Elevated phosphorylated ubiquitin level elicits neuro-degeneration by aggregating the decline of ubiquitin-dependent proteasomal degradation / 中国药理学与毒理学杂志

OBJECTIVE To determine the roles of phosphorylated ubiquitin(pUb)on ubiquitin-dependent proteasomal(UPS)degradation activity,and the roles of pUb on neurodegeneration.METHODS We use PTEN induced kinase 1(PINK1)to phosphorylate ubiquitin.The Ub/S65A cannot be phosphorylated by PINK1,and was used to antagonize the roles of pUb.The Ub/S65E was used to mimic the roles of pUb.The roles of pUb on UPS degradation activity were determined by immunoflu-orescence,Western blot and TIRF microscope at cellular and protein level.The roles of pUb on neurodegeneration were determined by behavior tests,immunofluorescence,Golgi staining,TEM,Western blot and proteomics sacle in mouse.RESULTS The level of soluble PINK1(sPINK1)and pUb increased in the neurons of aged mouse brain,and in the cells upon the administration of MG132,a proteasome inhibitor.The elevation of sPINK1 and pUb was accompanied by protein aggregation upon aging or the proteasomal inhibition.The pink1 knockout alleviated proteasomal inhibition induced protein aggregation and association of ubiquitinated proteins with proteasome.The over-expression of sPINK1 increased pUb level in hippocampal neuron,which chronically induced protein aggregation,mitochondrial damage and damage the structure of neuronal spines.Such neuronal injury lead to cognitive impairment of mice.The roles of sPINK1 was reversed by co-expression with Ub/S65A,and was mimic by over-expression with Ub/S65E.CONCLUSION The phosphorylation of ubiquitin aggravates UPS degrada-tion,and accelerates neuronal degeneration upon the decline of proteasomal degradation in aging and age-related neuronal diseases.

Coarse-Grained Simulation of Amyloid Nucleation under Cooperative Effects of Peptides / 医用生物力学

Objective To explore the cooperative effect from β-propensity of amyloidogenic peptides on amyloid nucleation and its related products. Methods Based on a coarse-grained model for amyloidogenic peptides containing two states ( a soluble state and a β-sheet-forming state), with the consideration of two kinds of cooperative effects on β-propensity of peptides ( inhibiting and promoting the conformational conversion of peptides), the regulation of cooperative effects from amyloidogenic peptides on amyloid nucleation was analyzed through Monte Carlo simulations. Results In the case of the cooperative effect inhibiting the conformational conversion of peptides, amyloid nucleation occurred only within a certain interval of the peptide concentration, as well as inside the oligomers with certain sizes. Besides, the coexistence of on-pathway and off-pathway oligomers was observed. In the case of the cooperative effect promoting the conformational conversion of peptides, the β-sheet protofibril could be observed at physiological concentration as low as 4 μmol / L. Conclusions In this study, a more realistic coarse-grained model for amyloidogenic peptides was developed by introducing the cooperative effects of local concentration on β-propensity of amyloidogenic peptides, with observation of some intriguing phenomena not reported in previous simulations. The research findings not only improve current understandings about the mechanism of amyloid formation, but also provide theoretic references for the therapeutic strategies for curing neurodegenerative diseases

Three ways for protein aggregation and the control strategies / 生物工程学报

Protein aggregation is a critical issue in the production of biopharmaceuticals. During protein production, transport and storage, various factors can lead to protein aggregation. With the in-depth study, different ways of protein aggregation and various influencing factors were identified. This includes physical and chemical factors, translation modifications and protein structure. Since protein aggregation exerts major impact on the activity and homogeneity of proteins, it is of great importance to study the ways of protein aggregation and how to control it to obtain high-quality proteins. The review focuses on three ways of protein aggregation, namely 3D domain swapping, salt bridge formation, and oxidative stress, as well as methods to control protein aggregation during protein production, transport and storage. This may facilitate reducing the loss caused by the formation of protein aggregation and improving the purity and homogeneity of protein in research and commercial production.

