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1.
Front Immunol ; 15: 1293883, 2024.
Article in English | MEDLINE | ID: mdl-38455057

ABSTRACT

Fibrotic diseases, such as idiopathic pulmonary fibrosis (IPF) and systemic scleroderma (SSc), are commonly associated with high morbidity and mortality, thereby representing a significant unmet medical need. Interleukin 11 (IL11)-mediated cell activation has been identified as a central mechanism for promoting fibrosis downstream of TGFß. IL11 signaling has recently been reported to promote fibroblast-to-myofibroblast transition, thus leading to various pro-fibrotic phenotypic changes. We confirmed increased mRNA expression of IL11 and IL11Rα in fibrotic diseases by OMICs approaches and in situ hybridization. However, the vital role of IL11 as a driver for fibrosis was not recapitulated. While induction of IL11 secretion was observed downstream of TGFß signaling in human lung fibroblasts and epithelial cells, the cellular responses induced by IL11 was quantitatively and qualitatively inferior to that of TGFß at the transcriptional and translational levels. IL11 blocking antibodies inhibited IL11Rα-proximal STAT3 activation but failed to block TGFß-induced profibrotic signals. In summary, our results challenge the concept of IL11 blockade as a strategy for providing transformative treatment for fibrosis.


Subject(s)
Interleukin-11 , Transforming Growth Factor beta , Humans , Transforming Growth Factor beta/metabolism , Signal Transduction , Fibrosis , Myofibroblasts/metabolism
2.
Toxicol Sci ; 191(2): 400-413, 2023 02 17.
Article in English | MEDLINE | ID: mdl-36515490

ABSTRACT

Administration of a novel and selective small molecule integrin αvß6 inhibitor, MORF-627, to young cynomolgus monkeys for 28 days resulted in the rapid induction of epithelial proliferative changes in the urinary bladder of 2 animals, in the absence of test agent genotoxicity. Microscopic findings included suburothelial infiltration by irregular nests and/or trabeculae of epithelial cells, variable cytologic atypia, and high mitotic rate, without invasion into the tunica muscularis. Morphologic features and patterns of tumor growth were consistent with a diagnosis of early-stage invasive urothelial carcinoma. Ki67 immunohistochemistry demonstrated diffusely increased epithelial proliferation in the urinary bladder of several monkeys, including those with tumors, and αvß6 was expressed in some epithelial tissues, including urinary bladder, in monkeys and humans. Spontaneous urothelial carcinomas are extremely unusual in young healthy monkeys, suggesting a direct link of the finding to the test agent. Inhibition of integrin αvß6 is intended to locally and selectively block transforming growth factor beta (TGF-ß) signaling, which is implicated in epithelial proliferative disorders. Subsequent in vitro studies using a panel of integrin αvß6 inhibitors in human bladder epithelial cells replicated the increased urothelial proliferation observed in monkeys and was reversed through exogenous application of TGF-ß. Moreover, analysis of in vivo models of liver and lung fibrosis revealed evidence of epithelial hyperplasia and cell cycle dysregulation in mice treated with integrin αvß6 or TGF-ß receptor I inhibitors. The cumulative evidence suggests a direct link between integrin αvß6 inhibition and decreased TGF-ß signaling in the local bladder environment, with implications for epithelial proliferation and carcinogenesis.


Subject(s)
Carcinoma, Transitional Cell , Integrins , Urinary Bladder Neoplasms , Animals , Humans , Mice , Carcinoma, Transitional Cell/chemically induced , Integrins/antagonists & inhibitors , Integrins/metabolism , Macaca fascicularis , Transforming Growth Factor beta/metabolism , Urinary Bladder Neoplasms/chemically induced
3.
Nat Commun ; 11(1): 1920, 2020 04 21.
Article in English | MEDLINE | ID: mdl-32317643

