scholarly journals Mechanisms of ligand specificity of the mineralocorticoid receptor

2011 ◽  
Vol 213 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Peter J Fuller ◽  
Yizou Yao ◽  
Jun Yang ◽  
Morag J Young
Keyword(s):  
Mineralocorticoid Receptor ◽  
Tissue Specificity ◽  
Steroid Receptors ◽  
Ligand Specificity ◽  
Structural Determinants ◽  
C Terminus ◽  
Agonist And Antagonist ◽  
The Central Nervous System ◽  
Antagonist Binding

The mineralocorticoid receptor (MR) differs from the other steroid receptors in that it responds to two physiological ligands, aldosterone and cortisol. In epithelial tissues, aldosterone selectivity is determined by the activity of 11β-hydroxysteroid dehydrogenase type 2, while in other tissues, including the heart and regions of the central nervous system, cortisol is the primary ligand for the MR where it may act as an antagonist. Clinical trials have demonstrated the potential of MR antagonists in the treatment of cardiovascular disease, though their use has been limited by concurrent hyperkalaemia. In order to better target the MR, an understanding of the structural determinants of tissue- and ligand-specific MR activation is needed. Interactions of the MR have been identified, which exhibit ligand discrimination and/or specificity. These interactions include those of the ligand-binding domain with ligand, with the N-terminal domain and with putative co-regulatory molecules. Agonist and antagonist binding have been characterised using chimeras between the human MR and the glucocorticoid receptor or the zebra fish MR together with molecular modelling. The interaction between the N-terminus and the C-terminus is aldosterone dependent but is unexpectedly antagonised by cortisol and deoxycorticosterone in the human MR. Nuclear receptor-mediated transactivation is critically dependent on, and modulated by, co-regulatory molecules. Proteins that interact with the MR in the presence of either aldosterone or cortisol, but not both, have been identified. The successful identification of ligand-specific interactions of the MR may provide the basis for the development of novel MR ligands with tissue specificity.

scholarly journals A Paradigm for Peptide Hormone-GPCR Analyses

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4272
Author(s):  
Fred Naider ◽  
Jeffrey M. Becker
Keyword(s):  
Conformational Dynamics ◽  
Peptide Hormone ◽  
Yeast Saccharomyces Cerevisiae ◽  
Peptide Analogs ◽  
C Terminus ◽  
Peptide Interactions ◽  
Agonist And Antagonist ◽  
Antagonist Binding ◽  
And Function ◽  
G Protein Coupled

Work from our laboratories over the last 35 years that has focused on Ste2p, a G protein-coupled receptor (GPCR), and its tridecapeptide ligand α-factor is reviewed. Our work utilized the yeast Saccharomyces cerevisiae as a model system for understanding peptide-GPCR interactions. It explored the structure and function of synthetic α-factor analogs and biosynthetic receptor domains, as well as designed mutations of Ste2p. The results and conclusions are described using the nuclear magnetic resonance interrogation of synthetic Ste2p transmembrane domains (TMs), the fluorescence interrogation of agonist and antagonist binding, the biochemical crosslinking of peptide analogs to Ste2p, and the phenotypes of receptor mutants. We identified the ligand-binding domain in Ste2p, the functional assemblies of TMs, unexpected and interesting ligand analogs; gained insights into the bound α-factor structure; and unraveled the function and structures of various Ste2p domains, including the N-terminus, TMs, loops connecting the TMs, and the C-terminus. Our studies showed interactions between specific residues of Ste2p in an active state, but not resting state, and the effect of ligand activation on the dimerization of Ste2p. We show that, using a battery of different biochemical and genetic approaches, deep insight can be gained into the structure and conformational dynamics of GPCR-peptide interactions in the absence of a crystal structure.

Central KATP channels modulate glucose effectiveness in humans and rodents

2020 ◽  
Author(s):  
Ada Admin ◽  
Michelle Carey ◽  
Eric Lontchi-Yimagou ◽  
William Mitchell ◽  
Sarah Reda ◽  
...  
Keyword(s):  
Katp Channel ◽  
Glucose Production ◽  
Katp Channels ◽  
Endogenous Glucose Production ◽  
Elevated Plasma ◽  
Sprague Dawley ◽  
Glucose Effectiveness ◽  
Sprague Dawley Rats ◽  
The Central Nervous System

Hyperglycemia is a potent regulator of endogenous glucose production (EGP). Loss of this ‘glucose effectiveness’ is a major contributor to elevated plasma glucose concentrations in type 2 diabetes (T2D). ATP-sensitive potassium channels (K<sub>ATP</sub> channels) in the central nervous system (CNS) have been shown to regulate EGP in humans and rodents. We examined the contribution of central K<sub>ATP</sub> channels to glucose effectiveness. Under fixed hormonal conditions (‘pancreatic clamp’ studies), hyperglycemia suppressed EGP by ~50% in both non-diabetic humans and normal Sprague Dawley rats. By contrast, antagonism of K<sub>ATP</sub> channels with glyburide significantly reduced the EGP-lowering effect of hyperglycemia in both humans and rats. Furthermore, the effects of glyburide on EGP and gluconeogenic enzymes in rats were abolished by intracerebroventricular (ICV) administration of the KATP channel agonist diazoxide. These findings indicate that about half of EGP suppression by hyperglycemia is mediated by central K<sub>ATP</sub> channels. These central mechanisms may offer a novel therapeutic target for improving glycemic control in T2D.

