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Parkin depletion delays motor decline dose-dependently without overtly affecting neuropathology in α-synuclein transgenic mice.

Fournier M, Roux A, Garrigue J, Muriel MP, Blanche P, Lashuel HA, Anderson JP, Barbour R, Huang J, du Montcel ST, Brice A, Corti O - BMC Neurosci (2013)

Bottom Line: Parkin overproduction protects against α-syn-dependent neurodegeneration in various in vitro and in vivo models, but it remains unclear whether this process is affected by Parkin deficiency.Some of these deposits colocalized with the LB markers ubiquitin and α-syn truncated at D135 (α-synD135), indicating that PS129α-syn is subjected to secondary posttranslational modification (PTM); these features were not significantly affected by parkin dysfunction.These findings suggest that Parkin deficiency acts as a protective modifier in α-syn-dependent neurodegeneration, without overtly affecting the composition and characteristics of α-syn deposits in end-stage disease.

View Article: PubMed Central - HTML - PubMed

Affiliation: Inserm, U 975, CRICM, Hôpital de la Pitié-Salpêtrière, F-75013 Paris, France. olga.corti@upmc.fr.

ABSTRACT

Background: Mutations of the gene encoding the major component of Lewy bodies (LB), α-synuclein (α-syn), cause autosomal dominant forms of Parkinson's disease (PD), whereas loss-of-function mutations of the gene encoding the multifunctional E3 ubiquitin-protein ligase Parkin account for autosomal recessive forms of the disease. Parkin overproduction protects against α-syn-dependent neurodegeneration in various in vitro and in vivo models, but it remains unclear whether this process is affected by Parkin deficiency. We addressed this issue, by carrying out more detailed analyses of transgenic mice overproducing the A30P variant of human α-syn (hA30Pα-syn) and with two, one or no parkin knockout alleles.

Results: Longitudinal behavioral follow-up of these mice indicated that Parkin depletion delayed disease-predictive sensorimotor impairment due to α-syn accumulation, in a dose-dependent fashion. At the end stage of the disease, neuronal deposits containing fibrillar α-syn species phosphorylated at S129 (PS129α-syn) were the predominant neuropathological feature in hA30Pα-syn mice, regardless of their parkin expression. Some of these deposits colocalized with the LB markers ubiquitin and α-syn truncated at D135 (α-synD135), indicating that PS129α-syn is subjected to secondary posttranslational modification (PTM); these features were not significantly affected by parkin dysfunction.

Conclusions: These findings suggest that Parkin deficiency acts as a protective modifier in α-syn-dependent neurodegeneration, without overtly affecting the composition and characteristics of α-syn deposits in end-stage disease.

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α-SynD135 accumulates specifically in the central nervous system of symptomatic hA30Pα-syn mice, regardless of parkin expression status. (A) Micrographs illustrating specific immunoreactivity in coronal brainstem sections from a representative symptomatic hA30Pα-syn mouse with functional parkin alleles, stained with anti-α-synD135 antibody before (left) and after absorption with recombinant α-synY133, full-length α-syn or α-synD135. Scale bars: 25 μm. (B) Comparative staining for α-synD135 in the brainstem of representative symptomatic and healthy hA30Pα-syn mice with functional parkin alleles; similar results were obtained in hA30Pα-syn mice with no functional parkin alleles. Scale bars: 100 μm. (C) Representative spectrum illustrating the detection, by MS, of the C-terminal fragment of full-length α-syn (mass/charge = 1441 with z = 3) and α-synD135 (mass/charge = 1243 with z = 3) in the SDS-soluble fraction of proteins from brain lysates from hA30Pα-syn+/+ mice; peptides (sequence indicated in blue) were fragmented and unambiguously identified by tandem MS.
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Figure 3: α-SynD135 accumulates specifically in the central nervous system of symptomatic hA30Pα-syn mice, regardless of parkin expression status. (A) Micrographs illustrating specific immunoreactivity in coronal brainstem sections from a representative symptomatic hA30Pα-syn mouse with functional parkin alleles, stained with anti-α-synD135 antibody before (left) and after absorption with recombinant α-synY133, full-length α-syn or α-synD135. Scale bars: 25 μm. (B) Comparative staining for α-synD135 in the brainstem of representative symptomatic and healthy hA30Pα-syn mice with functional parkin alleles; similar results were obtained in hA30Pα-syn mice with no functional parkin alleles. Scale bars: 100 μm. (C) Representative spectrum illustrating the detection, by MS, of the C-terminal fragment of full-length α-syn (mass/charge = 1441 with z = 3) and α-synD135 (mass/charge = 1243 with z = 3) in the SDS-soluble fraction of proteins from brain lysates from hA30Pα-syn+/+ mice; peptides (sequence indicated in blue) were fragmented and unambiguously identified by tandem MS.