In vitro stability of various enzymes by proline from H2O2 mediated oxidative damage

Plants under stress need to favour certain pathways so as to survive the stress period. Protection of specific enzymes by proline and other osmolytes could be one such mechanism to favour some pathways/processes. Therefore, the influence of osmolyte proline on conformational changes of various proteins caused by hydrogen peroxide (H2O2) was studied by intrinsic and extrinsic fluorescence emissions. H2O2 caused conformational change in proteins. Results indicated that for Alcohol dehydrogenase (AD) and Glutamate dehydrogenase (GD) enzymes, H2O2 induced conformational change was high and that for Glucose 6-phosphate dehydrogenase (G6PDH) and Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was low. Fluorescence and far-UV, CD measurements of catalase demonstrated that the H2O2 stabilized the protein secondary structure at low concentrations but destabilized it at higher concentrations. Intrinsic and ANS fluorescence results showed that proline at a concentration of 1.0 M prompted a reduction in the H2O2-induced exposed hydrophobic surfaces of studied enzymes, to different degrees which suggests its differential protective effect. Furthermore, SDS-PAGE studies revealed that proline was not able to reduce or inhibit the H2O2 mediated aggregation of GAPDH.

Botanical Therapeutics for Parkinson's Disease / 中国结合医学杂志

Parkinson's disease (PD) was first formally described by James Parkinson in 1817, but the shaking of limbs was described in the literature of several ancient civilizations, such as ancient Chinese civilization and ancient Indian civilization. Historically, botanical drugs were used as the main source for the treatment of such kind of disorders. In Western countries, plant extracts also occupied an important place in the earlier medications of PD. With the adventure of synthetic drugs, the role of plant-derived drugs in management of PD has been diminished. Nowadays, there is still no cure for PD, dopaminergic (DA) medication is the treatment of choice, which is just designed to ameliorate symptoms of PD, and long-term use of DA medication will result in reduced efficacy and severe adverse reactions. It is necessary to explore new methods for the treatment of PD. Chinese medicine (CM) developed a holistic and unique theoretical system, and botanical drugs are widely used in practice for more than two millennia. Modern pharmacological studies have proved that Chinese herbs have potential therapeutic effects on PD, such as enhancing neurotrophic activity, clearing protein aggregates, regulating neuroinflammation, etc. All the advances provide us with hope for developing CM as a mainstream medication for treating PD.

Effect of ginsenoside Rgl on cortical ubiquitin-modified protein aggregation after cerebral ischemia-reperfusion in rats / 吉林大学学报(医学版)

Objective: To explore the effect of ginsenoside Rgl on the ubiquitin-modified protein aggregation in the cortex after cerebral ischemia reperfusion (I / R) injury in the rats, and to further clarify the therapeutic mechanism of ginsenoside Rgl in the cerebral I/R injury. Methods: The middle cerebral artery occlusion (MCAO) model was set up with suture method for 1. 5 h of embolization. A total of 72 rats were divided into sham operation group, I/R model group, positive drug control (nimodipine) group, low, middle, and high doses 10, 20, and 40 mg ' k g - 1) of ginsenoside Rgl groups. All 12 rats in each group were given intraperitoneal injection. TTC staining and Longa' s score method were used to detect the infarction areas and the neurological deficit scores of the rats in various groups 24 h after modeling. The death of neurons in the cortex and hippocampus after cerebral ischemia of the rats in various groups were observed with HE staining. Immunohistochemistry and Western blotting method were used to detect the expression of ubiquitin-modified protein aggregation in the cortex of the rats in various groups. Results: Compared with I/R group, the percentages of infarction areas of the rats in nimodipine group and ginsenoside Rgl groups were significantly decreased (P < 0 . 05). and the neurological deficit scores were decreased (P < 0 . 05). The HE staining results showed that compared with sham operation group, the neurons in I/R model group were sparse, showing fragmentation and dissolution; compared with I/R model group, the phenomena of cell nucleus fragmentation, dissolution and powder staining in nimodipine group and different doses of ginsenoside Rgl groups were all improved to different degrees. The immunohistochemical results showed that compared with sham operation group, the positive expression level of ubiquitin-modified protein in I/R model group was increased significantly (P < 0 . 05); compared with I/R model group, the positive expression levels of ubiquitin-modified protein in nimodipine group and different doses of ginsenoside Rgl groups were decreased (P < 0 . 05), especially in high dose of ginsenoside Rgl group (P < 0 . 05). The Western blotting results showed that compared with sham operation group, the level of ubiquitin-modified protein aggregates in I/R model group was significantly increased (P < 0 . 0 5); compared with I/R model group, the levels of ubiquitin-modified protein aggregates in nimodipine group and different doses of ginsenoside Rgl were decreased (P < 0 . 05), especially in high dose of ginsenoside Rgl group. Conclusion: Ginsenoside Rgl can inhibit the formation of ubiquitin-modified protein aggregates induced by I/R injury in the cortex, thereby alleviating the I/R injury in the rats.

