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1
Walker, Micaela. "Biochemical characterisation of the type 3 ryanodine receptor." Thesis, University College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286791.
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Bertocchini, Federica. "Expression and functional analysis of murine ryanodine receptor type 3." Thesis, Open University, 1998. http://oro.open.ac.uk/57732/.
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Ryanodine receptors (RyRs) are intracellular homotetrameric Ca2+-release channels constituting a family of three different isoforms, named RyRl, RyR2 and RyR3. RyRl and RyR2 are highly expressed in skeletal and cardiac muscles respectively, where they localize in the terminal cisternae of the sarcoplasmic reticulum (SR). Although RyRl and RyR2 have been found to be expressed in several other tissues at much lower level than in striated muscles, their major functional role is related to Ca2+-release from the SR following electrical depolarization of the plasma membrane, a process referred to as excitation-contraction (e-c) coupling and known to regulate striated muscle contraction. The third isoform, RyR3, is characterized by a wide pattern of expression, without any specific association to a tissue or a cell-type. The finding that RyR3 is also expressed in mammalian skeletal muscles parallels the presence of two distinct isoforms, o- and P-RyR, in non-mammalian vertebrate skeletal muscles, and suggests that two functionally distinct RyRs may be involved in the regulation of skeletal muscle contraction. The expression of RyR3 was analyzed in murine skeletal muscle from late foetal stages to adult, throughout neonatal phases of development. RyR3 was expressed widely during skeletal muscle post-natal development, disappearing in all muscles analyzed except diaphragm and soleus. RyR3 knockout mice were generated, and contractile properties of skeletal muscles were analyzed. Skeletal muscle contraction in RyR3-/- mice was impaired during the neonatal phase of development. In skeletal muscles isolated from RyR3-1- mice, the twitch elicited by electrical stimulation was strongly depressed. A significant reduction of the contractile activity was also elicited after stimulation with caffeine, an activator of Ca2+-release through RyRs. In the adults, no differences were detected between wild-type and mutant mice. These results are the first demonstrations of a physiological role of RyR3 in excitation-contraction coupling mechanisms of skeletal muscle, and support the model of a two-channel system regulating skeletal muscle contraction. In order to further characterize the RyR3-1- mouse, [3H]ryanodine binding experiments were performed on diaphragm and total hindlimb skeletal muscles from RyR3+/+ and RyR3-1- mice. Preliminary results will be presented and discussed.
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Steer, Emma Jane. "The action of flecainide on the wild-type cardiac ryanodine receptor." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/18395/.
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The genetic disorder catecholaminergic polymorphic ventricular tachycardia (CPVT) causes the function of the sarcoplasmic reticulum (SR) Ca2+ release channel (RyR2) to be altered and induces fatal arrhythmias during stress or exercise. Flecainide, a class 1C sodium channel (Nav1.5) inhibitor and anti-arrhythmic agent, was recently observed to be effective against CPVT arrhythmias. Controversially, it was suggested that flecainide acted directly on RyR2, alongside its action on Nav1.5. The present study sought to establish whether flecainide affected RyR2 activity to prevent pro-arrhythmic Ca2+ waves in wild type (WT) cardiomyocytes and if so, to elucidate the mechanisms responsible. Flecainide or flecainide-FITC was applied to intact or saponin permeabilised cardiomyocytes isolated from WT rat ventricle. Confocal microscopy was used to image SR Ca2+ release after application of flecainide or trans-sarcolemmal movement of fluorescent flecainide-FITC. In intact myocytes, flecainide decreased pro-arrhythmic Ca2+ wave frequency although Ca2+ spark properties were unchanged, indicating no effect on RyR2 despite prolonged flecainide exposure (45 min). Flecainide-FITC traversed the sarcolemma over a period of hours and primarily accumulated in the mitochondria. In permeabilised myocytes, where flecainide had immediate access to RyR2 and Nav1.5 was non-functional, a 10-20% decrease in wave frequency was apparent, accompanied by sustained changes in Ca2+ spark properties. The effect on waves was potentiated when the SR counter-current was inhibited by substitution of K+ with Cs+. These results suggest that flecainide has an anti-arrhythmic effect on RyR2 in permeabilised WT cardiomyocytes. However, slow cytosolic accumulation and the requirement for an increased drug concentration may explain the absence of an effect on RyR2 in intact cells. Nevertheless, these findings support the concept that RyR2 channel activity can be pharmacologically manipulated and that RyR2 represents a potential pharmacological target in patients with arrhythmia.
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Bertan, Fabio [Verfasser]. "Ryanodine Receptor 2 (RyR2) underlies maintenance and remodeling of dendritic spines / Fabio Bertan." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1229989161/34.
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Vincent, Karla Kristine. "Transactivation of Beta 2 Adrenergic Receptor by Bradykinin type 2 Receptor via heterodimerization." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37117.
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Although a long standing convention maintained that G Protein Coupled Receptors (GPCRs) exist in the plasma membrane solely as monomers, substantial work over the last two decades has demonstrated that these ubiquitous receptors can and in many cases, preferentially, exist as homodimers, heterodimers, or higher order oligomers. Often, two GPCRs of the same class heterodimerize; it is less common for two GPCRs of different signaling pathways to interact. The work presented here studied the physical and functional interaction of two GPCRs from discrete classes, the Beta 2 Adrenergic Receptor (β2AR), a Gαs-coupled receptor, and Bradykinin type 2 Receptor (Bk2R), a Gαq coupled receptor. These data show that Bk2R and β2AR are physically coupled when heterologously expressed in Xenopus oocytes, and in pheochromocytoma (PC12) cells and in freshly isolated murine ventricular myocytes, two systems that endogenously express these receptors. This physical coupling led to functional consequences in heterologous and endogenous expression systems, as Bk2R was able to transactivate β2AR signaling via its direct interaction with the receptor. Furthermore, coexpression of Bk2R shifted the dose response curve of β2AR for its selective agonist rightward in Xenopus oocyte electrophysiology experiments, suggesting the presence of Bk2R negatively affected β2AR native pharmacology. Up to thirty minutes of either bradykinin (BK) or isoproterenol exposure did not change the relative amount of Bk2R/β2AR heterodimer in PC12 cells, a rat adrenal medulla tumor cell line that endogenously expresses these receptors. Despite the obvious signaling consequences, the Bk2R/β2AR heterodimer accounted for only 10% of the total β2AR protein detected and 20% of the total Bk2R protein detected. When other Bk2R-specific ligands were also tested to examine the extent of β2AR transactivation, our data showed that both Lys-des-Arg-Bradykinin, a Bk2R partial agonist and NPC 567, a Bk2R antagonist, transactivated β2AR to the same extent as BK. Taken together, our data provide a novel mode of receptor regulation and signaling via Bk2R/β2AR heterodimerization. Because a large percentage of therapeutics target GPCRs, a greater understanding of how a GPCR heterodimer functions could be beneficial for targeting new drugs and refining existing drugs. Understanding the Bk2R/β2AR heterodimer provides a new perspective on the myriad of fucntional consequences that occur when a GPCR is activated.
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Hower, Amy Elizabeth. "Receptor Functions of the Receptor-Type Protein Tyrosine Phosphatase PTPRO." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/303.
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Protein tyrosine phosphorylation regulates many aspects of cell growth and differentiation. Since cellular tyrosine phosphorylation levels are controlled by the antagonizing actions of the protein tyrosine kinases (PTKs) and the protein tyrosine phosphatases (PTPs), these enzymes play a direct role in regulating processes as diverse as oncogenesis and neuronal development. In particular, the transmembrane group of PTPs, known as the receptor-type protein tyrosine phosphatases (RPTPs), has been linked to regulation of axon growth and guidance during development and regeneration. The regulation of activity of these RPTPs is of clear importance, yet the fundamental mechanisms underlying this regulation are poorly understood. While extracellular ligands are well known to dimerize and activate the receptor protein tyrosine kinases, the extent to which RPTP regulation parallels this scenario is largely unknown. We have examined the dimerization state and the relationship this state has with the phosphatase activity of the neuronal RPTP, PTPRO. We have found that PTPRO, a Type III RPTP, can exist in a dimerized state, likely regulated by disulfide linkages in the intracellular domain. Ligand addition to a chimeric PTPRO increases dimerization of the transmembrane and intracellular domains. Ligand addition to the chimeric PTPRO also decreases its phosphatase activity towards artificial peptides and a putative substrate, TrkC, a protein also known to be important in neuronal development. PTPRO's regulation of TrkC may be physiologically relevant as the proteins can be co-precipitated from transfected cells and PTPRO's dephosphorylation of TrkC is efficient compared to that of other RPTPs. The decrease in PTPRO's activity upon ligand-induced dimerization was unexpected as dimerization of a structurally-similar RPTP family member suggested the opposite functional outcome. This work suggests a complex relationship between dimerization and activity for the Type III RPTPs, which include PTPRO. The results presented in this dissertation will extend the current knowledge on RPTP functions and the cellular processes they regulate.
