Chaperoning glucocerebrosidase:a therapeutic strategy for both Gaucher disease and Parkinsonism

Gaucher disease （GD） is a lysosomal storage disorder （LSD） affecting approximately 1 in 50,000 individuals in the general population. Mutations in both alleles of the GBA1 gene result in deficient glucocerebrosidase （GCase） activity, which in turn leads to the accumulation of glycolipid substrates and impaired lysosomal function. GD is a multisystern disorder with a vast spectrum of clinical phenotvpes,

Therapeutic targeting of cellular prion protein: toward the development of dual mechanism anti-prion compounds

PrPSc,a misfolded,aggregation-prone isoform of the cellular prion protein(PrPC),is the infectious prion agent responsible for fatal neurodegenerative diseases of humans and other mammals.PrPSccan adopt different pathogenic conformations(prion strains),which can be resistant to potential drugs,or acquire drug resistance,posing challenges for the development of effective therapies.Since PrPCis the obligate precursor of any prion strain and serves as the mediator of prion neurotoxicity,it represents an attractive therapeutic target fo r prion diseases.In this minireview,we briefly outline the approaches to target PrPCand discuss our recent identification of Zn(Ⅱ)-Bn PyP,a PrPC-targeting porphyrin with an unprecedented bimodal mechanism of action.We argue that in-depth understanding of the molecular mechanism by which Zn(Ⅱ)-Bn PyP targets PrPCmay lead toward the development of a new class of dual mechanism anti-prion compounds.

The Sigma-1 Receptor as a Pharmacologic Chaperone: Energetics

Initially thought to be an opioid receptor subtype, Sigma-1 receptors (S1R) are now known to be unique proteins that have chaperone-like properties. As such, they play critical roles in cellular signaling, homeostasis, and cell survival. These roles offer significant insight for understanding homeostasis of normal physiologic processes, and the pathophysiologic consequences of disruption of normal function. Because of the broad nature of chaperone action, S1R agonists and antagonists represent potential drug discovery goals for the pharmacotherapeutic treatment of a variety of disorders that result from dysfunctional proteins. The present study summarizes the S1R as a pharmacologic chaperone crucial for protein folding and cellular homeostasis. Through literature review and thermodynamic analysis, it explores how S1R stabilizes target proteins, influencing neuroprotection and potential drug therapies. The binding of chaperones to target proteins is thermodynamically favorable, offering insights into treating diseases linked to protein misfolding.

The nonstructural protein 2C of Coxsackie B virus has RNA helicase and chaperoning activities

RNA-remodeling proteins,including RNA helicases and chaperones,play vital roles in the remodeling of structured RNAs.During viral replication,viruses require RNA-remodeling proteins to facilitate proper folding and/or re-folding the viral RNA elements.Coxsackieviruses B3(CVB3)and Coxsackieviruses B5(CVB5),belonging to the genus Enterovirus in the family Picornaviridae,have been reported to cause various infectious diseases such as hand-foot-and-mouth disease,aseptic meningitis,and viral myocarditis.However,little is known about whether CVB3 and CVB5 encode any RNA remodeling proteins.In this study,we showed that 2C proteins of CVB3 and CVB5 contained the conserved SF3 helicase A,B,and C motifs,and functioned not only as RNA helicase that unwound RNA helix bidirectionally in an NTP-dependent manner,but also as RNA chaperone that remodeled structured RNAs and facilitated RNA strand annealing independently of NTP.In addition,we determined that the NTPase activity and RNA helicase activity of 2C proteins of CVB3 and CVB5 were dependent on the presence of divalent metallic ions.Our findings demonstrate that 2C proteins of CVBs possess RNA-remodeling activity and underline the functional importance of 2C protein in the life cycle of CVBs.

