Pathologic Changes and Glucose Homeostasis According to Expression of Human Islet Amyloid Polypeptide in Type 2 Diabetic Patients (original) (raw)
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Acta Histochemica, 1996
Programmed cell death or apoptosis is a process in which a specific cell population is eliminated from the living organism in response to a variety of extracellular and intracellular stimuli. Altering the apoptotic threshold may have the potential to change the natural progression of some diseases, including cancer, viral infection, autoimmune and neurodegenerative disorders and AIDS. Biochemical and morphological events, such as blebbing of the cell membrane, activation of proteases in the cytoplasm and fragmentation of nuclear DNA are initiated in this process (1-4). However, it is not clear how the biochemical events taking place in different cell compartments, coordinate during programmed cell death. Using electron microscopy, fluorescent-laser confocal microscopy, and 3D reconstruction, we carried out a comprehensive analysis of intracellular organization of an apoptotic cell correlated with critical biochemical processes during apoptosis. Using immortalized ovarian follicular cells as a model system (1, 2), we found that unlike in normal growing cells, during apoptosis the most abundant proteases, the proteasomes, (5, 6) are excluded from the nucleus and accumulate in the cell periphery, within the apoptotic blebs (7). This process involves reorganization of the actin cytoskeleton, which forms a spherical network, separating the apoptotic blebs from the cytoplasmic organelles, such as mitochondria and lipid droplets, remaining in the perinuclear region. We suggest that formation of apoptotic blebs, redistribution of pro
Molecular and Cellular Biochemistry, 1992
A three-step sequential detergent/salt extraction procedure was used in order to isolate three distinct subcellular fractions containing free (FP), cytoskeletal-bound (CBP) and membrane-bound polysomes (MBP), respectively, from Krebs II ascites cells (Vedeler et al., Mol Cell Biochem 100: 183-193, 1991). The purpose was to study changes in the distribution of polysomes in these three fractions during long-term incubation with insulin under either stationary conditions or in roller suspension culture. Insulin caused a redistribution of polysomes between FP, CBP and MBP fractions. The hormone appeared to promote an entry of ribosomes into polysomes both in CBP and MBP populations. When cells were grown in stationary culture in the presence of insulin and thus promoted to attach to the substratum and undergo morphological changes, a diversion of ribosomes from CBP into MBP was observed. The level of protein synthesis was apparently very high in this latter fraction since more then 70% of ribosomes were in polysomes. Morphological changes observed following insulin treatment were accompanied by a shift of certain proteins among subcellular fractions (for example actin and p35). The fibronectin content was about 20% higher in attached compared to non-attached cells. The results suggest that morphological changes induced by stimulation with insulin are associated with an increased activity of MBP, presumably reflecting a requirement for an increased synthesis of membrane proteins. (Mol Cell Biochem 118: 131-140, 1992)
Diabetes, 2007
OBJECTIVE-Endoplasmic reticulum (ER) stress-induced apoptosis may be a common cause of cell attrition in diseases characterized by misfolding and oligomerisation of amyloidogenic proteins. The islet in type 2 diabetes is characterized by islet amyloid derived from islet amyloid polypeptide (IAPP) and increased -cell apoptosis. We questioned the following: 1) whether IAPP-induced -cell apoptosis is mediated by ER stress and 2) whether -cells in type 2 diabetes are characterized by ER stress. RESEARCH DESIGN AND METHODS-The mechanism of IAPP-induced apoptosis was investigated in INS-1 cells and human IAPP (HIP) transgenic rats. ER stress in humans was investigated by -cell C/EBP homologous protein (CHOP) expression in 7 lean nondiabetic, 12 obese nondiabetic, and 14 obese type 2 diabetic human pancreata obtained at autopsy. To assure specificity for type 2 diabetes, we also examined pancreata from eight cases of type 1 diabetes. RESULTS-IAPP induces -cell apoptosis by ER stress in INS-1 cells and HIP rats. Perinuclear CHOP was rare in lean nondiabetic (2.6 Ϯ 2.0%) and more frequent in obese nondiabetic (14.6 Ϯ 3.0%) and obese diabetic (18.5 Ϯ 3.6%) pancreata. Nuclear CHOP was not detected in lean nondiabetic and rare in obese nondiabetic (0.08 Ϯ 0.04%) but six times higher (P Ͻ 0.01) in obese diabetic (0.49 Ϯ 0.17%) pancreata. In type 1 diabetic pancreata, perinuclear CHOP was rare (2.5 Ϯ 2.3%) and nuclear CHOP not detected. CONCLUSIONS-ER stress is a mechanism by which IAPP induces -cell apoptosis and is characteristic of -cells in humans with type 2 diabetes but not type 1 diabetes. These findings are consistent with a role of protein misfolding in -cell apoptosis in type 2 diabetes.
