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Effects of CD2-associated protein deficiency on amyloid-β in neuroblastoma cells and in an APP transgenic mouse model.

Liao F, Jiang H, Srivatsan S, Xiao Q, Lefton KB, Yamada K, Mahan TE, Lee JM, Shaw AS, Holtzman DM - Mol Neurodegener (2015)

Bottom Line: Our data show that suppressing CD2AP expression using shRNA in N2a-APP695 cells results in decreased cell membrane amyloid precursor protein, decreased Aβ release and a lower Aβ42/Aβ40 ratio.In 1-month old PS1APP mice, complete loss of CD2AP in brain resulted in a decreased Aβ42/Aβ40 ratio in brain tissue lysates while there was no effect on Aβ deposition or accumulation in PS1APP mice expressing one copy of CD2AP.The effect of CD2-Associated Protein on Aβ metabolism is subtle in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Hope Center for Neurological Disorders, Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA. liaof@neuro.wustl.edu.

ABSTRACT

Background: CD2-associated protein (CD2AP) is an SH3-containing scaffold adaptor protein which regulates the actin cytoskeleton. Recently, CD2AP was identified as a genetic risk factor for Alzheimer's disease (AD) by several genome-wide association studies. One of the hallmarks of AD is the accumulation of aggregated forms of Amyloid-β (Aβ) in the brain. In humans, CD2AP AD susceptibility locus (rs9349407) is associated with an increased plaque burden. Aβ production is highly regulated by endocytosis and is influenced by lysosomal function. Lysosomal trafficking is influenced by CD2AP. In this study, we decreased CD2AP levels in N2a neuroblastoma cultures and PS1APP mice and analyzed Aβ levels and plaque burden.

Results: Our data show that suppressing CD2AP expression using shRNA in N2a-APP695 cells results in decreased cell membrane amyloid precursor protein, decreased Aβ release and a lower Aβ42/Aβ40 ratio. CD2AP protein is expressed in the brain as detected by western blot, and the expression level is dependent on gene dosage. In 1-month old PS1APP mice, complete loss of CD2AP in brain resulted in a decreased Aβ42/Aβ40 ratio in brain tissue lysates while there was no effect on Aβ deposition or accumulation in PS1APP mice expressing one copy of CD2AP.

Conclusion: CD2-Associated Protein affects Aβ levels and Aβ42/Aβ40 ratio in vitro. The effect of CD2-Associated Protein on Aβ metabolism is subtle in vivo.

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Related in: MedlinePlus

Effects of CD2AP on Aβ levels in 1-month old PS1APP mice. PS1APP/CD2AP+/+ (n = 12 total, 6 females and 6 males) and PS1APP/CD2AP−/− (n = 12 total, 7 females and 5 males) mice were sacrificed at 1-month of age. The cortices were homogenized in PBS. Aβ40(A), Aβ42(B) and Aβ42/ Aβ40(C) ratio were measured. (**, p < 0.01, Student’s t-test).
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Fig4: Effects of CD2AP on Aβ levels in 1-month old PS1APP mice. PS1APP/CD2AP+/+ (n = 12 total, 6 females and 6 males) and PS1APP/CD2AP−/− (n = 12 total, 7 females and 5 males) mice were sacrificed at 1-month of age. The cortices were homogenized in PBS. Aβ40(A), Aβ42(B) and Aβ42/ Aβ40(C) ratio were measured. (**, p < 0.01, Student’s t-test).

Mentions: Next, we assessed whether CD2AP has similar effects on Aβ levels and Aβ42/Aβ40 ratio in vivo. If CD2AP affects Aβ production or release, we would expect to see the changes in young mice before plaque deposition. Therefore, we generated 1-month old PS1APP/CD2AP+/+ (female, n = 6; male, n = 6) and PS1APP/CD2AP−/− (female, n = 7; male, n = 5) mice and measured Aβ40 and Aβ42 levels in the PBS soluble fraction of cortical tissue. The results showed that there were no significant changes in the absolute concentration of Aβ40 and Aβ42 (Figure 4A,B). However, the ratio of Aβ42/Aβ40 was lower in PS1APP/CD2AP−/− mice as compared to PS1APP/CD2AP+/+ mice (Figure 4C). This effect was similar in both females (0.37 ± 0.008 vs 0.29 ± 0.0025 for PS1APP/CD2AP+/+vs PS1APP/CD2AP−/−, respectively, p < 0.05, Student’s t-test) and males (0.35 ± 0.015 vs 0.30 ± 0.010 for PS1APP/CD2AP+/+vs PS1APP/CD2AP−/−, respectively, p < 0.05, Student’s t-test).Figure 4


Effects of CD2-associated protein deficiency on amyloid-β in neuroblastoma cells and in an APP transgenic mouse model.

