Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:036206 (endoplasmic reticulum)
 63,868 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Different B-cell organelles (lamellar and vesicular endoplasmic reticulum, Golgi complex, whole secretory granules and secretory granule cores) were studied stereologically in pancreatic islets from control mice and mice killed 10 or 60 min following alloxan injection. Ten min following alloxan a significant decrease was observed in the volume, surface and numerical densities of whole secretory granules and their cores, and a significant increase was found in the volume and surface densities of vesicular endoplasmic reticulum. At the 60 min observation time, a significant decrease was seen in the volume density of lamellar endoplasmic reticulum and Golgi complex, and in the volume, surface and numerical densities of whole secretory granules and their cores, and a significant increase was observed in the volume and surface densities of vesicular endoplasmic reticulum, and in the mean values for volume and surface of whole secretory granules and their cores. The stereological data indicate swelling of endoplasmic reticulum, decreased Golgi area, and decreased number and total volume and surface of secretory granules during the first hour after alloxan administration to mice. The observations may be consistent with inhibited insulin synthesis.
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PMID:Stereological study of endoplasmic reticulum, Golgi complex and secretory granules in the B-cells of normal and alloxan-treated mice. 4 17

Thiole: Protein disulfide Oxidoreductase (E. C. 1.8.4.2) is capable of catalyzing thiole-disulfid exchange reactions and might have an important function in both protein biosynthesis and degradation. By using histochemical methods we were able to demonstrate the localization of this enzyme in the Langerhans'islets and in the acinus cells of rat pancreas. The reaction of the acinus cells, however, was much weaker than that of the islets. Electron microscopic experiments revealed the enzyme to be located in the outer membrane of the nucleus, in the membranes of the endoplasmic reticulum and B-cell granules, and in the plasmalemma also. All these structures are known to be involved in the insulin biosynthesis and secretion. There is a good correlation between morphological and biochemical findings. In acinus cells there are a few reaction in the outer nucleus membrane, the membranes of the endoplasmatic reticulum, and the plasmalemm.
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PMID:[The immunohistochemical demonstration of the Thiol: proteindisulfid oxidoreductase (TPO) in pancreas and isolated Langerhans'islets. A light-, fluorescent- and electron microscopic study (author's transl)]. 10 26

In order to define the effect of duration of diabetes on hepatic protein sysntesis, membrane-bound and free ribosomes were isolated from livers of rats, 3, 7 and 28 days after administration of intravenous streptozotocin (75 mg/kg). Hepatocytes from the same rats were subjected to ultrastructural quantitative analysis. By day 3 there was a significant loss in the amount of rough endoplasmic reticulum (RER) per volume cytoplasm; however, the normal ratio of membrane-bound ribosomes per unit length of membrane was maintained. These hepatocyte ultrastructural changes continued over the ensuing four weeks. In spite of this decrease in amount of RER, in vitro protein synthetic activity of hepatic membrane-bound polyribosomes was unchanged from controls at three days, and by 28 days protein synthetic activity of bound hepatic ribosomes from diabetic rats was almost twice that of normal controls (p less than .01). In contrast to the effect of diabetes on bound ribosomes, there was no change in protein synthetic activity of free polyribosomes isolated from livers of rats, 3, 7 or 28 days after induction of diabetes. Thus, the effect of any given degree of diabetes on hepatic protein synthesis appears to vary with the population of hepatic ribosomes being studied, and with duration of insulin deficiency.
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PMID:Effect of duration of insulin deficiency on membrane-bound and free ribosomes from livers of diabetic rats. 12 11

