Gedunin Degrades Aggregates of Mutant Huntingtin Protein and Intranuclear Inclusions via the Proteasomal Pathway in Neurons and Fibroblasts from Patients with Huntington's Disease / 神经科学通报·英文版

Huntington's disease (HD) is a deadly neurodegenerative disease with abnormal expansion of CAG repeats in the huntingtin gene. Mutant Huntingtin protein (mHTT) forms abnormal aggregates and intranuclear inclusions in specific neurons, resulting in cell death. Here, we tested the ability of a natural heat-shock protein 90 inhibitor, Gedunin, to degrade transfected mHTT in Neuro-2a cells and endogenous mHTT aggregates and intranuclear inclusions in both fibroblasts from HD patients and neurons derived from induced pluripotent stem cells from patients. Our data showed that Gedunin treatment degraded transfected mHTT in Neuro-2a cells, endogenous mHTT aggregates and intranuclear inclusions in fibroblasts from HD patients, and in neurons derived from induced pluripotent stem cells from patients in a dose- and time-dependent manner, and its activity depended on the proteasomal pathway rather than the autophagy route. These findings also showed that although Gedunin degraded abnormal mHTT aggregates and intranuclear inclusions in cells from HD patient, it did not affect normal cells, thus providing a new perspective for using Gedunin to treat HD.

Onjisaponin B derived from Radix Polygalae enhances autophagy and accelerates the degradation of mutant α-Synuclein and Huntingtin in PC-12 cells / 中国药理学与毒理学杂志

OBJECTIVE To investigate the autophagic effect of the compounds from the Chinese medicinal herbs, Radix polygalae as a potential neuroprotective agent that enhances the clearance of mutant Huntingtin and α- synuclein in PC- 12 cells. METHODS Radix polygalae was extracted with 75% ethanol using refluxing method, and its quality was assayed by UHPLC-TOF-MS. The autophagic effect of Radix polygalae extract, and its major components including polygalacic acid, senegenin and onjisaponin B were investigated using the green fluorescent protein-light chain 3 (GFP-LC3) autophagy detection and Western blot platforms for detecting the autophagic markers, GFP-LC3 puncta formation and LC3 II expression. The degradation of A53T α- synuclein and the inhibition ofα-synuclein oligo merization related to the Parkinson disease were assayed using Western blot and flow cytometer analysis, respectively. While the cytotoxicity and the degradation of the mutant Huntingtin associated with the Huntingtin disease were investigated using MTT method and flow cytometer analysis. RESULTS Radix polygalae ethanol extract and onjisaponin B improved the GFP-LC3 puncta formation and expression of LC3Ⅱ with time and dose manner, and this induction was activated via AMPK-mTOR and Atg 7 gene pathway. Furthermore, the clearance of α-synuclein and mutant Huntingtin was enhanced via autophagy induction with the treatment of Radix polygalae ethanol extract and onjisaponin B. CONCLUSION Findings in the current study provide detailed insights into the protective mechanism of a novel autophagy inducer, onjisaponin B, which is valuable for further investigation as a new candidate agent for modulating neurodegenerative disorders through the reduction of toxicity and clearance of mutant proteins in the cellular level.

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.

Américo Negrette and Huntington's disease / Américo Negrette e a doença de Huntington

The authors present a historical review of the seminal clinical contribution of Professor Américo Negrette, a Venezuelan neurologist, to the evolution of scientific knowledge about Huntington's disease.

Os autores apresentam uma revisão histórica sobre a magistral contribuição clínica do Professor Américo Negrette, neurologista venezuelano, na evolução do conhecimento científico sobre a doença de Huntington.

Effect of polyunsaturated fatty acid on the expression of Huntingtin associated protein 1 in hippocampus of rat model with Alzheimer' s disease / 中华行为医学与脑科学杂志

Objective To study the effect of docosahexaenoic acid ( DHA ) and eicosapentaenoic acid (EPA) on cognition impairment and huntingtin associated protein 1 ( HAP1 ) expression in hippocampus of rat model with Alzheimer' s disease(AD). Methods Forty healthy Sprague-Dawley rats were randomly divided into control group, AD group, DHA group and EPA group on average. Alcl3 was injected intraperitoneally and D-galac tose was injected into subcutaneous to establish the model of rat with AD. ABC method of immunohistochemistry was used to observe the expression level of HAP1 in the hippocampus. Morris water maze was used to study the spatial learning and memory in rats. Results Compared with control group,the HAP1-positive neurons of hippo campus decreased and poorer performance in Morris water maze test was observed in AD group. Compared with AD group, DHA and EPA treatments significantly caused the decreases in escape latency and searching distance in the Morris water maze test. The number of HAP1- positive cells in DG region of DHA group(43.57 ±6.14) increased obviously compared with AD group( 28.56 ± 4.23 ) (P ＜ 0.05 ＝. Conclusion The immunoreactivities of HAP1 decrease in hippocampus of AD rat. The applications of DHA and EPA in AD rats significantly improve the ability of learning and memory;and the mechanisms may be related to the decrease of HAP1 expressions in hippocampus.

