Motor neuron diseases (MNDs), such as amyotrophic lateral sclerosis (ALS) or spinal and bulbar muscular atrophy (SBMA), are associated with proteins (SOD1, TDP-43, DPRs from C9orf72, ARpolyQ, etc.) that can acquire aberrant conformations. A major consequence of misfolding is protein accumulation into aggregates in motor neurons. Protein quality control system prevents protein aggregation counteracting their toxicity by enhancing degradation via proteasome and/or autophagy. The chaperone assisted selective autophagy (CASA) with its complex formed by HSP70, HSPB8, BAG3 and CHIP is mainly involved in the misfolded protein degradation. Moreover, an efficient dynein mediated transport of misfolded proteins to the site of degradation is required as key point to control their aggregation and degradation. In fact, we found an altered expression and localization of SQSTM1/p62 and LC3 and a reduction of autophagosome number per cell when the dynein retrograde transport is blocked. Despite this, the blockage of dynein function reduced PBS insoluble fraction of mutated misfolded proteins (ARpolyQ, SOD1, TDP-43 and DPRs). Dynein inhibition selectively increased the mRNA level of the nucleotide exchange factor BAG1, both in NSC34 and in iPSC derived motor neurons. Notably, exogenous BAG1 overexpression reduced misfolded species aggregation increasing UPS dependent degradation of proteins recognized by HSP70. Notably, a dysregulation of HSP70 levels has been recently identified in peripheral cells from ALS patients and its downregulation increases TDP-43 protein levels. Moreover, dynein inhibition increased mRNA and protein levels of the chaperone mediated autophagy (CMA) receptor Lamp2A, suggesting that CMA may restore misfolded proteins degradation. As we observed in dynein depleted cells, BAG1 mRNA is increased also in Lamp2A depleted cells. We measured the protein levels of alpha-synuclein as CMA substrate. We found that BAG1 overexpression reduced alpha-synuclein level, while BAG1 depletion has an opposite effect. In parallel, Lamp2A depleted cells retained a very efficient proteasome system that rapidly cleared soluble alpha-synuclein, even if we observed alpha-synuclein PBS insoluble species accumulation. Collectively, these data suggest that BAG1 is an important player to assist the degradation via proteasome and CMA of MNDs related misfolded protein.

BAG1 assists the degradation of neurotoxic proteins related to motor neuron diseases counteracting dynein-mediated autophagy alteration / R. Cristofani, M. Cozzi, B. Tedesco, V. Ferrari, E. Casarotto, M. Chierichetti, M. Galbiati, P. Rusmini, V. Crippa, A. Poletti. ((Intervento presentato al convegno Vesicle Trafficking & Pathways to Neurodegeneration tenutosi a online nel 2021.

BAG1 assists the degradation of neurotoxic proteins related to motor neuron diseases counteracting dynein-mediated autophagy alteration

R. Cristofani;M. Cozzi;B. Tedesco;V. Ferrari;E. Casarotto;M. Chierichetti;M. Galbiati;P. Rusmini;V. Crippa;A. Poletti
2021-05-17

Abstract

Motor neuron diseases (MNDs), such as amyotrophic lateral sclerosis (ALS) or spinal and bulbar muscular atrophy (SBMA), are associated with proteins (SOD1, TDP-43, DPRs from C9orf72, ARpolyQ, etc.) that can acquire aberrant conformations. A major consequence of misfolding is protein accumulation into aggregates in motor neurons. Protein quality control system prevents protein aggregation counteracting their toxicity by enhancing degradation via proteasome and/or autophagy. The chaperone assisted selective autophagy (CASA) with its complex formed by HSP70, HSPB8, BAG3 and CHIP is mainly involved in the misfolded protein degradation. Moreover, an efficient dynein mediated transport of misfolded proteins to the site of degradation is required as key point to control their aggregation and degradation. In fact, we found an altered expression and localization of SQSTM1/p62 and LC3 and a reduction of autophagosome number per cell when the dynein retrograde transport is blocked. Despite this, the blockage of dynein function reduced PBS insoluble fraction of mutated misfolded proteins (ARpolyQ, SOD1, TDP-43 and DPRs). Dynein inhibition selectively increased the mRNA level of the nucleotide exchange factor BAG1, both in NSC34 and in iPSC derived motor neurons. Notably, exogenous BAG1 overexpression reduced misfolded species aggregation increasing UPS dependent degradation of proteins recognized by HSP70. Notably, a dysregulation of HSP70 levels has been recently identified in peripheral cells from ALS patients and its downregulation increases TDP-43 protein levels. Moreover, dynein inhibition increased mRNA and protein levels of the chaperone mediated autophagy (CMA) receptor Lamp2A, suggesting that CMA may restore misfolded proteins degradation. As we observed in dynein depleted cells, BAG1 mRNA is increased also in Lamp2A depleted cells. We measured the protein levels of alpha-synuclein as CMA substrate. We found that BAG1 overexpression reduced alpha-synuclein level, while BAG1 depletion has an opposite effect. In parallel, Lamp2A depleted cells retained a very efficient proteasome system that rapidly cleared soluble alpha-synuclein, even if we observed alpha-synuclein PBS insoluble species accumulation. Collectively, these data suggest that BAG1 is an important player to assist the degradation via proteasome and CMA of MNDs related misfolded protein.
Settore BIO/13 - Biologia Applicata
BAG1 assists the degradation of neurotoxic proteins related to motor neuron diseases counteracting dynein-mediated autophagy alteration / R. Cristofani, M. Cozzi, B. Tedesco, V. Ferrari, E. Casarotto, M. Chierichetti, M. Galbiati, P. Rusmini, V. Crippa, A. Poletti. ((Intervento presentato al convegno Vesicle Trafficking & Pathways to Neurodegeneration tenutosi a online nel 2021.
Conference Object
File in questo prodotto:
File Dimensione Formato  
2021-05-17_VTPN_Cristofani.pdf

accesso riservato

Tipologia: Altro
Dimensione 570.83 kB
Formato Adobe PDF
570.83 kB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/847016
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact