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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

CD2AP protein was expressed in the brain. (A) Western blot for CD2AP and tubulin in cortices from CD2AP−/−, CD2AP+/− and CD2AP+/+ mice. (B) Quantification of CD2AP levels in CD2AP+/− and CD2AP+/+ mice in western blot presented in A. (n = 3/group, **, p < 0.01, Student’s t-test).
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Fig3: CD2AP protein was expressed in the brain. (A) Western blot for CD2AP and tubulin in cortices from CD2AP−/−, CD2AP+/− and CD2AP+/+ mice. (B) Quantification of CD2AP levels in CD2AP+/− and CD2AP+/+ mice in western blot presented in A. (n = 3/group, **, p < 0.01, Student’s t-test).

Mentions: Before we studied the effects of CD2AP on Aβ pathology in vivo, we first determined whether CD2AP is expressed in the brain and whether the expression level correlates with CD2AP gene dosage. Using western blot, we detected CD2AP in CD2AP+/+ brains with CD2AP−/− brains serving as a negative control (Figure 3A). As reported in the kidney [17], CD2AP protein level in the brains of mice with CD2AP haploinsufficiency (CD2AP+/−) is about 50% of the level in CD2AP+/+ mice (Figure 3B).Figure 3


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)

CD2AP protein was expressed in the brain. (A) Western blot for CD2AP and tubulin in cortices from CD2AP−/−, CD2AP+/− and CD2AP+/+ mice. (B) Quantification of CD2AP levels in CD2AP+/− and CD2AP+/+ mice in western blot presented in A. (n = 3/group, **, 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

Fig3: CD2AP protein was expressed in the brain. (A) Western blot for CD2AP and tubulin in cortices from CD2AP−/−, CD2AP+/− and CD2AP+/+ mice. (B) Quantification of CD2AP levels in CD2AP+/− and CD2AP+/+ mice in western blot presented in A. (n = 3/group, **, p < 0.01, Student’s t-test).
Mentions: Before we studied the effects of CD2AP on Aβ pathology in vivo, we first determined whether CD2AP is expressed in the brain and whether the expression level correlates with CD2AP gene dosage. Using western blot, we detected CD2AP in CD2AP+/+ brains with CD2AP−/− brains serving as a negative control (Figure 3A). As reported in the kidney [17], CD2AP protein level in the brains of mice with CD2AP haploinsufficiency (CD2AP+/−) is about 50% of the level in CD2AP+/+ mice (Figure 3B).Figure 3

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