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Dimebon slows progression of proteinopathy in γ-synuclein transgenic mice.

Bachurin SO, Shelkovnikova TA, Ustyugov AA, Peters O, Khritankova I, Afanasieva MA, Tarasova TV, Alentov II, Buchman VL, Ninkina NN - Neurotox Res (2011)

Bottom Line: We detected statistically significant improvement of motor performance in a rotarod test in both dimebon-treated animal groups, with more pronounced effect in a group that received dimebon from an earlier age.We also revealed substantially reduced number of amyloid inclusions, decreased amount of insoluble γ-synuclein species and a notable amelioration of astrogliosis in the spinal cord of dimebon-treated compared with control transgenic animals.However, dimebon did not prevent the loss of spinal motor neurons in this model.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physiologically Active Compounds of RAS, 1 Severniy Proezd, Chernogolovka, 142432, Moscow Region, Russian Federation.

ABSTRACT
Intermediates and final products of protein aggregation play crucial role in the development of degenerative changes in a number of neurological diseases. Pathological protein aggregation is currently regarded as one of the most promising therapeutic targets for treatment of these diseases. Transgenic mouse models of proteinopathies are an effective tool for screening and validation of compounds, which can selectively affect metabolism of aggregate-prone proteins. In this study, we assessed effects of dimebon, a compound with known neuroprotective properties, on a recently established transgenic mouse model recapitulating key pathological features of amyotrophic lateral sclerosis (ALS) as the consequence of neuron-specific overexpression of γ-synuclein. Cohorts of experimental transgenic mice received dimebon in drinking water with this chronic treatment starting either before or after the onset of clinical signs of pathology. We detected statistically significant improvement of motor performance in a rotarod test in both dimebon-treated animal groups, with more pronounced effect in a group that received dimebon from an earlier age. We also revealed substantially reduced number of amyloid inclusions, decreased amount of insoluble γ-synuclein species and a notable amelioration of astrogliosis in the spinal cord of dimebon-treated compared with control transgenic animals. However, dimebon did not prevent the loss of spinal motor neurons in this model. Our results demonstrated that chronic dimebon administration is able to slow down but not halt progression of γ-synucleinopathy and resulting signs of pathology in transgenic animals, suggesting potential therapeutic use of this drug for treatment of this currently incurable disease.

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Dimebon decreases amount of detergent-insoluble γ-synuclein species in the spinal cord of γ-synuclein transgenic mice. Representative western blot of fractions obtained by sequential extraction of proteins from the spinal cord of 12-month-old control Thy1mγSN mice (−) and Thy1mγSN mice treated with dimebon from the age of 3 months (+) probed with an antibody against mouse γ-synuclein is shown. Proteins were extracted from pooled thoracic spinal cords of five animals for each group. To detect low-abundant high molecular weight γ-synuclein species (upper panel), the membrane was exposed for longer period than for detection of predominant monomeric form of the protein (lower panel). HS high salt-soluble fraction, TX Triton-X soluble fraction, and SDS detergent-insoluble fraction
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Fig3: Dimebon decreases amount of detergent-insoluble γ-synuclein species in the spinal cord of γ-synuclein transgenic mice. Representative western blot of fractions obtained by sequential extraction of proteins from the spinal cord of 12-month-old control Thy1mγSN mice (−) and Thy1mγSN mice treated with dimebon from the age of 3 months (+) probed with an antibody against mouse γ-synuclein is shown. Proteins were extracted from pooled thoracic spinal cords of five animals for each group. To detect low-abundant high molecular weight γ-synuclein species (upper panel), the membrane was exposed for longer period than for detection of predominant monomeric form of the protein (lower panel). HS high salt-soluble fraction, TX Triton-X soluble fraction, and SDS detergent-insoluble fraction

Mentions: To confirm observed effect of dimebon on accumulation of insoluble fibrillar γ-synuclein species by an alternative method, we used sequential fractionation of spinal cord proteins with buffers of different detergent composition. The presence of abundant aggregated γ-synuclein species in a detergent-insoluble fraction of the spinal cord of Thy1mγSN mice has been shown previously (Ninkina et al. 2009). Five samples of thoracic spinal cords were pooled for a group of 12-month-old mice treated with dimebon from the age of 3 months and five samples—for a group of age-matching control mice. Proteins were extracted from these pooled “averaged” samples by extraction/ultracentrifugation as described in Materials and Methods. Resulting salt-soluble (high salt, HS), detergent-soluble (Triton X-100, TX) and insoluble (SDS) fractions were analysed by gel electrophoresis and immunoblotting with antibodies against mouse γ-synuclein. We detected a substantial decrease in both monomeric and high molecular weight γ-synuclein species in detergent-insoluble fraction extracted from tissues of dimebon-treated compared with control transgenic mice, while the levels of salt-soluble (HS) and detergent-soluble (TX) forms were not essentially affected (Fig. 3). This effect was not because of reduced transgene expression in the drug-treated mice because quantitative RT-PCR analysis revealed no differences in spinal cord γ-synuclein mRNA levels between two groups of animals (data not shown).Fig. 3


Dimebon slows progression of proteinopathy in γ-synuclein transgenic mice.