Molecular chaperones in stroke-induced immunosuppression

Stroke-induced immunosuppression is a process that leads to peripheral suppression of the immune system after a stroke and belongs to the central nervous system injury-induced immunosuppressive syndrome.Stroke-induced immunosuppression leads to increased susceptibility to post-stroke infections,such as urinary tract infections and stroke-associated pneumonia,worsening prognosis.Molecular chaperones are a large class of proteins that are able to maintain proteostasis by directing the folding of nascent polypeptide chains,refolding misfolded proteins,and targeting misfolded proteins for degradation.Various molecular chaperones have been shown to play roles in stroke-induced immunosuppression by modulating the activity of other molecular chaperones,cochaperones,and their associated pathways.This review summarizes the role of molecular chaperones in stroke-induced immunosuppression and discusses new approaches to restore host immune defense after stroke.

Mortalin/Hspa9 involvement and therapeutic perspective in Parkinson's disease

By controlling the proper folding of proteins imported into mitochondria and ensuring crosstalk between the reticulum and mitochondria to modulate intra cellular calcium fluxes.Mortalin is a chaperone protein that plays crucial roles in neuronal homeostasis and activity.Howeve r,its expression and stability are strongly modified in response to cellular stresses,in particular upon alte red oxidative conditions during neurodegeneration.Here,we report and discuss the abundant literature that has highlighted its contribution to the pathophysiology of Parkinson's disease,as well as its therapeutic and prognostic potential in this still incurable pathology.

Roles of constitutively secreted extracellular chaperones in neuronal cell repair and regeneration

Protein quality control involves many processes that jointly act to regulate the expression, localization, turnover, and degradation of proteins, and has been highlighted in recent studies as critical to the differentiation of stem cells during regeneration. The roles of constitutively secreted extracellular chaperones in neuronal injury and disease are poorly understood. Extracellular chaperones are multifunctional proteins expressed by many cell types, including those of the nervous system, known to facilitate protein quality control processes. These molecules exert pleiotropic effects and have been implicated as playing important protective roles in a variety of stress conditions, including tissue damage, infections, and local tissue inflammation. This article aims to provide a critical review of what is currently known about the functions of extracellular chaperones in neuronal repair and regeneration and highlight future directions for this important research area. We review what is known of four constitutively secreted extracellular chaperones directly implicated in processes of neuronal damage and repair, including transthyretin, clusterin, α2-macroglobulin, and neuroserpin, and propose that investigation into the effects of these and other extracellular chaperones on neuronal repair and regeneration has the potential to yield valuable new therapies.

Effect of chaperone–client interaction strength on Hsp70-mediated protein folding

Protein folding in crowding cellular environment often relies on the assistance of various chaperones. Hsp70 is one of the most ubiquitous chaperones in cells. Previous studies showed that the chaperone–client interactions at the open state tend to remodel the protein folding energy landscape and direct the protein folding as a foldase. In this work, we further investigate how the chaperone–client interaction strength modulates the foldase function of Hsp70 by using molecular simulations. The results showed that the time of substrate folding(including the whole folding step and substrate release step) has a non-monotonic dependence on the interaction strength. With the increasing of the chaperone–client interaction strength, the folding time decreases first, and then increases. More detailed analysis showed that when the chaperone–client interaction is too strong, even small number of chaperones–client contacts can maintain the substrate bound with the chaperone. The sampling of the transient chaperones–client complex with sparse inter-molecule contacts makes the client protein have chance to access the misfolded state even it is bound with chaperone. The current results suggest that the interaction strength is an important factor controlling the Hsp70 chaperoning function.