The effect of insulin treatment on the exocrine pancreas of streptozotocin-diabetes rats was investigated by light and electron microscopy. In the diabetic rats treated with daily lente insulin injection for four weeks, the islets became hyperplastic and proliferative, although degenerative and atrophic islets caused by streptozotocin remained if diabetic rats were not treated with insulin. Fibrosis and degeneration of the acinar cells were not found in all the diabetic rats by light microscopic examinations. Electron microscopic examinations showed that acinar cells of the exocrine pancreas of the diabetic rats without insulin treatment were characterized by irregular dilatation and prominent lamellar arrangement of rough endoplasmic reticulum and by nuclear pyknosis. After one hour of a single injection of regular insulin, rough endoplasmic reticulum of the acinar cells of the diabetic rats was rapidly activated and many intracisternal granules appeared. When the daily injection of insulin was continued, the acinar cells became to show regular arrangement of rough endoplasmic reticulum, much less vacuolarizations and less immature zymogen granules in comparison with those of the untreated diabetic rats. Exocrine pancreas of the insulin-treated rats revealed a lot of autophagic vacuoles which were supposed to derive from lysosomes. These results suggested that insulin had a repairing effect on the damaged acinar cells in diabetic state.
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PMID:Exocrine pancreas of streptozotocin-diabetes rats treated with insulin. 13 71

Calcium concentrations of various pancreatic B cell organelles have been determined by X-ray microanalysis of areas of frozen sections of unfixed rat islets of Langerhans. Highest concentrations were detected in storage granules and in mitochondria, although calcium was also present in nuclei, in areas of endoplasmic reticulum and of cytoplasm. Accumulation of 45Ca by isolated organelles has been studied in homogenates and isolated subcellular fractions of rat islets of Langerhans. In the presence of a permeant anion (oxalate or phosphate), accumulation of 45Ca into mitochondria and microsomes was strongly stimulated by ATP. This net uptake was diminished during incubation of homogenates or of a mitochondria plus storage granule-rich fraction in the presence of cyclic AMP, dibutyryl cyclic GMP; 2:4-dinitrophenol or of ruthenium red. Investigations of the characteristics of 45Ca accumulation by homogenates prepared from storage granule-depleted islets showed no differences from those of normal islets, suggesting that the granules do not represent an important labile pool of calcium. With the exception of cyclic AMP and cyclic GMP none of the insulin secretagogues tested (glucose, leucine, arginine, adrenalin, noradrenalin, theophylline, glibenclamide) altered calcium accumulation by islet homogenates. On the basis of absolute calcium levels and of 45Ca uptake studies it is concluded that islet B cells contain a readily exchangeable mitochondrial calcium pool, and an endoplasmic reticulum pool containing a lower concentration of calcium which is also readily exchangeable. The storage granules, despite their high calcium content, do not appear to constitute a labile pool. It seems likely that the labile mitochondria and endoplasmic reticulum pools play a predominant role in the regulation of cytoplasmic free calcium levels, which may in turn be important in the regulation of rates of insulin secretion.
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PMID:Calcium distribution in islets of Langerhans: a study of calcium concentrations and of calcium accumulation in B cell organelles. 17 23

Electron microscopy, including phosphatase cytochemistry, indicates that the secretory granules of an insulinoma producing proinsulin and insulin are packaged by the endoplasmic reticulum (ER) and especially by a specialized region of ER which we call GERL because of the spatial relationship of this region to the Golgi apparatus and its apparent role in producing lysosomes. The granules are not derived from the Golgi apparatus. Preliminary evidence suggests this may be true also of pancreatic beta-cells.
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PMID:Cytochemical study of secretory process in transplantable insulinoma of syrian golden hamster. 17 11

