RESUMO
To better prepare future generations, knowledge about computers and programming are one of the many skills that are part of almost all Science, Technology, Engineering, and Mathematic programs; however, teaching and learning programming is a complex task that is generally considered difficult by students and teachers alike. One approach to engage and inspire students from a variety of backgrounds is the use of educational robots. Unfortunately, previous research presents mixed results on the effectiveness of educational robots on student learning. One possibility for this lack of clarity may be because students have a wide variety of styles of learning. It is possible that the use of kinesthetic feedback, in addition to the normally used visual feedback, may improve learning with educational robots by providing a richer, multi-modal experience that may appeal to a larger number of students with different learning styles. It is also possible, however, that the addition of kinesthetic feedback, and how it may interfere with the visual feedback, may decrease a student's ability to interpret the program commands being executed by a robot, which is critical for program debugging. In this work, we investigated whether human participants were able to accurately determine a sequence of program commands performed by a robot when both kinesthetic and visual feedback were being used together. Command recall and end point location determination were compared to the typically used visual-only method, as well as a narrative description. Results from 10 sighted participants indicated that individuals were able to accurately determine a sequence of movement commands and their magnitude when using combined kinesthetic + visual feedback. Participants' recall accuracy of program commands was actually better with kinesthetic + visual feedback than just visual feedback. Although the recall accuracy was even better with the narrative description, this was primarily due to participants confusing an absolute rotation command with a relative rotation command with the kinesthetic + visual feedback. Participants' zone location accuracy of the end point after a command was executed was significantly better for both the kinesthetic + visual feedback and narrative methods compared to the visual-only method. Together, these results suggest that the use of both kinesthetic + visual feedback improves an individual's ability to interpret program commands, rather than decreases it.
Assuntos
Aprendizagem , Visão Ocular , Humanos , Retroalimentação , Movimento , EstudantesRESUMO
In amyotrophic lateral sclerosis (ALS), the progressive loss of motor neurons is accompanied by extensive muscle denervation, resulting in paralysis and ultimately death. Upregulation of amyloid beta (A4) precursor protein (APP) in muscle fibres coincides with symptom onset in both sporadic ALS patients and the SOD1(G93A) mouse model of familial ALS. We have further characterized this response in SOD1(G93A) mice and also revealed elevated levels of ß-amyloid (Aß) peptides in the SOD1(G93A) spinal cord, which were predominantly localized within motor neurons and their surrounding glial cells. We therefore examined the effect of genetic ablation of APP on disease progression in SOD1(G93A) mice, which significantly improved multiple disease parameters, including innervation, motor function, muscle contractile characteristics, motor unit and motor neuron survival. These results therefore strongly suggest that APP actively contributes to SOD1(G93A)-mediated pathology. Together with observations from ALS cases, this study indicates that APP may contribute to human ALS pathology.
Assuntos
Substituição de Aminoácidos/genética , Precursor de Proteína beta-Amiloide/metabolismo , Esclerose Lateral Amiotrófica/enzimologia , Esclerose Lateral Amiotrófica/patologia , Superóxido Dismutase/genética , Esclerose Lateral Amiotrófica/fisiopatologia , Animais , Atrofia , Peso Corporal , Sobrevivência Celular , Cruzamentos Genéticos , Modelos Animais de Doenças , Feminino , Humanos , Longevidade , Masculino , Camundongos , Camundongos Knockout , Atividade Motora , Neurônios Motores/metabolismo , Neurônios Motores/patologia , Denervação Muscular , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Junção Neuromuscular/metabolismo , Junção Neuromuscular/patologia , Junção Neuromuscular/fisiopatologia , Processamento de Proteína Pós-Traducional , Solubilidade , Medula Espinal/patologia , Medula Espinal/fisiopatologia , Superóxido Dismutase/metabolismo , Superóxido Dismutase-1 , Regulação para CimaRESUMO
Breakdown of neuromuscular junctions (NMJs) is an early pathological hallmark of amyotrophic lateral sclerosis (ALS) that blocks neuromuscular transmission, leading to muscle weakness, paralysis and, ultimately, premature death. Currently, no therapies exist that can prevent progressive motor neuron degeneration, muscle denervation, or paralysis in ALS. Here, we report important advances in the development of an optogenetic, neural replacement strategy that can effectively restore innervation of severely affected skeletal muscles in the aggressive SOD1G93A mouse model of ALS, thus providing an interface to selectively control the function of targeted muscles using optical stimulation. We also identify a specific approach to confer complete survival of allogeneic replacement motor neurons. Furthermore, we demonstrate that an optical stimulation training paradigm can prevent atrophy of reinnervated muscle fibers and results in a tenfold increase in optically evoked contractile force. Together, these advances pave the way for an assistive therapy that could benefit all ALS patients.
