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Toth P, Tarantini S, Ashpole NM, Tucsek Z, Milne GL, Valcarcel‐Ares NM, Menyhart A, Farkas E, Sonntag WE, Csiszar A, Ungvari Z. IGF-1 deficiency impairs neurovascular coupling in mice: implications for cerebromicrovascular aging. Aging Cell 2015; 14:1034-44. [PMID: 26172407 PMCID: PMC4693458 DOI: 10.1111/acel.12372] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2015] [Indexed: 12/24/2022] Open
Abstract
Aging is associated with marked deficiency in circulating IGF‐1, which has been shown to contribute to age‐related cognitive decline. Impairment of moment‐to‐moment adjustment of cerebral blood flow (CBF) via neurovascular coupling is thought to play a critical role in the genesis of age‐related cognitive impairment. To establish the link between IGF‐1 deficiency and cerebromicrovascular impairment, neurovascular coupling mechanisms were studied in a novel mouse model of IGF‐1 deficiency (Igf1f/f‐TBG‐Cre‐AAV8) and accelerated vascular aging. We found that IGF‐1‐deficient mice exhibit neurovascular uncoupling and show a deficit in hippocampal‐dependent spatial memory test, mimicking the aging phenotype. IGF‐1 deficiency significantly impaired cerebromicrovascular endothelial function decreasing NO mediation of neurovascular coupling. IGF‐1 deficiency also impaired glutamate‐mediated CBF responses, likely due to dysregulation of astrocytic expression of metabotropic glutamate receptors and impairing mediation of CBF responses by eicosanoid gliotransmitters. Collectively, we demonstrate that IGF‐1 deficiency promotes cerebromicrovascular dysfunction and neurovascular uncoupling mimicking the aging phenotype, which are likely to contribute to cognitive impairment.
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Affiliation(s)
- Peter Toth
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- Department of Neurosurgery and Szentagothai Research Center Medical School University of Pecs Pecs 7624 Hungary
| | - Stefano Tarantini
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- Department of Physiology University of Oklahoma Health Sciences Center 940 S.L. Young Blvd. Rm. 653 Oklahoma City 73104OK USA
| | - Nicole M. Ashpole
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
| | - Zsuzsanna Tucsek
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
| | - Ginger L. Milne
- Division of Clinical Pharmacology Vanderbilt University Medical Center D‐3100 Medical Center North Nashville TN USA
| | - Noa M. Valcarcel‐Ares
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
| | - Akos Menyhart
- Department of Medical Physics and Informatics Faculty of Medicine and Faculty of Science and Informatics University of Szeged Szeged 6720Hungary
| | - Eszter Farkas
- Department of Medical Physics and Informatics Faculty of Medicine and Faculty of Science and Informatics University of Szeged Szeged 6720Hungary
| | - William E. Sonntag
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- The Peggy and Charles Stephenson Cancer Center University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
| | - Anna Csiszar
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- Department of Neurosurgery and Szentagothai Research Center Medical School University of Pecs Pecs 7624 Hungary
- Department of Physiology University of Oklahoma Health Sciences Center 940 S.L. Young Blvd. Rm. 653 Oklahoma City 73104OK USA
- The Peggy and Charles Stephenson Cancer Center University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
| | - Zoltan Ungvari
- Donald W. Reynolds Department of Geriatric Medicine Reynolds Oklahoma Center on Aging University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- Department of Neurosurgery and Szentagothai Research Center Medical School University of Pecs Pecs 7624 Hungary
- Department of Physiology University of Oklahoma Health Sciences Center 940 S.L. Young Blvd. Rm. 653 Oklahoma City 73104OK USA
- The Peggy and Charles Stephenson Cancer Center University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA
- Department of Pulmonology 1125 Budapest, Diós árok 1/c Semmelweis University Budapest Hungary
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2
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Geertz R, Kiess W, Kessler U, Hoeflich A, Tarnok A, Gercken G. Expression of IGF receptors on alveolar macrophages: IGF-induced changes in InsPi formation, [Ca2+]i, and pHi. Mol Cell Biochem 1997; 177:33-45. [PMID: 9450643 DOI: 10.1023/a:1006836631673] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Expression of insulin-like growth factor-I (IGF-I) receptors and insulin-like growth factor-II/mannose-6-phosphate (IGF-II/Man6P) receptors in cultured bovine alveolar macrophages (BAM) was demonstrated by competitive binding studies and crosslinking experiments. Western blotting of protein extracts from cultured BAM using an anti bovine IGF-II/Man6P receptor antiserum (#66416) confirmed the presence of IGF-II/Man6P receptors on BAM. The effects of IGFs and Man6P on generation of inositol phosphates was measured by HPLC analysis of perchloric acid extracts from myo-[3H]inositol-labelled cultured BAM. IGF-I at nanomolar concentrations and Man6P (10[-8]-10[-3] M) stimulated the accumulation of both Ins(1,4,5)P3 and Ins(1,3,4,5)P4 after 30 sec. IGF-II (up to 2.3 x 10[-8] M) had no significant effect on inositol phosphate accumulation under the same conditions. Both IGFs and Man6P induced a rise in [Ca2+]i in cultured BAM. In addition, using the fluorescent dye SNARF-1/AM we could demonstrate rapid but small IGF-II (10[-9] M) triggered acidification (0.07 pH units) of cultured BAM. Taken together, our results indicate not only the presence of both IGF-I and IGF-II/Man6P receptors on BAM, but also provide evidence of the linkage of the IGF-I receptor to the inositol phosphate system.