scholarly journals Attenuation of COVID-19-induced cytokine storm in a young male patient with severe respiratory and neurological symptoms

2021 ◽  
Author(s):  
Christian Muschitz ◽  
Anita Trummert ◽  
Theresa Berent ◽  
Norbert Laimer ◽  
Lukas Knoblich ◽  
...  
Keyword(s):  
Decision Making ◽  
Male Patient ◽  
Young Male ◽  
Standard Of Care ◽  
Multiple Organ ◽  
Cytokine Storm ◽  
Invasive Ventilation ◽  
Organ Systems ◽  
The Central Nervous System

SummarySevere acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), the etiological agent of coronavirus disease 2019 (COVID-19), produces protean manifestations and causes indiscriminate havoc in multiple organ systems. This rapid and vast production of proinflammatory cytokines contributes to a condition termed cytokine storm. A 35-year-old, otherwise healthy, employed, male patient was tested positive for COVID-19. He was admitted to the hospital on disease day 10 due to retarded verbal reactions and progressive delirium. On account of these conditions and the need for noninvasive/invasive ventilation, a combination treatment with baricitinib and remdesivir in conjunction with standard of care was initiated. The cytokine storm was rapidly blocked, leading to a vast pulmonary recovery with retarded recovery of the central nervous system. We conclude that the rapid blockade of the COVID-19-induced cytokine storm should be considered of avail as a principle of careful decision-making for effective recovery.

scholarly journals Antibodies Against the C-Terminus of ApoA-1 Are Inversely Associated with Cholesterol Efflux Capacity and HDL Metabolism in Subjects with and without Type 2 Diabetes Mellitus

2019 ◽  
Vol 20 (3) ◽  
pp. 732 ◽  
Author(s):  
Robin Dullaart ◽  
Sabrina Pagano ◽  
Frank Perton ◽  
Nicolas Vuilleumier
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Apolipoprotein B ◽  
Cholesterol Efflux ◽  
Hdl Cholesterol ◽  
Enzyme Linked Immunosorbent Assay ◽  
Cholesterol Efflux Capacity ◽  
C Terminus

Background: We determined relationships of cholesterol efflux capacity (CEC), plasma cholesterol esterification (EST) and cholesteryl ester transfer (CET) with anti-c-terminus apoA-1 (Ac-terAA1) and anti-apolipoprotein (apo)-1 (AAA1) autoantibodies in subjects with and without Type 2 diabetes mellitus (T2D). Methods: In 75 T2D subjects and 75 nondiabetic subjects, Ac-terAA1 and AAA1 plasma levels were measured by enzyme-linked immunosorbent assay. CEC was measured as [3H]-cholesterol efflux from human cultured fibroblasts to diluted individual subject plasma. Plasma EST and CET were assayed by isotope methods. Results: Ac-terAA1 and AAA1 levels and were similar between T2D and control subjects. Univariate regression analysis (n = 150) demonstrated that Ac-terAA1 levels were inversely correlated with CEC, EST, CET, total cholesterol, non-HDL cholesterol, triglycerides and apolipoprotein B, (p < 0.05 to p < 0.01), but not with glucose and HbA1c. In separate multivariable linear regression models, CEC, EST and CET were inversely associated with Ac-terAA1 levels independently of age, sex, T2D and drug use (β = −0.186, p = 0.026; β = −0.261, p < 0.001; and β = −0.321, p < 0.001; respectively). These associations were lost after additional adjustment for non-HDL cholesterol and triglycerides. No associations were observed for AAA1. Conclusions: CEC, plasma EST and CET are inversely associated with Ac-terAA1 autoantibodies, conceivably attributable to an inverse relationship of these autoantibodies with apolipoprotein B-containing lipoproteins.

scholarly journals NEUROPROTECTIVE ROLE OF ASCORBIC ACID: ANTIOXIDANT AND NON-ANTIOXIDANT FUNCTIONS

2018 ◽  
Vol 11 (10) ◽  
pp. 30 ◽  
Author(s):  
Arun Kumar ◽  
Reena V Saini ◽  
Adesh K Saini
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Glutamate Toxicity ◽  
Cellular Functions ◽  
Dietary Antioxidant ◽  
The Central Nervous System

