CDNF rescues motor neurons in models of amyotrophic lateral sclerosis by targeting endoplasmic reticulum stress

Abstract

Amyotrophic lateral sclerosis is a progressive neurodegenerative disease that affects motor neurons (MNs) in the spinal cord, brainstem, and motor cortex, leading to paralysis and eventually to death within 3 to 5 years of symptom onset. To date, no cure or effective therapy is available. The role of chronic endoplasmic reticulum (ER) stress in the pathophysiology of amyotrophic lateral sclerosis, as well as a potential drug target, has received increasing attention. Here, we investigated the mode of action and therapeutic effect of the ER-resident protein cerebral dopamine neurotrophic factor (CDNF) in three preclinical models of amyotrophic lateral sclerosis, exhibiting different disease development and etiology: (i) the conditional choline acetyltransferase (ChAT)-tTA/TRE-hTDP43-M337V rat model previously described, (ii) the widely used SOD1-G93A mouse model, and (iii) a novel slow-progressive TDP43-M337V mouse model. To specifically analyse the ER stress response in MNs, we used three main methods: (i) primary culture of MNs derived from E13 days embryos, (ii) immunohistochemical analyses of spinal cord sections with ChAT as spinal MNs marker, and (iii) qPCR analyses of lumbar MNs isolated via laser microdissection. We show that intracerebroventricular administration of CDNF significantly halts the progression of the disease and improves motor behavior in TDP43-M337V and SOD1-G93A rodent models of amyotrophic lateral sclerosis. CDNF rescues motor neurons 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 amyotrophic lateral sclerosis.

Neurotrophic factors in the physiology of motor neurons and their role in the pathobiology and therapeutic approach to amyotrophic lateral sclerosis

“…Small molecule receptor activators have the potential advantage that they may diffuse more readily through tissues and have a higher likelihood of crossing the blood brain barrier. In addition, more recently discovered neurotrophic factors, such as cerebral dopamine neurotrophic factor (CDNF), are being evaluated in preclinical ALS models, and CDNF recently was reported to slow progression of ALS in both Sod1 G93A and Tardbp M377V mouse models ( Lindahl et al, 2017 ; De Lorenzo et al, 2023 ). Another approach is to utilize multiple neurotrophic factors simultaneously.…”

Delivery of CDNF by AAV-mediated gene transfer protects dopamine neurons and regulates ER stress and inflammation in an acute MPTP mouse model of Parkinson’s disease

“…CDNF has a KTEL sequence in the C-terminus, which is known to be a signal for ER retention, and recently, CDNF was identified as a UPR pathway regulator in skeletal muscle in vivo 7 , 47 . Moreover, in genetic rodent models of ALS, hCDNF regulates the UPR pathway in motor neurons of the spinal cord 10 . Additionally, the upregulation of UPR pathway-associated proteins has been reported in the brains of PD model rodents 31 .…”

“…According to recent studies, in the skeletal muscle of CDNF knockout mice, the expression of UPR-related proteins such as GRP78 and Xbp1s is upregulated 7 , and in HEK293-T cells, CDNF modulates thapsigargin-induced ER stress 56 . Additionally, in diseases, such as ALS, CDNF rescues motor neurons in the spinal cord through the modulation of UPR signalling 10 . In a study of PD, the protein and mRNA levels of GRP78 and CHOP in PD patients and PD patients with dementia were found to be altered in the brain, specifically the temporal cortex, cingulate gyrus and SN, but not in the cerebrospinal fluid (CSF) 32 , 33 .…”

“…Delivery of CDNF gene using an adeno-associated viral (AAV) vector (AAV2-CDNF) was shown to improve long-term memory in APP/PS1 transgenic mice 8 . rhCDNF protein was found to prevent neuronal death in a quinolinic acid model of Huntington’s disease (HD) 9 and to improve motor coordination and protect motor neurons from degeneration through regulation of the UPR pathway in three different genetic rodent models of amyotrophic lateral sclerosis (ALS) 10 . Collectively, these findings indicate that CDNF has neurotrophic effects in various neurodegenerative diseases.…”

CDNF and MANF in the brain dopamine system and their potential as treatment for Parkinson’s disease

“…In a rodent model of intracerebral hemorrhage, by contrast, CDNF administration was shown to efficiently reduce expression of GRP78, ATF6α, ATF4, and CHOP in the hemorrhage area of the striatum ( 94 ). Furthermore, a recent study demonstrated that CDNF administration attenuated activation of all three UPR pathways in motoneurons isolated from the superoxide dismutase (SOD)-G93A mice model of amyotrophic lateral sclerosis (ALS) ( 150 ). Thus, CDNF is capable of downregulating UPR signaling in vivo .…”