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Affiliation(s)
- R Geertz
- University of Hamburg, Institute of Biochemistry and Food Chemistry, Department of Biochemistry and Molecular Biology, Germany
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3
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Doré S, Kar S, Quirion R. Presence and differential internalization of two distinct insulin-like growth factor receptors in rat hippocampal neurons. Neuroscience 1997; 78:373-83. [PMID: 9145794 DOI: 10.1016/s0306-4522(96)00594-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The pharmacological characteristics, localization and process of internalization of the insulin-like growth factor I and II receptors were studied in rat primary hippocampal cultured neurons grown under serum-free conditions. [125I]insulin-like growth factor-I binding was specific with an apparent affinity (Kd) of 0.1 nM and IC50 values of 0.1, 2.9 and 99.7 nM for insulin-like growth factor-I, insulin-like growth factor-II and insulin, respectively. The competition by insulin suggests the presence of genuine insulin-like growth factor-I receptors and not insulin-like growth factor binding proteins. In contrast, [125I]insulin-like growth factor-II binding showed a Kd of 0.1 nM and IC50 values of 0.2 and 20.5 nM for insulin-like growth factor-II and insulin-like growth factor-I while insulin was inactive, a well established characteristic of the insulin-like growth factor-II receptor. Using emulsion autoradiography, specific binding sites for [125I]insulin-like growth factor-I and -II were over the whole cultured neurons. The use of selective insulin-like growth factor-I and -II receptor antibodies further confirmed the existence of these receptors in rat hippocampal cultured neurons. To investigate the respective internalization profile of [125I]insulin-like growth factor-I and [125I]insulin-like growth factor-II receptor-ligand complexes in neurons, a technique of acid stripping was used. The apparent rate of endocytosis was found to be greater for the insulin-like growth factor-II than for the insulin-like growth factor-I receptor complexes. The internalization of [125I]insulin-like growth factor-I and [125I]insulin-like growth factor-II ligand-receptor complexes was confirmed using phenylarsine oxide which significantly blocked both internalization processes. In order to eliminate possible receptor recycling, monensin was used and shown to have no effect on the internalization of either ligand. Since the insulin-like growth factor-I receptor is coupled to tyrosine kinase activity, tyrphostin 47, a specific tyrosine kinase inhibitor. was used and shown to decrease [125I]insulin-like growth factor-I but not the [125I]insulin-like growth factor-II receptor internalization profile. Accordingly, insulin-like growth factor-I is apparently internalized mostly via the insulin-like growth factor-I tyrosine kinase type receptor, while insulin-like growth factor-II is not. The insulin-like growth factor-II receptor ligand complex is likely internalized via a pathway possibly related to mannose-phosphorylated residues as the insulin-like growth factor-II/mannose-6-phosphate receptor has been implicated in the intracellular targeting of lysosomal proteins containing glycosylated residues. Taken together, our results indicate that primary hippocampal cultured neurons represent a unique model for investigating the differential role and intracellular trafficking of both insulin-like growth factor-I and insulin-like growth factor-II receptor ligand complexes and their relevance to the respective functional role of these two-related trophic factors in the central nervous system.