Mentions: We then investigated the accumulation of α-synD135 species in hA30Pα-syn mice with functional or dysfunctional parkin. In the brainstem of symptomatic animals, the anti-α-synD135 antibody labeled numerous normally shaped or swollen processes and cell bodies (Figure 3A). This labeling was abolished by prior absorption with recombinant α-synD135 (Figure 3A), and was not detected in the brains of healthy hA30Pα-syn mice, regardless of their expression status for parkin, or in non transgenic animals (Figure 3B and data not shown). Qualitative comparisons of symptomatic hA30Pα-syn mice and hA30Pα-syn mice with no functional parkin alleles revealed no obvious differences attributable to Parkin deficiency in terms of the type of structures labeled (processes versus cell bodies) or the density of deposits (data not shown). MS analyses of brain lysates from symptomatic mice unambiguously identified the presence of α-syn and α-synD135 in both hA30Pα-syn mice and hA30Pα-syn mice lacking Parkin (representative spectrum shown in Figure 3C). By contrast, the signal potentially corresponding to α-synY133 was weak in all cases, precluding clear identification of this species (Table 2).


Parkin depletion delays motor decline dose-dependently without overtly affecting neuropathology in α-synuclein transgenic mice.

Fournier M, Roux A, Garrigue J, Muriel MP, Blanche P, Lashuel HA, Anderson JP, Barbour R, Huang J, du Montcel ST, Brice A, Corti O - BMC Neurosci (2013)

α-SynD135 accumulates specifically in the central nervous system of symptomatic hA30Pα-syn mice, regardless of parkin expression status. (A) Micrographs illustrating specific immunoreactivity in coronal brainstem sections from a representative symptomatic hA30Pα-syn mouse with functional parkin alleles, stained with anti-α-synD135 antibody before (left) and after absorption with recombinant α-synY133, full-length α-syn or α-synD135. Scale bars: 25 μm. (B) Comparative staining for α-synD135 in the brainstem of representative symptomatic and healthy hA30Pα-syn mice with functional parkin alleles; similar results were obtained in hA30Pα-syn mice with no functional parkin alleles. Scale bars: 100 μm. (C) Representative spectrum illustrating the detection, by MS, of the C-terminal fragment of full-length α-syn (mass/charge = 1441 with z = 3) and α-synD135 (mass/charge = 1243 with z = 3) in the SDS-soluble fraction of proteins from brain lysates from hA30Pα-syn+/+ mice; peptides (sequence indicated in blue) were fragmented and unambiguously identified by tandem MS.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4228309&req=5