ABSTRACT

Collagen-producing cells maintain the complex architecture of the lung and drive pathologic scarring in pulmonary fibrosis. Here we perform single-cell RNA-sequencing to identify all collagen-producing cells in normal and fibrotic lungs. We characterize multiple collagen-producing subpopulations with distinct anatomical localizations in different compartments of murine lungs. One subpopulation, characterized by expression of Cthrc1 (collagen triple helix repeat containing 1), emerges in fibrotic lungs and expresses the highest levels of collagens. Single-cell RNA-sequencing of human lungs, including those from idiopathic pulmonary fibrosis and scleroderma patients, demonstrate similar heterogeneity and CTHRC1-expressing fibroblasts present uniquely in fibrotic lungs. Immunostaining and in situ hybridization show that these cells are concentrated within fibroblastic foci. We purify collagen-producing subpopulations and find disease-relevant phenotypes of Cthrc1-expressing fibroblasts in in vitro and adoptive transfer experiments. Our atlas of collagen-producing cells provides a roadmap for studying the roles of these unique populations in homeostasis and pathologic fibrosis.


Subject(s)
Collagen/chemistry , Lung/metabolism , Pulmonary Fibrosis/metabolism , Animals , Cell Separation , Extracellular Matrix Proteins/metabolism , Female , Fibroblasts/metabolism , Flow Cytometry , Green Fluorescent Proteins/metabolism , High-Throughput Nucleotide Sequencing , Humans , Idiopathic Pulmonary Fibrosis/pathology , Lung/pathology , Male , Mice , Mice, Inbred C57BL , Phenotype , Pulmonary Fibrosis/pathology , Respiration Disorders/metabolism , Single-Cell Analysis
4.
Mol Pharmacol ; 94(4): 1197-1209, 2018 10.
Article in English | MEDLINE | ID: mdl-30068735

ABSTRACT

The D1 dopamine receptor is linked to a variety of neuropsychiatric disorders and represents an attractive drug target for the enhancement of cognition in schizophrenia, Alzheimer disease, and other disorders. Positive allosteric modulators (PAMs), with their potential for greater selectivity and larger therapeutic windows, may represent a viable drug development strategy, as orthosteric D1 receptor agonists possess known clinical liabilities. We discovered two structurally distinct D1 receptor PAMs, MLS6585 and MLS1082, via a high-throughput screen of the NIH Molecular Libraries program small-molecule library. Both compounds potentiate dopamine-stimulated G protein- and ß-arrestin-mediated signaling and increase the affinity of dopamine for the D1 receptor with low micromolar potencies. Neither compound displayed any intrinsic agonist activity. Both compounds were also found to potentiate the efficacy of partial agonists. We tested maximally effective concentrations of each PAM in combination to determine if the compounds might act at separate or similar sites. In combination, MLS1082 + MLS6585 produced an additive potentiation of dopamine potency beyond that caused by either PAM alone for both ß-arrestin recruitment and cAMP accumulation, suggesting diverse sites of action. In addition, MLS6585, but not MLS1082, had additive activity with the previously described D1 receptor PAM "Compound B," suggesting that MLS1082 and Compound B may share a common binding site. A point mutation (R130Q) in the D1 receptor was found to abrogate MLS1082 activity without affecting that of MLS6585, suggesting this residue may be involved in the binding/activity of MLS1082 but not that of MLS6585. Together, MLS1082 and MLS6585 may serve as important tool compounds for the characterization of diverse allosteric sites on the D1 receptor as well as the development of optimized lead compounds for therapeutic use.


