and HOMA-IR (r=0.459, p=0.028). CONCLUSION: Metabolic risk factor alterations are present in obese children, and these children show abnormalities in the diet regulatory system caused by leptin, NPY, and amylin resistance. Of particular note, amylin was found to be positively correlated with insulin resistance.

Morphological changes of rat pancreatic tissue induced by ligation of thoracic duct / 解剖学报

Objective To observe the morphological changes of pancreatic tissue of thoracic duct ligated rats in fine and ultrastructural levels, and to determine whether lymph block animal model can affect pancreatic islet amyloid polypeptide(PIAP)deposit in rat pancreas. Methods At the 6th month after the operation, some pancreatic tissue sections of 16-month-old experimental rats were embedded in paraffin wax and stained with HE and Congo red;immunohistochemical staining was performed on some frozen sections, which were then observed with light microscope;transmission electron microscope (TEM) specimen preparation and observation were performed on other samples. Results HE and Congo red stained sections showed that the pancreatic glandular lobule space was widened, with significant connective tissue hyperplasia, and fat accumulation when the islet was stained indistinctly or vermeil and tissue space was broadened. The sections with immunohistochemical staining displayed the pancreatic islet as well as the tissues around it were stained into dark brown being positive with PIAP antigen. TEM observation showed the pancreatic glandular interlobule space was widened, while blood vessels and enlarged lymphatic vessels were visible;within widened pancreatic islet interstitial space, a great quantity of lipid droplets and some collagen fibril structures could be seen.Conclusion The ligation of thoracic duct can contribute to pancreatic lymph draining block, lymphagiectasis, connective tissue space and interstitial space widening, fat accumulation, and PIAP deposit in rat pancreas. These structural changes may affect the function of pancreatic islets.

Expression of islet amyloid polypeptide in pancreas of patients with diabetrs and pancreatic cancer / 中华胰腺病杂志

Objective To detect the expression of islet amyloid polypeptide (IAPP) in the pancreatic tissues of patients with pancreatic cancer,and to explore the relation between diabetes and pancreatic cancer.Methods Surgically-removed 28 pancreatic cancer samples and adjacent normal pancreatic tissues were studied.Among these patients there were 12 patients complicated with diabetes while other 16 patients did not.Immunohistoehemieal method and Western blot method were used to detect the expression of IAPP in different tissue specimens.Results lAPP expressed in human pancreatic islet cell cytoplasm.Immanohistochcmical index of pancreatic cancer and adjacent normal pancreatic specimens of patients with diabetes,and pancreatic cancer and adjacent normal pancreatic specimens of patients without diabetes were 283 305±91 627,122 874±86 917,154 032±81 097 and 105 797±67 593,respectively;the relative IAPP expressions were (173.1±23.5) %,( 119.4±18.4) %,( 148.7±28.3 ) % and 100%.Irrespective of the presence of diabetes,expression of IAPP in pancreatic cancer specimens was significantly higher than that in adjacent normal pancreatic specimens ( P ＜ 0.01 );expression of IAPP in pancreatic cancer plus diabetes specimens was significantly higher than that in pancreatic cancer specimens without diabetes (P ＜0.01 );expression of IAPP in adjacent pancreatic specimens complicated with diabetes was significantly higher than that in adjacent pancreatic specimens without diabetes ( P ＜ 0.05).Conclusions LAPP participated in the course of diabetes and pancreatic cancer,and may be the common pathogenesis of the two diseases.

ONTOGENY OF IAPP,5-HT IMMUNOREACTIVE CELLS IN THE SMALL INTESTINE OF HUMAN FETUS / 解剖学报

Objective To investigate the ontogeny of the islet amyloid polypeptide immunoreactive (IAPP IR)cells and 5 hydroxytryptamine(5 HT)immunoreactive cells(EC cells)in human fetal small intestine and the relation between IAPP and 5 HT. Methods The immunohistochemical technique was used. Results IAPP IR cells were only observed in the fetal duodenum.At 16 weeks,single IAPP IR cell occurred in the epithelium of duodenum;From 22 to 27 weeks,the number of IAPP IR cells was gradually increased,which were mainly located in the intestinal glands.EC cells were detected in each section of small intestine,with the growth of fetus,the density of EC cells in small intestine decreased in order of duodenum,jejunum and ileum respectively.At the week of 11,EC cells were found in the epithelium of intestinal villi and undifferentiated glands.The number of EC cells showed a peak from 17 to 21 weeks of gestation.EC cells were dominantly concentrated in the epithelium of root villi and glands.After 22 weeks,EC cells decreased.The co existence of IAPP and 5 HT was not detected in the same cell,as compared with adjacent sections.Conclusion\ The results indicated that IAPP and 5 HT were expressed in endocrine cells of human fetal small intestine.IAPP IR cells and EC cells varied with the development of the human fetus. [

STUDY ON IAPP,5-HT IMMUNOREACTIVE CELLS IN THE COLON AND RECTUM OF HUMAN FETUS / 解剖学报

Objective To investigate the ontogeny of the islet amyloid polypeptide(IAPP)and explore the relationship IAPP and other classical hormones in human fetal colon and rectum. Methods The localization of IAPP immunoreactive(IR) cells and 5 hydroxytryptamine(5 HT) IR cells in 31 human fetal colon and rectum from 9\|27 weeks of gestation was investigated with immunohistochemical SABC method. Results At 9 weeks of fetal age,a lot of 5 HT IR cells were found in the colon,but IAPP IR cells appeared at 18 weeks.In the rectum,both 5 HT and IAPP IR cells were present at 11 weeks,the number of 5 HT IR cells ascended gradually with fetus aged,reached a peak at 20 weeks and dropped gradually after 21 weeks,while in the whole fetus period,IAPP IR cells appeared fewer and scattered.The co localization of IAPP and 5 HT in some cells of colon and rectum was proved as compared with adjacent sections.Immunohistochemical double staining procedures on the same tissue section also showed that IAPP co existed with 5 HT in some cells.Conclusion\ During the human fetus,IAPP were synthesized and co existed with 5 HT in endocrine cells of the colon and rectum.The possible function on the co existence of IAPP and 5 HT in the colon and rectum of fetal was discussed. [

LOCALIZATION STUDY OF ISLET AMYLOID POLYPEPTIDEIN THE STOMACH OF HUMAN FETUS / 解剖学报

Objective To observe the expression and localization of the islet amyloid polypeptide(IAPP) in the stomach of human fetus. Methods The localization of IAPP immunoreactive(IR) cells in 12 human fetal bodies of stomach from 11th to 20th week of gestation was investigated with immunohistochemical SABC method. Results At 11th week of human fetal age,the IAPP-IR cells had been found in the gastric mucosa.The IAPP-IR cells were dominantly concentrated in the fundic gland.The number of IAPP-IR cells increased gradually,and the immunostain of immunoreactive cells darkened gradually from 14th to 20th week of gestation.As compared with the adjacent sections which were stained by HE,some IAPP-IR cells were co-localization with parietal cells.Conclusion IAPP-IR cells exist in the human fetal body of stomach..