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  • 1
    Electronic Resource
    Electronic Resource
    Anti-insulin receptor antibodies inhibit insulin binding and stimulate glucose metabolism in skeletal muscle (1978)
    Springer
    Diabetologia 14 (1978), S. 311-317 
    Details
    ISSN: 1432-0428
    Keywords: Anti-insulin receptor antibodies ; insulin-like effects ; insulin resistance ; skeletal muscle ; insulin receptor ; insulin binding ; insulin action ; glucose transport ; glycolysis ; glycogen synthesis ; obese mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Autoantibodies against the insulin receptor are found in the serum of some patients with severe insulin resistance. The effects of one of these sera on insulin binding and on glucose transport and metabolism were investigated in the isolated mouse soleus muscle. Preincubation of muscles with the patient's serum resulted in an inhibition of subsequent125I-insulin binding (half-maximal effect at 1∶500 dilution) and in a two to three-fold stimulation of glucose transport and metabolism (half-maximal effect at 1∶2000 dilution). The insulin-like effects were blocked by anti-human IgG, but not by antiinsulin antibodies. The magnitude of the serum effects on 2-deoxyglucose uptake and glycolysis was similar to that of insulin, but the effect on glycogen synthesis was smaller than that of insulin. It is suggested that the patient's serum and insulin promote glucose transport and glycolysis through a common pathway, but act differently on glycogen synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01223022
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  • 2
    Electronic Resource
    Electronic Resource
    Photoaffinity labelling of the insulin receptor in intact rat hepatocytes, mouse soleus muscle, and cultured human lymphocytes (1982)
    Springer
    Diabetologia 23 (1982), S. 440-444 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; insulin receptors ; mouse skeletal muscle ; rat hepatocytes ; human lymphocytes ; photoaffinity labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using the photoreactive, biologically active insulin analogue, B2-(2 nitro, 4-azidophenylacetyl)des-PheB1 insulin, which can be covalently bound to receptor molecules upon photolysis, the insulin receptor has been studied in three different types of cells or tissues: isolated rat hepatocytes, intact murine soleus muscle and cultured human lymphocytes. When compared with native insulin, this analogue displayed a slightly reduced binding affinity. Accordingly, the biological potency of the photoreactive analogue was decreased by approximately 30% compared with native insulin when tested for its ability to stimulate amino acid transport in hepatocytes, and deoxyglucose uptake in soleus muscles. It was as effective as insulin, however, at maximally stimulating concentrations and therefore is a full insulin agonist. This photoprobe was used to specifically label the insulin receptor in the three tissues: after ultra-violet irradiation, sodium dodecyl sulphatepolyacrylamide gel analysis of extracts under reducing conditions revealed that most of the radioactivity was associated with a 130,000 dalton band. In isolated hepatocytes, two bands at 125,000 and 23,000 daltons were also specifically labelled. In three different cell types from three different animal species, the 130,000 dalton band appeared to be the major subunit of the insulin receptor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00260959
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Somatostatin in the pancreas and hypothalamus of obese mice (1979)
    Springer
    Diabetologia 17 (1979), S. 257-261 
    Details
    ISSN: 1432-0428
    Keywords: Somatostatin ; insulin ; glucagon ; endocrine pancreas ; hypothalamus ; obesity ; ob/ob mouse ; goldthioglucose-obese mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The pancreatic content of somatostatin, insulin, and glucagon and the hypothalamic content of somatostatin were examined inob/ob mice at various ages and in goldthioglucose-obese mice. The total pancreatic content of somatostatin was increased inob/ob mice compared to controls: 92 ng vs 75 ng (a 22% increase) at 2 months of age; 208 ng vs 131 ng (a 60% increase) at 6 months of age; and 184 ng vs 118 ng (a 60% increase) at 8 months of age. The total pancreatic content of glucagon inob/ ob mice was already enhanced by 70% over controls at 2 months of age (301 ng vs 173 ng) and did not increase further at later stages, whereas that of insulin progressively rose with age. In goldthioglucoseobese mice the pancreatic content of insulin was also increased but to a lesser extent than inob/ob mice; the pancreatic levels of somatostatin and glucagon were unaltered. In bothob/ob mice (regardless of age) and goldthioglucose-obese mice, there was no significant change in the hypothalamic content of somatostatin compared with that of lean controls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01235863