Bachurin SO, Shelkovnikova TA, Ustyugov AA, Peters O, Khritankova I, Afanasieva MA, Tarasova TV, Alentov II, Buchman VL, Ninkina NN - Neurotox Res (2011)

Dimebon decreases amount of detergent-insoluble γ-synuclein species in the spinal cord of γ-synuclein transgenic mice. Representative western blot of fractions obtained by sequential extraction of proteins from the spinal cord of 12-month-old control Thy1mγSN mice (−) and Thy1mγSN mice treated with dimebon from the age of 3 months (+) probed with an antibody against mouse γ-synuclein is shown. Proteins were extracted from pooled thoracic spinal cords of five animals for each group. To detect low-abundant high molecular weight γ-synuclein species (upper panel), the membrane was exposed for longer period than for detection of predominant monomeric form of the protein (lower panel). HS high salt-soluble fraction, TX Triton-X soluble fraction, and SDS detergent-insoluble fraction
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3351599&req=5

Fig3: Dimebon decreases amount of detergent-insoluble γ-synuclein species in the spinal cord of γ-synuclein transgenic mice. Representative western blot of fractions obtained by sequential extraction of proteins from the spinal cord of 12-month-old control Thy1mγSN mice (−) and Thy1mγSN mice treated with dimebon from the age of 3 months (+) probed with an antibody against mouse γ-synuclein is shown. Proteins were extracted from pooled thoracic spinal cords of five animals for each group. To detect low-abundant high molecular weight γ-synuclein species (upper panel), the membrane was exposed for longer period than for detection of predominant monomeric form of the protein (lower panel). HS high salt-soluble fraction, TX Triton-X soluble fraction, and SDS detergent-insoluble fraction
Mentions: To confirm observed effect of dimebon on accumulation of insoluble fibrillar γ-synuclein species by an alternative method, we used sequential fractionation of spinal cord proteins with buffers of different detergent composition. The presence of abundant aggregated γ-synuclein species in a detergent-insoluble fraction of the spinal cord of Thy1mγSN mice has been shown previously (Ninkina et al. 2009). Five samples of thoracic spinal cords were pooled for a group of 12-month-old mice treated with dimebon from the age of 3 months and five samples—for a group of age-matching control mice. Proteins were extracted from these pooled “averaged” samples by extraction/ultracentrifugation as described in Materials and Methods. Resulting salt-soluble (high salt, HS), detergent-soluble (Triton X-100, TX) and insoluble (SDS) fractions were analysed by gel electrophoresis and immunoblotting with antibodies against mouse γ-synuclein. We detected a substantial decrease in both monomeric and high molecular weight γ-synuclein species in detergent-insoluble fraction extracted from tissues of dimebon-treated compared with control transgenic mice, while the levels of salt-soluble (HS) and detergent-soluble (TX) forms were not essentially affected (Fig. 3). This effect was not because of reduced transgene expression in the drug-treated mice because quantitative RT-PCR analysis revealed no differences in spinal cord γ-synuclein mRNA levels between two groups of animals (data not shown).Fig. 3

Bottom Line: We detected statistically significant improvement of motor performance in a rotarod test in both dimebon-treated animal groups, with more pronounced effect in a group that received dimebon from an earlier age.We also revealed substantially reduced number of amyloid inclusions, decreased amount of insoluble γ-synuclein species and a notable amelioration of astrogliosis in the spinal cord of dimebon-treated compared with control transgenic animals.However, dimebon did not prevent the loss of spinal motor neurons in this model.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physiologically Active Compounds of RAS, 1 Severniy Proezd, Chernogolovka, 142432, Moscow Region, Russian Federation.

ABSTRACT
Intermediates and final products of protein aggregation play crucial role in the development of degenerative changes in a number of neurological diseases. Pathological protein aggregation is currently regarded as one of the most promising therapeutic targets for treatment of these diseases. Transgenic mouse models of proteinopathies are an effective tool for screening and validation of compounds, which can selectively affect metabolism of aggregate-prone proteins. In this study, we assessed effects of dimebon, a compound with known neuroprotective properties, on a recently established transgenic mouse model recapitulating key pathological features of amyotrophic lateral sclerosis (ALS) as the consequence of neuron-specific overexpression of γ-synuclein. Cohorts of experimental transgenic mice received dimebon in drinking water with this chronic treatment starting either before or after the onset of clinical signs of pathology. We detected statistically significant improvement of motor performance in a rotarod test in both dimebon-treated animal groups, with more pronounced effect in a group that received dimebon from an earlier age. We also revealed substantially reduced number of amyloid inclusions, decreased amount of insoluble γ-synuclein species and a notable amelioration of astrogliosis in the spinal cord of dimebon-treated compared with control transgenic animals. However, dimebon did not prevent the loss of spinal motor neurons in this model. Our results demonstrated that chronic dimebon administration is able to slow down but not halt progression of γ-synucleinopathy and resulting signs of pathology in transgenic animals, suggesting potential therapeutic use of this drug for treatment of this currently incurable disease.

Show MeSH
Related in: MedlinePlus