Coordinated and widespread expression of gamma-secretase in vivo: evidence for size and molecular heterogeneity.
Gamma-secretase is a high molecular weight protein complex composed of four subunits, namely, presenilin (PS; 1 or 2), nicastrin, anterior pharynx defective-1 (Aph-1; A or B), and presenilin enhancer-2 (Pen-2), and is responsible for the cleavage of a number of type-1 transmembrane proteins. A fundamental question is whether different gamma-secretase complexes exist in vivo. We demonstrate here by in situ hybridization and by Northern and Western blotting that the gamma-secretase components are widely distributed in all tissues investigated. The expression of the different subunits seems tightly coregulated. However, some variation in the expression of the Aph-1 proteins is observed, Aph-1A being more general and abundantly distributed than Aph-1B. The previously uncharacterized rodent-specific Aph-1C mRNA is highly expressed in the kidney and testis but not in brain or other tissues, indicating some tissue specificity for the Aph-1 component of the gamma-secretase complex. Blue-native electrophoresis revealed size heterogeneity of the mature gamma-secretase complex in various tissues. Using co-immunoprecipitations and blue-native electrophoresis at endogenous protein levels, we find evidence that several independent gamma-secretase complexes can coexist in the same cell type. In conclusion, our results suggest that gamma-secretase is a heterogeneous family of protein complexes widely expressed in the adult organism.
Neuronal Cell Biology and Gene Transfer, Center for Human Genetics, Flanders Interuniversity Institute for Biotechnology (VIB4) and K.U. Leuven, 3000 Leuven, Belgium.
Sébastien S
SS
Hébert
Lutgarde
L
Serneels
Tim
T
Dejaegere
Katrien
K
Horré
Michal
M
Dabrowski
Veerle
V
Baert
Wim
W
Annaert
Dieter
D
Hartmann
Bart
B
De Strooper
D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases; D000818:Animals; D016282:Aspartic Acid Endopeptidases; D015153:Blotting, Western; D002460:Cell Line; D020090:Chromosome Segregation; D010450:Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010447:Peptide Hydrolases; D053764:Presenilin-1; D053766:Presenilin-2; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014018:Tissue Distribution; D014162:Transfection
D007527:Isoenzymes; D008565:Membrane Proteins; C508853:PSEN1 protein, human; C508861:PSEN2 protein, human; C469349:PSENEN protein, human; D053764:Presenilin-1; D053766:Presenilin-2; D020033:Protein Isoforms; D012333:RNA, Messenger; C475154:APH1A protein, human; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D010447:Peptide Hydrolases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human; C509282:Bace1 protein, mouse