CDNF rescues motor neurons in three animal models of ALS by targeting ER stress

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease primarily afflicting motor neurons (MNs) of the spinal cord, brainstem, and motor cortex, leading to paralysis and eventually death within 3 to 5 years of diagnosis. No cure or effective therapy to halt ALS progression is available. The role of chronic endoplasmic reticulum (ER) stress in the pathophysiology of ALS, as well as a potential drug target, has received increasing attention. Here, we investigated the therapeutic effect of the ER resident protein cerebral dopamine neurotrophic factor (CDNF) in preclinical models of ALS harboring different genetic mutations. We identify that intracerebroventricular (i.c.v.) administration of CDNF significantly halts the progression of the disease and improves motor behavior in TDP43-M337V and SOD1-G93A rodent models of ALS. CDNF rescues MNs in vitro and in vivo from ER stress associated cell death and its beneficial effect is independent of genetic disease etiology. Notably, CDNF regulates the unfolded protein response (UPR) initiated by transducers IRE1α, PERK, and ATF6, thereby enhancing MN survival. Thus, CDNF holds great promise for the design of new rational treatments for ALS.