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Bonavita R, Scerra G, Di Martino R, Nuzzo S, Polishchuk E, Di Gennaro M, Williams SV, Caporaso MG, Caiazza C, Polishchuk R, D’Agostino M, Fleming A, Renna M. The HSPB1-p62/SQSTM1 functional complex regulates the unconventional secretion and transcellular spreading of the HD-associated mutant huntingtin protein. Hum Mol Genet 2023; 32:2269-2291. [PMID: 36971475 PMCID: PMC10321397 DOI: 10.1093/hmg/ddad047] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 03/06/2023] [Accepted: 03/23/2023] [Indexed: 07/20/2023] Open
Abstract
Conformational diseases, such as Alzheimer, Parkinson and Huntington diseases, are part of a common class of neurological disorders characterized by the aggregation and progressive accumulation of proteins bearing aberrant conformations. Huntington disease (HD) has autosomal dominant inheritance and is caused by mutations leading to an abnormal expansion in the polyglutamine (polyQ) tract of the huntingtin (HTT) protein, leading to the formation of HTT inclusion bodies in neurons of affected patients. Interestingly, recent experimental evidence is challenging the conventional view by which the disease pathogenesis is solely a consequence of the intracellular accumulation of mutant protein aggregates. These studies reveal that transcellular transfer of mutated huntingtin protein is able to seed oligomers involving even the wild-type (WT) forms of the protein. To date, there is still no successful strategy to treat HD. Here, we describe a novel functional role for the HSPB1-p62/SQSTM1 complex, which acts as a cargo loading platform, allowing the unconventional secretion of mutant HTT by extracellular vesicles. HSPB1 interacts preferentially with polyQ-expanded HTT compared with the WT protein and affects its aggregation. Furthermore, HSPB1 levels correlate with the rate of mutant HTT secretion, which is controlled by the activity of the PI3K/AKT/mTOR signalling pathway. Finally, we show that these HTT-containing vesicular structures are biologically active and able to be internalized by recipient cells, therefore providing an additional mechanism to explain the prion-like spreading properties of mutant HTT. These findings might also have implications for the turn-over of other disease-associated, aggregation-prone proteins.
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Affiliation(s)
| | | | - R Di Martino
- Institute for Endocrinology and Experimental Oncology “G. Salvatore,” National Research Council, 80131 Naples, Italy
- Institute of Biochemistry and Cell Biology, National Research Council, 80131 Naples, Italy
| | - S Nuzzo
- IRCCS SYNLAB SDN, 80143 Naples, Italy
| | - E Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM), 80078 Pozzuoli, Italy
| | - M Di Gennaro
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples “Federico II”, 80131 Naples, Italy
| | - S V Williams
- Department of Physiology, Development and Neuroscience, University of Cambridge, CB2 3DY Cambridge, UK
| | - M G Caporaso
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples “Federico II”, 80131 Naples, Italy
| | - C Caiazza
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples “Federico II”, 80131 Naples, Italy
| | - R Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM), 80078 Pozzuoli, Italy
| | - M D’Agostino
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples “Federico II”, 80131 Naples, Italy
| | - A Fleming
- Department of Physiology, Development and Neuroscience, University of Cambridge, CB2 3DY Cambridge, UK
| | - M Renna
- To whom correspondence should be addressed at: Department of Molecular Medicine and Medical Biotechnologies, School of Medicine, University of Naples “Federico II”, Via S. Pansini, 5, Building 19, Corpi Bassi Sud (I floor), 80131 Naples, Italy. Tel: +39 081/7463623, Fax: +39 081-7463205;
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D'Agostino M, Scerra G, Cannata Serio M, Caporaso MG, Bonatti S, Renna M. Unconventional secretion of α-Crystallin B requires the Autophagic pathway and is controlled by phosphorylation of its serine 59 residue. Sci Rep 2019; 9:16892. [PMID: 31729431 PMCID: PMC6858465 DOI: 10.1038/s41598-019-53226-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 08/14/2019] [Indexed: 01/26/2023] Open
Abstract
α-Crystallin B (CRYAB or HspB5) is a chaperone member of the small heat-shock protein family that prevents aggregation of many cytosolic client proteins by means of its ATP-independent holdase activity. Surprisingly, several reports show that CRYAB exerts a protective role also extracellularly, and it has been recently demonstrated that CRYAB is secreted from human retinal pigment epithelial cells by an unconventional secretion pathway that involves multi-vesicular bodies. Here we show that autophagy is crucial for this unconventional secretion pathway and that phosphorylation at serine 59 residue regulates CRYAB secretion by inhibiting its recruitment to the autophagosomes. In addition, we found that autophagosomes containing CRYAB are not able to fuse with lysosomes. Therefore, CRYAB is capable to highjack and divert autophagosomes toward the exocytic pathway, inhibiting their canonical route leading to the lysosomal compartment. Potential implications of these findings in the context of disease-associated mutant proteins turn-over are discussed.
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Affiliation(s)
- M D'Agostino
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy.
| | - G Scerra
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | - M Cannata Serio
- Laboratory of Epithelial Biology and Disease, Imagine Institute, Paris, France.,Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - M G Caporaso
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | - S Bonatti
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | - M Renna
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy.
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