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  • 4
    Electronic Resource
    Electronic Resource
    Autoantibodies to the insulin receptor are infrequent findings in Type 1 (insulin-dependent) diabetes mellitus of recent onset (1990)
    Springer
    Diabetologia 33 (1990), S. 411-416 
    Details
    ISSN: 1432-0428
    Keywords: Autoantibodies ; insulin receptor antibody ; Type 1 (insulin-dependent) diabetes ; diabetes autoimmunity ; ELISA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To determine whether autoantibodies to the insulin receptor may represent markers of Type 1 (insulin-dependent) diabetes, the prevalence of such antibodies was investigated in sera of 60 newly diagnosed untreated Type 1 diabetic patients. A sensitive assay, based on enzyme linked immunosorbent assay has been set up which detects antibodies to the insulin receptor irrespective of their potentially inhibiting effect on insulin binding. Moreover, this method allows easy determination of the immunoglobulin class involved in the anti-receptor activity. Among the 60 sera examined, only one was found to contain anti-insulin receptor autoantibodies (IgG class). In view of our data, we conclude that autoantibodies to the insulin receptor are infrequent findings in Type 1 diabetes of recent onset.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00404090
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  • 5
    Electronic Resource
    Electronic Resource
    GTPase activating protein activity for Rab4 is enriched in the plasma membrane of 3T3-L1 adipocytes. Possible involvement in the regulation of Rab4 subcellular localization (1996)
    Springer
    Diabetologia 39 (1996), S. 899-906 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Insulin ; small GTPases ; GLUT4 ; translocation ; adipocytes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The small guanosine 5 ′-triphosphate (GTP)ase Rab4 has been suggested to play a role in insulin-induced GLUT4 translocation. Under insulin stimulation, GLUT4 translocates to the plasma membranes, while Rab4 leaves the GLUT4-containing vesicles and becomes cytosolic. Rab proteins cycle between a GTP-bound active form and a guanosine 5 ′-diphosphate (GDP)-bound inactive form. The intrinsic GTPase activity of Rab proteins is low and the interconversion between the two forms is dependent on accessory factors. In the present work, we searched for a GTPase activating protein (GAP) for Rab4 in 3T3-L1 adipocytes. We used a glutathione-S-transferase (GST)-Rab4 protein which possesses the properties of a small GTPase (ability to bind GDP and GTP and to hydrolyse GTP) and can be isolated in a rapid and efficient way. This GAP activity was observed in 3T3-L1 adipocyte lysates, and was able to accelerate the hydrolysis of the [α-32P]GTP bound to GST-Rab4 into [α-32P]GDP. This activity, tentatively called Rab4-GAP, was also present in 3T3-L1 fibroblasts. The Rab4-GAP activity was present in total membrane fractions and nearly undetectable in cytosol. Following subcellular fractionation, Rab4-GAP was found to be enriched in plasma membranes when compared to internal microsomes. Insulin treatment of the cells had no effect on the total Rab4-GAP activity or on its subcellular localization. Taking our results together with the accepted model of Rab cycling in intracellular traffic, we propose that Rab4-GAP activity plays a role in the cycling between the GTP- and GDP-bound forms of Rab4, and thus possibly in the traffic of GLUT4-containing vesicles. [Diabetologia (1996) 39: 899–906]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403908
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  • 6
    Electronic Resource
    Electronic Resource
    Insulin receptor dephosphorylation by phosphotyrosine phosphatases obtained from insulin-resistant obese mice (1994)