Chaperon导引导管系统在颅内动脉瘤栓塞术中的应用

目的探讨Chaperon导引导管系统在颅内动脉瘤栓塞术中的应用。方法对20例患者行颅内动脉瘤栓塞术治疗。其中主动脉弓呈Ⅱ型及Ⅲ型弓11例,颈内动脉或椎动脉开口血管壁有粥样硬化斑块9例,采用Cordis导引导管系统难以到达所需血管。术中采用Chaperon导引导管系统,观察能否顺利到达所需血管位置。结果在颅内动脉瘤栓塞术中使用Chaperon导引导管系统,基本克服了患者主动脉弓等重要血管迂曲及血管壁存在粥样硬化斑块等不利因素,顺利到达所需血管位置。结论对于存在主动脉弓等重要血管迂曲及血管壁存在粥样硬化斑块的动脉瘤患者,Chaperon导引导管系统可在动脉瘤栓塞术中顺利到达所需血管位置。

Ischemic preconditioning induces chaperone hsp70 expression and inhibits protein aggregation in the CA1 neurons of rats

Objective To investigate the effect of ischemic preconditioning on chaperone hsp70 expression and protein aggregation in the CA1 neurons of rats, and to further explore its potential neuroprotective mechanism. Methods Two-vesseloccluded transient global ischemia rat model was used. The rats were divided into sublethal 3-min ischemia group, lethal 10- min ischemia group and ischemic preconditioning group. Neuronal death in the CA1 region was observed by hematoxylineosin staining, and number of live neurons was assessed by cell counting under a light microscope. Immunochemistry and laser scanning confocal microscopy were used to observe the distribution of chaperone hsp70 in the CA1 neurons. Differential centrifuge was used to isolate cytosol, nucleus and protein aggregates fractions. Western blot was used to analyze the quantitative alterations of protein aggregates and inducible chaperone hsp70 in cellular fractions and in protein aggregates under different ischemic conditions. Results Histological examination showed that ischemic preconditioning significantly reduced delayed neuronal death in the hippocampus CA1 region （P 〈 0.01 vs 10-min ischemia group）. Sublethal ischemic preconditioning induced chaperone hsp70 expression in the CA1 neurons after 24 h reperfusion following 10-min ischemia. Induced-hsp70 combined with the abnormal proteins produced during the secondary lethal 10-min ischemia and inhibited the formation of cytotoxic protein aggregates（P〈0.01 vs 10-min ischemia group）.Conelusion Ischemic preconditioning induced chaperone hsp70 expression and inhibited protein aggregates formation in the CA1 neurons when suffered secondary lethal ischemia, which may protect neurons from death.

选择性自噬的研究

自噬（autophagy）是广泛存在于真核细胞内的一种溶酶体降解途径。这个古老而保守的降解途径主要有三种形式：巨自噬（giant autophagy）、微自噬（microautophagy）和分子伴侣介导的自噬（chaperon－mediated autophagy，CMA）。自噬一直被认为是一个饥饿诱导的非选择性本体降解途径，通过细胞质成分的“自我消化”，细胞在有限的能源中回收所有的营养成分。泛素化底物通过泛素受体传递，后者包括 p62／SQSTM1（sequestosome1）、BRCA1基因1邻位（neighbor of BRCA1 gene 1，NRB1）、核点蛋白质52（nuclear protein 52，NDP52）、组蛋白去乙酰酶6（histone deacetylase 6，HDAC6）及自噬相关 FYVE 蛋白（autophagy－linked FYVE protein，ALFY），泛素依赖的传感器系统负责底物特异性。自噬清除之前，这些受体将泛素化底物连接到初期自噬体，后者携带有泛素样（ubiquitin－like，UbL）蛋白，如其表面的微管相关蛋白1轻链3（microtubule associated protein 1 light chain 3，LC3）或 GABAA 受体相关蛋白（GABAA receptor associated protein，GABARAP）。因此，自噬受体结合到泛素和 LC3或 GABARAP 蛋白能够通过选择性自噬调控蛋白质降解。依据其底物名称来区别各种类型的选择性途径，如线粒体自噬（mitophagy）、过氧化物酶体自噬（pexophagy）、内质网自噬（ reticulophagy）、核糖体自噬（ ribophagy）和异源自噬（xenophagy）。

AtFKBP53 is a histone chaperone required for repression of ribosomal RNA gene expression in Arabidopsis

