Introduction and objectives: ALS and FTD are two neurodegenerative diseases characterized by the presence within neurons of abnormal cytoplasmic inclusions containing the insoluble forms of the TAR DNA-binding protein of 43 KDa (TDP-43) and of its C-terminal fragments of 35 (TDP-35) and 25 KDa (TDP-25) (Neuman et al., 2006). These TDP inclusions are toxic and impair cell functionality (Berning at al., 2019). Cells can remove TDP species (TDPs) thanks to the protein quality control (PQC) system [i.e. chaperone proteins, ubiquitin-proteasome system (UPS) and autophagy]. Recently, TDPs have been also found into extracellular vesicles (EVs) suggesting that EVs may have a role in TDPs clearance (Iguchi et al., 2016). This observation led us to wonder if a possible interplay between PQC and EVs in TDPs disposal may exist. To answer this question, we pharmacologically blocked PQC in an immortalized neuronal cell line and analysed the effect on their released EVs in terms of number and protein cargo, with special attention to TDPs and some PQC components involved in TDPs disposal [i.e. the chaperone assisted selective autophagy (CASA) complex proteins (HSP70-CHIP-HSPB8-BAG3), MAP1LC3B and SQSTM1/p62] (Crippa et al., 2016). We considered all EVs, both large and small vesicles (LVs and SVs). Results: All TDPs are physiologically secreted in EVs, mainly as insoluble species. EVs also transported CASA proteins, MAP1LC3B and SQSTM1/p62. PQC blockage increased the number of secreted EVs and their TDPs content, particularly in LVs. Interestingly, this increase was paralleled by the enrichment of CASA complex proteins. Conclusions: In conclusion, EVs could represent an important mechanism for the clearance of insoluble TDPs which is specifically boosted when PQC is impaired and the CASA complex members could have a role in TDPs targeting to EVs. Bibliography: Neumann, M.; Sampathu, D.M.; Kwong, L.K.; Truax, A.C.; Micsenyi, M.C.; Chou, T.T.; Bruce, J.; Schuck, T.; Grossman, M.; Clark, C.M.; et al. Ubiquitinated TDP-43 in Frontotemporal Lobar Degeneration and Amyotrophic Lateral Sclerosis. Science 2006, 314, 130–133. Berning, B.A.; Walker, A.K. The Pathobiology of TDP-43 C-Terminal Fragments in ALS and FTLD. Frontiers in Neuroscience 2019, 13. Crippa, V.; Cicardi, M.E.; Ramesh, N.; Seguin, S.J.; Ganassi, M.; Bigi, I.; Diacci, C.; Zelotti, E.; Baratashvili, M.; Gregory, J.M.; et al. The Chaperone HSPB8 Reduces the Accumulation of Truncated TDP-43 Species in Cells and Protects against TDP-43-Mediated Toxicity. Human Molecular Genetics 2016, 25, 3908-3924. Iguchi, Y.; Eid, L.; Parent, M.; Soucy, G.; Bareil, C.; Riku, Y.; Kawai, K.; Takagi, S.; Yoshida, M.; Katsuno, M.; et al. Exosome Secretion Is a Key Pathway for Clearance of Pathological TDP-43. Brain 2016, 139, 3187–3201.

Extracellular vesicles cooperate with PQC system for the clearance of TDP-43 species associated with ALS and FTD / E. Casarotto, D. Sproviero, E. Corridori, M.C. Gagliani, M. Cozzi, M. Chierichetti, R. Cristofani, V. Ferrari, M. Galbiati, F. Mina, M. Piccolella, P. Rusmini, B. Tedesco, S. Gagliardi, K. Cortese, C. Cereda, A. Poletti, V. Crippa. ((Intervento presentato al convegno National meeting of PhD students in Neuroscience tenutosi a Brescia : 11 giugno nel 2022.