Assuntos
Esclerose Lateral Amiotrófica , Animais , Camundongos , Humanos , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/terapia , Optogenética , Músculo Esquelético , Paralisia , Terapia Baseada em Transplante de Células e Tecidos , Modelos Animais de DoençasRESUMO
Syngeneic graft-versus-host disease (SGVHD), a chronic inflammatory disease, develops following irradiation, syngeneic bone marrow transplantation (BMT) and treatment with the immunosuppressive agent cyclosporine A (CsA). We have shown that TH1 and TH17 cytokine responses are increased during the development of SGVHD. The current study was designed to further investigate the involvement of TH17 immunity in SGVHD-associated colitis. IL-23 is a TH17 cytokine responsible for maintaining the effector functions of TH17 cells. The administration of anti-mouse IL-23p19 was shown to significantly reduce the clinical symptoms of primary and secondary SGVHD-associated colitis resulting in a significant reduction in both TH1 and TH17 associated cytokine expression. These results demonstrate that the TH17-associated cytokine, IL-23, may prove to be a beneficial therapeutic target in the treatment of chronic colon inflammation.
Assuntos
Transferência Adotiva , Doença Enxerto-Hospedeiro/imunologia , Doença Enxerto-Hospedeiro/terapia , Subunidade p19 da Interleucina-23/antagonistas & inibidores , Animais , Citocinas/biossíntese , Feminino , Mediadores da Inflamação/metabolismo , Subunidade p19 da Interleucina-23/metabolismo , Camundongos , Transplante IsogênicoRESUMO
Murine syngeneic graft-versus-host disease (SGVHD) initiates colon and liver inflammation following lethal irradiation, reconstitution with syngeneic bone marrow transplantation, and therapy with the immunosuppressive agent cyclosporine A. Previous studies have demonstrated that the inducible disease is mediated by CD4(+) T cells with increased reactivity of peripheral and liver-associated lymphocytes against intestinal microbial Ags. In the current report, studies were performed to analyze the specificity of the CD4(+) T cell response of T cells isolated from diseased animals and to determine the in vivo role of the microbiota to the development of SGVHD. Increased major histocompatibility Ag (MHC) class II-restricted responsiveness of SGVHD CD4(+) T cells against microbial Ags isolated from the ceca of normal animals was observed. The enhanced proliferative response was observed in the CD62L(-) memory population of CD4(+) T cells. To determine the role of the bacterial microbiota in the development of murine SGVHD, control and CsA-treated bone marrow transplantation animals were treated with broad-spectrum antibiotics (metronidazole, ciprofloxacin) after transplantation. Cyclosporine A-treated animals that were given antibiotic therapy failed to develop clinical symptoms and pathological lesions in the target tissues characteristic of SGVHD. Furthermore, the reduction in intestinal bacteria resulted in the elimination of the enhanced antimicrobial CD4(+) T cell response and significantly reduced levels of the inflammatory cytokines, IFN-γ, IL-17, and TNF-α. The elimination of the disease-associated inflammatory immune responses and pathology by treatment with broad-spectrum antibiotics definitively links the role of the microbiota and microbial-specific immunity to the development of murine SGVHD.