Modeling α-Synuclein Propagation with Preformed Fibril Injections

The aggregation of α-synuclein (α-syn) has been implicated in the pathogenesis of many neurodegenerative disorders, including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Postmortem analyses of α-syn pathology, especially that of PD, have suggested that aggregates progressively spread from a few discrete locations to wider brain regions. The neuron-to-neuron propagation of α-syn has been suggested to be the underlying mechanism by which aggregates spread throughout the brain. Many cellular and animal models has been created to study cell-to-cell propagation. Recently, it has been shown that a single injection of preformed fibrils (PFFs) made of recombinant α-syn proteins into various tissues and organs of many different animal species results in widespread α-syn pathology in the central nervous system (CNS). These PFF models have been extensively used to study the mechanism by which aggregates spread throughout the brain. Here, we review what we have learned from PFF models, describe the nature of PFFs and the neuropathological features, neurophysiological characteristics, and behavioral outcomes of the models.

Solution pH jump during antibody and Fc-fusion protein thaw leads to increased aggregation / 药物分析学报

Freeze-thaw cycles impact the amount of aggregation observed in antibodies and Fc-fusion proteins. Various formulation strategies are used to mitigate the amount of aggregation that occurs upon putting a protein solution through a freeze-thaw cycle. Additionally, low pH solutions cause native antibodies to unfold, which are prone to aggregate upon pH neutralization. There is great interest in the mechanism that causes therapeutic proteins to aggregate since aggregate species can cause unwanted im-munogenicity in patients. Herein, an increase in aggregation is reported when the pH is adjusted from pH 3 up to a pH ranging from pH 4 to pH 7 during the thaw process of a frozen antibody solution. Raising the pH during the thaw process caused a significant increase in the percent aggregation observed. Two antibodies and one Fc-fusion protein were evaluated during the pH jump thaw process and similar ef-fects were observed. The results provide a new tool to study the kinetics of therapeutic protein ag-gregation upon pH increase.

Cell-to-cell Transmission of Polyglutamine Aggregates in C. elegans

Huntington disease (HD) is an inherited neurodegenerative disorder characterized by motor and cognitive dysfunction caused by expansion of polyglutamine (polyQ) repeat in exon 1 of huntingtin (HTT). In patients, the number of glutamine residues in polyQ tracts are over 35, and it is correlated with age of onset, severity, and disease progression. Expansion of polyQ increases the propensity for HTT protein aggregation, process known to be implicated in neurodegeneration. These pathological aggregates can be transmitted from neuron to another neuron, and this process may explain the pathological spreading of polyQ aggregates. Here, we developed an in vivo model for studying transmission of polyQ aggregates in a highly quantitative manner in real time. HTT exon 1 with expanded polyQ was fused with either N-terminal or C-terminal fragments of Venus fluorescence protein and expressed in pharyngeal muscles and associated neurons, respectively, of C. elegans. Transmission of polyQ proteins was detected using bimolecular fluorescence complementation (BiFC). Mutant polyQ (Q97) was transmitted much more efficiently than wild type polyQ (Q25) and forms numerous inclusion bodies as well. The transmission of Q97 was gradually increased with aging of animal. The animals with polyQ transmission exhibited degenerative phenotypes, such as nerve degeneration, impaired pharyngeal pumping behavior, and reduced life span. The C. elegans model presented here would be a useful in vivo model system for the study of polyQ aggregate propagation and might be applied to the screening of genetic and chemical modifiers of the propagation.