Chromatin structure is important for controlling gene expression, but mechanisms underlying chromatin remodel- ing are not fully understood. Here we report that an FKBP （FK506 binding protein） type immunophilin, AtFKBP53, possesses histone chaperone activity and is required for repressing ribosomal gene expression in Arabidopsis. The At- FKBP53 protein is a multidomain FKBP with a typical peptidylprolyl isomerase （PPIase） domain and several highly charged domains. Using nucleosome assembly assays, we showed that AtFKBP53 has histone chaperone activity and the charged acidic domains are sufficient for the activity. We show that AtFKBP53 interacts with histone H3 through the acidic domains, whereas the PPIase domain is dispensable for histone chaperone activity or histone binding. Ri- bosomal RNA gene （18S rDNA） is overexpressed when AtFKBP53 activity is reduced or eliminated in Arabidopsis plants. Chromatin immunoprecipitation assay showed that AtFKBP53 is associated with the 18S rDNA gene chro- matin, implicating that AtFKBP53 represses rRNA genes at the chromatin level. This study identifies a new histone chaperone in plants that functions in chromatin remodeling and regulation of transcription.

Application of heat shock protein expression for detecting natural adaptation and exposure to stress in natural populations

Heat-shock proteins （HSPs） play an undisputed role for maintaining cellular functioning under environmental challenges and protein denaturing conditions. Compelling evidence points to an evolutionary important role of HSPs and a strict evolutionary control of these proteins as a balance between benefits and costs. While there is a great potential for using HSP expression for detecting natural adaptation and exposure to stress in natural populations, some obstacles and key issues await investigation. From an ecological perspective these key issues needs to be resolved in order to fully appreciate the complex responses and adaptations to stress and to increase our understanding of HSPs and other molecular chaperones for stress adaptation and potential use as biomarkers. Here, the current knowledge and understanding of HSPs is reviewed and a number of key issues including the interpretation of elevated HSP levels, the complications of extrapolating between laboratory and field conditions, the effects of choice of traits and methodology and the larger intra-and extracellular networks of interactions that HSPs participate in are discussed [Current Zoology 56 （6）： 703-713, 2010].

Targeting collagen expression in alcoholic liver disease

Alcoholic liver disease （ALD） is a leading cause of liver disease and liver-related deaths globally, particularly in developed nations. Liver fibrosis is a consequence of ALD and other chronic liver insults, which can progress to cirrhosis and hepatocellular carcinoma if left untreated. Liver fibrosis is characterized by accumulation of excess extracellular matrix components, including type I collagen, which disrupts liver microcirculation and leads to injury. To date, there is no therapy for the treatment of liver fibrosis; thus treatments that either prevent the accumulation of type I collagen or hasten its degradation are desirable. The focus of this review is to examine the regulation of type I collagen in fibrogenic cells of the liver and to discuss current advances in therapeutics to eliminate excessive collagen deposition.

Promising drug targets and associated therapeutic interventions in Parkinson's disease

Parkinson's disease(PD) is one of the most debilitating brain diseases. Despite the availability of symptomatic treatments, response towards the health of PD patients remains scarce. To fulfil the medical needs of the PD patients, an efficacious and etiological treatment is required. In this review, we have compiled the information covering limitations of current therapeutic options in PD, novel drug targets for PD, and finally, the role of some critical beneficial natural products to control the progression of PD.

