Nuclear factor-kappaB activated by capacitative Ca2+ entry enhances muscarinic receptor-mediated soluble amyloid precursor protein (sAPPalpha) release in SH-SY5Y cells.
G(q/11) protein-coupled muscarinic receptors are known to regulate the release of soluble amyloid precursor protein (sAPPalpha) produced by alpha-secretase processing; however, their signaling mechanisms remain to be elucidated. It has been reported that a muscarinic agonist activates nuclear factor (NF)-kappaB, a transcription factor that has been shown to play an important role in the Alzheimer disease brain, and that NF-kappaB activation is regulated by intracellular Ca2+ level. In the present study, we investigated whether NF-kappaB activation plays a role in muscarinic receptor-mediated sAPPalpha release enhancement and contributes to a changed capacitative Ca2+ entry (CCE), which was suggested to be involved in the muscarinic receptor-mediated stimulation of sAPPalpha release. Muscarinic receptor-mediated NF-kappaB activation was confirmed by observing the translocation of the active subunit (p65) of NF-kappaB to the nucleus by the muscarinic agonist, oxotremorine M (oxoM), in SH-SY5Y neuroblastoma cells expressing muscarinic receptors that are predominantly of the M3 subtype. NF-kappaB activation and sAPPalpha release enhancement induced by oxoM were inhibited by NF-kappaB inhibitors, such as an NF-kappaB peptide inhibitor (SN50), an IkappaB alpha kinase inhibitor (BAY11-7085), a proteasome inhibitor (MG132), the inhibitor of proteasome activity and IkappaB phosphorylation, pyrrolidine dithiocarbamate, the novel NF-kappaB activation inhibitor (6-amino-4-(4-phenoxyphenylethylamino) quinazoline), and by an intracellular Ca2+ chelator (TMB-8). Furthermore, both oxoM-induced NF-kappaB activation and sAPPalpha release were antagonized by CCE inhibitors (gadolinium or SKF96365) but not by voltage-gated Ca2+-channel blockers. On the other hand, treatment of cells with NF-kappaB inhibitors (SN50, BAY11-7085, MG132, or pyrrolidine dithiocarbamate) did not inhibit muscarinic receptor-mediated CCE. These findings provide evidence for the involvement of NF-kappaB regulated by CCE in muscarinic receptor-mediated sAPPalpha release enhancement.
Choi
Shinkyu
S
Research Institute of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul 120-750, Korea.
Kim
Jin Hyoung
JH
Roh
Eun-Jihn
EJ
Ko
Moon-Jeong
MJ
Jung
Ji-Eun
JE
Kim
Hwa-Jung
HJ
D000544:Alzheimer Disease / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism*; D013450:Sulfones / Q000494:pharmacology
D016564:Amyloid beta-Protein Precursor; C416282:BAY 11-7085; D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D016328:NF-kappa B; D009570:Nitriles; D010455:Peptides; D011976:Receptors, Muscarinic; C118258:SN50 peptide; D013450:Sulfones; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D002118:Calcium