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Aging is not associated with proteasome impairment in UPS reporter mice.

Cook C, Gass J, Dunmore J, Tong J, Taylor J, Eriksen J, McGowan E, Lewis J, Johnston J, Petrucelli L - PLoS ONE (2009)

Bottom Line: Given its essential role in protein regulation, even slight perturbations in UPS activity can substantially impair cellular function.This UPS reporter contains a degron sequence attached to the C-terminus of green fluorescent protein, and is predominantly expressed in neurons throughout the brain of our transgenic model.We then demonstrated that this reporter system is sensitive to UPS inhibition in vivo.

View Article: PubMed Central - PubMed

Affiliation: Mayo Clinic, Jacksonville, FL, USA.

ABSTRACT

Background: Covalent linkage of ubiquitin regulates the function and, ultimately, the degradation of many proteins by the ubiquitin-proteasome system (UPS). Given its essential role in protein regulation, even slight perturbations in UPS activity can substantially impair cellular function.

Methodology/principal findings: We have generated and characterized a novel transgenic mouse model which expresses a previously described reporter for UPS function. This UPS reporter contains a degron sequence attached to the C-terminus of green fluorescent protein, and is predominantly expressed in neurons throughout the brain of our transgenic model. We then demonstrated that this reporter system is sensitive to UPS inhibition in vivo.

Conclusions/significance: Given the obstacles associated with evaluating proteasomal function in the brain, our mouse model uniquely provides the capability to monitor UPS function in real time in individual neurons of a complex organism. Our novel mouse model now provides a useful resource with which to evaluate the impact of aging, as well as various genetic and/or pharmacological modifiers of neurodegenerative disease(s).

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No effect of aging on GFPμ protein expression.Representative WB showing GFPμ expression in cortex (Ctx), cerebellum (Cb), midbrain (MID), and hippocampus (Hipp) from 6 to 18 months of age in heterozygous GFPμ mice. Quantification of GFP O.D. was normalized to actin to control for protein loading (each bar represents average GFP expression for n = 6 mice [3 males, 3 females] at each time point, with error bars depicting SEM).
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pone-0005888-g004: No effect of aging on GFPμ protein expression.Representative WB showing GFPμ expression in cortex (Ctx), cerebellum (Cb), midbrain (MID), and hippocampus (Hipp) from 6 to 18 months of age in heterozygous GFPμ mice. Quantification of GFP O.D. was normalized to actin to control for protein loading (each bar represents average GFP expression for n = 6 mice [3 males, 3 females] at each time point, with error bars depicting SEM).

Mentions: Given that aging has been reported to lead to UPS impairment [13], we evaluated GFP protein (Figure 4; Figure S1) and mRNA expression (Figure 5) in aged cohorts of Degron mice to determine if aging alone would lead to an increase in GFP expression. Surprisingly, as demonstrated in Figure 4, there was no change in GFP protein expression between the ages of 6 to 18 months in the cortex (F = 0.243, p = 0.788), hippocampus (F = 3.092, p = 0.075), midbrain (F = 2.598, p = 0.108), or cerebellum (F = 3.377, p = 0.062), which is consistent with results from immunohistochemical studies on aging GFPμ mice (Figure S1). In addition, there was no observed difference in GFP accumulation with age between male and female GFPμ mice. As shown in Figure 5, there was also no effect of aging on regional GFPμ mRNA expression (cortex, F = 0.963, p = 0.409; hippocampus, F = 0.831, p = 0.456; cerebellum, F = 0.265, p = 0.771; midbrain, F = 0.22, p = 0.806), indicating that aging alone does not significantly impair proteasomal function in our mouse model.


Aging is not associated with proteasome impairment in UPS reporter mice.

Cook C, Gass J, Dunmore J, Tong J, Taylor J, Eriksen J, McGowan E, Lewis J, Johnston J, Petrucelli L - PLoS ONE (2009)

No effect of aging on GFPμ protein expression.Representative WB showing GFPμ expression in cortex (Ctx), cerebellum (Cb), midbrain (MID), and hippocampus (Hipp) from 6 to 18 months of age in heterozygous GFPμ mice. Quantification of GFP O.D. was normalized to actin to control for protein loading (each bar represents average GFP expression for n = 6 mice [3 males, 3 females] at each time point, with error bars depicting SEM).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2690827&req=5

pone-0005888-g004: No effect of aging on GFPμ protein expression.Representative WB showing GFPμ expression in cortex (Ctx), cerebellum (Cb), midbrain (MID), and hippocampus (Hipp) from 6 to 18 months of age in heterozygous GFPμ mice. Quantification of GFP O.D. was normalized to actin to control for protein loading (each bar represents average GFP expression for n = 6 mice [3 males, 3 females] at each time point, with error bars depicting SEM).
Mentions: Given that aging has been reported to lead to UPS impairment [13], we evaluated GFP protein (Figure 4; Figure S1) and mRNA expression (Figure 5) in aged cohorts of Degron mice to determine if aging alone would lead to an increase in GFP expression. Surprisingly, as demonstrated in Figure 4, there was no change in GFP protein expression between the ages of 6 to 18 months in the cortex (F = 0.243, p = 0.788), hippocampus (F = 3.092, p = 0.075), midbrain (F = 2.598, p = 0.108), or cerebellum (F = 3.377, p = 0.062), which is consistent with results from immunohistochemical studies on aging GFPμ mice (Figure S1). In addition, there was no observed difference in GFP accumulation with age between male and female GFPμ mice. As shown in Figure 5, there was also no effect of aging on regional GFPμ mRNA expression (cortex, F = 0.963, p = 0.409; hippocampus, F = 0.831, p = 0.456; cerebellum, F = 0.265, p = 0.771; midbrain, F = 0.22, p = 0.806), indicating that aging alone does not significantly impair proteasomal function in our mouse model.

Bottom Line: Given its essential role in protein regulation, even slight perturbations in UPS activity can substantially impair cellular function.This UPS reporter contains a degron sequence attached to the C-terminus of green fluorescent protein, and is predominantly expressed in neurons throughout the brain of our transgenic model.We then demonstrated that this reporter system is sensitive to UPS inhibition in vivo.

View Article: PubMed Central - PubMed

Affiliation: Mayo Clinic, Jacksonville, FL, USA.

ABSTRACT

Background: Covalent linkage of ubiquitin regulates the function and, ultimately, the degradation of many proteins by the ubiquitin-proteasome system (UPS). Given its essential role in protein regulation, even slight perturbations in UPS activity can substantially impair cellular function.

Methodology/principal findings: We have generated and characterized a novel transgenic mouse model which expresses a previously described reporter for UPS function. This UPS reporter contains a degron sequence attached to the C-terminus of green fluorescent protein, and is predominantly expressed in neurons throughout the brain of our transgenic model. We then demonstrated that this reporter system is sensitive to UPS inhibition in vivo.

Conclusions/significance: Given the obstacles associated with evaluating proteasomal function in the brain, our mouse model uniquely provides the capability to monitor UPS function in real time in individual neurons of a complex organism. Our novel mouse model now provides a useful resource with which to evaluate the impact of aging, as well as various genetic and/or pharmacological modifiers of neurodegenerative disease(s).

Show MeSH