Isolated adipocytes, incubated in the presence of extracellular 32Pi to steady state 32P incorporation into cellular phosphopeptides, were exposed to hormones for 5 min. Epinephrine (10(-6) M) stimulated 32P incorporation into at least 12 major phosphopeptides, distributed in the cytoplasm, endoplasmic reticulum, and plasma membrane. Quantitatively pre-eminent among these were peptides of molecular weight 123,000 and 69,000, each located both in the cytoplasm and endoplasmic reticulum. The effect of epinephrine (10(-7) M) on 32P incorporation into these two peptides was augmented by theophylline (10(-3) M) in a synergistic fashion. Norepinephrine, dibutyryl N6,O2'-dibutyryl adenosine 3':5'-monophosphate, adrenocorticotropic hormone (ACTH) (synthetic 1 to 24 fragment), and glucagon mimicked the effect of epinephrine. Insulin modified adipocyte peptide phosphorylation in two ways. When present as the sole hormone, insulin (100 microunits/ml) consistently and selectively stimulated the 32P incorporation into a peptide of molecular weight 123,000 (endoplasmic reticulum, cytoplasm) without significant alteration in the 32P content of any other major peptide. A second effect of insulin was evident when epinephrine (10(-6) M) was present simultaneously. Insulin significantly inhibited the epinephrine-stimulated phosphorylation of the molecular weight 69,000 (endoplasmic reticulum, cytoplasm) and 26,000 (plasma membrane) peptides. Nevertheless, persistence of insulin-stimulated phosphorylation of the 123,000 peptide in the presence of epinephrine was shown by a 32P content of this peptide that was greater in the presence of both hormones than with either individually. These findings indicate that in intact adipocytes: (a) epinephrine acutely alters the phosphorylation of a large number of adipocyte peptides, partly at least, via activation of adenosine 3':5'-monophosphate (cyclic AMP)-dependent protein kinase; (b) insulin opposes several epinephrine-stimulated phosphorylations in a manner consitent with its ability to lower epinephrine-stimulated intracellular cyclic AMP accumulation in adipocytes; and (c) insulin, in addition, exerts a unique stimulatory effect on adipocyte peptide phosphorylation that is independent of its effects on cyclic AMP metabolism and may be medicated by the generation of an as yet undefined intracellular "messenger" unique to insulin.
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PMID:Effects of epinephrine and insulin on phosphopeptide metabolism in adipocytes. 17 55

We examined whether hormones would modify the carcinogenic action of aflatoxin B1 (AFB1). Four groups of inbred Fischer rats received AFB1, 125 mug per animal, weekly per os. In three of the groups, certain hormones were administered simultaneously: One group received 1 U growth hormone (GH) sc weekly, another was given 4 U adrenocorticotropin (ACTH) weekly, and a third received 0.5 U insulin weekly sc. AFB1, ACTH, and insulin were given for 20 weeks; GH was given for only 10 weeks. The control group did not receive hormone adjuvant. In each group, 4 animals were killed at 7, 14, 21, 28, and 35 weeks; the remaining rats were killed at 77 weeks. Their livers were carefully examined and samples prepared for light and electron microscopy. Animals receiving AFB1 and ACTH failed to exhibit hepatocellular carcinoma. On the other hand, malignant lymphoma appeared at 56 weeks in 3 of the 6 surviving males on this regime. AFB1, alone or when given with insulin or GH, caused hepatocellular carcinoma in all animals; in these, lymphoma was not observed. Lymphoma comprised two cell types, each with similar neclear characteristics but differing in their nucleocytoplasmic ratios and in the amount and distribution of cytoplasmic organelles. Alterations leading to hepatocellular carcinoma were examined at various stages of development. "Basophilic hyperplasia" reflected an increase in free ribosomes. "Hyperplastic nodules" were composed of hepatocyte aggregates with characteristics similar to those encountered in the earlier stage. Both the "neoplastic nodules" and hepatocellular carcinomas were formed by cells containing large, "smooth fingerprints" and free ribosomal aggregates. These features supported the concept that AFB1 impairs ribosomal binding to endoplasmic reticulum membranes. The failure of ACTH-treated animals to develop hepatocellular carcinoma was ascribed to the effect of adrenal cortical stimulation upon membrane-polysome binding.
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PMID:Inhibition of hepatocarcinogenesis by adrenocorticotropin in aflatoxin B1-treated rats. 18 49

