Deletion of Nampt in Projection Neurons of Adult Mice Leads to Motor Dysfunction, Neurodegeneration, and Death

Publication date: 29 August 2017
Source:Cell Reports, Volume 20, Issue 9
Author(s): Xiaowan Wang, Qiao Zhang, Ruisi Bao, Nannan Zhang, Yingzhen Wang, Luis Polo-Parada, Andrew Tarim, Aidan Alemifar, Xianlin Han, Heather M. Wilkins, Russell H. Swerdlow, Xinglong Wang, Shinghua Ding
Intracellular nicotinamide phosphoribosyltransferase (iNAMPT) is the rate-limiting enzyme of the mammalian NAD⁺ biosynthesis salvage pathway. Using inducible and conditional knockout (cKO) mice, we show that Nampt gene deletion in adult projection neurons leads to a progressive loss of body weight, hypothermia, motor neuron (MN) degeneration, motor function deficits, paralysis, and death. Nampt deletion causes mitochondrial dysfunction, muscle fiber type conversion, and atrophy, as well as defective synaptic function at neuromuscular junctions (NMJs). When treated with nicotinamide mononucleotide (NMN), Nampt cKO mice exhibit reduced motor function deficits and prolonged lifespan. iNAMPT protein levels are significantly reduced in the spinal cord of amyotrophic lateral sclerosis (ALS) patients, indicating the involvement of NAMPT in ALS pathology. Our findings reveal that neuronal NAMPT plays an essential role in mitochondrial bioenergetics, motor function, and survival. Our study suggests that the NAMPT-mediated NAD⁺ biosynthesis pathway is a potential therapeutic target for degenerative MN diseases.

Graphical abstract

Teaser

Wang et al. find that projection neuron NAMPT is essential for mitochondrial bioenergetics, motor function, and survival of adult mice and that iNAMPT is reduced in ALS patients. NMN improves health and extends the lifespan of Nampt knockout mice. Their findings suggest therapeutic avenues for motor neuron degenerative diseases.


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