Assuntos
Antibacterianos/uso terapêutico , Doença Enxerto-Hospedeiro/tratamento farmacológico , Doença Enxerto-Hospedeiro/imunologia , Animais , Antibacterianos/classificação , Transplante de Medula Óssea/imunologia , Transplante de Medula Óssea/patologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/microbiologia , Linfócitos T CD4-Positivos/patologia , Linhagem Celular , Proliferação de Células , Ciprofloxacina/uso terapêutico , Feminino , Doença Enxerto-Hospedeiro/patologia , Antígenos de Histocompatibilidade Classe II/imunologia , Inflamação/tratamento farmacológico , Inflamação/imunologia , Inflamação/patologia , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Mucosa Intestinal/patologia , Metronidazol/uso terapêutico , Camundongos , Camundongos Endogâmicos C3HRESUMO
Objective: Previously, we demonstrated that Amyloid Precursor Protein (APP) contributes to pathology in the SOD1G93A mouse model of ALS and that genetic ablation of APP in SOD1G93A mice significantly improved multiple disease parameters, including muscle innervation and motor neuron survival. We also observed elevated levels of potentially neurotoxic Aß peptides that have been implicated in Alzheimer's Disease (AD) pathogenesis, within motor neurons and astrocytes in SOD1G93A mice. More recently, it has been shown that blocking Aß production improves outcome measures in SOD1G93A mice. The cyclodextrin, (2-Hydroxypropyl)-ß-cyclodextrin (HP-ß-CD), has previously been shown to deplete intraneuronal unesterified cholesterol, resulting in effective reduction of Aß production and amelioration of disease progression in mouse models of AD and Niemann Pick Type C (NPC) disease. Here, we tested whether HP-ß-CD could also improve phenotypic progression in SOD1G93A mice. Methods: Pre-symptomatic male SOD1G93A mice were randomly assigned to the following treatment groups: HP-ß-CD (4000mg/kg, n = 9) or vehicle (saline; n = 10), delivered by weekly subcutaneous injection, commencing at 67 days of age. Longitudinal grip-strength and body mass analysis was performed until late-stage disease (120 days of age), followed by in vivo bilateral isometric muscle tension analysis of tibialis anterior (TA) and extensor digitorum longus (EDL) muscles. Results: HP-ß-CD administration had no effect on body mass or grip-strength compared to vehicle treated SOD1G93A mice. Similarly, HP-ß-CD treatment had no effect on muscle force, contractile properties or motor unit number estimates (MUNE) at late-stage disease in SOD1G93A mice. Conclusion: This study shows that HP-ß-CD does not confer any therapeutic benefit in SOD1G93A mice. However, the absence of detrimental effects is informative, given the common use of cyclodextrins as complexing agents for other pharmaceutical products, their standalone therapeutic potential and the emerging association between dyslipidaemia and ALS progression.
RESUMO
The world is not on track to achieve Agenda 2030-the approach chosen in 2015 by all UN member states to engage multiple stakeholders for the common goal of sustainable development. The creation of the 17 Sustainable Development Goals (SDGs) arguably offered a new take on sustainable development by adopting hybrid and principle-based governance approaches, where public, private, not for profit and knowledge-institutions were invited to engage around achieving common medium-term targets. Cross-sector partnerships and multi-stakeholder engagement for sustainability have consequently taken shape. But the call for collaboration has also come with fundamental challenges to meaningful engagement strategies-when private enterprises try to establish elaborate multi-stakeholder configurations. How can the purpose of businesses be mitigated through multi-stakeholder principle-based partnerships to effectively serve the purpose of a common sustainability agenda? In selecting nine scholarly contributions, this special issue aims at advancing this discourse. To stimulate further progress in business studies, this introductory essay, furthermore, identifies three pathways for research on multi-stakeholder engagement processes in support of the Decade of Action along three coupling lines: multi-sector alignment (relational coupling), operational perception alignment (cognitive coupling) and goal and strategic alignment (material coupling).
RESUMO
An ideal therapeutic for stroke or spinal cord injury should promote survival and regeneration in the CNS. Arginase 1 (Arg1) has been shown to protect motor neurons from trophic factor deprivation and allow sensory neurons to overcome neurite outgrowth inhibition by myelin proteins. To identify small molecules that capture Arg1's protective and regenerative properties, we screened a hippocampal cell line stably expressing the proximal promoter region of the arginase 1 gene fused to a reporter gene against a library of compounds containing clinically approved drugs. This screen identified daidzein as a transcriptional inducer of Arg1. Both CNS and PNS neurons primed in vitro with daidzein overcame neurite outgrowth inhibition from myelin-associated glycoprotein, which was mirrored by acutely dissociated and cultured sensory neurons primed in vivo by intrathecal or subcutaneous daidzein infusion. Further, daidzein was effective in promoting axonal regeneration in vivo in an optic nerve crush model when given intraocularly without lens damage, or most importantly, when given subcutaneously after injury. Mechanistically, daidzein requires transcription and induction of Arg1 activity for its ability to overcome myelin inhibition. In contrast to canonical Arg1 activators, daidzein increases Arg1 without increasing CREB phosphorylation, suggesting its effects are cAMP-independent. Accordingly, it may circumvent known CNS side effects of some cAMP modulators. Indeed, daidzein appears to be safe as it has been widely consumed in soy products, crosses the blood-brain barrier, and is effective without pretreatment, making it an ideal candidate for development as a therapeutic for spinal cord injury or stroke.
