TY - JOUR
T1 - S-Palmitoylation of γ-secretase subunits nicastrin and aph-1
AU - Cheng, Haipeng
AU - Vetrivel, Kulandaivelu S.
AU - Drisdel, Renaldo C.
AU - Meckler, Xavier
AU - Gong, Ping
AU - Leem, Jae Yoon
AU - Li, Tong
AU - Carter, Meghan
AU - Chen, Ying
AU - Nguyen, Phuong
AU - Iwatsubo, Takeshi
AU - Tomita, Taisuke
AU - Wong, Philip C.
AU - Green, William N.
AU - Kounnas, Maria Z.
AU - Thinakaran, Gopal
PY - 2009/1/16
Y1 - 2009/1/16
N2 - Proteolytic processing of amyloid precursor protein (APP) by β- and γ-secretases generates β-amyloid (Aβ) peptides, which accumulate in the brains of individuals affected by Alzheimer disease. Detergent-resistant membrane microdomains (DRM) rich in cholesterol and sphingolipid, termed lipid rafts, have been implicated in Aβ production. Previously, we and others reported that the four integral subunits of the γ-secretase associate with DRM. In this study we investigated the mechanisms underlying DRM association of γ-secretase subunits. We report that in cultured cells and in brain the γ-secretase subunits nicastrin and APH-1 undergo S-palmitoylation, the post-translational covalent attachment of the long chain fatty acid palmitate common in lipid raft-associated proteins. By mutagenesis we show that nicastrin is S-palmitoylated at Cys 689, and APH-1 is S-palmitoylated at Cys 182 and Cys 245. S-Palmitoylation-defective nicastrin and APH-1 form stable γ-secretase complexes when expressed in knock-out fibroblasts lacking wild type sub-units, suggesting that S-palmitoylation is not essential for γ-secretase assembly. Nevertheless, fractionation studies show that S-palmitoylation contributes to DRM association of nicastrin and APH-1. Moreover, pulse-chase analyses reveal that S-palmitoylation is important for nascent polypeptide stability of both proteins. Co-expression of S-palmitoylation-deficient nicastrin and APH-1 in cultured cells neither affects Aβ40, Aβ42, and AICD production, nor intramembrane processing of Notch and N-cadherin. Our findings suggest that S-palmitoylation plays a role in stability and raft localization of nicastrin and APH-1, but does not directly modulate γ-secretase processing of APP and other substrates.
AB - Proteolytic processing of amyloid precursor protein (APP) by β- and γ-secretases generates β-amyloid (Aβ) peptides, which accumulate in the brains of individuals affected by Alzheimer disease. Detergent-resistant membrane microdomains (DRM) rich in cholesterol and sphingolipid, termed lipid rafts, have been implicated in Aβ production. Previously, we and others reported that the four integral subunits of the γ-secretase associate with DRM. In this study we investigated the mechanisms underlying DRM association of γ-secretase subunits. We report that in cultured cells and in brain the γ-secretase subunits nicastrin and APH-1 undergo S-palmitoylation, the post-translational covalent attachment of the long chain fatty acid palmitate common in lipid raft-associated proteins. By mutagenesis we show that nicastrin is S-palmitoylated at Cys 689, and APH-1 is S-palmitoylated at Cys 182 and Cys 245. S-Palmitoylation-defective nicastrin and APH-1 form stable γ-secretase complexes when expressed in knock-out fibroblasts lacking wild type sub-units, suggesting that S-palmitoylation is not essential for γ-secretase assembly. Nevertheless, fractionation studies show that S-palmitoylation contributes to DRM association of nicastrin and APH-1. Moreover, pulse-chase analyses reveal that S-palmitoylation is important for nascent polypeptide stability of both proteins. Co-expression of S-palmitoylation-deficient nicastrin and APH-1 in cultured cells neither affects Aβ40, Aβ42, and AICD production, nor intramembrane processing of Notch and N-cadherin. Our findings suggest that S-palmitoylation plays a role in stability and raft localization of nicastrin and APH-1, but does not directly modulate γ-secretase processing of APP and other substrates.
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U2 - 10.1074/jbc.M806380200
DO - 10.1074/jbc.M806380200
M3 - Article
C2 - 19028695
AN - SCOPUS:59449106952
SN - 0021-9258
VL - 284
SP - 1373
EP - 1384
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 3
ER -