Cellular clearance mechanisms including the autophagy-lysosome pathway are impaired in the central nervous system (CNS) of amyotrophic lateral sclerosis (ALS) patients. However, how the defects in lysosomal function contribute to the pathogenesis of ALS is unclear. Therefore, we investigated the role of lysosomal function in an in vitro model of amyotrophic lateral sclerosis/Parkinson-dementia complex (i.e. motor neurons exposed to the cycad neurotoxin beta-methylamino-L-alanine named L-BMAA). Considering that the lysosomal Ca2+ channel Mucolipin TRP channel 1 (TRPML1) plays a crucial role in lysosomal function, we studied the role of the channel in this neurotoxic model. Under physiological conditions, TRPML1 colocalized with the endoplasmic reticulum (ER), that drives calcium refilling of lysosomes. In fact, the specific and irreversible SERCA inhibitor thapsigargin reduced lysosomal Ca2+ refilling measured by the genetically-encoded Ca2+ indicator GCaMP3 attached to the lysosomal channel (GCaMP3-ML1). However, TRPML1 expression was dramatically reduced in motor neurons exposed to the L-BMAA, a condition characterized by the impairment of ER Ca2+ store. Therefore, lysosomal Ca2+ release and ER Ca2+ content were both dysregulated by L-BMAA. Very interestingly, the specific membrane-permeable synthetic agonist of TRPML1, ML-SA1, rescued motor neurons from death and ER stress induced by chonic exposure to L-BMAA. Furthermore, under the same conditions, the pre-incubation of ML-SA1 prevented the elevation of the ER stress marker GRP78 and of the autophagy-related proteins p62/SQSTM1 and LC3-II. Notably, ML-SA1 per se induced the activation of the autophagy initiators p-AMPK and beclin 1. Collectively, we propose that the pharmacological stimulation of lysosomal Ca2+ channel TRPML1 can efficiently rescue motor neurons from L-BMAA toxicity by improving autophagy-dependent clearance mechanisms.

The pharmacological activation of Mucolipin TRP channel 1 (TRPML1) protects motor neurons exposed to the cycad neurotoxin L-BMAA by promoting autophagic clearance / Tedeschi, V.; Petrozziello, T.; Sisalli, Mj.; Boscia, F.; Canzoniero, L. M. T.; Secondo, A.. - (2018). (Intervento presentato al convegno Membrane Trafficking and Organelle Biogenesis Meeting (MTOB) tenutosi a Sorrento (NA), Italia nel 14-15 ottobre 2018).

The pharmacological activation of Mucolipin TRP channel 1 (TRPML1) protects motor neurons exposed to the cycad neurotoxin L-BMAA by promoting autophagic clearance

V. Tedeschi;T. Petrozziello;MJ. Sisalli;F. Boscia;A. Secondo
2018

Abstract

Cellular clearance mechanisms including the autophagy-lysosome pathway are impaired in the central nervous system (CNS) of amyotrophic lateral sclerosis (ALS) patients. However, how the defects in lysosomal function contribute to the pathogenesis of ALS is unclear. Therefore, we investigated the role of lysosomal function in an in vitro model of amyotrophic lateral sclerosis/Parkinson-dementia complex (i.e. motor neurons exposed to the cycad neurotoxin beta-methylamino-L-alanine named L-BMAA). Considering that the lysosomal Ca2+ channel Mucolipin TRP channel 1 (TRPML1) plays a crucial role in lysosomal function, we studied the role of the channel in this neurotoxic model. Under physiological conditions, TRPML1 colocalized with the endoplasmic reticulum (ER), that drives calcium refilling of lysosomes. In fact, the specific and irreversible SERCA inhibitor thapsigargin reduced lysosomal Ca2+ refilling measured by the genetically-encoded Ca2+ indicator GCaMP3 attached to the lysosomal channel (GCaMP3-ML1). However, TRPML1 expression was dramatically reduced in motor neurons exposed to the L-BMAA, a condition characterized by the impairment of ER Ca2+ store. Therefore, lysosomal Ca2+ release and ER Ca2+ content were both dysregulated by L-BMAA. Very interestingly, the specific membrane-permeable synthetic agonist of TRPML1, ML-SA1, rescued motor neurons from death and ER stress induced by chonic exposure to L-BMAA. Furthermore, under the same conditions, the pre-incubation of ML-SA1 prevented the elevation of the ER stress marker GRP78 and of the autophagy-related proteins p62/SQSTM1 and LC3-II. Notably, ML-SA1 per se induced the activation of the autophagy initiators p-AMPK and beclin 1. Collectively, we propose that the pharmacological stimulation of lysosomal Ca2+ channel TRPML1 can efficiently rescue motor neurons from L-BMAA toxicity by improving autophagy-dependent clearance mechanisms.
2018
The pharmacological activation of Mucolipin TRP channel 1 (TRPML1) protects motor neurons exposed to the cycad neurotoxin L-BMAA by promoting autophagic clearance / Tedeschi, V.; Petrozziello, T.; Sisalli, Mj.; Boscia, F.; Canzoniero, L. M. T.; Secondo, A.. - (2018). (Intervento presentato al convegno Membrane Trafficking and Organelle Biogenesis Meeting (MTOB) tenutosi a Sorrento (NA), Italia nel 14-15 ottobre 2018).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/741913
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