Cataract-causing mutation S228P promotes βB1-crystallin aggregation and degradation by separating two interacting loops in C-terminal domain

β/γ-Crystallins are predominant structural proteins in the cytoplasm of lens fiber cells and share a similar fold composing of four Greek-key motifs divided into two domains. Numerous cataract-causing mutations have been identified in various β/γ-crystallins, but the mechanisms underlying cataract caused by most mutations remains uncharacterized. The S228P mutation in βB1-crystallin has been linked to autosomal dominant congenital nuclear cataract. Here we found that the S228P mutant was prone to aggregate and degrade in both of the human and E. coli cells. The intracellular S228P aggregates could be redissolved by lanosterol. The S228P mutation modified the refolding pathway of βB1-crystallin by affecting the formation of the dimeric intermediate but not the monomeric intermediate. Compared with native βB1-crystallin, the refolded S228P protein had less packed structures, unquenched Trp fluorophores and increased hydrophobic exposure. The refolded S228P protein was prone to aggregate at the physiological temperature and decreased the protective effect of βB1-crystallin on βA3-crystallin. Molecular dynamic simulation studies indicated that the mutation decreased the subunit binding energy and modified the distribution of surface electrostatic potentials. More importantly, the mutation separated two interacting loops in the C-terminal domain, which shielded the hydrophobic core from solvent in native βB1-crystallin. These two interacting loops are highly conserved in both of the N- and C-terminal domains of all β/γ-crystallins. We propose that these two interacting loops play an important role in the folding and structural stability of β/γ-crystallin domains by protecting the hydrophobic core from solvent access.

Therapeutic Approaches for Inhibition of Protein Aggregation in Huntington's Disease

Huntington's disease (HD) is a late-onset and progressive neurodegenerative disorder that is caused by aggregation of mutant huntingtin protein which contains expanded-polyglutamine. The molecular chaperones modulate the aggregation in early stage and known for the most potent protector of neurodegeneration in animal models of HD. Over the past decades, a number of studies have demonstrated molecular chaperones alleviate the pathogenic symptoms by polyQ-mediated toxicity. Moreover, chaperone-inducible drugs and anti-aggregation drugs have beneficial effects on symptoms of disease. Here, we focus on the function of molecular chaperone in animal models of HD, and review the recent therapeutic approaches to modulate expression and turn-over of molecular chaperone and to develop anti-aggregation drugs.

Autophagic failure promotes the exocytosis and intercellular transfer of alpha-synuclein

The accumulation of abnormal protein aggregates is a major characteristic of many neurodegenerative disorders, including Parkinson's disease (PD). The intracytoplasmic deposition of alpha-synuclein aggregates and Lewy bodies, often found in PD and other alpha-synucleinopathies, is thought to be linked to inefficient cellular clearance mechanisms, such as the proteasome and autophagy/lysosome pathways. The accumulation of alpha-synuclein aggregates in neuronal cytoplasm causes numerous autonomous changes in neurons. However, it can also affect the neighboring cells through transcellular transmission of the aggregates. Indeed, a progressive spreading of Lewy pathology among brain regions has been hypothesized from autopsy studies. We tested whether inhibition of the autophagy/lysosome pathway in alpha-synuclein-expressing cells would increase the secretion of alpha-synuclein, subsequently affecting the alpha-synuclein deposition in and viability of neighboring cells. Our results demonstrated that autophagic inhibition, via both pharmacological and genetic methods, led to increased exocytosis of alpha-synuclein. In a mixed culture of alpha-synuclein-expressing donor cells with recipient cells, autophagic inhibition resulted in elevated transcellular alpha-synuclein transmission. This increase in protein transmission coincided with elevated apoptotic cell death in the recipient cells. These results suggest that the inefficient clearance of alpha-synuclein aggregates, which can be caused by reduced autophagic activity, leads to elevated alpha-synuclein exocytosis, thereby promoting alpha-synuclein deposition and cell death in neighboring neurons. This finding provides a potential link between autophagic dysfunction and the progressive spread of Lewy pathology.

