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Macroautophagy--a novel Beta-amyloid peptide-generating pathway activated in Alzheimer's disease.

Yu WH, Cuervo AM, Kumar A, Peterhoff CM, Schmidt SD, Lee JH, Mohan PS, Mercken M, Farmery MR, Tjernberg LO, Jiang Y, Duff K, Uchiyama Y, Näslund J, Mathews PM, Cataldo AM, Nixon RA - J. Cell Biol. (2005)

Bottom Line: Purified AVs contain APP and beta-cleaved APP and are highly enriched in PS1, nicastrin, and PS-dependent gamma-secretase activity.Inducing or inhibiting macroautophagy in neuronal and nonneuronal cells by modulating mammalian target of rapamycin kinase elicits parallel changes in AV proliferation and Abeta production.Our results, therefore, link beta-amyloidogenic and cell survival pathways through macroautophagy, which is activated and is abnormal in AD.

View Article: PubMed Central - PubMed

Affiliation: Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY 10962, USA.

ABSTRACT
Macroautophagy, which is a lysosomal pathway for the turnover of organelles and long-lived proteins, is a key determinant of cell survival and longevity. In this study, we show that neuronal macroautophagy is induced early in Alzheimer's disease (AD) and before beta-amyloid (Abeta) deposits extracellularly in the presenilin (PS) 1/Abeta precursor protein (APP) mouse model of beta-amyloidosis. Subsequently, autophagosomes and late autophagic vacuoles (AVs) accumulate markedly in dystrophic dendrites, implying an impaired maturation of AVs to lysosomes. Immunolabeling identifies AVs in the brain as a major reservoir of intracellular Abeta. Purified AVs contain APP and beta-cleaved APP and are highly enriched in PS1, nicastrin, and PS-dependent gamma-secretase activity. Inducing or inhibiting macroautophagy in neuronal and nonneuronal cells by modulating mammalian target of rapamycin kinase elicits parallel changes in AV proliferation and Abeta production. Our results, therefore, link beta-amyloidogenic and cell survival pathways through macroautophagy, which is activated and is abnormal in AD.

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Related in: MedlinePlus

Immunolocalization of Aβ in AVs from L/APP cells and PS1/APP brains and γ-secretase components (PS1 and nicastrin) in L/APP cells. Immunogold localization of Aβ40 (A), Aβ42 (B), PS1 (C), nicastrin (D), and in the absence of primary antibody (E) in L/APP cells grown for 6 h in the absence of Leu and His. (F) Quantification of gold particle frequency in AV or tubulovesicular compartments (TBV), which comprise 27.0 ± 11.0 and 19.2 ± 7.2%, respectively, of the total cell area. Error bars represent SEM. (G and H) IEM followed by silver stain enhancement for Aβ40 was performed in 9-mo-old PS1/APP mice.
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fig6: Immunolocalization of Aβ in AVs from L/APP cells and PS1/APP brains and γ-secretase components (PS1 and nicastrin) in L/APP cells. Immunogold localization of Aβ40 (A), Aβ42 (B), PS1 (C), nicastrin (D), and in the absence of primary antibody (E) in L/APP cells grown for 6 h in the absence of Leu and His. (F) Quantification of gold particle frequency in AV or tubulovesicular compartments (TBV), which comprise 27.0 ± 11.0 and 19.2 ± 7.2%, respectively, of the total cell area. Error bars represent SEM. (G and H) IEM followed by silver stain enhancement for Aβ40 was performed in 9-mo-old PS1/APP mice.

Mentions: Using immunogold labeling and EM in Leu- and His-deprived L/APP cells, we observed that Aβ and γ-secretase components were preferentially localized to AVs in situ and, as previously described (Cupers et al., 2001), were localized to tubulovesicular compartments corresponding morphologically to ER/Golgi/endosomes. Immunolabeling for Aβ40 or Aβ42 using COOH-terminal–specific antibodies (Mathews et al., 2002) preferentially decorated the same compartments (Fig. 6, A and B, respectively). PS1 and nicastrin antibodies directed against endogenously expressed proteins also principally decorated both internal and limiting membrane components of AVs in L/APP cells (Fig. 6, C and D, respectively). Quantitative analysis of gold particles showed high proportions of immunogold staining for Aβ40, Aβ42, PS1, and nicastrin that were associated with AVs (43, 35, 48, and 35%, respectively) and tubulovesicular compartments (31, 37, 33, and 35%, respectively; Fig. 6 F). We found that the AV and tubulovesicular compartments comprise 27.0 ± 11.0 and 19.2 ± 7.2%, respectively, of the total cell area, indicating that PS1 signal in these organelles was five times higher than in other subcellular compartments and was similar to the organellar distribution in the PS1/APP brain (Fig. 3, C and D). Immunolabeling of brains from 9-mo-old PS1/APP mice with Aβ40 antibody also indicated a significant localization of Aβ40 in AVs (Fig. 6, G and H).