Assuntos
Arginase/genética , AMP Cíclico/metabolismo , Isoflavonas/farmacologia , Regeneração Nervosa/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Regiões Promotoras Genéticas/fisiologia , Análise de Variância , Animais , Animais Recém-Nascidos , Arginase/metabolismo , Células CHO , Células Cultivadas , Cerebelo/citologia , Cricetinae , Cricetulus , Relação Dose-Resposta a Droga , Embrião de Mamíferos , Inibidores Enzimáticos/farmacologia , Proteína GAP-43/metabolismo , Gânglios Espinais/citologia , Ensaios de Triagem em Larga Escala/métodos , Hipocampo/citologia , Masculino , Glicoproteína Associada a Mielina/farmacologia , Regeneração Nervosa/fisiologia , Neurônios/citologia , Doenças do Nervo Óptico/tratamento farmacológico , Doenças do Nervo Óptico/patologia , Estresse Oxidativo/efeitos dos fármacos , Regiões Promotoras Genéticas/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Receptores de Estrogênio/metabolismo , Bibliotecas de Moléculas PequenasRESUMO
Syngeneic graft vs. host disease (SGVHD) was first described as a graft vs. host disease-like syndrome that developed in rats following syngeneic bone marrow transplantation (BMT) and cyclosporin A (CsA) treatment. SGVHD can be induced by reconstitution of lethally irradiated mice with syngeneic bone marrow cells followed by 21 days of treatment with the immunosuppressive agent CsA. Clinical symptoms of the disease appear 2-3 wk following cessation of CsA therapy, and disease-associated inflammation occurs primarily in the colon and liver. CD4(+) T cells have been shown to play an important role in the inflammatory response observed in the gut of SGVHD mice. Time-course studies revealed a significant increase in migration of CD4(+) T cells into the colon during CsA therapy, as well as significantly elevated mRNA levels of TNF-α, proinflammatory chemokines, and cell adhesion molecules in colonic tissue of CsA-treated animals compared with BMT controls, as early as day 14 post-BMT. Homing studies revealed a greater migration of labeled CD4(+) T cells into the gut of CsA-treated mice at day 21 post-BMT than control animals via CsA-induced upregulation of mucosal addressin cell adhesion molecule. This study demonstrates that, during the 21 days of immunosuppressive therapy, functional mechanisms are in place that result in increased homing of CD4(+) T effector cells to colons of CsA-treated mice.
Assuntos
Transplante de Medula Óssea/fisiologia , Medula Óssea/fisiologia , Linfócitos T CD4-Positivos/fisiologia , Colo/química , Colo/efeitos dos fármacos , Ciclosporina/farmacologia , Imunossupressores/farmacologia , Condicionamento Pré-Transplante , Animais , Western Blotting , Moléculas de Adesão Celular/biossíntese , Movimento Celular/efeitos dos fármacos , Quimiocinas/biossíntese , Colo/metabolismo , Citocinas/biossíntese , Citometria de Fluxo , Imunofluorescência , Camundongos , Camundongos Endogâmicos C3H , Receptores de Retorno de Linfócitos/fisiologia , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Resonant ultrasound spectroscopy has been used to follow elastic softening in SrTi(18)O3 in the frequency range â¼0.2-1 MHz. A dramatic softening of C44 occurs as the Curie temperature T(c) = 24 K is approached from above or below, which correlates with the development of a central peak in Raman and Brillouin spectra. This is attributed to strong coupling between the acoustic mode and the central peak mode. A weaker anomaly is seen in a resonance mode which is believed to be controlled by 1/2(C11-C12). Significant attenuation accompanies this softening and an additional dissipation peak has also been observed at â¼80-90 K. This extends earlier work by a factor of 150,000× from the 30 GHz regime and helps address the question as to whether the ferroelectricity is stimulated primarily by a soft mode into a homogeneous ground state or by clustering of rhombohedral nanoregions into an inhomogeneous ground state.
