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. Author manuscript; available in PMC: 2009 May 14.
Published in final edited form as: J Neurochem. 2008 Nov 25;108(2):350–360. doi: 10.1111/j.1471-4159.2008.05760.x

Figure 3. N-cadherin expression in CHO cells increases PS1-APP interactions and induces conformational change of PS1/γ-secretase.

Figure 3

(A and B) For the FLIM assay, PS1 is stained at its loop region with Alexa 488 (FRET donor) and APP is stained at its CT with Cy3(FRET acceptor). The fluorescence lifetime of Alexa 488 is displayed as a pseudocolor image: if PS1 and APP molecules are closer together, the donor fluorescence lifetime will be shorter, and the color will be closer to red. Alexa488 lifetime was significantly shortened in APPSw/Ncad-CHO cells (B), compared to that in APPSw-CHO cells (A), indicating that PS1 and APP came into closer proximity in the presence of N-cadherin. Scale bar: 10μm

(C and D) APPSw-CHO (C) or APPSw/Ncad-CHO (D) cells were immunostained with antibodies against PS1 NT (Alexa 488) and CT (Cy3). The proximity between PS1 NT and CT was evaluated by measuring lifetime of the Alexa 488 donor fluorophore (PS1 NT Alexa 488) in the FLIM assay. The fluorescence lifetime of Alexa 488 is displayed as a pseudocolor image. Red pixels indicate close proximity between PS1 N- and C-termini. Alexa 488 lifetime in APPSw/Ncad-CHO (D) cells was significantly increased, compared to that in APPSw-CHO cells (C), indicating that N-cadherin “opened” PS1 conformation with NT and CT further apart. Scale bar: 10μm