Elevated ferric, calcium and magnesium ions in the brain induce protein aggregation in brain mitochondria / El aumento de iones férricos, calcio y magnesio en el cerebro induce la agregación de proteínas en las mitocondrias del cerebro

OBJECTIVE: Alzheimer s disease and Parkinson s disease are two of several neurodegenerative disorders that affect the elderly. Although their aetiology remains uncertain, studies suggest that elevated aluminium or other metal ions in the brain directly influence the development of the histological abnormalities normally associated with these diseases; other investigations suggest that metal-ion-induced-dysfunction of mitochondria might be a critical factor. METHODS: In this study, the impact of elevated aluminum (Al3+), ferric (Fe3+), calcium (Ca2+) and magnesium (Mg2+) ions on brain histology and on the protein composition of brain mitochondria were evaluated. Rabbits were injected intra-cerebrally with 1.4% solutions of either aluminium chloride (AlCl3), ferric chloride (FeCl2), calcium chloride (CaCl2) or magnesium chloride (MgCl2) and sacrificed 10 days later. RESULTS: Histological analysis revealed that Al3+ but not the other ions induced neurofibrillary degeneration within the midbrain and medulla. Alternatively, SDS-PAGE revealed that Fe3+, Ca2+ and Mg2+ but not Al3+ induced alterations to the distribution of brain mitochondrial proteins. Both Fe3+ and Ca2+ triggered decreased concentration of three low molecular weight proteins (~7-14 kd) but Ca precipitated their total absence. Both ions led to increased concentration of a high molecular weight protein (~ 110 kd). In contrast, Mg2+ led to the total absence of the protein of lowest molecular weight (~7 kd) and increased concentration of a ~36 kd protein. CONCLUSION: These results suggest that elevation of some metal ions in the brain induces protein aggregation with the nature of the aggregation being highly ion dependent. The results also point toward major differences between the histopathological effect of Al3+ and other ions.

OBJETIVO: La enfermedad de Alzheimer y la enfermedad de Parkinson son dos de los varios trastornos neurodegenerativos que afectan al anciano. Aunque su etiologia sigue siendo incierta, los estudios sugieren que el aumento de los iones de aluminio, influyen directamente sobre el desarrollo de las anormalidades histológicas asociadas normalmente con estas enfermedades. Otras investigaciones sugieren que la disfunción de las mitocondrias, inducida por iones metálicos, pudiera ser un factor critico. MÉTODOS: Este estudio evalúa el impacto del aumento de los iones de aluminio (Al3+), los iones férricos (Fe3+), y los iones de calcio (Ca2+) y magnesio (Mg2+) sobre la histologia del cerebro y la composición proteica de las mitocondrias del cerebro. Un número de conejos recibieron inyecciones intracerebrales de soluciones al 1.4% de soluciones de cloruro de aluminio (AlCl3), cloruro ferroso (FeCl3), cloruro de calcio (CaCl2), o cloruro de magnesio (MgCl2), y fueron sacrificados después de 10 días. RESULTADOS: El análisis histológico reveló que el Al3+ indujo una degeneración neurofibrilar dentro del mesencéfalo y la médula, Sin embargo, esto no ocurrió con los otros iones. Alternativamente, la técnica de electroforesis SDS-PAGE reveló que los iones Fe3+, Ca2+ y Mg2+, a diferencia del ión Al3+, inducían alteraciones de la distribución de las proteínas mitocondriales cerebrales. Tanto el Fe3+ como el Ca2+ desencadenaron una disminución de la concentración de tres proteínas de bajo peso molecular (~7-14 kd) pero Ca2+ precipitó su ausencia total. Ambos iones condujeron a un aumento de una proteína de peso molecular alto (~ 110 kd). En cambio, Mg2+ llevó a la ausencia total de la proteína de más bajo peso molecular (~7 kd) y al aumento de la concentración de una proteína de ~36 kd. CONCLUSIÓN: Estos resultados parecen sugerir que la elevación de algunos iones de metal en el cerebro induce la agregación de la proteína, siendo la naturaleza de la agregación altamente dependiente de los iones. Los resultados también apuntan a grandes diferencias entre el efecto histopatológico del Al3+ y otros iones.