Chaperones in hepatitis C virus infection

The hepatitis C virus(HCV) infects approximately 3% of the world population or more than 185 million people worldwide. Each year, an estimated 350000-500000 deaths occur worldwide due to HCV-associated diseases including cirrhosis and hepatocellular carcinoma. HCV is the most common indication for liver transplantation in patients with cirrhosis worldwide. HCV is an enveloped RNA virus classified in the genus Hepacivirus in the Flaviviridae family. The HCV viral life cycle in a cell can be divided into six phases:(1) binding and internalization;(2) cytoplasmic release and uncoating;(3) viral polyprotein translation and processing;(4) RNA genome replication;(5) encapsidation(packaging) and assembly; and(6) virus morphogenesis(maturation) and secretion. Many host factors are involved in the HCV life cycle. Chaperones are an important group of host cytoprotective molecules that coordinate numerous cellular processes including protein folding, multimeric protein assembly, protein trafficking, and protein degradation. All phases of the viral life cycle require chaperone activity and the interaction of viral proteins with chaperones. This review will present our current knowledge and understanding of the role of chaperones in the HCV life cycle. Analysis of chaperones in HCV infection will provide further insights into viral/host interactions and potential therapeutic targets for both HCV and other viruses.

The Life of a Protein Molecule——Protein Quality Control

The research progress in molecular chaperones, unfolded protein response （UPR） and ER-associated degradation （ERAD） involved in the protein quality control was summarized in this paper, and then the existing problems and the future devel- opment prospect were also discussed. It was pointed out that the life process of protein experienced four stages including synthesizing, folding, assembling and degradation, while each stage required strict quality control. In endoplasmic reticulum （ER）, a variety of proteins had been synthesized, folded and modified to form func- tional proteins with certain conformation. When the folding was blocked in ER, the unfolded proteins would aggregate and induce the UPR, which up-regulated the level of modification enzymes folded by a series of molecular chaperones and proteins to help them accomplish folding and assembling. If these proteins were still folded incorrectly, they would enter into ERAD for being degraded.

A novel protein refolding method integrating ion exchange chromatography with artificial molecular chaperone

Artificial molecular chaperone （AMC） and ion exchange chromatography （IEC） were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography （AMC-IEC） was developed. Compared with AMC and IEC, the activity recovery of lysozyme obtained by AMC-IEC was much higher in the investigated range of initial protein concentrations, and the results show that AMC-IEC is very efficient for protein refolding at high concentrations. When the initial concentration of lysozyme is 180 mg/mL, its activity recovery obtained by AMC-IEC is still as high as 76.6%, while the activity recoveries obtained by AMC and IEC are 45.6% and 42.4%, respectively.

Heterologous expression,chaperone mediated solubilization and purification of parasitic nematode-specific growth factor-like protein of Setaria digitata

Objective:To clone,express and purify a putative parasitic nematode specific protein of Setaria digitata(S.digitata),filarial nematode that infects livestock and cause significant economic losses in Far East and Asia to he used for structural and functional analyses.Methods:To characterize uneharacterized gene of,S.digitata(SDUG),the herterologous expression of SDUG was carried out in the pET[cloned into pET45b(+)]expression system initially and co-expression of SDUC using chaperoiie plasmids pG-KJE8,pGro 7,pKJE7,pG-Tf2 and pTf16 containing chapcrone proteins of dnaK-dnaJ-grpE-groES-gro-E,groES-groEL,dnaK-dnaJ-grpE,groES-groEL-tig,and tig respectively,was carried out subsequently.Results:Expression of SDUG was seen when Escherichia coli strain BI.21(DE3)is used,while concentrating protein largely into the insoluble fraction.The co-expression of SDUG using chaperoiie plasmid mediated system indicated a significant increase of the protein in the soluble fraction.Of the chaperon plasniid sets,the highest amount of recombinant SDUP in the soluble fraction was seen when pGro7 was used in the presence of2 mg/mL L-arabinosc and 0.6M IPTG concentration in the culture medium and for 3 h of incubation at the temperature of 28℃.Recombinant SDUG was purified both from soluble and insoluble fractions using Ni affinity chromatography.SDS-PAGE and western blot analyses of these proteins revealed a single band having expected size of^24 kDa.Conclusions:SDUG seems to be more aggregate-prone and hydrophobic in nature and such protein can make soluble by correct selecting the inducer concentrations and induction temperature and its duration.