Nicastrin interacts with gamma-secretase complex components via the N-terminal part of its transmembrane domain.
Two secretases are involved in the generation of amyloid beta-peptide, the principal component of amyloid plaques in the brains of Alzheimer's disease patients. While beta-secretase is a classical aspartyl protease, gamma-secretase activity is associated with a high molecular weight complex. One of the complex components, which is critically required for gamma-secretase activity is nicastrin (NCT). Here we investigate the assembly of NCT into the gamma-secretase complex. NCT mutants either lacking the entire cytoplasmic tail, the cytoplasmic tail, and the transmembrane domain (TMD), or containing a set of heterologous TMDs were expressed in cells with strongly reduced levels of endogenous NCT. Maturation of exogenous NCT, gamma-secretase complex formation and proteolytic function was then investigated. This revealed that the cytoplasmic tail of NCT is dispensable for gamma-secretase complex assembly and function. In contrast, the authentic TMD of NCT is critically required for the interaction with gamma-secretase complex components and for formation of an active gamma-secretase complex. Neither soluble NCT lacking any membrane anchor nor NCT containing a heterologous TMD were inserted into the gamma-secretase complex. We identified the N-terminal region of the NCT TMD as a functionally important entity of NCT. These data thus demonstrate that NCT interacts with other gamma-secretase complex components via its TMD.
Capell
Anja
A
Adolf-Butenandt-Institute, Department of Biochemistry, Laboratory for Alzheimer's and Parkinson's Disease Research, Schillerstrasse 44, Ludwig-Maximilians-University, 80336 Munich, Germany.
Kaether
Christoph
C
Edbauer
Dieter
D
Shirotani
Keiro
K
Merkl
Sabine
S
Steiner
Harald
H
Haass
Christian
C
D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; D015153:Blotting, Western; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D015536:Down-Regulation; D010450:Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; C413604:nicastrin protein; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human