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Affiliation(s)
- S Doré
- Douglas Hospital Research Centre, Department of Psychiatry, McGill University, Montreal, Quebec, Canada
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4
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Ikezu T, Okamoto T, Giambarella U, Yokota T, Nishimoto I. In vivo coupling of insulin-like growth factor II/mannose 6-phosphate receptor to heteromeric G proteins. Distinct roles of cytoplasmic domains and signal sequestration by the receptor. J Biol Chem 1995; 270:29224-8. [PMID: 7493951 DOI: 10.1074/jbc.270.49.29224] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We examined the signaling function of the IGF-II/mannose 6-phosphate receptor (IGF-IIR) by transfecting IGF-IIR cDNAs into COS cells, where adenylyl cyclase (AC) was inhibited by transfection of constitutively activated G alpha i cDNA (G alpha i2Q205L). In cells transfected with IGF-IIR cDNA, IGF-II decreased cAMP accumulation promoted by cholera toxin or forskolin. This effect of IGF-II was not observed in untransfected cells or in cells transfected with IGF-IIRs lacking Arg2410-Lys2423. Thus, IGF-IIR, through its cytoplasmic domain, mediates the Gi-linked action of IGF-II in living cells. We also found that IGF-IIR truncated with C-terminal 28 residues after Ser2424 caused G beta gamma-dominant response of AC in response to IGF-II by activating Gi. Comparison with the G alpha i-dominant response of AC by intact IGF-IIR suggests that the C-terminal 28-residue region inactivates G beta gamma. This study not only provides further evidence that IGF-IIR has IGF-II-dependent signaling function to interact with heteromeric G proteins with distinct roles by different cytoplasmic domains, it also suggests that IGF-IIR can separate and sequestrate the G alpha and G beta gamma signals following Gi activation.
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Affiliation(s)
- T Ikezu
- Shriners Hospitals for Crippled Children, Boston, Massachusetts 02114, USA
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5
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Martinez DA, Zuscik MJ, Ishibe M, Rosier RN, Romano PR, Cushing JE, Puzas JE. Identification of functional insulin-like growth factor-II/mannose-6-phosphate receptors in isolated bone cells. J Cell Biochem 1995; 59:246-57. [PMID: 8904318 DOI: 10.1002/jcb.240590213] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The role of the IGF-II/cation independent mannose-6-phosphate (IGF-II/M6P) receptor in the transduction of cellular effects evoked by IGF-II has been extensively debated in the literature. Many reports suggest that IGF-II transduces its effects through the IGF-I receptor, while others show that IGF-II utilizes the type II receptor to affect cellular activity. This study 1) verifies the presence of the IGF-II/M6P receptor in rat calvarial osteoblasts, and 2) evaluates the ability of the receptor to initiate intracellular signals. Using conventional receptor binding assays, it was found that osteoblasts bind IGF-II with high affinity. Scatchard analyses indicated that there are 5.08 x 10(4) IGF-II/M6P receptors per osteoblast with a Kd near 2.0 nM). The receptor protein was further identified by cross-linking with 125I-IGF-II. Northern analysis was used to identify an mRNA transcript for the IGF-II/M6P receptor protein. To examine if the IGF-II/M6P receptor can initiate second messenger signals, the ability of IGF-II to evoke Ca2+ transients was evaluated. Osteoblasts pretreated with IGF-I did not lose their ability to respond to IGF-II. Further, a polyclonal antibody against the rat IGF-II/M6P receptor (R-II-PAB1) 1) was able to evoke its own Ca2+ response, and 2) was able to block the generation of Ca2+ transients caused by IGF-II. The data in this report show that the osteoblastic Ca2+ response to IGF-II appears to be caused by an intracellular release of Ca2+ which is mediated by the IGF-II/M6P receptor making it possible to envision how the receptor may be an important modulator of osteoblast mediated osteogenesis.
