Amyotrophic lateral sclerosis (ALS) is neurodegenerative disease in which the damage of upper and lower motor neurons cause their dysfunction and death. As with other neurodegenerative disorders, formation of aggregates of misfolded proteins are present in affected motor neurons and are often considered responsible for neurotoxicity. Thus, the removal of these species is important for cell survival. In some familiar form of ALS (fSLA), gene mutations of superoxide dismutase 1 (SOD1) are linked to disease. Mutant SOD1s misfold and form insoluble aggregates impairing the proteasome. In transgenic G93A-SOD1 mice, we observed spinal cord over-expression of the small heat shock protein B8 (HSPB8). In motor neuronal fALS models, by real-time PCR, WB and ICC we observed that HSPB8 is stimulated by proteasome inhibition. We also demonstrated that HSPB8 reduces aggregates by increasing mutant SOD1 solubility and clearance. HSPB8 acts on mutant SOD1 even when the proteasome activity is blocked, but is ineffective when the autophagy is blocked. These data has led to the hypothesis that HSPB8 acts by activating the autophagy. It is known that in muscle the HSPB8/Bag3/Hsc70/CHIP complex directs damaged proteins to autophagy. Through immunoprecipitation studies, we have investigated the interaction between misfoded SOD1 and HSPB8. In normal condition we did not observe formation of complex. This possibly because the complex once formed has a short lifespan being quickly removed via autophagy. Conversely when we blocked autophagy with 3-MA the cell did not remove the HSPB8/Bag3/Hsc70/CHIP multimeric complex and co-immunoprecipitated with SOD1. In conclusion HSPB8 play its role only in presence of alteration of degradative pathway, a condition in which there is a general accumulation of the HSPB8 client proteins to be degraded. GRANTS: Telethon, Italy | Fondazione CARIPLO, Italy | AriSLA, Italy | Fondazione Thierry Latran, France

The HSPB8 by complexing with Bag3/Hsc70/CHIP removes mutant SOD1 in models of familiar amyotrophic lateral sclerosis / V. Crippa, R. Cristofani, A. Boncoraglio, P. Rusmini, E. Giorgetti, A. Poletti. ((Intervento presentato al convegno Cell Stress: Survival and Apoptosis tenutosi a Palermo nel 2012.

The HSPB8 by complexing with Bag3/Hsc70/CHIP removes mutant SOD1 in models of familiar amyotrophic lateral sclerosis

V. Crippa;R. Cristofani;A. Boncoraglio;P. Rusmini;E. Giorgetti;A. Poletti
2012

Abstract

Amyotrophic lateral sclerosis (ALS) is neurodegenerative disease in which the damage of upper and lower motor neurons cause their dysfunction and death. As with other neurodegenerative disorders, formation of aggregates of misfolded proteins are present in affected motor neurons and are often considered responsible for neurotoxicity. Thus, the removal of these species is important for cell survival. In some familiar form of ALS (fSLA), gene mutations of superoxide dismutase 1 (SOD1) are linked to disease. Mutant SOD1s misfold and form insoluble aggregates impairing the proteasome. In transgenic G93A-SOD1 mice, we observed spinal cord over-expression of the small heat shock protein B8 (HSPB8). In motor neuronal fALS models, by real-time PCR, WB and ICC we observed that HSPB8 is stimulated by proteasome inhibition. We also demonstrated that HSPB8 reduces aggregates by increasing mutant SOD1 solubility and clearance. HSPB8 acts on mutant SOD1 even when the proteasome activity is blocked, but is ineffective when the autophagy is blocked. These data has led to the hypothesis that HSPB8 acts by activating the autophagy. It is known that in muscle the HSPB8/Bag3/Hsc70/CHIP complex directs damaged proteins to autophagy. Through immunoprecipitation studies, we have investigated the interaction between misfoded SOD1 and HSPB8. In normal condition we did not observe formation of complex. This possibly because the complex once formed has a short lifespan being quickly removed via autophagy. Conversely when we blocked autophagy with 3-MA the cell did not remove the HSPB8/Bag3/Hsc70/CHIP multimeric complex and co-immunoprecipitated with SOD1. In conclusion HSPB8 play its role only in presence of alteration of degradative pathway, a condition in which there is a general accumulation of the HSPB8 client proteins to be degraded. GRANTS: Telethon, Italy | Fondazione CARIPLO, Italy | AriSLA, Italy | Fondazione Thierry Latran, France
19-mag-2012
Settore BIO/13 - Biologia Applicata
Associazione di biologia cellulare e del differenziamento
The HSPB8 by complexing with Bag3/Hsc70/CHIP removes mutant SOD1 in models of familiar amyotrophic lateral sclerosis / V. Crippa, R. Cristofani, A. Boncoraglio, P. Rusmini, E. Giorgetti, A. Poletti. ((Intervento presentato al convegno Cell Stress: Survival and Apoptosis tenutosi a Palermo nel 2012.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/174368
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