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Hatcher-Solis, Candice N. "PHARMACOLOGICAL IMPLICATIONS OF ADENOSINE 2A RECEPTOR- DOPAMINE TYPE 2 RECEPTOR HETEROMERIZATION." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4458.
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G protein-coupled receptors (GPCRs) are heptahelical, transmembrane proteins that mediate a plethora of physiological functions by binding ligands and releasing G proteins that interact with downstream effectors. GPCRs signal as monomers, complexes of the same receptor subtype (homomers), or complexes of different receptor subtypes (heteromers). Recently, heteromeric GPCR complexes have become attractive targets for drug development since they exhibit distinct signaling and cell-specific localization from their homomeric counterparts. Yet, the effect of heteromerization on the pharmacology of many GPCR homomers remains unknown. Therefore, we have undertaken the task to examine the effect of heteromerization on Gs signaling through the adenosine 2A receptor (A2AR) and Gi signaling through the dopamine type 2 receptor (D2R) since the A2AR-D2R heteromer is an emerging therapeutic target for Parkinson’s disease (PD). We examined the effect of heteromerization on A2AR and D2R homomeric signaling using electrophysiology and the Xenopus laevis oocyte heterologous expression system. G protein-coupled inwardly rectifying potassium channels (GIRKs) were used as reporters for Gi signaling because activation leads to direct Gbeta-gamma (Gβγ)-mediated stimulation of the GIRK current. We also coupled GIRK channels to Gs signaling by overexpressing Gαs and signaling throughGαsβγ. Our electrophysiological assay is innovative because it allows us to optimize the conditions of heteromerization and directly observe GPCR signaling at the G protein level. Our data demonstrate that heteromer formation alone decreases dopamine-elicited Gi signaling through the D2R and CGS-21680-elicited Gs signaling through the A2AR. Furthermore, this reciprocal antagonism was predominately due to changes in efficacy versus potency. We also examined crosstalk observing that applying agonists or antagonists to the adjacent receptor further modulate this inhibition with the combination of agonists and antagonists relieving inhibition. Mutating the A2AR-D2R heteromer interface abrogated all of the aforementioned ligand-induced effects on G protein signaling through the A2AR-D2R heteromer. We are currently aiming to validate our results from the oocyte experiments with an in vivo model. Our data further elucidate the effect of various ligands on G protein signaling through the A2AR- D2R heteromer, which may facilitate future studies that examine A2AR-D2R heteromer signaling.
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Phillips, Timothy Trevor. "A study of metabotropic glutamate receptor type 2." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624330.
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Puente, de Las Cuevas Elena. "Molecular genetic studies on the ryanodine receptor (sarcoplasmic reticulum Ca'2'+ channel) from Heliothis virescens (Lepidoptera: Noctuidae)." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394523.
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Viana, Dias Jose Miguel. "Insights into the regulation of the ryanodine receptor Differential effects of calcium(2+), magnesium(2+) and pharmacological agents on ATP binding /." Ann Arbor, Mich. : ProQuest, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3244456.
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Thesis (Ph.D. in Molecular and Cell Biology)--S.M.U., 2007.Title from PDF title page (viewed Mar. 18, 2008). Source: Dissertation Abstracts International, Volume: 67-12, Section: B, page: 6904. Adviser: Pia D. Vogel. Includes bibliographical references.
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Sophocleous, Antonia. "Role of type 2 cannabinoid receptor in bone metabolism." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/5940.
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Cannabinoid receptors play an important role in regulating bone mass and bone turnover. Studies in our laboratories have shown that young mice lacking type 1 cannabinoid receptor (CNR1-/-) had increased bone mass and were resistant to ovariectomy-induced bone loss. Other workers have reported that type 2 cannabinoid receptor knockout mice (CNR2-/-) develop age-related osteoporosis. The aim of this PhD thesis was to further investigate the role of CNR2 in bone metabolism in vitro and in vivo, using genetic and pharmacological approaches. This study showed that CNR2-/- mice had normal bone mass and bone turnover at 3 months of age, but following ovariectomy, CNR2-/- mice were partially protected from bone loss, because of a mild defect in osteoclast formation and bone resorption. In keeping with this, studies in vitro showed that RANKL-stimulated bone marrow cultures from CNR2-/- mice had fewer osteoclasts than cultures from wild type littermates. The CNR2-selective antagonist/inverse agonist AM630, inhibited osteoclast formation in wild type bone marrow cultures in vitro and prevented ovariectomy-induced bone loss in wild type mice in vivo. In contrast, osteoclast cultures from CNR2-/- mice were resistant to the inhibitory effects of AM630 at low concentrations and CNR2-/- ovariectomised mice did not respond to its protective effects at low doses, consistent with a CNR2- mediated effect. These results indicate that CNR2 regulates bone loss under conditions of increased bone turnover, such as ovariectomy, by affecting osteoclast differentiation and function. CNR2-deficient mice developed accelerated age-related osteoporosis and by 12 months of age they had a significant reduction in osteoblast numbers and bone formation, whereas osteoclast numbers remained comparable to wild type littermates. In agreement with this, osteoblasts derived from bone marrow of CNR2-/- mice had reduced PTHstimulated alkaline phosphatase activity and ability to form bone nodules, when compared with wild type cultures. The CNR2-selective agonist, HU308, stimulated bone nodule formation in wild type calvarial osteoblast cultures in vitro and reversed ovariectomy-induced bone loss in wild type mice in vivo. HU308 had blunted effects on bone nodule formation in cultures from CNR2-/- mice and no significant effects on ovariectomy-induced bone loss in CNR2-/- mice, indicating a CNR2-mediated effect. These studies demonstrate that CNR2 protects against age-related bone loss by mainly enhancing osteoblast differentiation and bone formation. In conclusion, type 2 cannabinoid receptors protect from bone loss by maintaining bone remodelling at balance. In addition, type 2 cannabinoid receptor agonists show evidence of anabolic activity, whereas antagonists/inverse agonists show evidence of antiosteoclastic activity in vitro and in vivo.
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Netherland, Courtney Denise. "Role of Type 2 Cannabinoid Receptor (CB2) in Atherosclerosis." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1392.
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Atherosclerosis is a macrophage-dominated nonresolving inflammatory disease of the arterial wall. Macrophage processes, including apoptosis, influence lesion development in atherosclerosis. Cannabinoids, compounds structurally related to Δ9-tetrahydrocannabinol (THC), the active ingredient in marijuana, exert their effects through cannabinoid receptors, CB1 and CB2. Cannabinoid treatment, THC or Win55,212-2, reduces atherosclerosis in ApoE-null mice by a mechanism thought to involve CB2. However, the exact role of CB2 in atherosclerosis remains unclear. We found that CB2-null macrophages are resistant to oxysterol/oxLDL-induced apoptosis leading us to hypothesize that CB2 may modulate macrophage apoptosis in atherosclerosis. To determine the functions of CB2 in atherosclerosis, we fed low density lipoprotein receptor-null (Ldlr-/-) and Ldlr-/- mice genetically deficient in CB2, an atherogenic diet for 8 and 12 weeks. CB2 deficiency did not significantly affect aortic root lesion area after 8 or 12 weeks; however, after 12 weeks, CB2-deficient lesions displayed increased lesional macrophage and smooth muscle cell (SMC) content and a ~2-fold reduction in lesional apoptosis. CB2-deficienct lesions also displayed reduced collagen content and elevated elastin fiber fragmentation that was associated with elevated levels of the extracellular matrix degrading enzyme, matrix metalloproteinase 9 (MMP9). These results demonstrate that although CB2 signaling does not affect atherosclerotic lesion size it does modulate lesional apoptosis, cellularity and ECM composition. Ldlr-/- and CB2-deficient Ldlr-/- mice were also subjected to daily treatments with Win55,212-2, a synthetic cannabinoid, over the last 2 weeks of an 8 week atherogenic diet to identify CB2-dependent and CB2-independent effects of cannabinoid receptor stimulation on atherosclerosis. Win55,212-2 did not affect hypercholesterolemia, aortic root lesion area, lesional macrophage infiltration, or ECM composition in either genotype but did significantly reduce total plasma triglyceride levels and lesional SMC content, independent of CB2. Surprisingly, lesional apoptosis was dose-dependently repressed by Win55,212-2 in Ldlr-/- mice by a CB2-dependent mechanism. All together, these results support the suggestion that CB2 may be a target for novel therapies aimed at modulating lesional apoptosis and cellularity to increase lesion stability and reduce the vulnerability to rupture.
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de, Bock Charles Edo St George Clinical School UNSW. "Novel protein interactors of urokinase-type plasminogen activator receptor." Awarded by:University of New South Wales. St George Clinical School, 2005. http://handle.unsw.edu.au/1959.4/23009.
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The plasminogen activator (PA) system plays an important role in cell adhesion, migration and invasion, and may require the coordinated expression of various proteins. The human urokinase-type plasminogen activator (uPA) receptor (uPAR) is a central protein component of the PA system. By binding its ligand uPA, uPAR can direct proteolysis of the extracellular matrix. Also, it is now apparent that uPAR can initiate proteolytic independent signal transduction to influence angiogenesis, inflammation, wound repair and tumour progression. To determine whether any novel proteins interacted with uPAR, a yeast two-hybrid screening analysis was undertaken using alternate uPAR domain constructs as baits. These included full-length three domain uPAR (uPAR-DIDIIDIII), two domain uPAR (uPAR-DIIDIII), and each individual uPAR domain (uPAR-DI, uPAR-DII and uPAR-DIII). A number of proteins were identified as putative candidate interactors for the alternate constructs, with two of special interest for uPAR-DIDIIDIII. These were the heat shock protein Mrj, and the extracellular matrix protein fibulin-2. The protein Mrj was shown to bind uPAR both in vitro and in vivo using GST-pull down and co-immunoprecipitation assays respectively. The GST-pull down assay identified the interaction between Mrj and uPAR dependent on the C-terminal domain of Mrj and DI of uPAR. Using in vivo co-immunoprecipitation analysis, Mrj also bound to uPAR. Preliminary data suggest the association between uPAR and Mrj may play a role in the regulation of apoptosis. In regard to the uPAR interactor of fibulin-2, a calcium dependent binding interaction with uPAR was identified using the GST-pull down assay. However due to the large molecular weight and stringent conditions needed to solubilise fibulin-2, it was not possible to co-immunoprecipitate both uPAR and fibulin-2. Together, the identification of both Mrj and fibulin-2 amongst other candidate interactors of uPAR presented here provides further insight into the intricate relationship between uPAR and other proteins which may influence a range of biological functions.
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Fulmer, Makenzie. "Role of Cannabinoid Receptor Type 2 (CB2) in Late Stage Atherosclerosis." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etd/3328.
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Atherosclerosis is a chronic inflammatory disorder of medium and large vessels. Immune signaling and dyslipidemia are two of several processes which influence lesion development in atherosclerosis. Cannabinoids, such as those found in marijuana, exert their effects through two cannabinoid receptors, CB1 and CB2. Recent studies using CB2 knockout mice and CB2-selective ligands have shed light on a protective role of CB2 in early stages of atherosclerosis. However, the role of CB2 in advanced stages of atherosclerosis remains unclear. To determine if CB2 plays a role in advanced atherosclerotic lesion composition and progression, we investigated the effects of systemic CB2 gene deletion on advanced atherogenesis in Ldlr-null mice fed an atherogenic high fat diet (HFD) for 20-24 weeks. CB2 deficiency did not significantly affect aortic root lesion area, however, CB2-/- mice had a significant increase (~1.9 fold) in the percentage of abdominal aorta surface occupied by lesion. CB2-/- mice also displayed increased lesional macrophage content (~2.3 fold) and an unstable phenotype characterized by significantly reduced smooth muscle cell/macrophage ratio and increased matrix metalloproteinase-9 activity and mineralization. These results suggest that although CB2 does not affect the size of atherosclerotic lesions, it does modulate the cellular and extracellular matrix composition and promotes a stable phenotype. CB2+/+ and CB2-/- mice were also subjected to treatments with either CB2-selective agonist, JWH-015, or antagonist, SR144528, over the last four weeks of a 24 week atherogenic diet to identify the effects of CB2 stimulation on calcification of advanced lesions. No change was observed in body weight or cholesterol in response to either treatment. SR144528 reduced triglycerides and mineralization of aortic root lesions in CB2+/+ mice only. Aortic Runx2 and osteopontin were increased in response to JWH-015 by a CB2-dependent mechanism. Administration of synthetic cannabinoids in an ex vivo organ culture of CB2+/+ aortas revealed increased vascular calcification in response to CB2 blockade and decreased vascular calcification in response to CB2 activation. All together, these results support a protective role for CB2 in late stages of atherosclerosis and suggests that drugs targeting CB2 may be beneficial in the treatment of advanced atherosclerosis by affecting osteogenic mechanisms implicated in the mineralization of lesions.
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Rodríguez, Eduardo. "Virion- and VAP-receptor recognition in the human adenovirus type 2 system." Lund : Lund University, 1998. http://catalog.hathitrust.org/api/volumes/oclc/68945080.html.
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Stumpf, Alexander [Verfasser]. "Cannabinoid type 2 receptor-mediated cell type-specific self-inhibition in hippocampal and cortical neurons / Alexander Stumpf." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1190087871/34.
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Metcalfe, Beverly Lynn. "Defining the role of the angiotensin ii type 2 receptor in cardiovascular disease." [Gainesville, Fla.] : University of Florida, 2004. http://wwwlib.umi.com/cr/ufl/fullcit?p3136977.
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Thesis (Ph.D.)--University of Florida, 2004.Typescript. Title from title page of source document. Document formatted into pages; contains 136 pages. Includes Vita. Includes bibliographical references.
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Bhandari, R. N. B. "Characterization of a cell adhesion receptor on rat lung alveolar type 2 cells." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/46962.
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Chu, Yatson. "Herpes simplex virus type 2 regulates the IFN-gamma receptor expression and function." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26460.
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This study shows that HSV-2 can cause down-regulation in IFN-gammaR expression on the monocyte surface in both HSV-2 seropositive and seronegative patients. The objective of this work is to examine and explain the mechanisms involved in the viral down-regulation of IFN-gammaR. The first question I tried to answer was whether humoral factors might participate in this down-regulation. Humoral factors were not involved in this phenomenon. Next, cell-to-cell interactions were examined. T, B or natural killer cell depletion experiments were conducted in peripheral blood mononuclear cells of both HSV2 seropositive and seronegative patients. The results suggest that NK cells and T cells but not B cells were involved in the IFN-gammaR downregulation in HSV-2 seropositive patients. In addition, purified monocytes also demonstrated IFN-gammaR down-regulation after HSV-2 exposure in seropositive patients. I concluded that, in HSV-2 seropositive patients, NK cells may have an inhibitory effect and T cells may have a facilitatory role in the down-regulation of IFN-gammaR. (Abstract shortened by UMI.)
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Franklin, Zara Jane. "Evaluation and characterisation of novel glucagon receptor antagonists for type 2 diabetes therapy." Thesis, University of Ulster, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.588499.
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Glucagon receptor antagonism is becoming a key target area for type 2 diabetes treatment. This thesis evaluates the potential of novel peptide-based glucagon receptor analogues for type 2 diabetes therapy. Structural modifications of the well established glucagon analogue, desHis1Glu9-glucagon, was used to develop novel glucagon analogues. All peptide analogues were resistant to DPP-4 degradation and effectively antagonised glucagon-mediated cAMP production and insulin secretion when tested in vitro. desl-lis'Glu'-glucagon had a duration of biological action of 8 h and effectively antagonised glucagon-mediated glucose and insulin release in vivo. Mid-chain acylation of desl-lis'Glu/-glucagon did not hinder acute antagonistic properties and prolonged the duration of biological action to 24 h. An additional y-glutamyl Iinker in combination with acylation resulted in similar biological activity. C-terminal acylation also effectively antagonised acute glucagon-mediated glucose production in vivo. However, a C-terminal miniPEGylated version did not exhibit antagonistic properties. In general C-terminal modifications resulted in analogues with reduced acute biological activity indicating that mid-chain acylation was more effective. Pro4 substitution for Gly" without G1u9 replacement also resulted in reduced biological efficacy in relation to antagonising glucagon-mediated actions. However, Pro4 substitution did not hinder the activity of desl-lis'Glu'i-glucagon, emphasising the important role of Glu9 in biological activity. C-terminal acylation of this Pro4 analogue reduced its acute action in animals. However, chronic administration of non-acylated and mid-chain acylated forms of this Pr04 analogue improved metabolic status in high fat fed mice. Furthermore, chronic administration of the non-acylated Pro4 analogue exhibited similar beneficial effects as exendin-4 in high fat fed mice, but additive effects of combined administration were not evident. This thesis demonstrates that peptide-based glucagon antagonists exhibit prominent anti-diabetic effects in animal models of obesity-diabetes, and illustrates the necessity to further establish peptide-based glucagon receptor antagonists for type 2 diabetes therapy
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Ma, Ching-man, and 馬靜雯. "Molecular epidemiology and characterization of the receptor binding ofporcine circovirus type 2 (PCV2)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B38227204.
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Li, K. "Interactions of complement receptor type 2 with C3d and factor H with C3u." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/769696/.
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Complement receptor type 2 (CR2, CD21) is a cell surface protein that links the innate and adaptive immune response through its binding to C3d, a cleavage fragment of the major complement component C3. Factor H (FH) is a major plasma protein that is the major regulator of the activity of C3b in the alternative pathway. FH binds to C3u, which is formed from C3 by hydrolysis, and C3u shows functional similarities to C3b. In this thesis, X-ray scattering, analytical ultracentrifugation and constrained modelling were used to determine solution structures and interactions of CR2 with C3d and FH with C3u. Structural studies reveal that the overall CR2 structure is unaffected by change in ionic strength or when C3d is bound to it. Unbound C3d exists in monomerdimer and monomer-trimer equilibria in low salt buffer, but as a monomer only in physiological buffer. The CR2-C3d interaction is not formed in physiological salt conditions, but was observed in low salt conditions. The solution structure and selfassociation of C3u were investigated. C3u underwent weak salt-dependent dimerisation, similar to that for C3d. Modelling showed that the functionally-important TED/CUB domains in the C3d part of C3u were extended away from the rest of the C3u structure. This TED/CUB conformation is intermediate between those of C3 and C3b. C3u and FH were observed to interact as 1:1 and 2:1 complexes in a salt-dependent manner. The modelling of the interaction showed that no major conformational changes occurred in C3u or FH, and suggested that C3u binds separately to FH at two independent sites. These results provide new insights in the activation of C3 and the complement regulatory activity of CR2 and FH.
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Souto, Maior Mourão Sá D. "Characterisation of the C-type lectin receptor CLEC-2 : expression, ligands and functions." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1302407/.
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Myeloid cells express a plethora of C-type lectin receptors (CLR) that can regulate inflammatory responses. Dectin-1 belongs to a sub-family of CLRs that possesses an extracellular C-type lectin domain (CTLD) and a single YxxL intracellular motif (hemITAM) that allows signalling via Syk kinase and induction of downstream functions. Based on consensus sequences for the CTLD and hemITAM, we identified CLEC-2 as a dectin-1-like receptor. CLEC-2 was previously characterised as a Syk-coupled platelet receptor able to induce platelet aggregation when targeted by the snake venom rhodocytin and by cells expressing the endogenous protein podoplanin. I generated monoclonal antibodies against mouse CLEC-2 and found that CLEC-2 is also expressed on lymphoid and myeloid cells, including dendritic cells (DC). Notably, treatment with LPS increases CLEC-2 expression by myeloid cells and synergises with CLEC-2 signaling to induce increased secretion of IL-10 but not IL-12. This increased IL-10 production is also observed in the serum of mice administered with anti-CLEC-2 mAb and LPS, and is dependent on the presence of macrophages and DCs. Furthermore, I generated a CLEC-2 conditional KO mouse line that will provide a tool to study CLEC-2 function in myeloid cells in vivo. Collectively, these data indicate that CLEC-2 expression is not restricted to platelets and that it plays a role on the vascular development and modulation of TLR responses.
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Seta, Koichi. "Study on mechanisms for angiotensin 2 type 1 receptor-mediated tyrosine kinase activation." Kyoto University, 2008. http://hdl.handle.net/2433/135926.
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Goto, Masahisa. "Growth-Dependent Induction of Angiotensin II Type 2 Receptor in Rat Mesangial Cells." Kyoto University, 2001. http://hdl.handle.net/2433/150550.
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Adachi, Yuichiro. "Angiotensin 2 type 2 receptor deficiency exacerbates heart failure and reduces survival after acute myocardial infarction in mice." Kyoto University, 2006. http://hdl.handle.net/2433/144310.
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Ruch, Claudia. "Structure / function analysis of the extracellular domain of vascular endothelial growth factor receptor-2 (VEGFR-2) /." Zürich : ETH/PSI, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17030.
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Ma, Ching-man. "Molecular epidemiology and characterization of the receptor binding of porcine circovirus type 2 (PCV2)." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B38227204.
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Surovy, André Martin. "Toll like Receptor 2 is highly expressed in lesions of Acne Inversa and colocalizes with C-type Lectin Receptor expression /." Bern : [s.n.], 2007. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Pickel, Lara Michelle. "Study of the role of the Angiotensin II (Ang II) type 2 receptor (AT[subscript]2) in lung tumorigenesis." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/788.
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Kyriakou, Theodosios. "Identification and analysis of multiple promoters of the corticotropin releasing hormone type 2 receptor gene." Thesis, University of Warwick, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397012.
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Fulmer, Makenzie L., Emilee Englehaupt, Chris Garst, and Stacy D. Brown. "Type 2 Cannabinoid Receptor Deficiency is Associated with Atherosclerotic Lesion Calcification in Ldr-null Mice." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etsu-works/5271.
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Background: Calcification of atherosclerotic plaques is associated with vulnerability to rupture and increased risk of myocardial infarction. The mechanism of plaque calcification is unclear, but has been shown to be a cell-mediated process involving complex signaling pathways affecting the osteogenic transcription factor Runt-related transcription factor 2 (Runx2). The type-2 cannabinoid receptor (CB2) modulates processes involved in bone remodeling and our prior studies determined that CB2 alters the composition of early lesions in hyperlipidemic Ldlr-/- mice; however, the function of CB2 in plaque calcification is unknown. Therefore, we tested the hypothesis that CB2 modulates plaque calcification by evaluating the effects of systemic CB2 gene deletion on lesion calcification and aortic expression of Runx2 in Ldlr-/- mice.
Results: Groups (n≥8) of 8-week old CB2+/+Ldlr-/- (WT) and CB2-/- Ldlr-/- (CB2-/-) mice were fed a high fat diet (HFD) for up to 24 weeks. Standard blood plasma analysis showed no difference in HFD-induced hyperlipidemia between WT and CB2-/- mice. Aortic levels of endocannabinoids, anandamide and 2-archidonylglycerol, were significantly elevated after 12 weeks of HFD feeding as determined by LC-MS/MS. En face analysis revealed the extent of atherosclerosis in the aortic arch and thoracic aorta did not differ between WT and CB2-/- mice, but was ~1.9-fold greater in the abdominal aortas of CB2-/- mice (17.0±1.3% vs 9.0±1.3%, p=0.002). Calcification of aortic root lesions was ~2.3 fold greater in CB2-/- mice compared to WT mice (12.9±1.1% vs 5.6±1.2%, p=0.002) as revealed by von Kossa staining. Western blot analysis showed significantly increased expression of Runx2 in aortas of WT mice compared to CB2-/- after 20 weeks of HFD (2.55±0.25 fold, p
Conclusion: Systemic CB2 deficiency enhances lesion calcification and is associated with altered aortic expression of Runx2. These results provide novel mechanistic insights into the function of CB2 signaling in the pathogenesis of atherosclerosis and vascular calcification that may lead to the development of therapies aimed at stabilizing calcified plaque.
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Dunn, Stanley Ingrid P. "The neurofibromatosis type 2 gene product, merlin, binds, directly to the epidermal growth factor receptor, ErbB2." Honors in the Major Thesis, University of Central Florida, 2000. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/188.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Health and Public Affairs
Molecular and Microbiology
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Shy, Adia. "Bioinformatic Analysis of Angiotensin II Receptor Type 2 Expression and Its Potential Role in Neuropathic Pain." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/560826.
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Neuropathic pain is a tremendous medical problem that afflicts millions. It is also distinct from other pain conditions. It persists in the absence of non-noxious stimuli or in response to formerly innocuous stimuli due to unique neurochemical and neurophysiological changes. These changes include acute excitation of peripheral neurons associated with regeneration of axons near the injury site. The causes of injuries leading to neuropathic pain include viral infection as well as trauma. Recently, a highly specific angiotensin II type 2 receptor (AGTR2) antagonist known as EMA401 showed efficacy as a treatment for postherpetic neuralgia in clinical trials. Together with previous immunohistochemical studies of the effects of EMA401 on in vitro neurite outgrowth and the presence of AGTR2 in rodent and human dorsal root ganglion, it ignited interest in AGTR2 as a pharmacological target for neuropathic pain. However, the role of AGTR2 in the modulation of neuropathic pain is not well understood. Despite previous studies, its anatomical expression in dorsal root ganglion and trigeminal ganglion remains uncertain. Additionally, few mechanisms for its modulation of nociceptive transmission have been extensively elucidated. Finally, differential expression of AGTR2 between mouse and human dorsal root ganglion has not been fully explored, especially given the availability of high-throughput expression data. Therefore, this study attempts to develop understanding of the role of AGTR2 in neuropathic pain through bioinformatic analysis of Gene Expression Omnibus (GEO) microarray data for multiple tissues and RNA Seq data acquired for human DRG.
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Mancini, Johanna. "Role of the G protein-coupled receptor kinase 2 in mediating transforming growth factor beta and G protein-coupled receptor signaling and crosstalk mechanisms." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112540.
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Transforming growth factor beta (TGFbeta) and Angiotensin II (AngII) signaling occurs through two distinct receptor superfamilies, the serine/threonine kinase and G protein-coupled receptors (GPCRs). Through diametric actions, TGFbeta and AngII regulate various biological responses, including cell proliferation and migration. Previously, we identified the G protein-coupled receptor kinase 2 (GRK2), which acts through a negative feedback loop mechanism to terminate Smad signaling. To investigate the impact of TGFbeta-induced GRK2 expression on GPCR signaling, we examined its effect on AngII signaling in vascular smooth muscle cells (VSMCs). We show that activation of the TGFbeta signaling cascade results in increased GRK2 expression levels, consequently inhibiting AngII-induced ERK phosphorylation and antagonizing AngII-induced VSMC proliferation and migration. The inhibitory effect of TGFbeta on AngII signaling occurs at the MEK-ERK interface and is abrogated when an anti-sense oligonucleotide directed against GRK2 is used. Thus, we conclude that TGFbeta signaling antagonizes AngII-induced VSMC proliferation and migration through the inhibition of ERK phosphorylation. GRK2 is a key factor in mediating this crosstalk.
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Nassanian, Hoorig. "The biology of the C-Type lectin receptor DC-SIGN." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1627802281&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Lorenz, Viola [Verfasser], and Bernhard [Gutachter] Nieswandt. "Cellular regulation of the hemITAM-coupled platelet receptor C-type lectin-like receptor 2 (CLEC-2): In vitro and in vivo studies in mice / Viola Lorenz ; Gutachter: Bernhard Nieswandt." Würzburg : Universität Würzburg, 2018. http://d-nb.info/1163536202/34.
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Li, Wener [Verfasser], Kaomei [Akademischer Betreuer] Guan-Schmidt, Swen [Gutachter] Hülsmann, and Viacheslav [Gutachter] Nikolaev. "Functional analysis of ryanodine receptor 2 mutations in induced pluripotent stem cell-derived cardiomyocytes from CPVT patients / Wener Li ; Gutachter: Swen Hülsmann, Viacheslav Nikolaev ; Betreuer: Kaomei Guan-Schmidt." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1128902737/34.
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Vieillevoye, Maud. "Role and expression of transferrin receptor 2 in erythropoiesis." Thesis, Paris 5, 2013. http://www.theses.fr/2013PA05S020.
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L’érythropoïèse est le processus de différentiation d’un progéniteur érythroïde multipotent en globules rouges. La différentiation érythroïde est essentiellement contrôlée par le récepteur à l’érythropoïétine (EPOR). Nous avons montré que le récepteur à la transferrine de type 2 (TFR2) est un membre important du complexe formé par l’EPOR. Le TFR2 présente, comme l’EPOR une expression restreinte qui dépend du type cellulaire. Ainsi son expression n’a pu être détectée que dans le foie, l’érythron et l’intestin grêle. Le rôle du TFR2 a été exploré dans les hépatocytes et il a été montré qu’il joue le rôle d’un senseur de fer dans cette lignée et de ce fait contribue à l’homéostasie du fer. Nous avons déterminé le rôle du TFR2 dans les érythroblastes et montré que TFR2 est une protéine escorte de l’EPOR qui contribue à l’érythropoïèse in vitro et in vivo. De plus, nos travaux montrent que le TFR2 est requis pour la production de GDF15 (Growth Differentiation Factor 15) dans les érythroblastes. D’autre part nous avons démontré que la production de GDF15 est augmentée par l’EPO, la déplétion intracellulaire en fer et l’activité transactivatrice de P53. L’inhibition de l’expression de P53, réalisée au cours de l’étude de son rôle dans la production de GDF15, a révélé son implication dans l’érythropoïèse normale. Nous avons mis en évidence l’existence de plusieurs formes du TFR2. Deux d’entre elles résultent de l’utilisation de sites distincts d’initiation de la traduction. Ces deux isoformes sont régulée différemment au cours de la maturation des érythroblastes. La troisième isoforme, appelée TFR2 soluble (sTFR2), est relargée dans le plasma suite au clivage du TFR2. Nous avons montré que la production du sTFR2 est inhibée en présence du ligand de TFR2, la transferrine saturée en fer (holoTF) alors que le TFR2 est stabilisé dans ces mêmes conditions. Les rôles spécifiques des trois formes du TFR2 doivent encore être élucidésErythropoiesis is the differentiation process of a multipotent erythroid progenitor into red blood cells. Erythroid differentiation is primarily controlled by the erythropoietin receptor (EPOR). We showed that the Transferrin receptor 2 (TFR2) is an important member of the EPOR complex. TFR2 has like EPOR a lineage-restricted expression and can solely be detected in the liver, erythron and small intestine. TFR2 function has been explored in hepatocytes where it plays the role of an iron sensor and contributes to iron homeostasis. We determined the role of TFR2 in erythroblasts and showed that TFR2 is an escort protein for EPOR that contributes to optimal erythropoiesis in vitro and in vivo. Moreover we evidenced that TFR2 is absolutely required for the production of Growth differentiation factor 15 (GDF15) in erythroblasts. We further demonstrated that GDF15 production is increased by EPO levels, by intracellular iron depletion as well as by P53 trans-activation activity. The inhibition of P53 expression, realized for the study of its role in GDF15 production, revealed its implication in normal erythropoiesis. We evidenced that TFR2 is expressed under several forms, two of which result from the utilization of distinct translational initiation sites. These two isoforms are differently regulated during erythroid maturation. The third form called soluble TFR2 (sTFR2) is released in the plasma after TFR2 cleavage. We showed that sTFR2 production is inhibited in the presence of TFR2 ligand, iron loaded transferrin (holoTF) whereas cell surface TFR2 expression is stabilized by holoTF. The specific roles of the three forms of TFR2 expressed by erythroblasts remain to be elucidated
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Chow, Samuel Zhong Wei. "Regulation of alpha cell function by gp130 receptor signalling in a rodent model of type 2 diabetes." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/51699.
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Dysregulated α cell glucagon secretion contributes to post-meal hyperglycemia in pre-diabetes and to hyperglycemia in type 2 diabetes (T2D). Islets in T2D are characterized by chronic inflammation, and recent human data showed increased IL-6 family cytokine expression in T2D islets in a global gene expression study (IL6 mRNA increased 2.75-fold, IL11 mRNA increased 1.61-fold). We recently discovered that IL-6 stimulates glucagon secretion from human and rodent islets. Cytokines of the IL-6 family all require the gp130 receptor to signal. Therefore, we were interested in elucidating the effects of α cell gp130 receptor signalling on glycemic control in T2D. IL-6 family cytokines were elevated in islets in rodent models of T2D. IL-6 induced STAT3 activation in primary α cells and stimulated glucagon secretion in a gp130 receptor-dependent manner. Pancreatic α cell specific gp130 knockout (αgp130KO) mice showed no differences in glycemic control, α cell function or α cell mass. However, when subjected to streptozotocin (STZ) plus high fat diet (HFD) to induce islet inflammation and pathophysiology modelling T2D, αgp130KO mice had reduced fasting glycemia, improved glucose tolerance, and improved α cell function. Hyperinsulinemic-euglycemic clamps revealed no differences in insulin sensitivity. Our data strongly suggest that reduced glycemia and improved glucose tolerance in our αgp130KO mice is due to improved α cell function, however further studies are required to elucidate the mechanism of action of gp130 receptor signalling in α cells. We conclude that in a setting of increased islet inflammation such as observed in T2D, activation of α cell gp130 receptor signalling has long-lasting deleterious effects on α cell function, promoting hyperglycemia. Antagonism of α cell gp130 receptor signalling may be useful for the treatment of T2D.Medicine, Faculty of
Medicine, Department of
Experimental Medicine, Division of
Graduate
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Zimmerman, Brandon. "Regulation of angiotension II type I receptor signalling by beta-arrestin and the clathrin adaptor AP-2." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107645.
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G protein-coupled receptors (GPCRs) play fundamental roles in our homeostatic balance through their involvement in numerous physiological processes. In order to maintain their responsiveness to the extracellular environment, a complex process of receptor desensitization and resensitization has evolved. To allow receptors to be resensitized, they must first undergo endocytosis, a process involving numerous adaptor proteins, which facilitate the internalization of the receptor into the cell. The most common method of GPCR internalization engages the clathrin-dependent pathway, where the two most prominent adaptors are βarrestin and AP-2. While there is a relatively clear picture of how these proteins mediate receptor endocytosis, regulatory mechanisms through which these endocytic adaptors may affect or be affected by signalling events is significantly less well described.The angiotensin II type I receptor is used as the model receptor in our studies, as previous work in our lab characterized some of the protein factors necessary for the endocytic process. While the previous work demonstrated phosphorylation-dependent regulation of βarrestin and AP-2 complex at a putative tyrosine residue, these results were solely in vitro, and had not been confirmed in living cells. As such we generated a polyclonal antibody against this putative phosphorylation site and revealed that not only did this phosphorylation event occur in multiple cell types in response to angiotensin II (AngII) treatment but that the activation of multiple receptors including a non-GPCR, the epidermal growth factor receptor, induced phosphorylation on the β-subunit of AP-2, the main subunit involved in βarrestin binding. My work, which is published in a previous manuscript, also revealed that prevention of this phosphorylation event stabilizes βarrestin/AP-2 complex dramatically. While our initial studies revealed that this phosphorylation event had little impact on receptor endocytosis, new tools have since been developed in the lab. Mainly, we generated a single chain antibody that can be expressed intracellularly targeting the phosphosite, and demonstrated that binding to this phosphorylated residue results in a prolonged endocytic block. We further established this phosphorylated tyrosine residue as a putative binding motif for certain Src homology 2 (SH2) domain containing proteins as three are capable of binding phosphorylated β2adaptin. Finally, due to the βarrestin-dependent nature of this phosphorylation event, we characterized four AngII analogs with single amino acid substitutions in their octapeptide sequence. Our findings established a correlative relationship between the strength of βarrestin to receptor avidity and the level of extracellular signal-regulated kinase (ERK) activation. Presumably, the differences in avidity would alter the trafficking of the receptor affecting its fate towards recycling or degradation. Furthermore, we establish that the conformation of βarrestin can alter the pathways activated downstream of the receptor resulting in alternative cellular outcomes like cell growth or migration. These results highlight how important regulation of these endocytic adaptors is to overall GPCR fate, not only due to their role in internalization but also for their own signalling potential.Les récepteurs couplés aux protéines G (RCPGs) jouent un rôle fondamental dans notre équilibre homéostatique par leur implication dans de nombreux processus physiologiques. Afin de maintenir leur réactivité à l'environnement extracellulaire, un processus complexe de désensibilisation et resensibilisation des récepteurs a évolué. Afin de permettre aux récepteurs d'être resensibilisés, ils doivent d'abord être internalisés par endocytose, un processus impliquant de nombreuses protéines adaptatrices. La méthode la plus commune de l'internalisation des RCPGs est la voie dépendante à la clathrine, où les deux adaptateurs les plus importants sont βarrestine et AP-2. Bien que nous ayons une image relativement claire de la façon dont ces protéines conduisent à l'endocytose du récepteur, les mécanismes de régulation où ces adaptateurs de l'endocytose peuvent affecter ou être affecté par des processus de signalisation sont nettement moins bien décrits. Le récepteur de l'angiotensine II de type I est utilisé comme récepteur modèle dans nos études. Les études antérieures de notre laboratoire ont caractérisé certains des facteurs protéiques nécessaires pour le processus d'endocytose. Bien que les études précédentes ont démontré une régulation dépendante à la phosphorylation des complexes βarrestine et AP-2, ces résultats ont été exclusivement in vitro et n'ont pas été confirmés dans les cellules vivantes. Nous avons généré un anticorps polyclonal dirigé contre le site de phosphorylation putatif et avons révélé que non seulement cet évènement de phosphorylation se produit dans plusieurs types de cellules en réponse au traitement à l'angiotensine II (AngII), mais que l'activation de récepteurs multiples, comprenant un non-RCPG, le récepteur du facteur de croissance de l'épiderme, induisait la phosphorylation sur l'unité β de AP-2. Mon travail, précédemment publié dans un manuscrit, a également révélé que la prévention de cet évènement de phosphorylation stabilise les complexes βarrestine/AP-2 de façon significative. Bien que nos études initiales aient révélé que cette phosphorylation a peu d'impact sur l'endocytose des récepteurs, de nouveaux outils ont depuis été développés dans le laboratoire. Premièrement, nous avons généré un anticorps à chaîne unique qui peut être exprimé de façon intracellulaire et cible les phosphosites, et avons démontré que la liaison à ce résidu phosphorylé résulte dans un arrêt prolongé de l'endocytose. Nous avons également démontré que ce résidu tyrosine phosphorylé est un motif putatif de liaison pour certaines protéines contenant un domaine SH2 étant donné que trois de ces protéines sont capables de se lier à une β2adaptine phosphorylée. Enfin, en raison de la nature dépendate à βarrestine de cet évènement de phosphorylation, nous avons characterise quatre analogies de AngII avec une seule substitution d'acide amine dans leur sequence octapeptidique. Nos conclusions établissent une relation corrélative entre la force d'avidité de βarrestine pour son récepteur et le niveau d'activation de la kinase ERK suite aux signaux extracellulaires. Vraisemblablement, les différences d'avidité modifient le trafic du récepteur dans son destin vers le recyclage ou la dégradation. Par ailleurs, nous établissons que la conformation de βarrestine peut altérer les voies activées en aval du récepteur, entraînant d'autres effets cellulaires comme la croissance cellulaire ou la migration. Ces résultats mettent en évidence l'importance de la régulation par ces adaptateurs de l'endocytose sur le destin du RCPG, non seulement par leur rôle dans l'internalisation, mais aussi par leur propre potentiel de signalisation.
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Perlyn, Chad. "Signalling paradigms of fibroblast growth factor receptor type 2 : studies from a Crouzon-Pfeiffer syndrome mouse model." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433337.
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Mackay, Melanie E. H. "Isolation, characterisation, and chromosomal localisation of the mouse and human vasoactive intestinal peptide receptor type 2 genes." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/21377.
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As a result of hybridisation screening of a mouse genomic λ2001 library and a human genomic P1 library, 6 bacteriophage clones that together span the entire coding region of the mouse VIP2 receptor (Vipr2) gene, and a single P1 clone that was shown to contain at least part of human VIP2 receptor (VIPR2) gene, were isolated. Characterisation of the intron/exon structure of the mouse Vipr2 gene, achieved mainly by direct sequencing of λ DNA and PCR amplification of introns, revealed that the gene contained at least 12 introns, with sizes that range from 66 bp to at least 12 kb, and spans a minimum of 50 kb in total. Following the isolation of a 6 kb subclone which included the first exon and 5' sequence from the Vipr2 gene, 3 kb of the putative promoter region of the gene was sequenced. The proximal 5' region of the Vipr2 gene was found to be GC rich and CpG rich. No TATA box sequences were apparent within the region immediately upstream of the proposed transcription start site, but a computer-based search for possible transcription factor binding sites identified potential Sp1 and AP2 sites. Other potential regulatory sites that were found within the 3 kb sequence included possible binding sites for islet-1-like factors, the pituitary factor Pit-1, cAMP responsive factors, serum response factor, interferon stimulated gene factor-2, STAT factors, and factors that bind to the conserved lymphokine element 0. The chromosomal localisation of the VIP2 receptor gene in human and mouse was determined through collaborative work, in which the VIPR2 P1 clone and a 4kb subclone from the mouse gene were used as probes in fluorescence in situ hybridisation experiments. The mouse gene was mapped to the telomeric region of mouse chromosome 12 (12F2), and the human gene was mapped to 7q36.3, within the previously defined minimal critical region for the brain developmental disorder holoprosencephaly type 3 (HPE3). More detailed mapping demonstrated that although one copy of the VIPR2 gene is deleted in some patients who have HPE3 and may contribute to the phenotype observed in these cases, it is not the gene responsible for HPE3.