RESUMO
Adult spinal axons do not spontaneously regenerate after injury. However, if the peripheral branch of dorsal root ganglion neurons is lesioned before lesioning the central branch of the same neurons in the dorsal column, these central axons will regenerate and, if cultured, are not inhibited from extending neurites by myelin-associated inhibitors of regeneration such as myelin-associated glycoprotein (MAG). This effect can be mimicked by elevating cAMP and is transcription dependent. The ability of cAMP to overcome inhibition by MAG in culture involves the upregulation of the enzyme arginase I (Arg I) and subsequent increase in synthesis of polyamines such as putrescine. Now we show that a peripheral lesion also induces an increase in Arg I expression and synthesis of polyamines. We also show that the conditioning lesion effect in overcoming inhibition by MAG is initially dependent on ongoing polyamine synthesis but, with time after lesion, becomes independent of ongoing synthesis. However, if synthesis of polyamines is blocked in vivo the early phase of good growth after a conditioning lesion is completely blocked and the later phase of growth, when ongoing polyamine synthesis is not required during culture, is attenuated. We also show that putrescine must be converted to spermidine both in culture and in vivo to overcome inhibition by MAG and that spermidine can promote optic nerve regeneration in vivo. These results suggest that spermidine could be a useful tool in promoting CNS axon regeneration after injury.
Assuntos
Arginase/metabolismo , Axônios/fisiologia , Regeneração Nervosa/fisiologia , Espermidina/metabolismo , Animais , Axônios/enzimologia , Células Cultivadas , Gânglios Espinais/enzimologia , Gânglios Espinais/fisiologia , Masculino , Bainha de Mielina/metabolismo , Glicoproteína Associada a Mielina/metabolismo , Compressão Nervosa , Neurônios/enzimologia , Neurônios/fisiologia , Nervo Óptico/enzimologia , Nervo Óptico/fisiologia , Traumatismos do Nervo Óptico/enzimologia , Traumatismos do Nervo Óptico/fisiopatologia , Poliaminas/metabolismo , Putrescina/metabolismo , Ratos , Ratos Endogâmicos F344 , Nervo Isquiático/enzimologia , Nervo Isquiático/lesões , Nervo Isquiático/fisiologia , Transdução de Sinais/efeitos dos fármacos , Regulação para CimaRESUMO
The murine model of cyclosporine A (CsA)-induced syngeneic graft-versus-host disease (SGVHD) is a bone marrow (BM) transplantation model that develops chronic colon inflammation identical to other murine models of CD4(+) T cell-mediated colitis. Interestingly, SGVHD animals develop chronic liver lesions that are similar to the early peribiliary inflammatory stages of clinical chronic liver disease, which is frequently associated with inflammatory bowel disease (IBD). Therefore, studies were initiated to investigate the chronic liver inflammation that develops in the SGVHD model. To induce SGVHD, mice were lethally irradiated, reconstituted with syngeneic BM, and treated with CsA. All of the SGVHD animals that developed colitis also develop chronic liver inflammation. Liver samples from control and SGVHD animals were monitored for tissue pathology, RNA for inflammatory mediators, and phenotypic analysis and in vitro reactivity of the inflammatory infiltrate. Diseased animals developed lesions of intrahepatic and extrahepatic bile ducts. Elevated levels of mRNA for molecules associated with chronic liver inflammation, including mucosal cellular adhesion molecule -1, the chemokines CCL25, CCL28, CCR9, and T(H)1- and T(H)17-associated cytokines were observed in livers of SGVHD mice. CD4(+) T cells were localized to the peribiliary region of the livers of diseased animals, and an enhanced proliferative response of liver-associated mononuclear cells against colonic bacterial antigens was observed. The murine model of SGVHD colitis may be a valuable tool to study the entero-hepatic linkage between chronic colon inflammation and inflammatory liver disease.
