Analysis of the gamma-secretase interactome and validation of its association with tetraspanin-enriched microdomains.
Gamma-secretase, an aspartyl protease that belongs to the iCLiPs (intramembrane cleaving proteases) family, is a multiprotein complex that consists of presenilin (PS), nicastrin (NCT), Aph-1 and Pen-2 (ref. 1). It is responsible for generation of the beta-amyloid peptide (Abeta), the primary component of senile plaques in the brains of patients with Alzheimer's disease. Although the four components are necessary and sufficient for gamma-secretase activity, additional proteins are possibly involved in its regulation. Consequently, we purified proteins associated with the active gamma-secretase complex from reconstituted PS-deficient fibroblasts, using tandem affinity purification (TAP) and identified a series of proteins that transiently interact with the gamma-secretase complex and are probably involved in complex maturation, membrane trafficking and, importantly, the tetraspanin web. Tetraspanins form detergent-resistant microdomains in the cell membrane and regulate cell adhesion, cell signalling and proteolysis. Association of the gamma-secretase complex with tetraspanin-enriched microdomains provides an explanation for the previously documented localization of gamma-secretase to raft-like domains. Thus, these studies suggest that maintenance of the integrity of tetraspanin microdomains contributes to the refinement of proteolytic activity of the gamma-secretase complex.
Wakabayashi
Tomoko
T
Center for Human Genetics, K.U.Leuven, Herestraat 49, B-3000 Leuven, Belgium.
Craessaerts
Katleen
K
Bammens
Leen
L
Bentahir
Mostafa
M
Borgions
Filip
F
Herdewijn
Piet
P
Staes
An
A
Timmerman
Evy
E
Vandekerckhove
Joël
J
Rubinstein
Eric
E
Boucheix
Claude
C
Gevaert
Kris
K
De Strooper
Bart
B
D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D011485:Protein Binding
D008565:Membrane Proteins; D053829:Amyloid Precursor Protein Secretases