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Shah, Urjita H. "A Roadmap for Development of Novel Antipsychotic Agents Based on a Risperidone Scaffold." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4804.
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Schizophrenia is a chronic psychotic illness affecting ~21 million people globally. Currently available antipsychotic agents act through a dopamine D2 receptor mechanism, and produce extrapyramidal or metabolic side effects. Hence, there is a need for novel targets and agents. The mGlu2/5-HT2A receptor heteromer has been implicated in the action of antipsychotic agents, and represents a novel and attractive therapeutic target for the treatment of schizophrenia. A long-term goal of this project is to synthesize bivalent ligands where a 5-HT2A receptor antagonist is tethered to an mGlu2 PAM via a linker.
The goals of the investigation were to study the SAR of risperidone (an atypical antipsychotic agent) at 5-HT2A receptors using a “deconstruction-reconstruction-elaboration” approach to determine the minimal structural features of risperidone that contribute to its 5-HT2A receptor affinity and antagonism, and to determine where on the “minimized risperidone” structure an mGlu2 PAM can be introduced. Additional goals included studying the binding modes of various mGlu2 PAMs and identifying where on an mGlu2 PAM a risperidone “partial” structure could be introduced.
Biological studies of deconstructed/elaborated analogs of risperidone suggest that the entire structure of risperidone is not necessary for 5-HT2A receptor affinity and antagonism, and that a fluoro group contributes to 5-HT2A binding. 6-Fluoro-3-(4-piperidinyl)-1,2-benz[d]isoxazole that has only half the structural features of risperidone retains 5-HT2A receptor affinity and antagonist activity, and represents the “minimized risperidone” structure with the piperidine nitrogen atom representing a potential linker site for eventual construction of bivalent ligands. Molecular modeling studies at 5-HT2A receptors suggest that risperidone and its analogs have more than one binding mode.
Modeling studies to evaluate binding modes of various PAMs at mGlu2 receptors, coupled with known SAR information, were used to identify a PAM (JNJ-40411813), and the pyridone nitrogen atom of JNJ-40411813 as a potential linker site. Additionally, potential synthetic routes for JNJ-40411813 were explored that might be of value in the synthesis of bivalent ligands.
Based on the structural features of 6-fluoro-3-(4-piperidinyl)-1,2-benz[d]isoxazole, a new pharmacophore for 5-HT2A receptor antagonists, consisting of one aromatic region, a basic protonated amine and hydrogen bond acceptors, has been proposed.
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Husarek, Kathryn. "The Roles of the Angiotensin Type 1 Receptor and Vascular Smooth Muscle Cell Phenotype in Vascular Bed-Specific Remodeling in Type 2 Diabetes." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437135678.
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Cheema, Amanpreet K. "Peroxisome Proliferator-Activated Receptor-γ Coactivator 1-α (PPARGC1A) Genetic Associations with Type 2 Diabetes in Three Ethnicities." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1577.
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Genetic heterogeneity, lifestyle factors, gene-gene or gene-environment interactions are the determinants of T2D which puts Hispanics and populations with African ancestry at higher risk of developing T2D. In this dissertation, the genetic associations of PPARGC1A polymorphisms with T2D and its related phenotypes (metabolic markers) in Haitian Americans (cases=110, controls=116), African Americans (cases=120, controls=124) and Cuban Americans (cases=160, controls=181) of South Florida were explored. Five single nucleotide polymorphisms of gene PPARGC1A were evaluated in each ethnicity for their disease association. In Haitian Americans, rs7656250 (OR= 0.22, pp=0.03) had significant protective association with T2D but had risk association in African Americans for rs7656250 (OR=1.02, p=0.96) and rs4235308 (OR=2.53, p=0.03). We found that in Haitian American females, both rs7656250 (OR=0.23, pp=0.03) had protective association with T2D. In African American females, rs7656250 (OR=1.14, p=0.78) had risk association whereas in males, it had significant protective effect (OR=0.37, p=0.04). However, the risk association exhibited by rs4235308 was stronger in African American females (OR=2.69, p=0.03) than males (OR=1.16, p=0.72). In Cuban Americans, only rs7656250 showed significant risk association with T2D (OR=6.87, p=0.02) which was stronger in females alone (OR=7.67, p=0.01). We also observed significant differences among correlations of PPARGC1A SNPs and T2D phenotypes. Positive correlation was observed for log Hs-CRP with rs3774907 (pp=0.03) in Cuban Americans respectively. Correlation of log A1C with rs7656250 (p=0.02) was positive in Cuban Americans while it was negative for rs3774907 in Haitian Americans (ppPPARGC1A correlations with T2D and its phenotypes among the three ethnicities studied (ii) the associations of PPARGC1A SNPs showed significant effect modification by sex. The findings suggest that variations in effects of PPARGC1A gene polymorphisms among three ethnicities and between sexes may have biomedical implications for the development of T2D as well as the phenotypes related to T2D.
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Fetter, Katie L. "Efficacy of Bydureon in Adults with Type 2 Diabetes." UNF Digital Commons, 2014. http://digitalcommons.unf.edu/etd/490.
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Type 2 diabetes is still rapidly on the rise today, affecting 10.5% of individuals in the United States between the ages 45 to 64 and 18.4% of those between the ages of 65 to 74. In the past two decades, type 2 diabetes has doubled in all age groups. Many adults with type 2 diabetes experience difficulty managing their blood sugars, which can result in a range of further complications. One of the newest treatment options on the market today is a glucagon-like peptide-1 (GLP-1) receptor agonist, Bydureon. Similar to Byetta, Bydureon has a main ingredient of exenatide. It offers once a week dosing as opposed to twice-a-day, which may be more appealing to patients.
The purpose of this study was to examine the efficacy of a newly FDA released medication, Bydureon, once weekly dosage in adults with type 2 diabetes. A descriptive, comparative, retrospective study of 35 patients evaluated efficacy by examining Hgb A1C and body mass index in adults with type 2 diabetes at baseline and 3 months after Bydureon was prescribed. Data were collected by a chart review of records in a primary care practice.
Results demonstrated a statistically significant difference between baseline to 3 month means in both Hgb A1C (t (34)= -3.05, p=.0044) and BMI (t (34) = -2.86, p = .0072) for patients using Bydureon.
Health care providers need to individualize the patients’ plans of care to address multifactorial areas of their diabetes care and provide them with an opportunity to successfully meet their goals. Practitioners must be knowledgeable about the treatment options available, including the newer GLP-1 receptor agonist, Bydureon and its efficacy for adults with type 2 diabetes.
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Marinik, Elaina. "Angiotensin II receptor blockade and insulin sensitivity in overweight and obese adults with elevated blood pressure." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/37369.
Full textAbstract:
Currently, it is reported that ~65% and 34% of the U.S. population is overweight and obese, respectively. Obesity is a major risk factor for cardiovascular disease. Overweight and obese individuals are also at an increased risk of developing hypertension. Whole-body insulin sensitivity is reduced in obesity, resulting in insulin resistance and increased risk of type 2 diabetes. One possible mechanism contributing to insulin resistance in obesity hypertension is renin-angiotensin system (RAS) overactivation. The RAS exhibits vasocontricting and sodium-retaining properties, yet in vivo and in vitro animal experiments suggest impairment of whole-body insulin sensitivity with increased angiotensin II (Ang II) exposure. Furthermore, evidence from clinical studies indicates Ang II receptor blockers (ARBs) may reduce the incidence of new-onset diabetes compared to other antihypertensive agents in at-risk hypertensive patients. However, it is unclear if whole-body insulin sensitivity is improved with Ang II receptor blockade in humans. Thus, we tested the hypothesis that 8-week Ang II receptor blockade with olmesartan would improve whole-body insulin sensitivity in overweight and obese individuals with elevated blood pressure (BP). Olmesartan was selected for the present study because it is devoid of partial PPARγ agonist activity. To test our hypothesis, intravenous glucose tolerance tests were performed to measure insulin sensitivity before and after control and ARB treatment in a randomized crossover manner. Because skeletal muscle tissue accounts for ~75-90% of insulin-stimulated glucose uptake, a secondary exploratory aim was to examine skeletal muscle inflammatory and collagen response in relation to insulin sensitivity during ARB treatment. No baseline differences were observed between treatments (P>0.05). Both systolic (-11.7 mmHg; P=0.008) and diastolic (-12.1 mmHg; P=0.000) BP were reduced with ARB treatment. Insulin sensitivity was not different between treatments (P>0.05). No correlates of insulin sensitivity were identified. In addition, skeletal muscle inflammatory and collagen gene expression did not change from pre- to post-ARB treatment (P>0.05). Our findings suggest that short-term RAS blockade in overweight and obese adults with elevated BP does not improve whole-body insulin sensitivity, despite a significant BP reduction. Further studies are needed to clarify the role of individual RAS blockers on insulin sensitivity during RAS inhibition in obesity hypertension.Ph. D.