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Affiliation(s)
- D A Martinez
- Department of Orthopaedics, University of Rochester School of Medicine and Dentistry, New York 14642, USA
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6
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Bornfeldt KE, Raines EW, Graves LM, Skinner MP, Krebs EG, Ross R. Platelet-derived growth factor. Distinct signal transduction pathways associated with migration versus proliferation. Ann N Y Acad Sci 1995; 766:416-30. [PMID: 7486687 DOI: 10.1111/j.1749-6632.1995.tb26691.x] [Citation(s) in RCA: 157] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Figure 2 summarizes our current interpretation of data concerning signals from the activated PDGF receptor involved in directed migration and proliferation of human arterial SMC. Binding of PDGF (PDGF-BB or PDGF-AA) causes PDGF-receptor dimerization, tyrosine autophosphorylation, and subsequent binding of several molecules containing SH2 domains to the activated receptor. Binding and activation of PLC gamma by the PDGF receptor leads to PIP2 hydrolysis, resulting in generation of diacylglycerol (DAG) and IP3. Subsequently, intracellular levels of calcium are elevated as a result of IP3-mediated calcium release from intracellular compartments. The decreased levels of PIP2 and increased levels of calcium both favor actin-filament disassembly by inducing capping of actin-filament barbed ends and actin-monomer sequestration. A localized, and transient, actin-filament disassembly enables the cell to extend filopodia towards PDGF, thereby enabling chemotaxis to take place. At a later time and/or in a different compartment, actin-filament assembly is promoted by PDGF by a mechanism that is not completely understood, but that may involve small GTP-binding proteins, such as Rho, and formation of DAG. Migration on collagen requires functional alpha 2 beta 1 integrins, which may either constitute a permissive state required for a cell to migrate, or which may be actively involved in intracellular signals leading to migration. PDGF-induced DNA synthesis and proliferation involves activation of Ras, MAP kinase kinase, and MAP kinase. Cross-talk between PKA signaling and tyrosine-kinase receptor signaling results in PKA inhibition of the MAP kinase cascade, probably at the level of Raf. Activation of PI 3-kinase, or a PI 3-kinase-like enzyme, is also likely to contribute to the mitogenic effects of PDGF in these cells (Bornfeldt, unpublished observation). What determines if a SMC will migrate and/or proliferate in response to PDGF? Results are starting to emerge that show regulation of expression of molecules involved in intracellular signaling with different phenotypic states of SMC. For example, expression of PLC gamma is very low in intact vascular wall (where SMC show a "contractile phenotype"), and induced when SMC are converted to a "synthetic phenotype" in culture. Proliferation and expression of MAP kinase, but not calcium signaling, appear to be regulated by the extracellular matrix, and the profile of integrin expression is different in SMC in culture compared to SMC in the vascular wall. Thus, the relation between expression of signaling molecules involved in migration and signaling molecules involved in proliferation, as well as cross-talk between different signal-transduction pathways, may determine the net effect of PDGF.
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Affiliation(s)
- K E Bornfeldt
- Department of Pathology, University of Washington, Seattle 98195, USA
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7
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Holden RJ. The estrogen connection: the etiological relationship between diabetes, cancer, rheumatoid arthritis and psychiatric disorders. Med Hypotheses 1995; 45:169-89. [PMID: 8531840 DOI: 10.1016/0306-9877(95)90066-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
For some considerable time, there has been a growing awareness that defective essential fatty acid metabolism plays a causal role in the pathogenesis of both schizophrenia and non-insulin-dependent diabetes mellitus (NIDDM) but the influence of defective essential fatty acid metabolism in the pathogenesis of rheumatoid arthritis and cancer is less well appreciated. An EFA deficiency, or defective EFA metabolism, negatively influences prostaglandin synthesis and glucose regulation and transport. Moreover, defective EFA metabolism negatively influences estrogen availability which contributes to the observed gender bias some of these illnesses manifest. While fluctuations of estrogen are known to contribute to the pathogenesis of these conditions, so also do fluctuations of IGF-II and there is some suggestion that IGF-II and insulin may well be inversely regulated. In addition, insulin-dependent diabetes mellitus (IDDM), rheumatoid arthritis, and schizophrenia are thought to be autoimmune disorders, while cancer is associated with immune system failure. Consequently, this paper aims to examine the pathophysiological similarities and differences between mental illness, diabetes, rheumatoid arthritis and cancer in respect of which the causal relationship that obtains between essential fatty acids, estrogen, IGF-II, glucose regulation and autoimmunity will be addressed.