    Springer
    Diabetologia 37 (1994), S. 56-60 
    Details
    ISSN: 1432-0428
    Keywords: Insulin resistance ; experimental obesity ; phosphotyrosine phosphatase ; muscle ; liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To study the possible involvement of phosphotyrosine phosphatases in insulin resistance, the ability of cytosolic and membrane preparations to dephosphorylate insulin receptors was examined in lean and goldthioglucose-treated insulin-resistant and obese mice. Preparations were obtained from liver, heart, diaphragm and hindleg muscle and their phosphotyrosine phosphatase activities were measured using an immunoenzymatic assay with phosphorylated insulin receptors as substrate. Liver cytosolic and particulate phosphotyrosine phosphatases were more potent than preparations from other tissues and were able to almost completely dephosphorylate the insulin receptor in a dose- and time-dependent manner. No change was observed in cytosolic and membrane-associated phosphotyrosine phosphatases in liver, diaphragm, and heart of obese mice compared with lean mice. In contrast, cytosolic, but not membrane-associated, phosphotyrosine phosphatase activity was decreased in hindleg muscles of obese mice. These results suggest that the regulation of phosphotyrosine phosphatases is tissue-specific. In addition, alterations in total phosphotyrosine phosphatase activity do not appear to play an important role in insulin resistance in all tissues of obese mice, although specific changes cannot be excluded.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428778
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  • 7
    Electronic Resource
    Electronic Resource
    Alterations in insulin signalling pathway induced by prolonged insulin treatment of 3T3-L1 adipocytes (1995)
    Springer
    Diabetologia 38 (1995), S. 1148-1156 
    Details
    ISSN: 1432-0428
    Keywords: Key words Insulin signalling ; MAP-kinase ; PI3-kinase ; IRS 1 ; GLUT 4 translocation ; insulin resistance ; wortmannin.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Insulin-induced glucose transport stimulation, which results from the translocation of glucose transporter 4 (GLUT 4)-containing vesicles, is completely blocked after prolonged insulin treatment of 3T3-L1 adipocytes. Since GLUT 4 expression was reduced by only 30 %, we looked at the insulin signalling pathway in this insulin-resistant model. Insulin-induced tyrosine phosphorylation of the major insulin receptor substrate IRS 1 was reduced by 50 ± 7 %, while its expression was decreased by 70 ± 4 %. When cells were treated with wortmannin (a PI3-kinase inhibitor) together with insulin, the expression of IRS 1 diminished to a much lower extent. Associated with the decrease in IRS 1 expression and phosphorylation, the activation by insulin of antiphosphotyrosine immunoprecipitable PI3-kinase activity and of p44mapk and p42mapk activities was altered. However, the expression of these proteins was normal and p44mapk activity remained responsive to the tumour promoter TPA. Those results indicate that prolonged insulin treatment of 3T3-L1 adipocytes induces an insulin-resistant state with a reduced ability of insulin to stimulate the PI3-kinase and the MAP-kinases and a blockade of glucose transporter translocation. [Diabetologia (1995) 38: 1148–1156]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422363
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    GTPase activating protein activity for Rab4 is enriched in the plasma membrane of 3T3-L1 adipocytes. Possible involvement in the regulation of Rab4 subcellular localization (1996)
    Springer
    Diabetologia 39 (1996), S. 899-906 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; small GTPases ; GLUT4 ; translocation ; adipocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The small guanosine 5′-triphosphate (GTP)ase Rab4 has been suggested to play a role in insulin-induced GLUT4 translocation. Under insulin stimulation, GLUT4 translocates to the plasma membranes, while Rab4 leaves the GLUT4-containing vesicles and becomes cytosolic. Rab proteins cycle between a GTP-bound active form and a guanosine 5′-diphosphate (GDP)-bound inactive form. The intrinsic GTPase activity of Rab proteins is low and the interconversion between the two forms is dependent on accessory