Subject(s)
Allosteric Regulation/physiology , Allosteric Site/physiology , Receptors, Dopamine/metabolism , Animals , CHO Cells , Cricetulus , Cyclic AMP/metabolism , Dopamine/metabolism , GTP-Binding Proteins/metabolism , HEK293 Cells , Humans , Signal Transduction/physiology , beta-Arrestins/metabolism
5.
J Neurosci ; 31(1): 126-32, 2011 Jan 05.
Article in English | MEDLINE | ID: mdl-21209197

ABSTRACT

Bacteria artificial chromosome (BAC) transgenic mice expressing the reporter protein enhanced green fluorescent protein (EGFP) under the control of the D1 and D2 dopamine receptor promoters (Drd1-EGFP and Drd2-EGFP) have been widely used to study striatal function and have contributed to our understanding of the physiological and pathological functions of the basal ganglia. These tools were produced and promptly made available to address questions in a cell-specific manner that has transformed the way we frame hypotheses in neuroscience. However, these mice have not been fully characterized until now. We found that Drd2-EGFP mice display an ∼40% increase in membrane expression of the dopamine D2 receptor (D2R) and a twofold increase in D2R mRNA levels in the striatum when compared with wild-type and Drd1-EGFP mice. D2R overexpression was accompanied by behavioral hypersensitivity to D2R-like agonists, as well as enhanced electrophysiological responses to D2R activation in midbrain dopaminergic neurons. Dopamine (DA) transients evoked by stimulation in the nucleus accumbens showed slower clearance in Drd2-EGFP mice, and cocaine actions on DA clearance were impaired in these mice. Thus, it was not surprising to find that Drd2-EGFP mice were hyperactive when exposed to a novel environment and locomotion was suppressed by acute cocaine administration. All together, this study demonstrates that Drd2-EGFP mice overexpress D2R and have altered dopaminergic signaling that fundamentally differentiates them from wild-type and Drd1-EGFP mice.


Subject(s)
Gene Expression Regulation/genetics , Receptors, Dopamine D2/genetics , Receptors, Dopamine D2/metabolism , Animals , Ankyrin Repeat/genetics , Behavior, Animal/physiology , Cocaine/pharmacology , Corpus Striatum/drug effects , Corpus Striatum/metabolism , Dopamine Agonists/pharmacology , Dopamine Uptake Inhibitors/pharmacology , Dose-Response Relationship, Drug , Electrochemistry/methods , Green Fluorescent Proteins/genetics , In Vitro Techniques , Locomotion/drug effects , Mice , Mice, Transgenic , Neurons/drug effects , Neurons/physiology , Protein Binding/drug effects , Quinpirole/pharmacology , RNA, Messenger/metabolism , Radioligand Assay/methods , Receptors, Dopamine D1/genetics , Signal Transduction/drug effects , Signal Transduction/genetics , Statistics, Nonparametric , Time Factors , Ventral Tegmental Area/cytology
6.
Law Hum Behav ; 34(1): 66-78, 2010 Feb.
Article in English | MEDLINE | ID: mdl-19462223

ABSTRACT

Traditionally, high levels of suggestibility have been widely assumed to be linked with diminished Miranda abilities, especially in relationship to the voluntariness of waivers. The current investigation examined suggestibility on the Gudjonsson Suggestibility Scales in a multisite study of pretrial defendants. One important finding was the inapplicability of British norms to American jurisdictions. Moreover, suggestibility appeared unrelated to Miranda comprehension, reasoning, and detainees' perceptions of police coercion. In testing rival hypotheses, defendants with high compliance had significantly lower Miranda comprehension and ability to reason about exercising Miranda rights than their counterparts with low compliance. Implications of these findings to forensic practice are examined.


Subject(s)
Coercion , Crime/legislation & jurisprudence , Prisoners/psychology , Suggestion , Vulnerable Populations/psychology , Humans , Oklahoma , Texas
7.
Am J Physiol Regul Integr Comp Physiol ; 298(2): R411-8, 2010 Feb.
Article in English | MEDLINE | ID: mdl-19939975

