TY - JOUR
T1 - Pathomechanisms of ALS8: altered autophagy and defective RNA binding protein (RBP) homeostasis due to the VAPB P56S mutation
AU - Tripathi, Priyanka
AU - Guo, Haihong
AU - Dreser, Alice
AU - Yamoah, Alfred
AU - Sechi, Antonio
AU - Jesse, Christopher Marvin
AU - Katona, Istvan
AU - Doukas, Panagiotis
AU - Nikolin, Stefan
AU - Ernst, Sabrina
AU - Aronica, Eleonora
AU - Glaß, Hannes
AU - Hermann, Andreas
AU - Steinbusch, Harry
AU - Feller, Alfred C.
AU - Bergmann, Markus
AU - Jaarsma, Dick
AU - Weis, Joachim
AU - Goswami, Anand
N1 - Funding Information: This work was supported by the Confocal Microscopy Facility, a Core Facility of the Interdisciplinary Center for Clinical Research (IZKF) Aachen within the Faculty of Medicine at RWTH Aachen University. We are grateful to the patients and their relatives for their support. We sincerely thank Stichting ALS Nederland and ALS Centre Netherlands (AE) for our ALS research support. We thank A. Knischewski and C. Krude (Institute of Neuropathology, RWTH Aachen University Hospital) for technical support and S. Gründer (Institute of Physiology, RWTH Aachen University Hospital) and his lab members for confocal microscopy. We are grateful to Prof: Anthony A. Hyman, (MPI-CGP, Munich), for G3BP-RFP stable cell line for SG analysis. This work was supported by the German Research Foundation (DFG; WE 1406/16-1 to J.W. and A.G.), the EU Joint Program Neurodegenerative Disease Research (JPND: FLY-SMALS; to J. W.), Forschungs förderung der Medizinschen Fakultät UK Aachen (START grant-AZ 43/14) and Interdisciplinary Centre for Clinical Research (IZKF Aachen, N7-4), the Initiative Therapieforschung ALS e.V. and the German Society for Muscle Diseases, DGM (to J.W. and A.G.). Human IPSCs derived MNs work was supported, in part, by the NOMIS foundation to A.H. A.H. is supported by the Hermann und Lilly Schilling-Stiftung für medizinische Forschung im Stifterverband. Publisher Copyright: © 2021, The Author(s).
PY - 2021/5/1
Y1 - 2021/5/1
N2 - Mutations in RNA binding proteins (RBPs) and in genes regulating autophagy are frequent causes of familial amyotrophic lateral sclerosis (fALS). The P56S mutation in vesicle-associated membrane protein-associated protein B (VAPB) leads to fALS (ALS8) and spinal muscular atrophy (SMA). While VAPB is primarily involved in the unfolded protein response (UPR), vesicular trafficking and in initial steps of the autophagy pathway, the effect of mutant P56S-VAPB on autophagy regulation in connection with RBP homeostasis has not been explored yet. Examining the muscle biopsy of our index ALS8 patient of European origin revealed globular accumulations of VAPB aggregates co-localised with autophagy markers LC3 and p62 in partially atrophic and atrophic muscle fibres. In line with this skin fibroblasts obtained from the same patient showed accumulation of P56S-VAPB aggregates together with LC3 and p62. Detailed investigations of autophagic flux in cell culture models revealed that P56S-VAPB alters both initial and late steps of the autophagy pathway. Accordingly, electron microscopy complemented with live cell imaging highlighted the impaired fusion of accumulated autophagosomes with lysosomes in cells expressing P56S-VAPB. Consistent with these observations, neuropathological studies of brain and spinal cord of P56S-VAPB transgenic mice revealed signs of neurodegeneration associated with altered protein quality control and defective autophagy. Autophagy and RBP homeostasis are interdependent, as demonstrated by the cytoplasmic mis-localisation of several RBPs including pTDP-43, FUS, Matrin 3 which often sequestered with P56S-VAPB aggregates both in cell culture and in the muscle biopsy of the ALS8 patient. Further confirming the notion that aggregation of the RBPs proceeds through the stress granule (SG) pathway, we found persistent G3BP- and TIAR1-positive SGs in P56S-VAPB expressing cells as well as in the ALS8 patient muscle biopsy. We conclude that P56S-VAPB-ALS8 involves a cohesive pathomechanism of aberrant RBP homeostasis together with dysfunctional autophagy.
AB - Mutations in RNA binding proteins (RBPs) and in genes regulating autophagy are frequent causes of familial amyotrophic lateral sclerosis (fALS). The P56S mutation in vesicle-associated membrane protein-associated protein B (VAPB) leads to fALS (ALS8) and spinal muscular atrophy (SMA). While VAPB is primarily involved in the unfolded protein response (UPR), vesicular trafficking and in initial steps of the autophagy pathway, the effect of mutant P56S-VAPB on autophagy regulation in connection with RBP homeostasis has not been explored yet. Examining the muscle biopsy of our index ALS8 patient of European origin revealed globular accumulations of VAPB aggregates co-localised with autophagy markers LC3 and p62 in partially atrophic and atrophic muscle fibres. In line with this skin fibroblasts obtained from the same patient showed accumulation of P56S-VAPB aggregates together with LC3 and p62. Detailed investigations of autophagic flux in cell culture models revealed that P56S-VAPB alters both initial and late steps of the autophagy pathway. Accordingly, electron microscopy complemented with live cell imaging highlighted the impaired fusion of accumulated autophagosomes with lysosomes in cells expressing P56S-VAPB. Consistent with these observations, neuropathological studies of brain and spinal cord of P56S-VAPB transgenic mice revealed signs of neurodegeneration associated with altered protein quality control and defective autophagy. Autophagy and RBP homeostasis are interdependent, as demonstrated by the cytoplasmic mis-localisation of several RBPs including pTDP-43, FUS, Matrin 3 which often sequestered with P56S-VAPB aggregates both in cell culture and in the muscle biopsy of the ALS8 patient. Further confirming the notion that aggregation of the RBPs proceeds through the stress granule (SG) pathway, we found persistent G3BP- and TIAR1-positive SGs in P56S-VAPB expressing cells as well as in the ALS8 patient muscle biopsy. We conclude that P56S-VAPB-ALS8 involves a cohesive pathomechanism of aberrant RBP homeostasis together with dysfunctional autophagy.
UR - http://www.scopus.com/inward/record.url?scp=85105573384&partnerID=8YFLogxK
U2 - https://doi.org/10.1038/s41419-021-03710-y
DO - https://doi.org/10.1038/s41419-021-03710-y
M3 - Article
C2 - 33972508
SN - 2041-4889
VL - 12
JO - Cell Death & Disease
JF - Cell Death & Disease
IS - 5
M1 - 466
ER -