Liao F, Jiang H, Srivatsan S, Xiao Q, Lefton KB, Yamada K, Mahan TE, Lee JM, Shaw AS, Holtzman DM - Mol Neurodegener (2015)

Effects of CD2AP on Aβ levels in 1-month old PS1APP mice. PS1APP/CD2AP+/+ (n = 12 total, 6 females and 6 males) and PS1APP/CD2AP−/− (n = 12 total, 7 females and 5 males) mice were sacrificed at 1-month of age. The cortices were homogenized in PBS. Aβ40(A), Aβ42(B) and Aβ42/ Aβ40(C) ratio were measured. (**, p < 0.01, Student’s t-test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4374406&req=5

Fig4: Effects of CD2AP on Aβ levels in 1-month old PS1APP mice. PS1APP/CD2AP+/+ (n = 12 total, 6 females and 6 males) and PS1APP/CD2AP−/− (n = 12 total, 7 females and 5 males) mice were sacrificed at 1-month of age. The cortices were homogenized in PBS. Aβ40(A), Aβ42(B) and Aβ42/ Aβ40(C) ratio were measured. (**, p < 0.01, Student’s t-test).
Mentions: Next, we assessed whether CD2AP has similar effects on Aβ levels and Aβ42/Aβ40 ratio in vivo. If CD2AP affects Aβ production or release, we would expect to see the changes in young mice before plaque deposition. Therefore, we generated 1-month old PS1APP/CD2AP+/+ (female, n = 6; male, n = 6) and PS1APP/CD2AP−/− (female, n = 7; male, n = 5) mice and measured Aβ40 and Aβ42 levels in the PBS soluble fraction of cortical tissue. The results showed that there were no significant changes in the absolute concentration of Aβ40 and Aβ42 (Figure 4A,B). However, the ratio of Aβ42/Aβ40 was lower in PS1APP/CD2AP−/− mice as compared to PS1APP/CD2AP+/+ mice (Figure 4C). This effect was similar in both females (0.37 ± 0.008 vs 0.29 ± 0.0025 for PS1APP/CD2AP+/+vs PS1APP/CD2AP−/−, respectively, p < 0.05, Student’s t-test) and males (0.35 ± 0.015 vs 0.30 ± 0.010 for PS1APP/CD2AP+/+vs PS1APP/CD2AP−/−, respectively, p < 0.05, Student’s t-test).Figure 4

Bottom Line: Our data show that suppressing CD2AP expression using shRNA in N2a-APP695 cells results in decreased cell membrane amyloid precursor protein, decreased Aβ release and a lower Aβ42/Aβ40 ratio.In 1-month old PS1APP mice, complete loss of CD2AP in brain resulted in a decreased Aβ42/Aβ40 ratio in brain tissue lysates while there was no effect on Aβ deposition or accumulation in PS1APP mice expressing one copy of CD2AP.The effect of CD2-Associated Protein on Aβ metabolism is subtle in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Hope Center for Neurological Disorders, Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA. liaof@neuro.wustl.edu.

ABSTRACT

Background: CD2-associated protein (CD2AP) is an SH3-containing scaffold adaptor protein which regulates the actin cytoskeleton. Recently, CD2AP was identified as a genetic risk factor for Alzheimer's disease (AD) by several genome-wide association studies. One of the hallmarks of AD is the accumulation of aggregated forms of Amyloid-β (Aβ) in the brain. In humans, CD2AP AD susceptibility locus (rs9349407) is associated with an increased plaque burden. Aβ production is highly regulated by endocytosis and is influenced by lysosomal function. Lysosomal trafficking is influenced by CD2AP. In this study, we decreased CD2AP levels in N2a neuroblastoma cultures and PS1APP mice and analyzed Aβ levels and plaque burden.

Results: Our data show that suppressing CD2AP expression using shRNA in N2a-APP695 cells results in decreased cell membrane amyloid precursor protein, decreased Aβ release and a lower Aβ42/Aβ40 ratio. CD2AP protein is expressed in the brain as detected by western blot, and the expression level is dependent on gene dosage. In 1-month old PS1APP mice, complete loss of CD2AP in brain resulted in a decreased Aβ42/Aβ40 ratio in brain tissue lysates while there was no effect on Aβ deposition or accumulation in PS1APP mice expressing one copy of CD2AP.

Conclusion: CD2-Associated Protein affects Aβ levels and Aβ42/Aβ40 ratio in vitro. The effect of CD2-Associated Protein on Aβ metabolism is subtle in vivo.

Show MeSH
Related in: MedlinePlus