Tumor necrosis factor-alpha-elicited stimulation of gamma-secretase is mediated by c-Jun N-terminal kinase-dependent phosphorylation of presenilin and nicastrin.
Gamma-secretase is a multiprotein complex composed of presenilin (PS), nicastrin (NCT), Aph-1, and Pen-2, and it catalyzes the final proteolytic step in the processing of amyloid precursor protein to generate amyloid-beta. Our previous results showed that tumor necrosis factor-alpha (TNF-alpha) can potently stimulate gamma-secretase activity through a c-Jun N-terminal kinase (JNK)-dependent pathway. Here, we demonstrate that TNF-alpha triggers JNK-dependent serine/threonine phosphorylation of PS1 and NCT to stimulate gamma-secretase activity. Blocking of JNK activity with a potent JNK inhibitor (SP600125) reduces TNF-alpha-triggered phosphorylation of PS1 and NCT. Consistent with this, we show that activated JNKs can be copurified with gamma-secretase complexes and that active recombinant JNK2 can promote the phosphorylation of PS1 and NCT in vitro. Using site-directed mutagenesis and a synthetic peptide, we clearly show that the Ser(319)Thr(320) motif in PS1 is an important JNK phosphorylation site that is critical for the TNF-alpha-elicited regulation of gamma-secretase. This JNK phosphorylation of PS1 at Ser(319)Thr(320) enhances the stability of the PS1 C-terminal fragment that is necessary for gamma-secretase activity. Together, our findings strongly suggest that JNK is a critical intracellular mediator of TNF-alpha-elicited regulation of gamma-secretase and governs the pivotal step in the assembly of functional gamma-secretase.
Kuo
Lan-Hsin
LH
Laboratory of Molecular Neurobiology, Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan.
Hu
Ming-Kuan
MK
Hsu
Wen-Ming
WM
Tung
Ying-Tsen
YT
Wang
Bo-Jeng
BJ
Tsai
Wang-Wei
WW
Yen
Chen-Tung
CT
Liao
Yung-Feng
YF
D053829:Amyloid Precursor Protein Secretases / Q000737:chemistry*; D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008954:Models, Biological; D009154:Mutation; D010766:Phosphorylation; D053763:Presenilins / Q000737:chemistry*; D011485:Protein Binding; D020033:Protein Isoforms; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D004791:Enzyme Inhibitors; D008562:Membrane Glycoproteins; D053763:Presenilins; D020033:Protein Isoforms; D014409:Tumor Necrosis Factor-alpha; C413604:nicastrin protein; D053829:Amyloid Precursor Protein Secretases