Assuntos
Transplante de Medula Óssea/efeitos adversos , Doenças do Colo/etiologia , Doença Enxerto-Hospedeiro/complicações , Hepatopatias/etiologia , Transplante Isogênico , Animais , Doença Crônica , Doenças do Colo/patologia , Ciclosporina/uso terapêutico , Modelos Animais de Doenças , Feminino , Doença Enxerto-Hospedeiro/patologia , Imunossupressores/uso terapêutico , Inflamação/etiologia , Hepatopatias/patologia , Camundongos , Camundongos Endogâmicos C3H , Receptores Toll-Like/metabolismo , Transplante Isogênico/efeitos adversosRESUMO
Syngeneic graft-versus-host disease (SGVHD) develops following lethal irradiation, reconstitution with syngeneic bone marrow (BM) and treatment with a 21 day course of the immunosuppressive agent cyclosporine A (CsA). Clinical symptoms of SGVHD appear 2-3 weeks post-CsA with inflammation occurring in the colon and liver. Previously we have demonstrated that CD4(+) T cells and a T helper cell type 1 cytokine response (T(H)1) are involved in the development of SGVHD associated intestinal inflammation. Studies have recently discovered an additional T cell lineage that produces IL-17 and is termed T(H)17. It has been suggested that inflammatory bowel disease is a result of a T(H)17 response rather than a T(H)1 response. This study was designed to investigate T(H)17 involvement in SGVHD-associated colitis. Following induction of SGVHD, the levels of T(H)17 and T(H)1 cytokine mRNA and protein were measured in control and SGVHD animals. In vivo cytokine neutralization was performed to determine the role of the prototypic T(H)17 cytokine, IL-17, in the disease process. We found that during CsA-induced murine SGVHD there was an increase in both T(H)17 and T(H)1 mRNA and cytokines within the colons of diseased mice. The administration of an anti-mouse IL-17A mAb did not alter the course of disease. However, neutralization of IL-17A resulted in an increased production of IL-17F, a related family member, with an overlapping range of effector activities. These results demonstrate that in the pathophysiology of SGVHD, there is a redundancy in the T(H)17 effector molecules that mediate the development of SGVHD.
Assuntos
Doença Enxerto-Hospedeiro/imunologia , Células Th17/imunologia , Animais , Camundongos , Camundongos Endogâmicos C3H , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
In 2007, we surveyed the alien and endemic scolytine (bark and ambrosia beetles) fauna of northeastern Ohio, and for the most abundant species, we characterized their seasonal activity and response to three semiochemical baits. In total ,5,339 scolytine beetles represented by 47 species and 29 genera were caught in Lindgren funnel traps. Three species constituted 57% of the total catch, including Xylosandrus germanus (Blandford), Tomicus piniperda (L.), and Dryocoetes autographus (Ratzeburg). Of the total captured, 32% of the species and approximately 60% of the individuals were exotic, suggesting that exotic species numerically dominate the scolytine fauna in some urban areas. More native and exotic species were caught in traps baited with ethanol alone than in traps baited with other lures. However, significantly more individuals, especially of T. piniperda, D. autographus, Gnathotrichus materiarius (Fitch), and Ips grandicollis (Eichhoff), and species were caught in traps baited with ethanol plus alpha-pinene than in traps baited with ethanol alone or the exotic Ips lure. This suggests that among these baits, the ethanol plus alpha-pinene baits may be useful in maximizing scolytine beetle catches of these species within this region. Species diversity and richness for both native and exotic beetles was greatest in traps baited with ethanol alone. The period of peak trap capture varied depending upon species: X. germanus was most abundant in traps in mid-May and early-August; T. piniperda in mid-May; D. autographus in early June, mid-July, and mid-September; Anisandrus sayi Hopkins and G. materiarius in mid-May, mid-July, and early September; and I. grandicollis in early April, mid-July, and late September.
Assuntos
Besouros/fisiologia , Feromônios/fisiologia , Animais , Demografia , Ohio , Estações do Ano , Especificidade da Espécie , Fatores de TempoRESUMO
Structural insights have been provided by mercury-199 nuclear magnetic resonance (NMR) into the metal receptor site of the MerR metalloregulatory protein alone and in a complex with the regulatory target, DNA. The one- and two-dimensional NMR data are consistent with a trigonal planar Hg-thiolate coordination environment consisting only of Cys side chains and resolve structural aspects of both metal ion recognition and the allosteric mechanism. These studies establish 199Hg NMR techniques as useful probes of the metal coordination environment of regulatory proteins, copper enzymes, and zinc transcription factor complexes as large as 50 kilodaltons.