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Affiliation(s)
- R J Holden
- Medical Research Unit, University of Wollongong, NSW, Australia
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8
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Raper S, Kothary P, Ishoo E, Dikin M, Kokudo N, Hashimoto M, DeMatteo RP. Divergent mechanisms of insulin-like growth factor I and II on rat hepatocyte proliferation. REGULATORY PEPTIDES 1995; 58:55-62. [PMID: 8570860 DOI: 10.1016/0167-0115(95)00058-j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Insulin-like growth factors I and II are peptides with a structural homology for proinsulin, and are involved in hepatocyte proliferation. IGF-I and IGF-II, however, have different metabolic roles, and their mechanisms of action are incompletely known. We hypothesized that IGF-I and IGF-II act by different signal transduction pathways. To test this hypothesis, hepatocytes from 200 g male Sprague-Dawley rats were isolated by a two-step collagenase perfusion technique and plated at a density of 10(5) cells/16 mm Primaria plate. Proliferation was measured by [3H]thymidine ([3H]thy) incorporation into DNA, and an autoradiographic nuclear labeling index (LI). To analyze signal transduction, cyclic AMP (cAMP) levels were measured 5 min after addition of reagents by a radioimmunoassay. Reagents (doses) used were: IGF-I (2 nM), IGF-II (2 nM), the inhibitory peptide somatostatin-14 (SS14) (10 nM), and the adenylyl cyclase antagonist dideoxyadenosine (DDA) (10 microM). A summary of the findings is as follows: (1) IGF-I stimulates [3H]thy, LI and cAMP accumulation. (2) IGF-II stimulates [3H]thy and LI but not cAMP; (3) IGF-I but not IGF-II effects are inhibited by SS14 and DDA. We conclude that the hepatotrophic effects of IGF-I and IGF-II occur by different mechanisms: IGF-I is cAMP-dependent, IGF-II is cAMP-independent.
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Affiliation(s)
- S Raper
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia 19104-4268, USA
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Körner C, Nürnberg B, Uhde M, Braulke T. Mannose 6-phosphate/insulin-like growth factor II receptor fails to interact with G-proteins. Analysis of mutant cytoplasmic receptor domains. J Biol Chem 1995; 270:287-95. [PMID: 7814388 DOI: 10.1074/jbc.270.1.287] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The binding of insulin-like growth factor II (IGF II) to the mannose 6-phosphate (M6P)/IGF II receptor has previously been reported to induce the activation of trimeric G(i)2 proteins by functional coupling to a 14-amino acid region within the cytoplasmic receptor domain (Nishimoto, I., Murayama, Y., Katada, T., Ui, M., and Ogata, E. (1989) J. Biol. Chem. 264, 14029-14038). In the present study, we examined further the potential functional coupling of G-proteins with the human M6P/IGF II receptor and mutant receptors lacking the proposed G-protein activator sequence. IGF II treatment of mouse L-cells expressing either wild type or mutant M6P/IGF II receptors failed to attenuate the pertussis toxin-catalyzed modification of a 40-kDa protein or enhance GTPase activity. In broken L-cell membranes expressing wild type or mutant M6P/IGF II receptors, 30 nM IGF II also failed to affect the pertussis toxin substrate activity. By using phospholipid vesicles reconstituted with human wild type or mutant M6P/IGF II receptors and pertussis toxin-sensitive G-proteins, no stimulation of GTP gamma S binding to or GTPase activity of G(i)2, G(o)1, or G(i)/G(o) mixtures were observed in response to 1 microM IGF II. Furthermore, in vesicles containing purified wild type M6P/IGF II receptors and monomeric G alpha o1 or G alpha i2 and beta gamma dimers no effects of IGF II on GTP gamma S binding could be detected. However, when vesicles reconstituted with M6P/IGF II receptors and G(i)2 proteins were incubated with 100 microM mastoparan GTP gamma S binding was stimulated and GTPase activity was increased significantly. These results indicate that the human M6P/IGF II receptor neither interacts with G-proteins in mouse L-cell membranes nor is coupled to G(i)2 proteins in phospholipid vesicles. This study suggests strongly that the M6P/IGF II receptor does not function in transmembrane signaling in response to IGF II.
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Affiliation(s)
- C Körner
- Institut für Biochemie II, Georg-August-Universität Göttingen, Federal Republic of Germany
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