Figure 3: α-SynD135 accumulates specifically in the central nervous system of symptomatic hA30Pα-syn mice, regardless of parkin expression status. (A) Micrographs illustrating specific immunoreactivity in coronal brainstem sections from a representative symptomatic hA30Pα-syn mouse with functional parkin alleles, stained with anti-α-synD135 antibody before (left) and after absorption with recombinant α-synY133, full-length α-syn or α-synD135. Scale bars: 25 μm. (B) Comparative staining for α-synD135 in the brainstem of representative symptomatic and healthy hA30Pα-syn mice with functional parkin alleles; similar results were obtained in hA30Pα-syn mice with no functional parkin alleles. Scale bars: 100 μm. (C) Representative spectrum illustrating the detection, by MS, of the C-terminal fragment of full-length α-syn (mass/charge = 1441 with z = 3) and α-synD135 (mass/charge = 1243 with z = 3) in the SDS-soluble fraction of proteins from brain lysates from hA30Pα-syn+/+ mice; peptides (sequence indicated in blue) were fragmented and unambiguously identified by tandem MS.
Mentions: We then investigated the accumulation of α-synD135 species in hA30Pα-syn mice with functional or dysfunctional parkin. In the brainstem of symptomatic animals, the anti-α-synD135 antibody labeled numerous normally shaped or swollen processes and cell bodies (Figure 3A). This labeling was abolished by prior absorption with recombinant α-synD135 (Figure 3A), and was not detected in the brains of healthy hA30Pα-syn mice, regardless of their expression status for parkin, or in non transgenic animals (Figure 3B and data not shown). Qualitative comparisons of symptomatic hA30Pα-syn mice and hA30Pα-syn mice with no functional parkin alleles revealed no obvious differences attributable to Parkin deficiency in terms of the type of structures labeled (processes versus cell bodies) or the density of deposits (data not shown). MS analyses of brain lysates from symptomatic mice unambiguously identified the presence of α-syn and α-synD135 in both hA30Pα-syn mice and hA30Pα-syn mice lacking Parkin (representative spectrum shown in Figure 3C). By contrast, the signal potentially corresponding to α-synY133 was weak in all cases, precluding clear identification of this species (Table 2).

Bottom Line: Parkin overproduction protects against α-syn-dependent neurodegeneration in various in vitro and in vivo models, but it remains unclear whether this process is affected by Parkin deficiency.Some of these deposits colocalized with the LB markers ubiquitin and α-syn truncated at D135 (α-synD135), indicating that PS129α-syn is subjected to secondary posttranslational modification (PTM); these features were not significantly affected by parkin dysfunction.These findings suggest that Parkin deficiency acts as a protective modifier in α-syn-dependent neurodegeneration, without overtly affecting the composition and characteristics of α-syn deposits in end-stage disease.

View Article: PubMed Central - HTML - PubMed

Affiliation: Inserm, U 975, CRICM, Hôpital de la Pitié-Salpêtrière, F-75013 Paris, France. olga.corti@upmc.fr.

ABSTRACT

Background: Mutations of the gene encoding the major component of Lewy bodies (LB), α-synuclein (α-syn), cause autosomal dominant forms of Parkinson's disease (PD), whereas loss-of-function mutations of the gene encoding the multifunctional E3 ubiquitin-protein ligase Parkin account for autosomal recessive forms of the disease. Parkin overproduction protects against α-syn-dependent neurodegeneration in various in vitro and in vivo models, but it remains unclear whether this process is affected by Parkin deficiency. We addressed this issue, by carrying out more detailed analyses of transgenic mice overproducing the A30P variant of human α-syn (hA30Pα-syn) and with two, one or no parkin knockout alleles.

Results: Longitudinal behavioral follow-up of these mice indicated that Parkin depletion delayed disease-predictive sensorimotor impairment due to α-syn accumulation, in a dose-dependent fashion. At the end stage of the disease, neuronal deposits containing fibrillar α-syn species phosphorylated at S129 (PS129α-syn) were the predominant neuropathological feature in hA30Pα-syn mice, regardless of their parkin expression. Some of these deposits colocalized with the LB markers ubiquitin and α-syn truncated at D135 (α-synD135), indicating that PS129α-syn is subjected to secondary posttranslational modification (PTM); these features were not significantly affected by parkin dysfunction.

Conclusions: These findings suggest that Parkin deficiency acts as a protective modifier in α-syn-dependent neurodegeneration, without overtly affecting the composition and characteristics of α-syn deposits in end-stage disease.

Show MeSH
Related in: MedlinePlus