Ascorbic acid (AA) or Vitamin C is an important antioxidant which participates in numerous cellular functions. Although in human plasma its concentration is in micromolars but it reaches millimolar concentrations in most of the human tissues. The high ascorbate cellular concentrations are generated and maintained by a specific sodium-dependent Vitamin C transporter type 2 (SVCT2, member of Slc23 family). Metabolic processes recycle Vitamin C from its oxidized forms (ascorbate) inside the cells. AA concentration is highest in the neurons of the central nervous system (CNS) of mammals, and deletion of its transporter affects mice brain and overall survival. In the CNS, intracellular ascorbate serves several functions including antioxidant protection, peptide amidation, myelin formation, synaptic potentiation, and protection against glutamate toxicity. SVCT2 maintains neuronal ascorbate content in CNS which has relevance for neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and Huntington’s disease. As ascorbate supplements decrease infarct size in ischemia-reperfusion injury and protect neurons from oxidative damage, it is a vital dietary antioxidant. The aim of this review is to assess the role of the SVCT2 in regulating neuronal ascorbate homeostasis in CNS and the extent to which ascorbate affects brain function as an antioxidant.

scholarly journals The Mineralocorticoid Receptor Antagonist Eplerenone Suppress Interstitial Fibrosis in Subcutaneous Adipose Tissue in Type 2 Diabetes Patients

2020 ◽  
Author(s):  
Ada Admin ◽  
Marie Louise Johansen ◽  
Jaime Ibarrola ◽  
Amaya Fernández-Celis ◽  
Morten Schou ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Adipose Tissue ◽  
Receptor Antagonist ◽  
Subcutaneous Adipose Tissue ◽  
Mineralocorticoid Receptor ◽  
Prostaglandin D2 ◽  
Type I ◽  
Mineralocorticoid Receptor Antagonist ◽  
Subcutaneous Adipose

Activation of the mineralocorticoid receptor (MR) may promote dysfunctional adipose tissue in patients with type 2 diabetes, where increased pericellular fibrosis has emerged as a major contributor. The knowledge of the association between the MR, fibrosis and the effects of an MR antagonist (MRA) in human adipocytes remains very limited. The present sub-study including 30 participants was prespecified as part of the Mineralocorticoid Receptor Antagonist in type 2 Diabetes (MIRAD) trial, randomizing patients to either high dose eplerenone or placebo for 26 weeks. In adipose tissue biopsies, changes in fibrosis were evaluated by immunohistological examinations and by the expression of mRNA and protein markers of fibrosis. Treatment with an MRA reduced pericellular fibrosis, synthesis of the major subunits of collagen type I and VI, and the profibrotic factor α-smooth muscle actin, as compared to placebo in subcutaneous adipose tissue. Furthermore, we found decreased expression of the MR and downstream molecules neutrophil gelatinase–associated lipocalin, galectin-3, and lipocalin-like prostaglandin D2 synthase with an MRA. In conclusions, we present original data demonstrating reduced fibrosis in adipose tissue with inhibition of the MR, which could be a potential therapeutic approach to prevent the extracellular matrix remodeling of adipose tissue in type 2 diabetes.

Quantitative neurogenetics: applications in understanding disease

2021 ◽  
Author(s):  
Ali Afrasiabi ◽  
Jeremy T. Keane ◽  
Julian Ik-Tsen Heng ◽  
Elizabeth E. Palmer ◽  
Nigel H. Lovell ◽  
...  
Keyword(s):  
Gene Expression ◽  
Genetic Risk ◽  
Tissue Specificity ◽  
High Throughput Sequencing ◽  
Molecular Genetic ◽  
Brain Dysfunction ◽  
Neural Cells ◽  
Expression Index ◽  
The Central Nervous System ◽  
The Brain

Neurodevelopmental and neurodegenerative disorders (NNDs) are a group of conditions with a broad range of core and co-morbidities, associated with dysfunction of the central nervous system. Improvements in high throughput sequencing have led to the detection of putative risk genetic loci for NNDs, however, quantitative neurogenetic approaches need to be further developed in order to establish causality and underlying molecular genetic mechanisms of pathogenesis. Here, we discuss an approach for prioritizing the contribution of genetic risk loci to complex-NND pathogenesis by estimating the possible impacts of these loci on gene regulation. Furthermore, we highlight the use of a tissue-specificity gene expression index and the application of artificial intelligence (AI) to improve the interpretation of the role of genetic risk elements in NND pathogenesis. Given that NND symptoms are associated with brain dysfunction, risk loci with direct, causative actions would comprise genes with essential functions in neural cells that are highly expressed in the brain. Indeed, NND risk genes implicated in brain dysfunction are disproportionately enriched in the brain compared with other tissues, which we refer to as brain-specific expressed genes. In addition, the tissue-specificity gene expression index can be used as a handle to identify non-brain contexts that are involved in NND pathogenesis. Lastly, we discuss how using an AI approach provides the opportunity to integrate the biological impacts of risk loci to identify those putative combinations of causative relationships through which genetic factors contribute to NND pathogenesis.

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