ABSTRACT

ANG II, the main circulating effector hormone of the renin-angiotensin system, is produced by enzymatic cleavage of angiotensinogen. The present study aimed to examine whether targeted deletion of the angiotensinogen gene (Agt) altered brain ANG II receptor density or responsiveness to ANG II. In vitro autoradiography was used to examine the distribution and density of angiotensin type 1 (AT(1)) and type 2 receptors. In most brain regions, the distribution and density of angiotensin receptors were similar in brains of Agt knockout mice (Agt(-/-)) and wild-type mice. In Agt(-/-) mice, a small increase in AT(1) receptor binding was observed in the rostral ventrolateral medulla (RVLM), a region that plays a critical role in blood pressure regulation. To examine whether Agt(-/-) mice showed altered responses to ANG II, blood pressure responses to intravenous injection (0.01-0.1 microg/kg) or RVLM microinjection (50 pmol in 50 nl) of ANG II were recorded in anesthetized Agt(-/-) and wild-type mice. Intravenous injections of phenylephrine (4 microg/kg and 2 microg/kg) were also made in both groups. The magnitude of the pressor response to intravenous injections of ANG II or phenylephrine was not different between Agt(-/-) and wild-type mice. Microinjection of ANG II into the RVLM induced a pressor response, which was significantly smaller in Agt(-/-) compared with wild-type mice (+10 + or - 1 vs. +23 + or - 4 mmHg, respectively, P = 0.004). Microinjection of glutamate into the RVLM (100 pmol in 10 nl) produced a robust pressor response, which was not different between Agt(-/-) and wild-type mice. A diminished response to ANG II microinjection in the RVLM of Agt(-/-) mice, despite an increased density of AT(1) receptors suggests that signal transduction pathways may be altered in RVLM neurons of Agt(-/-) mice, resulting in attenuated cellular excitation.


Subject(s)
Angiotensinogen/physiology , Angiotensins/pharmacology , Blood Pressure/drug effects , Medulla Oblongata/physiology , Receptor, Angiotensin, Type 1/metabolism , Anesthesia , Angiotensinogen/genetics , Angiotensins/administration & dosage , Animals , Binding Sites , Glutamic Acid/pharmacology , Heart Rate/drug effects , Medulla Oblongata/drug effects , Mice , Mice, Knockout , Microinjections , Phenylephrine/administration & dosage , Phenylephrine/pharmacology , Vasoconstrictor Agents/administration & dosage , Vasoconstrictor Agents/pharmacology
8.
Curr Protoc Neurosci ; Chapter 5: Unit 5.28, 2009 Jan.
Article in English | MEDLINE | ID: mdl-19170023

ABSTRACT

Proteomics has evolved from genomic science due to the convergence of advances in protein chemistry, separations, mass spectroscopy, and peptide and protein databases. Where identifying protein-protein interactions was once limited to yeast two-hybrid analyses or empirical data, protein-protein interactions can now be examined in both cells and native tissues by precipitation of the protein complex of interest. Coupling this field to receptor pharmacology has recently allowed for the identification of proteins that differentially and selectively interact with receptors and are integral to their biological effects. It is becoming increasingly apparent that receptors in neurons do not exist as singular independent units, but rather are part of large macromolecular complexes of interacting proteins. It is a primary quest of neuroscience to piece together these interactions and to characterize the regulatory signalplexes of all proteins. This unit presents co-immunoprecipitation-coupled mass spectroscopy as one way of identifying signalplex partners.


Subject(s)
Immunoprecipitation/methods , Mass Spectrometry/methods , Multiprotein Complexes/metabolism , Protein Interaction Mapping/methods , Proteomics/methods , Animals , Cells, Cultured , Multiprotein Complexes/chemistry , Nervous System Physiological Phenomena , Neurochemistry/methods , Neurons/chemistry , Neurons/metabolism , Receptors, Cell Surface/chemistry , Receptors, Cell Surface/metabolism , Signal Transduction/physiology
9.
Law Hum Behav ; 33(5): 381-92, 2009 Oct.
Article in English | MEDLINE | ID: mdl-18953641

ABSTRACT

Miranda vocabulary forms the essential foundation for Miranda comprehension and subsequent decisions to exercise or waive Miranda rights. The purpose of the current study is the development of the Miranda Vocabulary Scale (MVS), designed to evaluate key vocabulary words found in Miranda warnings and waivers across American jurisdictions. A preliminary list of MVS words was refined by expert ratings and by each word's discriminability between failed and good Miranda comprehension. Miranda and other measures were collected at multiple sites on 376 pretrial defendants. With further refinements, the MVS is composed of 36 words with excellent scale homogeneity and interrater reliability (r = .99). It also demonstrated good convergent and discriminant validity for cognitive abilities and psychological impairment.


