Nmnat2 attenuates amyloidogenesis and up-regulates ADAM10 in AMPK activity-dependent manner

Amyloid-β (Aβ) accumulating is considered as a causative factor for formation of senile plaque in Alzheimer's disease (AD), but its mechanism is still elusive. The Nicotinamide mononucleotide adenylyltransferase 2 (Nmnat2), a key redox cofactor for energy metabolism, is reduced in AD. Accumulative evidence has shown that the decrease of α-secretase activity, a disintegrin and metalloprotease domain 10 (ADAM10), is responsible for the increase of Aβ productions in AD patient's brain. Here, we observe that the activity of α-secretase ADAM10 and levels of Nmnat2 are significantly decreased, meanwhile there is a simultaneous elevation of Aβ in Tg2576 mice. Over-expression of Nmnat2 increases the mRNA expression of α-secretase ADAM10 and its activity and inhibits Aβ production in N2a/APPswe cells, which can be abolished by Compound C, an AMPK antagonist, suggesting that AMPK is involved in over-expression of Nmnat2 against Aβ production. The further assays demonstrate that Nmnat2 activates AMPK by up-regulating the ratio of NAD⁺/NADH, moreover AMPK agonist AICAR can also increase ADAM10 activity and reduces Aβ1-40/1-42. Taken together, Nmnat2 suppresses Aβ production and up-regulates ADAM10 in AMPK activity-dependent manner, suggesting that Nmnat2 may serve as a new potential target in arresting AD.