Transmission of Synucleinopathies in the Enteric Nervous System of A53T Alpha-Synuclein Transgenic Mice

Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are characterized by abnormal deposition of alpha-synuclein aggregates in many regions of the central and peripheral nervous systems. Accumulating evidence suggests that the alpha-synuclein pathology initiates in a few discrete regions and spreads to larger areas in the nervous system. Recent pathological studies of PD patients have raised the possibility that the enteric nervous system is one of the initial sites of alpha-synuclein aggregation and propagation. Here, we evaluated the induction and propagation of alpha-synuclein aggregates in the enteric nervous system of the A53T alpha-synuclein transgenic mice after injection of human brain tissue extracts into the gastric walls of the mice. Western analysis of the brain extracts showed that the DLB extract contained detergent-stable alpha-synuclein aggregates, but the normal brain extract did not. Injection of the DLB extract resulted in an increased deposition of alpha-synuclein in the myenteric neurons, in which alpha-synuclein formed punctate aggregates over time up to 4 months. In these mice, inflammatory responses were increased transiently at early time points. None of these changes were observed in the A53T mice injected with saline or the normal brain extract, nor were these found in the wild type mice injected with the DLB extract. These results demonstrate that pathological alpha-synuclein aggregates present in the brain of DLB patient can induce the aggregation of endogenous alpha-synuclein in the myenteric neurons in A53T mice, suggesting the transmission of synucleinopathy lesions in the enteric nervous system.

Analysis of the Globular Nature of Proteins

Numerous restraints and simplifications have been developed for methods that anticipate protein structure to reduce the colossal magnitude of possible conformational states. In this study, we investigated if globularity is a general characteristic of proteins and whether they can be applied as a valid constraint in protein structure simulations with approximated measurements (Gb-index). Unexpectedly, most of the proteins showed strong structural globularity (i.e., mode of approximately 76% similarity to the perfect globe) with only a few percent of proteins being outliers. Small proteins tended to be significantly non-globular (R2=0.79) and the minimum Gb-index showed a logarithmic increase with the increase in protein size (R2=0.62), strongly implying that the non-globular characteristics might be more acceptable for smaller proteins than larger ones. The strong perfect globe-like character and the relationship between small size and the loss of globular structure of a protein may imply that living organisms have mechanisms to aid folding into the globular structure to reduce irreversible aggregation. This also implies the possible mechanisms of diseases caused by protein aggregation, including some forms of trinucleotide repeat expansion-mediated diseases.

Dopamine promotes formation and secretion of non-fibrillar alpha-synuclein oligomers

Parkinson's disease (PD) is characterized by selective and progressive degeneration of dopamine (DA)-producing neurons in the substantia nigra pars compacta (SNpc) and by abnormal aggregation of alpha-synuclein. Previous studies have suggested that DA can interact with alpha-synuclein, thus modulating the aggregation process of this protein; this interaction may account for the selective vulnerability of DA neurons in patients with PD. However, the relationship between DA and alpha-synuclein, and the role in progressive degeneration of DA neurons remains elusive. We have shown that in the presence of DA, recombinant human alpha-synuclein produces non-fibrillar, SDS-resistant oligomers, while beta-sheet-rich fibril formation is inhibited. Pharmacologic elevation of the cytoplasmic DA level increased the formation of SDS-resistant oligomers in DA-producing neuronal cells. DA promoted alpha-synuclein oligomerization in intracellular vesicles, but not in the cytosol. Furthermore, elevation of DA levels increased secretion of alpha-synuclein oligomers to the extracellular space, but the secretion of monomers was not changed. DA-induced secretion of alpha-synuclein oligomers may contribute to the progressive loss of the dopaminergic neuronal population and the pronounced neuroinflammation observed in the SNpc in patients with PD.