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Sharaf, Sharaf Ezzat. "The effect of exercise in NAFLD and a GLP-1 receptor agonist in type 2 diabetes on lipid metabolism." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/813082/.
Full textAbstract:
Background: Hypertriglyceridaemia increases the risk of developing an atherogenic lipoprotein phenotype (ALP) in patients with type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD). An ALP is associated with an increased the risk of coronary heart disease (CHD) and cardiovascular disease (CVD). Objectives: To determine the effects of exercise and a glucagon like peptide-1 (GLP-1) receptor agonists on hypertriglyceridaemia and high-density lipoprotein (HDL) metabolism in patients with altered lipid metabolism, by conducting two clinical trials using stable isotope trace labelling technique: 1. To determine the effect of exercise on HDL apolipoprotein A-I (apoA-I) and very low-density lipoprotein (VLDL) apoB-100 subgroups (VLDL1-apoB-100 and VLDL2-apoB-100) kinetics in NAFLD. 2. To determine the effect of the GLP-1 receptor agonist lixisenatide on postprandial triacylglycerol-rich lipoprotein (TRL) apo-B-100 and B-48 and HDL-apoA-I kinetics in T2D. Study design: In the NAFLD study, participants were randomised into two groups for a period of 16 weeks. The first group received a supervised moderate-intensity exercise programme and the second group was the control group. Total HDL-apoA-I was measured using a primed constant intravenous infusion of 1-13C leucine for 9 hours in a total of 27 recruited participants; 15 participants in the exercise group and 12 in the control group. In the lixisenatide study participants were randomised in a double-blinded two-period cross-over design (lixisenatide versus placebo). Participants received treatment with lixisenatide or placebo for four weeks followed by a four-week washout period then another four weeks with the other treatment. TRL-apoB-100, TRL-apoB-48 and total HDL-apoA-I were measured using a primed constant intravenous infusion of 1-13C leucine for 8 hours during repeated meal feeding in a total of six participants. Laboratory protocol: For both studies, hourly blood samples were taken during the study period. TRL-apoB-100, TRL-apoB-48 and total HDL-apoA-I fractions were isolated using ultracentrifugation. Fractions were delipidated and separated by sodium dodecyl sulphate – polyacrylamide gel electrophoresis (SDS-PAGE). Protein bands from SDS-PAGE were hydrolysed, purified, and then derivatised. The isotopic enrichment of 13C leucine in TRL-apoB-100, TRL-apoB-48 and total HDL-apoA-I were measured using gas chromatography – mass spectrometry (GC-MS). Fractional catabolic rate (FCR) and production rate (PR) were calculated for TRL-apoB-100, TRL-apoB-48 and total HDL-apoA-I. TRL-apoB-100 and TRL-apoB-48 concentrations were measured using competitive ELISA. Total HDL-apoA-I, lipid profile including triacylglycerol (TG), cholesterol, and free fatty acids (FFA), also called non-esterified fatty acids (NEFA), and glucose concentrations were measured using automatic analysers. Results: In the NAFLD study, sixteen weeks of exercise had no significant effect on HDL-apoA-I kinetics. However, the HDL-apoA-I pool size (PS) was significantly increased from [17.4±0.8 g/l to 18.9±0.75 g/l (P =0.05)] after exercise in the exercise group. VLDL1-apoB-100 FCR and PR were significantly increased between the exercise and control group; Exercise group FCR [(7.2±0.6) vs (10.9±1.5) pools/day P=0.02]; PR [(3.7±0.7) vs (5.5±0.5) mg/kg/day P= 0.003]. Fasting hypertriglyceridaemia was not significantly changed after exercise. In the lixisenatide study, TRL-apoB-100 FCR significantly increased after lixisenatide treatment versus placebo; (6.3±0.4 vs 4.1±0.6 pools/day P=0.01). TRL-apoB-100 PR was increased with borderline significance after lixisenatide treatment (P=0.06) versus placebo. TRL-apoB-48 and HDL-apoA-I kinetics were not significantly changed after lixisenatide treatment versus placebo. Fasting and postprandial plasma glucose concentrations were significantly lower after lixisenatide treatment (P=0.05 and P=0.001 respectively) versus placebo. Postprandial serum insulin concentration was significantly higher after lixisenatide treatment (P=0.001) versus placebo. Postprandial plasma TG, cholesterol and FFA concentrations were significantly lower after lixisenatide treatment (P=0.002, P=0.02 and P=0.05 respectively) versus placebo. Conclusion: Exercise and lixisenatide were both effective in increasing VLDL-apoB-100 FCR which has the potential to reduce plasma TG concentrations in patients with altered lipid metabolism. However, exercise did not correct fasting hypertriglyceridaemia in patients with NAFLD due to increased VLDL1-apoB-100 PR. Liver fat was reduced by over 50% in the exercise group although was not normalised suggesting hepatic IR was maintained. To correct fasting hypertriglyceridaemia, accumulated liver fat must be further cleared to restore hepatic insulin sensitivity which would decrease VLDL1-apoB-100 PR. A longer exercise period is therefore needed to remove more liver fat and to correct fasting hypertriglyceridaemia. Postprandial hypertriglyceridaemia was lowered after lixisenatide treatment despite the fact that VLDL-apoB-100 PR was increased with borderline significance. A decrease in plasma TG concentration would be expected to reduce the rate of transfer of TG and CE between TRL and HDL via cholesteryl ester transfer protein (CETP) and increase HDL-cholesterol (HDL-C) concentration. The lack of effect of exercise on HDL kinetics in the NAFLD study reflects the failure to lower hypertriglyceridaemia. The lack of effect of lixisenatide to increase HDL despite lower plasma TG may be due to the study being underpowered.
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Morrice, Nicola. "Endocrine and genomic analysis of Fenretinide-mediated retinoic acid receptor signalling in models of obesity and type-2 diabetes." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=232274.
Full textAbstract:
Obesity and type-2 diabetes are major global health crises. The synthetic retinoid compound 4-hydroxy(phenyl)retinamide (Fenretinide, FEN), has been shown to inhibit adiposity and reverse insulin resistance in pre-clinical studies. Fenretinide acts via several different mechanisms, including induction of retinoid signalling and increased hepatic lipid oxidation to exert its metabolic effects. However, the signalling mechanisms behind these effects have yet to be fully elucidated. A number of approaches were taken in this thesis to investigate the signalling mechanisms of Fenretinide. To characterise the relationship between Fenretinide and leptin signalling, Fenretinide treatment was administered in two different leptin-deficient mouse models. Fenretinide effects on hepatic signalling mechanisms were further characterised by performing global transcriptomics analysis in liver from mice receiving HFD ± Fenretinide. In this analysis, the important metabolic hormone fibroblast growth factor (FGF) 21 was identified as a novel retinoid-dependent target of Fenretinide signalling, which was further characterised in multiple mouse models. Retinoic-acid receptor-specific ChIP-sequencing was performed in order to identify other liver genes that are regulated by Fenretinide via retinoid-dependent signalling mechanisms. This work has shown that the beneficial effects of Fenretinide on adiposity occur via a mechanism independent of that through which Fenretinide mediates effects on glucose homeostasis. Fenretinide effects on insulin sensitivity and glucose homeostasis are most likely mediated via the inhibition of ceramide synthesis in the liver and other metabolically active tissues. This work also shows that Fenretinide can normalise the effects of chronic HFD-feeding by targeting the expression of a set of PPARα-target genes in the liver via a retinoid-dependent signalling mechanism. Overall, the work described in this thesis both uncovers more detail about the signalling mechanisms of Fenretinide and identifies novel target genes that may be exploited for the development of new therapeutics to treat obesity and type 2 diabetes.