Subject(s)
Civil Rights/legislation & jurisprudence , Comprehension , Crime/legislation & jurisprudence , Guilt , Law Enforcement/methods , Prisoners/legislation & jurisprudence , Vocabulary , Adult , Humans , Insanity Defense , Mental Competency/legislation & jurisprudence , Oklahoma , Prisoners/psychology , Security Measures/legislation & jurisprudence , Texas
10.
Law Hum Behav ; 33(1): 61-9, 2009 Feb.
Article in English | MEDLINE | ID: mdl-18317890

ABSTRACT

Spanish-translated Miranda warnings are administered annually to thousands of Hispanic custodial suspects. In examining 121 Spanish translations and their English counterparts from 33 states, the lengths of Miranda warnings were generally comparable but marked differences were observed in the reading levels for individual Miranda components. The adequacy of Miranda translations varies markedly from minor variations to substantive errors. The most serious problems involved the entire omission of Miranda components; several omissions were observed in the Spanish translations for even the basic rights to silence and counsel. More commonly, Miranda discrepancies involved dissimilar content with a substantial trend toward more information in English than Spanish versions. Findings related to the Miranda translations, different word lengths, and varied reading levels are discussed using the totality of circumstances as its framework.


Subject(s)
Human Rights/legislation & jurisprudence , Language , Prisoners/legislation & jurisprudence , Humans , United States
11.
J Biol Chem ; 283(52): 36441-53, 2008 Dec 26.
Article in English | MEDLINE | ID: mdl-18984584

ABSTRACT

It is well documented that dopamine can increase or decrease the activity of the Na+,K+-ATPase (NKA, sodium pump) in an organ-specific fashion. This regulation can occur, at least partially, via receptor-mediated second messenger activation and can promote NKA insertion or removal from the plasma membrane. Using co-immunoprecipitation and mass spectrometry, we now show that, in both brain and HEK293T cells, D1 and D2 dopamine receptors (DARs) can exist in a complex with the sodium pump. To determine the impact of NKA on DAR function, biological assays were conducted with NKA and DARs co-expressed in HEK293T cells. In this system, expression of NKA dramatically decreased D1 and D2 DAR densities with a concomitant functional decrease in DAR-mediated regulation of cAMP levels. Interestingly, pharmacological inhibition of endogenous or overexpressed NKA enhanced DAR function without altering receptor number or localization. Similarly, DAR function was also augmented by small interfering RNA reduction of the endogenous NKA. These data suggest that, under basal conditions, NKA negatively regulates DAR function via protein-protein interactions. In reciprocal fashion, expression of DARs decreases endogenous NKA function in the absence of dopamine, implicating DAR proteins as regulators of NKA activity. Notably, dopamine stimulation or pertussis toxin inhibition of D2 receptor signaling did not alter NKA activity, indicating that the D2-mediated decrease in NKA function is dependent upon protein-protein interactions rather than signaling molecules. This evidence for reciprocal regulation between DARs and NKA provides a novel control mechanism for both DAR signaling and cellular ion balance.


