Effects of sulindac sulfide on the membrane architecture and the activity of gamma-secretase.
gamma-Secretase is a membrane-embedded multi-protein complex that catalyzes the final cut of the Alzheimer's disease-related amyloid precursor protein (APP) to amyloid-beta peptides of variable length (37-43 amino acids) via an unusual intramembrane cleavage. Recent findings propose that some commonly used non-steroidal anti-inflammatory drugs (NSAIDs) have the ability to modulate specifically gamma-secretase activity without inhibiting the enzyme as a whole. These drugs may shift the processing of APP from the longer amyloid-beta 42 peptide towards shorter, less fibrillogenic and less toxic amyloid-beta species. We hypothesize that gamma-secretase activity, as an enzyme that is strictly associated with cellular membranes, is sensitive to alterations of the hydrophobic membrane environment. Here, we show that the gamma-secretase modulator and amyloid-beta 42-lowering drug sulindac sulfide alters the physical state of the membrane and strongly decreases fluidity of cellular membranes. Furthermore, sulindac sulfide changed the protein composition of membrane microdomains, the so-called lipid rafts. Most significantly, APP C-terminal fragments (CTFs) were redistributed from rafts towards non-raft membrane domains. This could be demonstrated also in cell-free assays, where in addition presenilin-1, the catalytic subunit of the gamma-secretase complex, was shifted out of lipid rafts. Together, these findings suggest that sulindac sulfide directly alters the membrane architecture and shifts the gamma-secretase-mediated cleavage of APP towards a hydrophobic environment where the enzyme-substrate complex is in a conformation for processing preferentially shorter amyloid-beta peptides.
Gamerdinger
Martin
M
Department of Pathobiochemistry, Institute for Physiological Chemistry and Pathobiochemistry, Medical School, Johannes Gutenberg University Mainz, Duesbergweg 6, 55099 Mainz, Germany.
Clement
Angela B
AB
Behl
Christian
C
D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D015153:Blotting, Western; D016466:CHO Cells; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D021962:Membrane Microdomains / Q000187:drug effects; D053764:Presenilin-1 / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D013467:Sulindac / Q000494:pharmacology*
D016564:Amyloid beta-Protein Precursor; D000894:Anti-Inflammatory Agents, Non-Steroidal; D053764:Presenilin-1; D013467:Sulindac; D053829:Amyloid Precursor Protein Secretases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases