Supplementary Material for: Shared Molecular Mechanisms in Alzheimer's Disease and Amyotrophic Lateral Sclerosis: Neurofilament-Dependent Transport of sAPP, FUS, TDP-43 and SOD1, with Endoplasmic Reticulum-Like Tubules Muresan V. Ladescu Muresan Z. 10.6084/m9.figshare.4047375.v1 https://karger.figshare.com/articles/figure/Supplementary_Material_for_Shared_Molecular_Mechanisms_in_Alzheimer_s_Disease_and_Amyotrophic_Lateral_Sclerosis_Neurofilament-Dependent_Transport_of_sAPP_FUS_TDP-43_and_SOD1_with_Endoplasmic_Reticulum-Like_Tubules/4047375 <br><strong><em>Background:</em></strong> Amyotrophic lateral sclerosis (ALS), a debilitating neurodegenerative disorder of the motor neurons, leads to the disorganization of the neurofilament (NF) cytoskeleton and - ultimately - the deterioration of the neuromuscular junction. Some familial cases of ALS are caused by mutated FUS, TDP-43 or SOD1; it is thought that the mutated proteins inflict pathology either by gain or loss of function. The proper function of the neuromuscular junction requires sAPP, a soluble proteolytic fragment of the amyloid-β precursor protein (APP) - a transmembrane protein implicated in the pathology of Alzheimer's disease (AD). Whether sAPP, FUS, TDP-43 and SOD1 are mechanistically linked in a common pathway deregulated in both AD and ALS is not known. <b><i>Summary:</i></b> We show that sAPP, TDP-43, FUS and SOD1 are transported to neurite terminals by a mechanism that involves endoplasmic reticulum (ER)-like tubules and requires peripherin NFs. The transport of these proteins, and the translocation of the ER protein reticulon 4 (Rtn4) into neurites was studied in CAD cells, a brainstem-derived neuronal cell line highly relevant to AD and ALS. We show that a significant fraction of sAPP is generated in the soma and accumulates in a juxtanuclear ER subdomain. In neurites, sAPP localizes to Rtn4-positive ER-like tubules that extend from the soma into the growth cone and colocalizes with peripherin NFs. Knocking down peripherin disrupts the NF network and diminishes the accumulation of sAPP, TDP-43, FUS, SOD1 and Rtn4 at terminals. <b><i>Key Messages:</i></b> We propose that the impediment of a common, ER-mediated mechanism of transport of sAPP, TDP-43, FUS and SOD1, caused by a disrupted NF network, could be part of the mechanisms leading to AD and ALS. 2016-10-21 09:04:25 Alzheimer’s disease Amyotrophic lateral sclerosis Amyloid-β precursor protein FUS TDP-43 SOD1 Motor neurons Neurofilaments Endoplasmic reticulum Converging mechanisms of neurodegenerative diseases