Subject(s)
Receptors, Dopamine D1/metabolism , Receptors, Dopamine D2/metabolism , Sodium-Potassium-Exchanging ATPase/metabolism , Amino Acid Sequence , Brain/metabolism , Cell Line , Cell Membrane/metabolism , Dopamine/metabolism , Humans , Ions , Mass Spectrometry/methods , Models, Biological , Molecular Sequence Data , Pertussis Toxin/pharmacology , Signal Transduction
12.
Law Hum Behav ; 32(2): 124-36, 2008 Apr.
Article in English | MEDLINE | ID: mdl-17597389

ABSTRACT

Miranda warnings are remarkably heterogeneous in their language, length, and content. Past research has focused mostly on individual Miranda warnings. Lacking in generalizability, these studies have limited applicability to both public policy and professional practice. A large-scale survey by R. Rogers et al. [2007b, Law and Human Behavior, 31, 177-192] examined Miranda warnings from across the United States and documented striking differences in the length, content, and reading comprehension. In moving from single jurisdiction studies to nationally representative research, the replication of the Rogers et al. survey is essential. With an additional 385 general Miranda warnings, most of the original findings were confirmed; this replication allows Miranda researchers to use findings based upon nationally-representative warnings for their subsequent research. Beyond reading comprehension, the study makes an original contribution to the understanding of Miranda vocabulary that is often infused with abstruse words and legalistic terms. It provides the first analysis of sentence complexity, which affects both Miranda comprehension and retention. As a result of these analyses, preliminary guidelines are provided for increasing the comprehension and understanding of Miranda warnings.


Subject(s)
Language , Vocabulary , Humans , Jurisprudence , Public Policy , Surveys and Questionnaires , United States
13.
J Biol Chem ; 282(29): 21285-300, 2007 Jul 20.
Article in English | MEDLINE | ID: mdl-17395585

ABSTRACT

As for all proteins, G protein-coupled receptors (GPCRs) undergo synthesis and maturation within the endoplasmic reticulum (ER). The mechanisms involved in the biogenesis and trafficking of GPCRs from the ER to the cell surface are poorly understood, but they may involve interactions with other proteins. We have now identified the ER chaperone protein calnexin as an interacting protein for both D(1) and D(2) dopamine receptors. These protein-protein interactions were confirmed using Western blot analysis and co-immunoprecipitation experiments. To determine the influence of calnexin on receptor expression, we conducted assays in HEK293T cells using a variety of calnexin-modifying conditions. Inhibition of glycosylation either through receptor mutations or treatments with glycosylation inhibitors partially blocks the interactions with calnexin with a resulting decrease in cell surface receptor expression. Confocal fluorescence microscopy reveals the accumulation of D(1)-green fluorescent protein and D(2)-yellow fluorescent protein receptors within internal stores following treatment with calnexin inhibitors. Overexpression of calnexin also results in a marked decrease in both D(1) and D(2) receptor expression. This is likely because of an increase in ER retention because confocal microscopy revealed intracellular clustering of dopamine receptors that were co-localized with an ER marker protein. Additionally, we show that calnexin interacts with the receptors via two distinct mechanisms, glycan-dependent and glycan-independent, which may underlie the multiple effects (ER retention and surface trafficking) of calnexin on receptor expression. Our data suggest that optimal receptor-calnexin interactions critically regulate D(1) and D(2) receptor trafficking and expression at the cell surface, a mechanism likely to be of importance for many GPCRs.


Subject(s)
Calnexin/chemistry , Gene Expression Regulation , Receptors, Dopamine D1/chemistry , Receptors, Dopamine D2/chemistry , Calnexin/metabolism , Cell Line , Cyclic AMP/metabolism , Endoplasmic Reticulum/metabolism , Humans , Immunoprecipitation , Kinetics , Mass Spectrometry , Microscopy, Confocal , Peptides/chemistry , Polysaccharides/metabolism , Protein Binding
14.
Law Hum Behav ; 31(4): 401-18, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17245635

ABSTRACT

A conservative estimate is that 695,000 mentally disordered offenders are arrested and Mirandized annually in the United States. Past research has focused almost exclusively on cognitive factors affecting the comprehension of Miranda rights. The current study broadens the scope by including diagnostic variables and by extending the investigation to basic elements of Miranda reasoning. A sample of 107 mentally disordered defendants was administered two research measures, the Miranda Statements Scale (MSS) and Miranda Rights Scale (MRS), in addition to standardized tests. Most defendants lacked good comprehension of all but the simplest (Flesch-Kincaid<6th grade) Miranda warnings. Defendants with the poorest understanding (i.e., comprehending about 25% of the warnings) had marked deficits in multiple domains including cognitive abilities (intelligence and comprehension) and general adjustment. Different background and clinical variables predicted defendants' abilities to generate reasons either to exercise or waive their Miranda rights.