Topographical Propagation of alpha-synuclein Pathology in Parkinson's Disease: Phenomenology and Hypothetical Mechanism

Parkinson's disease is an age-related, slowly progressing neurodegenerative disorder characterized by abnormal deposition of aggregated alpha-synuclein in neuronal cell bodies (Lewy bodies) and neurites (Lewy neurites), as well as in glia. Based on semiquantitative assessment of Lewy pathologies in autopsy samples, a staging system was proposed indicating a highly predictable sequence of pathological progression. This staging system implicates a propagation of alpha-synuclein aggregation throughout the brain with an ascending pattern from lower brain stem to neocortex. The underlying mechanism for the pathological propagation is unknown. However, the recent discoveries on the secretion of neuronal alpha-synuclein and subsequent uptake of the protein by neighboring cells propose an interneuronal transmission of alpha-synuclein aggregates as a novel mechanism for the spread of Lewy pathology in PD. Elucidation of this mechanism is likely to identify novel therapeutic strategies that halt the progression of PD.

Alterations of chaperone hsp40 anti its influence on the CAI neurons death after transient cerebral ischemia / 中华急诊医学杂志

Objective To investigate the alteration of chaperone hsp40 and its effects on the dealyed neuron death in the CAI neurons after transient cerebral ischemia.Method Twenty-minute transient global ischemia rat model was used.Following different repeffusion period,all the 28 wistar rats were divided into sham-operation group ,4-hour recovery group,24-honr recovery group and 72-hour recovery gronp,7 ratsin in each group,Immunochemistry and laser scanning confocal microscopy were used to observe the distributional alteration of hsp40 in the neurons.Differential centrifuge and westemblot analysis were used to analyze the quantitative alteration of hsp40 and its redistribution in the neurons.Results lnanunechemistry and laser scanning confocal microscopy showedthe reduction of hsp40 first in cytosol,then in the nucleus until all the neurons in the CAI region died.Differential centrifuge and westemblot analysis showed the quantity of hsp40 decreased from (1.00_+0.21) to (0.23±0.13)(P<0.01) after 24-hour repeffusion;the quantity of hsp40 in the protein aggregates increased from (1.00±0.18) to(8.61±1.89)(P<0.01) after24-hour reperfusion.Conclusions The reduction of hsp40 in the neurons of hippocampus CA1 region is an important factor resulting in protein aggregates formation.

Selective Cytotoxic Mechanism of Homocysteine to Motor Neuronal Cells Expressing the Mutant Cu,Zn-superoxide Dismutase

BACKGROUND: Mutations in Cu, Zn-superoxide dismutase (SOD1) cause about 20% of familial amyotrophic lateral sclerosis (FALS) cases. The mechanism of late-onset disease manifestation despite the innate mutation has no clear explanation. The relationship between homocysteine (HC) and amyotrophic lateral sclerosis (ALS) has not been investigated fully, in spite of the similarity in their pathogenesis. METHODS: We investigated the effect of HC on the motor neuronal cell-line (VSC4.1) transfected with SOD1 of either wild-type or mutant forms (G93A and A4V) using various methods including the MTT assay for the cytotoxic assay, the immunocytochemical staining using anti-SOD1 for the aggregation of SOD1, the western blotting using anti-nitrotyrosine and anti-DNPH for the oxidative protein damage, and the measurement of the intracellular Ca2+ concentration using Fura2-AM. RESULTS: In the MTT assay, the HC induced significant cytotoxicity in the mutants, as compared with wild-type. This HC-induced cytotoxicity was inhibited by the trolox and the bathocuproinedisulfonate (BC). HC increased the carbonylation and nitrosylation of the mutant proteins. HC also increased significant SOD1-aggregation in mutants. This HC-induced SOD1-aggregation in mutants was inhibited by trolox, N-nitro-L-arginine methyl ester, BC, and z-VAD-FMK. HC did not change the intracellular concentration of Ca2+ in the mutants compared with the wild-type. CONCLUSIONS: The authors showed that the vulnerability of the SOD1 mutant motor neuronal cells to HC involves the copper-mediated oxygen radical toxicity, and that HC may be a lifelong precipitating factor in some forms of FALS, suggesting a possible treatment modality with vitamin supplements.