Journal of Clinical Investigation, 1996
This study demonstrates that rat islet  cells constitutively express an apoptotic program which is activated when mRNA or protein synthesis is blocked. Apoptotic  cells were detectable by electron microscopy after treatment with actinomycin D or cycloheximide. With a fluorescence microscopic assay both agents were found to increase the number of apoptotic  cells dose-and time-dependently, up to 70% after 1 wk of culture; virtually no apoptotic  cells occurred in control preparations or in conditions leading to primary necrosis. Thus, survival of  cells seems dependent on synthesis of proteins which suppress an endogenous suicide program. This mechanism explains earlier observed effects of glucose on survival of cultured  cells. Glucose is known to dose-dependently increase the percentage of  cells in active biosynthesis and the percentage that survives during culture. It is now demonstrated that the glucose-induced survival of  cells cultured for 1 wk results from a dose-dependent reduction in the percentage of  cells dying in apoptosis (49% at 3 mM glucose, 40% at 6 mM, 9% at 10 mM). Thus, intercellular differences in glucose sensitivity appear responsible for the heterogeneity in  cell sensitivity to apoptotic conditions. These data indicate that glucose promotes survival of  cells by activating synthesis of proteins which suppress apoptosis. The present model allows for further investigation of the regulation of apoptosis in  cells and the identification of agents which induce or prevent  cell death. ( J. Clin. Invest. 1996. 98:1568-1574.) Key words: apoptosis • insulin • endocrine pancreas • diabetes • islets of Langerhans 1. Abbreviations used in this paper: AMD, actinomycin D; CHX, cycloheximide; HO 342, Hoechst 33342; PI, propidium iodide.
Third International Congress of Histochemistry and Cytochemistry
Third International Congress of Histochemistry and Cytochemistry, 1968
The tissue distribution of enzymatic actlv1t1es in intestinal metaplasia stomachs exhibiting chronic gastritis was compared histochemically with that of the small intestine in man. Examined enzymes were: Alkaline phosphatase (AlP), Acid phosphatase (AcP), Leueine aminopeptidase (LAP), Succinate dehydrogenase (SDH), Lactate dehydrogenase (LDH), NADH-diaphorase (NADHD), Glucose-6-phosphate dehydrogenase (G6PDH). The reaction pattern of surface and foveolar cells in intestinal metaplasia was the same as that of villus cells of the small intestine, exhibiting high activities of AlP, LAP, SDH, LDH, NADHD and moderate activities of G6PDH and AcP. Activity of AlP was localized to the striated border and juxtaapical portion of cytoplasm. In crypts of intestinal metaplasia, moderate activities of SDH, LDH, and NADHD were seen, while no or little activities of AlP, G6PDH and LAP were observed. This reaction pattern was similar to that in crypts of the small intestine. In addition, intense activities of SDH, LDH and NADHD were detected at the base of crypts of metaplasia. However, these patterns of activities of the enzymes were altered in irregularly proliferated areas. Activities of these enzymes varied occasionally from place to place, suggesting multifocal irregular proliferation of tissue. In the striated border, reactive figures of AlP was variable, showing thinning of reactive zone and dot-like positive granules in some cells. From these observations, it will be stressed that enzymatic reaction patterns in intestinal metaplasia are influenced by the state of cell proliferation.
International Journal of Gastrointestinal Cancer, 1994
Mutations of the p53 tumor suppressor gene are quite common in pancreatic cancer. In l 7% of the patients with cancer of the pancreas autoantibodies, directed again.st this mutated nucleus protein (and-p53-Ab), are detectable. The aim of our study was to determine, whether the presence of and-p53-Ab has an influence in the development of distant metastases. Methods: Sere of 130 patients suffering from pancreatic carcinoma were tested for anti-p53-Ab via ELISA and immunoblorting using recombinant p53-protein as a target. These patients were classified according to UICC-criteria: stage I: 14%, stage II: 5%, stage III: 48% and stage IV: 32%. Results: In 22 patients anti-p53-Ab were detectable (stage I: 11%, stage II: 5%, stage III: 74% and stage IV: 1t%). Only 2./21 had liver metastases, Comparing primary tumor expansion (T3) with occurrence of liver metastases, we found that in the anti-p53-Ab negative group 65% of the patients with T3-mmor had liver metastases, whereas in the anti-p53-Ab positive group only 17% had liver metastases. Conclusion: Autoantibodies directed against p53 occur in 16% of patients with pancreatic cancer. The presence of these autoantibodies seems to have a protective function for the development of liver metastases. Further studies comparing anti-p53-Ab status with survival times and disease free suv:ival are in progress.