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Reciprocal relationship between APP positioning relative to the membrane and PS1 conformation.

Uemura K, Farner KC, Nasser-Ghodsi N, Jones P, Berezovska O - Mol Neurodegener (2011)

Bottom Line: Several familial Alzheimer disease (FAD) mutations within the transmembrane region of the amyloid precursor protein (APP) increase the Aβ42/40 ratio without increasing total Aβ production.In the present study, we analyzed the impact of FAD mutations and γ-secretase modulators (GSMs) that alter the Aβ42/40 ratio on APP C-terminus (CT) positioning relative to the membrane, reasoning that changes in the alignment of the APP intramembranous domain and presenilin 1 (PS1) may impact the PS1/γ-secretase cleavage site on APP.Thus, we propose that there is a reciprocal relationship between APP-CT positioning relative to the membrane and PS1 conformation, suggesting that factors that modulate either APP positioning in the membrane or PS1 conformation could be exploited therapeutically.

View Article: PubMed Central - HTML - PubMed

Affiliation: Alzheimer Research Unit, MassGeneral Institute for Neurodegenerative Diseases, Massachusetts General Hospital, Charlestown, MA 02129, USA. oberezovska@partners.org.

ABSTRACT

Background: Several familial Alzheimer disease (FAD) mutations within the transmembrane region of the amyloid precursor protein (APP) increase the Aβ42/40 ratio without increasing total Aβ production. In the present study, we analyzed the impact of FAD mutations and γ-secretase modulators (GSMs) that alter the Aβ42/40 ratio on APP C-terminus (CT) positioning relative to the membrane, reasoning that changes in the alignment of the APP intramembranous domain and presenilin 1 (PS1) may impact the PS1/γ-secretase cleavage site on APP.

Results: By using a Förster resonance energy transfer (FRET)-based technique, fluorescent lifetime imaging microscopy (FLIM), we show that Aβ42/40 ratio-modulating factors which target either APP substrate or PS1/γ-secretase affect proximity of the APP-CT to the membrane and change PS1 conformation.

Conclusions: Thus, we propose that there is a reciprocal relationship between APP-CT positioning relative to the membrane and PS1 conformation, suggesting that factors that modulate either APP positioning in the membrane or PS1 conformation could be exploited therapeutically.

No MeSH data available.


Related in: MedlinePlus

FAD-linked PS1 mutations alter APP CT positioning . FLIM analysis of the myrGFP lifetime in PS1/2 dKO cells stably (A) or transiently (B) expressing wild-type or mutant PS1. The cells were co-transfected with myrGFP and wild-type APP-RFP as a FRET pair, and the proximity between myrGFP (membrane) and RFP (APP-CT) was monitored. All FAD-linked PS1 mutations significantly shortened myrGFP lifetime compared to that in the wild-type PS1 expressing cells. The expression of E318G PS1 caused no significant difference in the donor lifetime. Three independent experiments were performed. Data from a representative experiment is shown (n: number of cells; mean ± SD;*p < 0.05; **p < 0.01; ANOVA).
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Figure 3: FAD-linked PS1 mutations alter APP CT positioning . FLIM analysis of the myrGFP lifetime in PS1/2 dKO cells stably (A) or transiently (B) expressing wild-type or mutant PS1. The cells were co-transfected with myrGFP and wild-type APP-RFP as a FRET pair, and the proximity between myrGFP (membrane) and RFP (APP-CT) was monitored. All FAD-linked PS1 mutations significantly shortened myrGFP lifetime compared to that in the wild-type PS1 expressing cells. The expression of E318G PS1 caused no significant difference in the donor lifetime. Three independent experiments were performed. Data from a representative experiment is shown (n: number of cells; mean ± SD;*p < 0.05; **p < 0.01; ANOVA).

Mentions: We have previously found that FAD-linked PS1 mutants modify PS1 conformation, and as a result alter an alignment of PS1/γ-secretase with the APP substrate [27]. To test whether this may lead to a change in the positioning of APP-CT relative to the membrane, we monitored proximity between the membrane and APP-CT in PS1/2 dKO cell lines, reconstituted by stable expression of either wild-type PS1 or PS1 with FAD-linked mutations (L166P, Delta9, A246E). Indeed, we found that expression of each FAD-linked PS1 mutation caused a change in the APP-CT positioning (shortening of the GFP donor lifetime) (Figure 3A), similar to that caused by the FAD APP mutations.