HSP40 and HSP70 inhibit the accumulation and toxicity of mutant huntingtin in N2a cells / 解剖学报

Objective To study the effect of heat shock protein 40(HSP40) and heat shock protein 70(HSP70) on the aggregate formation of mutant huntingtin (htt) and its toxicity in N2a cells. Methods The effect of the over-expression of HSP40 and HSP70 alone or co-over-expression of them on aggregate formation of transfected mutant htt (containing 150 glutamine repeats, 150Q) in N2a cells was detected by fluorescence microcopy and Western blotting. Cell viabilities were detected by MTT assay. Reactive oxygen species (ROS) production was detected by colorimetric method. Results The over-expression of HSP40 and HSP70 alone, especially the co-over-expression of them, dramatically decreases the formation of 150Q htt aggregates in N2a cells. The numbers of aggregates in each group are as follows ( n = 1 000): about 50% in the group of 150Q htt-expressing alone, about 12% in the group of over-expression of HSP40, about 15% in the group of over-expression of HSP70, about 5% in the group of co-over-expression of HSP40 and HSP70. The result of MTT assay shows that the over-expression of HSP40 and HSP70 alone, especially the co-over-expression of them, dramatically increases cell viabilities ( P<0.01, n =3) and reduces the production of ROS ( P<0.01, n =3). Conclusion HSP40 and HSP70 can increase cell viabilities of 150Q N2a cells via inhibiting the aggregates formation of mutant huntingtin and reducing oxidative stress.

Effect of cold stress on the expression of Huntingtin-associated protein 1 in the rat adrenal medulla / 解剖学报

Objective To observe the ultrastructure location of Huntingtin-associated protein 1(HAP1) in rat adrenal medulla and the effect of cold stress on the expression of HAP1 in rat adrenal medulla. Methods Fourteen healthy male Wistar rats were used in the present study and among them two rats were used for immune electron microscopy and twelve rats for cold stress experiment. In the cold stress experiment, animals were divided into control and cold groups randomly with six rats in each group. During the experiment, rats were housed in a room at the temperature of 4℃ for 12 hours and then immunohistochemistry and Western blotting were used to measure the expression of HAP1 in adrenal medulla. Results By using the immune electron microscopy, the results showed HAP1 was located on the external membrane of secretory vesicles of adrenal medulla and their membranous organelles. The expression of HAP1 in adrenal medulla of cold group significantly decreased as compared with that of control group ( P <0.01). Conclusion HAP1 might be related with the adrenal medulla cells endocrine granula and involved in the transmission and release of adrenaline or noradrenaline in secretory granule.

Diagnóstico molecular de la enfermedad de Huntington / Molecular diagnosis in Huntington's disease

La enfermedad de Huntington es un padecimiento neurológico degenerativo, de herencia autosómica dominante, causado por una expansión CAG que codifica una secuencia de poliglutamina en la proteína huntingtina. Su frecuencia varía de cinco a 10 afectados por 100 mil individuos en población caucásica. Clínicamente muestra manifestaciones motoras, cognoscitivas, psicológicas y muerte en 10 a 15 años. Avances concretos se han logrado en el conocimiento del mecanismo mutacional, alteraciones del producto proteico y su efecto neuropatológico. Un conjunto de procedimientos como PCR con o sin modificación del ADN, Southern blot y métodos mixtos son analizados en sus características y eficiencia para el diagnóstico molecular de esta enfermedad.

Huntington's disease (HD) is a neurological degenerative disorder, inherited by an autosomal dominant mode, and caused by a CAG triplet expansion coding for a poly-glutamine sequence in the huntingtin protein. HD affects 5-10 in 100,000 individuals from Caucasian population. Clinically patients display motor, cognitive and psychological impairment, and death within 10-15 years. Concrete advances have been achieved in the knowledge of the mutational mechanism, alteration of the protein product and their neuropathological effects. A number of tests such as PCR with or without DNA modification, Southern blot and mixed methods are analyzed. We describe their characteristics and effectiveness for the molecular diagnosis of HD.

Therapeutic Strategies in Huntington's Disease

This article provides an overview of the therapeutic strategies, from ordinary classical drugs to the modern molecular strategy at experimental level, for Huntington's disease. The disease is characterized by choreic movements, psychiatric disorders, striatal atrophy with selective small neuronal loss, and autosomal dominant inheritance. The genetic abnormality is CAG expansion in huntingtin gene. Mutant huntingtin with abnormally long glutamine stretch aggregates and forms intranuclear inclusions. In this review, I summarize the results of previous trials from the following aspects; 1. symptomatic/palliative therapies including drugs, stereotaxic surgery and repetitive transcranial magnetic stimulation, 2. anti-degenerative therapies including anti-excitotoxicity, reversal of mitochondrial dysfunction and anti-apoptosis, 3. restorative/reparative therapies including neural trophic factors and tissue or stem cell transplantation, and 4. molecular targets in specific and radical therapies including inhibition of truncation of huntingtin, inhibition of aggregate formation, normalization of transcriptional dysregulation, enhancement of autophagic clearance of mutant huntingtin, and specific inhibition of huntingtin expression by sRNAi. Although the strategies mentioned in the latter two categories are mostly at laboratory level at present, we are pleased that one can discuss such "therapeutic strategies", a matter absolutely impossible before the causal gene of Huntington's disease was identified more than 10 years ago. It is also true, however, that some of the "therapeutic strategies" mentioned here would be found difficult to implement and abandoned in the future.

Research progress in molecular pathology of Huntington's disease / 中国药理学通报

Huntington's disease is a fetal neurological disorder manifested as movement disorder accompanied by cognitive and psychological impairments. The disease is inherited as autosomal dominant. Huntington's disease is caused by an expansion of a polyglutamine tract in a protein named huntingtin. The length of polyglutamine tract in huntingtin in normal individual is less than 35 glutamines. In Huntington's disease patients the length of polyglutamine tract increases to more than 37 glutamines. The pathogenic mechanisms by which mutant huntingtin causes Huntington's disease have not been fully understood. This paper reviews main progresses in studying the pathogenic mechanisms of mutant huntingtin.