Extracellular vesicles cooperate with PQC system for the clearance of TDP-43 species associated with ALS and FTD

E. Casarotto;E. Corridori;M. Cozzi;M. Chierichetti;R. Cristofani;V. Ferrari;M. Galbiati;F. Mina;M. Piccolella;P. Rusmini;B. Tedesco;A. Poletti;V. Crippa
2022

Abstract

Introduction and objectives: ALS and FTD are two neurodegenerative diseases characterized by the presence within neurons of abnormal cytoplasmic inclusions containing the insoluble forms of the TAR DNA-binding protein of 43 KDa (TDP-43) and of its C-terminal fragments of 35 (TDP-35) and 25 KDa (TDP-25) (Neuman et al., 2006). These TDP inclusions are toxic and impair cell functionality (Berning at al., 2019). Cells can remove TDP species (TDPs) thanks to the protein quality control (PQC) system [i.e. chaperone proteins, ubiquitin-proteasome system (UPS) and autophagy]. Recently, TDPs have been also found into extracellular vesicles (EVs) suggesting that EVs may have a role in TDPs clearance (Iguchi et al., 2016). This observation led us to wonder if a possible interplay between PQC and EVs in TDPs disposal may exist. To answer this question, we pharmacologically blocked PQC in an immortalized neuronal cell line and analysed the effect on their released EVs in terms of number and protein cargo, with special attention to TDPs and some PQC components involved in TDPs disposal [i.e. the chaperone assisted selective autophagy (CASA) complex proteins (HSP70-CHIP-HSPB8-BAG3), MAP1LC3B and SQSTM1/p62] (Crippa et al., 2016). We considered all EVs, both large and small vesicles (LVs and SVs). Results: All TDPs are physiologically secreted in EVs, mainly as insoluble species. EVs also transported CASA proteins, MAP1LC3B and SQSTM1/p62. PQC blockage increased the number of secreted EVs and their TDPs content, particularly in LVs. Interestingly, this increase was paralleled by the enrichment of CASA complex proteins. Conclusions: In conclusion, EVs could represent an important mechanism for the clearance of insoluble TDPs which is specifically boosted when PQC is impaired and the CASA complex members could have a role in TDPs targeting to EVs. Bibliography: Neumann, M.; Sampathu, D.M.; Kwong, L.K.; Truax, A.C.; Micsenyi, M.C.; Chou, T.T.; Bruce, J.; Schuck, T.; Grossman, M.; Clark, C.M.; et al. Ubiquitinated TDP-43 in Frontotemporal Lobar Degeneration and Amyotrophic Lateral Sclerosis. Science 2006, 314, 130–133. Berning, B.A.; Walker, A.K. The Pathobiology of TDP-43 C-Terminal Fragments in ALS and FTLD. Frontiers in Neuroscience 2019, 13. Crippa, V.; Cicardi, M.E.; Ramesh, N.; Seguin, S.J.; Ganassi, M.; Bigi, I.; Diacci, C.; Zelotti, E.; Baratashvili, M.; Gregory, J.M.; et al. The Chaperone HSPB8 Reduces the Accumulation of Truncated TDP-43 Species in Cells and Protects against TDP-43-Mediated Toxicity. Human Molecular Genetics 2016, 25, 3908-3924. Iguchi, Y.; Eid, L.; Parent, M.; Soucy, G.; Bareil, C.; Riku, Y.; Kawai, K.; Takagi, S.; Yoshida, M.; Katsuno, M.; et al. Exosome Secretion Is a Key Pathway for Clearance of Pathological TDP-43. Brain 2016, 139, 3187–3201.
Settore BIO/13 - Biologia Applicata
Extracellular vesicles cooperate with PQC system for the clearance of TDP-43 species associated with ALS and FTD / E. Casarotto, D. Sproviero, E. Corridori, M.C. Gagliani, M. Cozzi, M. Chierichetti, R. Cristofani, V. Ferrari, M. Galbiati, F. Mina, M. Piccolella, P. Rusmini, B. Tedesco, S. Gagliardi, K. Cortese, C. Cereda, A. Poletti, V. Crippa. ((Intervento presentato al convegno National meeting of PhD students in Neuroscience tenutosi a Brescia : 11 giugno nel 2022.
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