factors. In the present work, we searched for a GTPase activating protein (GAP) for Rab4 in 3T3-L1 adipocytes. We used a glutathione-S-transferase (GST)-Rab4 protein which possesses the properties of a small GTPase (ability to bind GDP and GTP and to hydrolyse GTP) and can be isolated in a rapid and efficient way. This GAP activity was observed in 3T3-L1 adipocyte lysates, and was able to accelerate the hydrolysis of the [α-32P]GTP bound to GST-Rab4 into [α-32P]GDP. This activity, tentatively called Rab4-GAP, was also present in 3T3-L1 fibroblasts. The Rab4-GAP activity was present in total membrane fractions and nearly undetectable in cytosol. Following subcellular fractionation, Rab4-GAP was found to be enriched in plasma membranes when compared to internal microsomes. Insulin treatment of the cells had no effect on the total Rab4-GAP activity or on its subcellular localization. Taking our results together with the accepted model of Rab cycling in intracellular traffic, we propose that Rab4-GAP activity plays a role in the cycling between the GTP- and GDP-bound forms of Rab4, and thus possibly in the traffic of GLUT4-containing vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403908
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Hypoglycaemia induced by antibodies to insulin receptor following a bone marrow transplantation in an immunodeficient child (1989)
    Springer
    Diabetologia 32 (1989), S. 167-172 
    Details
    ISSN: 1432-0428
    Keywords: Insulin receptor ; tyrosine kinase ; insulin-like activity ; antibodies to insulin receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Severe hypoglycaemia developed seven months after a bone marrow transplantation in a child with severe combined immunodeficiency. His serum exerted potent insulin-like activity: (a) it stimulated insulin receptor autophosphorylation and kinase activity in cell-free systems, this effect being additive to insulin; (b) it increased glucose transport in isolated soleus muscle. These insulin-like effects were due to immunoglobulins against the insulin receptor. Indeed, the patient serum immunoprecipitated human or murine insulin receptors from different tissues and inhibited insulin binding to receptor on human IM-9 lymphocytes. After corticoids and immunosuppressive therapy by azathioprine, the patient hypoglycaemic episodes disappeared, and concomitantly, the antibodies to insulin receptor were no longer detected, as judged by both immunoprecipitation of insulin receptor and stimulation of glucose transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00265089
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Alterations in insulin signalling pathway induced by prolonged insulin treatment of 3T3-L1 adipocytes (1995)
    Springer
    Diabetologia 38 (1995), S. 1148-1156 
    Details
    ISSN: 1432-0428
    Keywords: Insulin signalling ; MAP-kinase ; PI3-kinase ; IRS 1 ; GLUT 4 translocation ; insulin resistance ; wortmannin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Insulin-induced glucose transport stimulation, which results from the translocation of glucose transporter 4 (GLUT 4)-containing vesicles, is completely blocked after prolonged insulin treatment of 3T3-L1 adipocytes. Since GLUT 4 expression was reduced by only 30%, we looked at the insulin signalling pathway in this insulin-resistant model. Insulin-induced tyrosine phosphorylation of the major insulin receptor substrate IRS 1 was reduced by 50±7%, while its expression was decreased by 70±4%. When cells were treated with wortmannin (a PI3-kinase inhibitor) together with insulin, the expression of IRS 1 diminished to a much lower extent. Associated with the decrease in IRS 1 expression and phosphorylation, the activation by insulin of antiphosphotyrosine immunoprecipitable PI3-kinase activity and of p44mapk and p42mapk activities was altered. However, the expression of these proteins was normal and p44mapk activity remained responsive to the tumour promoter TPA. Those results indicate that prolonged insulin treatment of 3T3-L1 adipocytes induces an insulin-resistant state with a reduced ability of insulin to stimulate the PI3-kinase and the MAP-kinases and a blockade of glucose transporter translocation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422363
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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