Subject(s)
Human Rights/legislation & jurisprudence , Mental Disorders , Prisoners/legislation & jurisprudence , Adult , Female , Humans , Male , Middle Aged , Personality Assessment , Texas
15.
Law Hum Behav ; 31(2): 177-92, 2007 Apr.
Article in English | MEDLINE | ID: mdl-17051442

ABSTRACT

Miranda warnings enshrine the constitutional rights of custodial suspects against self-incrimination. However, the wording and sentence complexity of Miranda warnings and waivers vary dramatically from jurisdiction to jurisdiction. This study is the first extensive investigation of Miranda warning variations examining 560 Miranda warnings from across the United States. With Flesch-Kincaid reading comprehension as a useful metric, Miranda warnings varied from very simple comprehension (i.e., grade 2.8) to requiring postgraduate education. Miranda warnings are composed of five components (e.g., silence and evidence against you); marked variations were also observed in the comprehensibility of individual components. On average, the Miranda warning component on "continuing rights" requires a reading comprehension level six grades higher than the comparatively simple expression of the right to silence. Similar analyses were conducted on Miranda waivers. The content of these warnings differed on such issues as communicating (a) when access to an attorney would be granted (e.g., 45.9% specified only "during questioning") and (b) explicitly that indigent legal services were free (e.g., 31.8% directly informed suspects). Finally, the study identified representative Miranda components at different levels of reading comprehension as a template for further research.


Subject(s)
Criminal Law/legislation & jurisprudence , Guilt , Humans , United States
16.
Glia ; 51(3): 235-40, 2005 Aug 15.
Article in English | MEDLINE | ID: mdl-15812814

ABSTRACT

Recent studies of axon-glia and glia-glia communication have emphasized interactivity and interdependence between central nervous system (CNS) components. Concurrently, data from imaging, biochemical, and morphological studies have changed the view of multiple sclerosis (MS) from a neuroinflammatory condition with primary demyelination to one in which cumulative axonal damage drives progression. We therefore studied axonal damage in the context of inflammation and glial responses, from the pre-clinical to onset stage of murine experimental autoimmune encephalomyelitis (EAE), an established MS model. We report three major findings: (1) the first evidence of axonal injury before significant T-cell entry into the parenchyma, (3) coincidence of the earliest manifestation of axonal damage and astrocytic responses, and (3) an association between accumulation of axonal and astrocytic changes and specific forms of MS. These data demonstrate the relationship between the initiation of axonal injury and early inflammation. Significantly, we show that, in common with a growing number of neurodegenerative conditions, the pathology of murine EAE is characterized by early active contribution from astrocytes. This marks a change in the understanding of the role of astrocytes in MS pathogenesis and has important implications for the development of neuroprotective strategies.


Subject(s)
Astrocytes/physiology , Axons/pathology , Central Nervous System/physiopathology , Encephalomyelitis, Autoimmune, Experimental/physiopathology , Gliosis/physiopathology , Wallerian Degeneration/physiopathology , Animals , Astrocytes/ultrastructure , Axons/ultrastructure , Biomarkers/metabolism , Cell Communication/physiology , Cell Shape/physiology , Central Nervous System/pathology , Central Nervous System/ultrastructure , Chemotaxis, Leukocyte/physiology , Disease Models, Animal , Disease Progression , Encephalitis/pathology , Encephalitis/physiopathology , Encephalomyelitis, Autoimmune, Experimental/pathology , Female , Gliosis/pathology , Mice , Mice, Inbred C57BL , Mice, Neurologic Mutants , Microscopy, Electron, Transmission , Multiple Sclerosis/pathology , Multiple Sclerosis/physiopathology , Myelin Sheath/pathology , Myelin Sheath/ultrastructure , Nerve Tissue Proteins/metabolism , T-Lymphocytes/physiology , Time Factors , Wallerian Degeneration/pathology
17.
Mol Pharmacol ; 66(5): 1293-300, 2004 Nov.
Article in English | MEDLINE | ID: mdl-15496511

