Dataset Information

HSP90 Co-Chaperone, CacyBP/SIP, Protects ?-Synuclein from Aggregation.

ABSTRACT: Recently, it has been found that the CacyBP/SIP protein acts as HSP90 co-chaperone and exhibits chaperone properties itself. Namely, CacyBP/SIP has been shown to protect citrate synthase from aggregation and to recover the activity of thermally denatured luciferase in vitro. In the present work, we have analyzed the influence of CacyBP/SIP on aggregation of ?-synuclein, a protein present in Lewy bodies of Parkinson's disease brain. By applying a thioflavin T (ThT) fluorescence assay, we have found that CacyBP/SIP protects ?-synuclein from aggregation and that the fragment overlapping the N-terminal part and the CS domain of CacyBP/SIP is crucial for this activity. This protective effect of CacyBP/SIP has been confirmed by results obtained using high-speed ultracentrifugation followed by dot-blot and by transmission electron microscopy (TEM). Interestingly, CacyBP/SIP exhibits the protective effect only at the initial phase of ?-synuclein aggregation. In addition, we have found that, in HEK293 cells overexpressing CacyBP/SIP, there are less ?-synuclein inclusions than in control ones. Moreover, these cells are more viable when treated with rotenone, an agent that mimics PD pathology. By applying proximity ligation assay (PLA) on HEK293 cells and in vitro assays with the use of purified recombinant proteins, we have found that CacyBP/SIP directly interacts with ?-synuclein. Altogether, in this work, we show for the first time that CacyBP/SIP is able to protect ?-synuclein from aggregation in in vitro assays. Thus, our results point to an important role of CacyBP/SIP in the pathology of Parkinson's disease and other synucleinopathies.

SUBMITTER: Bohush A

PROVIDER: S-EPMC7600563 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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HSP90 Co-Chaperone, CacyBP/SIP, Protects α-Synuclein from Aggregation.

Bohush Anastasiia A Filipek Anna A

Cells 20201008 10

Recently, it has been found that the CacyBP/SIP protein acts as HSP90 co-chaperone and exhibits chaperone properties itself. Namely, CacyBP/SIP has been shown to protect citrate synthase from aggregation and to recover the activity of thermally denatured luciferase in vitro. In the present work, we have analyzed the influence of CacyBP/SIP on aggregation of α-synuclein, a protein present in Lewy bodies of Parkinson's disease brain. By applying a thioflavin T (ThT) fluorescence assay, we have fou ...[more]

PMID: 33049998

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Project description:In neurodegenerative diseases, it remains unclear why certain brain regions are selectively vulnerable to protein aggregation. In transgenic mice expressing human A53T ?-synuclein, the brainstem and spinal cord develop the most prominent ?-synuclein inclusions which correlate with age-dependent motor dysfunction. Herein we present the novel finding that this selective aggregation is in part dependent on the inability of chaperone-mediated autophagy (CMA) to effectively degrade ?-synuclein in these brain regions. Lysosomal assays revealed that CMA activity was significantly decreased in aggregation-prone regions compared to the remainder of the brain. Previously, CMA activity has been shown to be proportional to levels of the CMA receptor Lamp-2a. Using antibodies, brain tissue from Lamp-2a null mice, enzymatic deglycosylation, and mass spectrometry, we identified Lamp2a as a novel 72kDa glycoprotein in the mouse brain. Examination of Lamp-2a levels revealed differences in expression across brain regions. The brainstem and the spinal cord had a more than three-fold greater levels of Lamp-2a as compared to regions less vulnerable to aggregation and exhibited a selective upregulation of Lamp-2a during development of ?-synuclein inclusions. Despite this dynamic response of Lamp-2a, the levels of substrates bound to the brain lysosomes as well as the rates of substrate uptake and degradation were not proportional to the levels of Lamp-2a. These regional differences in CMA activity and Lamp-2a expression were found in both non-transgenic mice as well as A53T ?-syn mice. Therefore, these are inherent variations and not a transgene-specific effect. However, differences in CMA activity may render select brain regions vulnerable to homeostatic dysfunction in the presence of stressors such as overexpression of human A53T ?-syn. Collectively, the data provide a potential mechanism to explain the dichotomy of vulnerability or resistance that underlies brain regions during aggregate formation in neurodegenerative disease.

Dataset Information

HSP90 Co-Chaperone, CacyBP/SIP, Protects ?-Synuclein from Aggregation.

Publications

HSP90 Co-Chaperone, CacyBP/SIP, Protects α-Synuclein from Aggregation.

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