The nonproliferating chicken liver cell culture system described yields cell monolayers with morphological and lipogenic properties characteristic of the physiological-nutritional state of donor animals. Synthesis and secretion of fatty acid, cholesterol, and very low density lipoprotein (VLDL) occur at in vivo rates and respond to hormones and agents which affect these processes in vivo. Cells derived from fed chickens maintain high rates of synthesis of fatty acid and cholesterol for several days if insulin is present in the medium. High rates of fatty acid synthesis are correlated with the appearance of membrane-enclosed triglyceride-rich vesicles in the cytoplasm; deletion of insulin causes a decrease (T1/2 = 22 h) in fatty acid synthetic activity. Addition of glucagon or cyclic AMP (cAMP) causes an immediate cessation of fatty acid synthesis and blocks the appearance of the triglyceride-rich vesicles. Fatty acid synthesis in liver cells prepared from fasted chickens is less than 5% that of cells from fed animals. After 2-3 days in culture with serum-free medium containing insulin +/- triiodothyronine, fatty acid synthesis is restored to normal; glucagon or dibutyryl cAMP blocks this recovery. Liver cells derived from estradiol-treated chickens synthesize and secrete VLDL for at least 48 h in culture. Electron micrographs of these cells reveal more extensive development of the rough endoplasmic reticulum and Golgi complex compared to cells from untreated chickens. Whereas [3H]leucine incorporation into total protein is unaffected by estrogen treatment, [3H]leucine incorporation into cellular and secreted immunoprecipitable VLDL is markedly increased indicating specific activation of VLDL apopeptide synthesis; 8-10% of the labeled protein synthesized and secreted is VLDL. Dodecyl sulfate-acrylamide gel electrophoresis of immunoprecipitated 3H-VLDL reveals three major apopepetides of 300,000, 11,000, and 8,000 daltons corresponding to those of purified chicken VLDL.
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PMID:Lipogenesis and the synthesis and secretion of very low density lipoprotein by avian liver cells in nonproliferating monolayer culture. Hormonal effects. 19 33

Cell fractionation, enzyme analysis, and electron microscopy were used to study the effects of streptozotocin-induced diabetes and insulin replacement on liver structure and function. In liver homogenates from diabetic rats, glucose-6-phosphatase (G-6-Pase) activity was stimulated about 2 1/2-fold over that found in normal animals. Analyses of isolated rough and smooth microsomes from diabetic rats for G-6-Pase activity showed a fourfold increase in the smooth microsomes and a small increase in enzyme activity in rough microsomes when compared with these fractions from control animals. Associated with the increased enzyme activity was a reduction in liver glycogen. Insulin treatment of the diabetic rats caused a fall in homogenate G-6-Pase levels to approximately normal values and stimulated the accumulation of hepatic glycogen. Administration of insulin to these animals also caused a decrease in G-6-Pase activity, which was most pronounced in the smooth microsomes. Studies with the electron microscope revealed ultrastructural alterations in livers of the diabetic rats, which were most striking in the periportal region of the lobule. Periportal hepatocytes from diabetic rats displayed dispersed particles of glycogen separated by cytoplasm rich in SER rather than dense masses of glycogen with little SER, as is characteristic of these cells in normal animals. Centrilobular cells from the diabetic animals displayed some disorganization of the RER and a dispersed pattern of glycogen with abundant SER, similar to the pattern found in these cells from normal animals. After insulin treatment the periportal cells appeared normal morphologically, whereas the centrilobular hepatocytes displayed regions of both dense masses and dispersed glycogen. In the glycogen masses, little SER was found; however, in the areas of dispersed glycogen particles, an abundance of this organelle was evident. We conclude from these studies that diabetes causes an increase in amount of hepatic smooth endoplasmic reticulum (SER), especially within periportal hepatocytes. The results of cell fractionation indicate that membranes of the smooth endoplasmic reticulum are enriched in G-6-pase. We interpret these results to indicate that diabetes causes hepatocytes to form additional smooth endoplasmic reticulum with specialized membranes, at least with respect to G-6-Pase. It is suggested that this cellular specialization is a response of the hepatocyte to the diabetic state, namely, a demand for increased hepatic glucose production and release into the blood stream, thus contributing to the hyperglycemia characteristic of this disease. Insulin administration to the diabetic animals reverses the above alterations.
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PMID:Hepatic glucose-6-phosphatase activities and correlated ultrastructural alterations in hepatocytes of diabetic rats. 22 Dec 99


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