Reciprocal relationship between APP positioning relative to the membrane and PS1 conformation.

Uemura K, Farner KC, Nasser-Ghodsi N, Jones P, Berezovska O - Mol Neurodegener (2011)

FAD-linked PS1 mutations alter APP CT positioning . FLIM analysis of the myrGFP lifetime in PS1/2 dKO cells stably (A) or transiently (B) expressing wild-type or mutant PS1. The cells were co-transfected with myrGFP and wild-type APP-RFP as a FRET pair, and the proximity between myrGFP (membrane) and RFP (APP-CT) was monitored. All FAD-linked PS1 mutations significantly shortened myrGFP lifetime compared to that in the wild-type PS1 expressing cells. The expression of E318G PS1 caused no significant difference in the donor lifetime. Three independent experiments were performed. Data from a representative experiment is shown (n: number of cells; mean ± SD;*p < 0.05; **p < 0.01; ANOVA).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3046905&req=5

Figure 3: FAD-linked PS1 mutations alter APP CT positioning . FLIM analysis of the myrGFP lifetime in PS1/2 dKO cells stably (A) or transiently (B) expressing wild-type or mutant PS1. The cells were co-transfected with myrGFP and wild-type APP-RFP as a FRET pair, and the proximity between myrGFP (membrane) and RFP (APP-CT) was monitored. All FAD-linked PS1 mutations significantly shortened myrGFP lifetime compared to that in the wild-type PS1 expressing cells. The expression of E318G PS1 caused no significant difference in the donor lifetime. Three independent experiments were performed. Data from a representative experiment is shown (n: number of cells; mean ± SD;*p < 0.05; **p < 0.01; ANOVA).
Mentions: We have previously found that FAD-linked PS1 mutants modify PS1 conformation, and as a result alter an alignment of PS1/γ-secretase with the APP substrate [27]. To test whether this may lead to a change in the positioning of APP-CT relative to the membrane, we monitored proximity between the membrane and APP-CT in PS1/2 dKO cell lines, reconstituted by stable expression of either wild-type PS1 or PS1 with FAD-linked mutations (L166P, Delta9, A246E). Indeed, we found that expression of each FAD-linked PS1 mutation caused a change in the APP-CT positioning (shortening of the GFP donor lifetime) (Figure 3A), similar to that caused by the FAD APP mutations.

Bottom Line: Several familial Alzheimer disease (FAD) mutations within the transmembrane region of the amyloid precursor protein (APP) increase the Aβ42/40 ratio without increasing total Aβ production.In the present study, we analyzed the impact of FAD mutations and γ-secretase modulators (GSMs) that alter the Aβ42/40 ratio on APP C-terminus (CT) positioning relative to the membrane, reasoning that changes in the alignment of the APP intramembranous domain and presenilin 1 (PS1) may impact the PS1/γ-secretase cleavage site on APP.Thus, we propose that there is a reciprocal relationship between APP-CT positioning relative to the membrane and PS1 conformation, suggesting that factors that modulate either APP positioning in the membrane or PS1 conformation could be exploited therapeutically.

View Article: PubMed Central - HTML - PubMed

Affiliation: Alzheimer Research Unit, MassGeneral Institute for Neurodegenerative Diseases, Massachusetts General Hospital, Charlestown, MA 02129, USA. oberezovska@partners.org.

ABSTRACT

Background: Several familial Alzheimer disease (FAD) mutations within the transmembrane region of the amyloid precursor protein (APP) increase the Aβ42/40 ratio without increasing total Aβ production. In the present study, we analyzed the impact of FAD mutations and γ-secretase modulators (GSMs) that alter the Aβ42/40 ratio on APP C-terminus (CT) positioning relative to the membrane, reasoning that changes in the alignment of the APP intramembranous domain and presenilin 1 (PS1) may impact the PS1/γ-secretase cleavage site on APP.

Results: By using a Förster resonance energy transfer (FRET)-based technique, fluorescent lifetime imaging microscopy (FLIM), we show that Aβ42/40 ratio-modulating factors which target either APP substrate or PS1/γ-secretase affect proximity of the APP-CT to the membrane and change PS1 conformation.

Conclusions: Thus, we propose that there is a reciprocal relationship between APP-CT positioning relative to the membrane and PS1 conformation, suggesting that factors that modulate either APP positioning in the membrane or PS1 conformation could be exploited therapeutically.

No MeSH data available.


Related in: MedlinePlus