Macroautophagy--a novel Beta-amyloid peptide-generating pathway activated in Alzheimer's disease.

Yu WH, Cuervo AM, Kumar A, Peterhoff CM, Schmidt SD, Lee JH, Mohan PS, Mercken M, Farmery MR, Tjernberg LO, Jiang Y, Duff K, Uchiyama Y, Näslund J, Mathews PM, Cataldo AM, Nixon RA - J. Cell Biol. (2005)

Immunolocalization of Aβ in AVs from L/APP cells and PS1/APP brains and γ-secretase components (PS1 and nicastrin) in L/APP cells. Immunogold localization of Aβ40 (A), Aβ42 (B), PS1 (C), nicastrin (D), and in the absence of primary antibody (E) in L/APP cells grown for 6 h in the absence of Leu and His. (F) Quantification of gold particle frequency in AV or tubulovesicular compartments (TBV), which comprise 27.0 ± 11.0 and 19.2 ± 7.2%, respectively, of the total cell area. Error bars represent SEM. (G and H) IEM followed by silver stain enhancement for Aβ40 was performed in 9-mo-old PS1/APP mice.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171227&req=5

fig6: Immunolocalization of Aβ in AVs from L/APP cells and PS1/APP brains and γ-secretase components (PS1 and nicastrin) in L/APP cells. Immunogold localization of Aβ40 (A), Aβ42 (B), PS1 (C), nicastrin (D), and in the absence of primary antibody (E) in L/APP cells grown for 6 h in the absence of Leu and His. (F) Quantification of gold particle frequency in AV or tubulovesicular compartments (TBV), which comprise 27.0 ± 11.0 and 19.2 ± 7.2%, respectively, of the total cell area. Error bars represent SEM. (G and H) IEM followed by silver stain enhancement for Aβ40 was performed in 9-mo-old PS1/APP mice.
Mentions: Using immunogold labeling and EM in Leu- and His-deprived L/APP cells, we observed that Aβ and γ-secretase components were preferentially localized to AVs in situ and, as previously described (Cupers et al., 2001), were localized to tubulovesicular compartments corresponding morphologically to ER/Golgi/endosomes. Immunolabeling for Aβ40 or Aβ42 using COOH-terminal–specific antibodies (Mathews et al., 2002) preferentially decorated the same compartments (Fig. 6, A and B, respectively). PS1 and nicastrin antibodies directed against endogenously expressed proteins also principally decorated both internal and limiting membrane components of AVs in L/APP cells (Fig. 6, C and D, respectively). Quantitative analysis of gold particles showed high proportions of immunogold staining for Aβ40, Aβ42, PS1, and nicastrin that were associated with AVs (43, 35, 48, and 35%, respectively) and tubulovesicular compartments (31, 37, 33, and 35%, respectively; Fig. 6 F). We found that the AV and tubulovesicular compartments comprise 27.0 ± 11.0 and 19.2 ± 7.2%, respectively, of the total cell area, indicating that PS1 signal in these organelles was five times higher than in other subcellular compartments and was similar to the organellar distribution in the PS1/APP brain (Fig. 3, C and D). Immunolabeling of brains from 9-mo-old PS1/APP mice with Aβ40 antibody also indicated a significant localization of Aβ40 in AVs (Fig. 6, G and H).

Bottom Line: Purified AVs contain APP and beta-cleaved APP and are highly enriched in PS1, nicastrin, and PS-dependent gamma-secretase activity.Inducing or inhibiting macroautophagy in neuronal and nonneuronal cells by modulating mammalian target of rapamycin kinase elicits parallel changes in AV proliferation and Abeta production.Our results, therefore, link beta-amyloidogenic and cell survival pathways through macroautophagy, which is activated and is abnormal in AD.

View Article: PubMed Central - PubMed

Affiliation: Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY 10962, USA.

ABSTRACT
Macroautophagy, which is a lysosomal pathway for the turnover of organelles and long-lived proteins, is a key determinant of cell survival and longevity. In this study, we show that neuronal macroautophagy is induced early in Alzheimer's disease (AD) and before beta-amyloid (Abeta) deposits extracellularly in the presenilin (PS) 1/Abeta precursor protein (APP) mouse model of beta-amyloidosis. Subsequently, autophagosomes and late autophagic vacuoles (AVs) accumulate markedly in dystrophic dendrites, implying an impaired maturation of AVs to lysosomes. Immunolabeling identifies AVs in the brain as a major reservoir of intracellular Abeta. Purified AVs contain APP and beta-cleaved APP and are highly enriched in PS1, nicastrin, and PS-dependent gamma-secretase activity. Inducing or inhibiting macroautophagy in neuronal and nonneuronal cells by modulating mammalian target of rapamycin kinase elicits parallel changes in AV proliferation and Abeta production. Our results, therefore, link beta-amyloidogenic and cell survival pathways through macroautophagy, which is activated and is abnormal in AD.

Show MeSH
Related in: MedlinePlus