Assuntos
Proteínas de Bactérias/química , Proteínas de Ligação a DNA/química , DNA/metabolismo , Mercúrio/metabolismo , Sítio Alostérico , Proteínas de Bactérias/metabolismo , Sequência de Bases , Proteínas de Ligação a DNA/metabolismo , Espectroscopia de Ressonância Magnética , Isótopos de Mercúrio , Metaloproteínas/química , Dados de Sequência Molecular , Prótons , TermodinâmicaRESUMO
The de novo design of peptides and proteins has recently emerged as an approach for investigating protein structure and function. Designed, helical peptides provide model systems for dissecting and quantifying the multiple interactions that stabilize secondary structure formation. De novo design is also useful for exploring the features that specify the stoichiometry and stability of alpha-helical coiled coils and for defining the requirements for folding into structures that resemble native, functional proteins. The design process often occurs in a series of discrete steps. Such steps reflect the hierarchy of forces required for stabilizing tertiary structures, beginning with hydrophobic forces and adding more specific interactions as required to achieve a unique, functional protein.
Assuntos
Conformação Proteica , Engenharia de Proteínas , Sequência de Aminoácidos , Cristalografia por Raios X , Proteínas de Ligação a DNA/química , Ligação de Hidrogênio , Modelos Moleculares , Dados de Sequência Molecular , Dobramento de Proteína , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Termodinâmica , Dedos de ZincoRESUMO
Inhibitors in myelin play a major role in preventing spontaneous axonal regeneration after CNS injury. Elevation of cAMP overcomes this inhibition, in a transcription-dependent manner, through the upregulation of Arginase I (Arg I) and increased synthesis of polyamines. Here, we show that the cAMP effect requires activation of the transcription factor cAMP response element binding protein (CREB) to overcome myelin inhibitors; a dominant-negative CREB abolishes the effect, and neurons expressing a constitutively active form of CREB are not inhibited. Activation of CREB is also required for cAMP to upregulate Arg I, and the ability of constitutively active CREB to overcome inhibition is blocked by an inhibitor of polyamine synthesis. Finally, expression of constitutively active CREB in DRG neurons is sufficient to promote regeneration of subsequently lesioned dorsal column axons. These results indicate that CREB plays a central role in overcoming myelin inhibitors and so encourages regeneration in vivo.
Assuntos
Axônios/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Bainha de Mielina/metabolismo , Regeneração Nervosa/fisiologia , Animais , Arginase/metabolismo , Axônios/patologia , Western Blotting , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Cerebelo/metabolismo , AMP Cíclico/metabolismo , Gânglios Espinais/metabolismo , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Transgênicos , Glicoproteína Associada a Mielina/metabolismo , Ratos , Ratos Long-EvansRESUMO
Myelin-associated glycoprotein (MAG) is a potent inhibitor of axonal regeneration. It contains five Ig-like domains and is a sialic binding protein. Previously, we showed that the sialic acid binding site on MAG maps to arginine 118 in Ig domain 1 (Kelm et al., 1994). However, sialic acid binding was neither necessary nor sufficient for MAG to bring about inhibition of neurite outgrowth. Consistent with this, we now map a distinct inhibition site on MAG to Ig domain 5 (Ig-5). We show that when a truncated form of MAG missing Ig domains 1 and 2 is expressed by Chinese hamster ovary (CHO) cells, it does not bind sialic acid, but still inhibits neurite outgrowth almost as effectively as full-length MAG. To determine whether the inhibition site mapped to Ig-3, Ig-4, or Ig-5, we made chimeric molecules of various combinations of these three MAG Ig domains fused to Ig domains from another Ig family member, sialoadhesin (Sn), which also binds to sialic acid in the same linkage as MAG. The MAG-Sn molecules were expressed in CHO cells and all contained five Ig domains and were able to bind sialic acid. However, only the chimeric molecules containing MAG Ig-5 inhibited neurite outgrowth. Furthermore, peptides corresponding to sequences in MAG Ig-5, but not Ig-4 or Sn Ig-5, are able to block inhibition of neurite outgrowth by both wild-type MAG and CNS myelin. We conclude that the inhibition site on MAG is carried by Ig domain 5 and that this site is distinct from the sialic-acid binding site.