ABSTRACT

Naturally occurring variation within the human 5-HT(2A) receptor results in an amino acid substitution in the carboxyl terminus of the receptor. This single nucleotide polymorphism (SNP), encoding a His452Tyr substitution, occurs at a frequency of 9% in the general population. It is noteworthy that this SNP has been linked to attention deficit hyperactivity disorder and has been associated with schizophrenic patients that do not respond to treatment with clozapine. To evaluate functional consequences of this SNP, agonist-stimulated signaling was investigated in NIH3T3 cells stably expressing either wild-type or 452Tyr variant receptors. The 452Tyr variant of the 5-HT(2a) receptor had reduced ability to activate phospholipases C and D, suggesting that signaling through both G(q) and G(13) pathways is hindered. This conclusion was supported by assays of G protein coupling, which documented a loss of agonist-induced high affinity binding and a decreased turnover of guanosine 5'-O-(3-[(35)S]thio)triphosphate after agonist stimulation. Kinetic analysis of time-course data revealed an altered desensitization phenotype, resulting in a blunted signal downstream of receptor activation. This diminished signaling implies that the His452Tyr variant receptor alters physiological responses, possibly contributing to psychiatric disease.


Subject(s)
Histidine/chemistry , Receptor, Serotonin, 5-HT2A/chemistry , Tyrosine/chemistry , Amino Acid Substitution , Cells, Cultured , GTP-Binding Proteins/metabolism , Histidine/genetics , Humans , Polymorphism, Genetic , Protein Conformation , Receptor, Serotonin, 5-HT2A/genetics , Receptor, Serotonin, 5-HT2A/metabolism , Serotonin Receptor Agonists/pharmacology , Signal Transduction , Tyrosine/genetics
18.
Neurochem Int ; 45(2-3): 409-19, 2004.
Article in English | MEDLINE | ID: mdl-15145555

ABSTRACT

Investigations of functional interactions among axons and glia over the last decade have revealed the extent and complexity of glial-neuronal and glial-glial communication during development, adult function and recovery from injury. These data have profound implications for the understanding of central nervous system (CNS) disorders, which until recently, have been classified as either neuronal or glial diseases. Re-evaluation of the pathological processes in a number of conditions has clearly shown involvement of both neurons and glia in early pathology. In multiple sclerosis (MS), the myelin sheath has traditionally been regarded as the primary target. However, recent evidence has clearly demonstrated axonal damage in new lesions. We have addressed the question of the role of axonal pathology in early MS by using well-characterized murine models for the relapsing-remitting (RR) or the primary progressive (PP) forms of the disease. We performed a histopathological survey of the CNS, following induction of the disease, to determine the timing of appearance, as well as the development of lesions. Then we analysed the relationship between inflammation, demyelination and axonal damage together with responses from astrocytes and microglia in each model from the earliest evidence of inflammation. We found that axonal damage begins well ahead of the appearance of motor symptoms. Pathology appears to be more closely related to the degree of inflammation than to demyelination. We also show that early astrocyte responses and the degree of axonal loss are markedly different in the two models and relate to the severity of pathology. These data support the now widely accepted hypothesis that axonal damage begins early in the disease process, but also suggest modulation of axonal loss and disease progression by the astrocytic response.


Subject(s)
Multiple Sclerosis/pathology , Multiple Sclerosis/physiopathology , Neuroglia/pathology , Animals , Disease Models, Animal , Disease Progression , Mice , Mice, Inbred C57BL , Mice, Inbred NOD , Neuroglia/physiology , Optic Nerve/pathology , Spinal Cord/pathology , Time Factors
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