UBL3 Interacts with PolyQ-Expanded Huntingtin Fragments and Modifies Their Intracellular Sorting

Background/Objectives: UBL3 (Ubiquitin-like 3) is a protein that plays a crucial role in post-translational modifications, particularly in regulating protein transport within small extracellular vesicles. While previous research has predominantly focused on its interactions with α-synuclein, this st...

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Main Authors: Soho Oyama, Hengsen Zhang, Rafia Ferdous, Yuna Tomochika, Bin Chen, Shuyun Jiang, Md. Shoriful Islam, Md. Mahmudul Hasan, Qing Zhai, A. S. M. Waliullah, Yashuang Ping, Jing Yan, Mst. Afsana Mimi, Chi Zhang, Shuhei Aramaki, Yusuke Takanashi, Tomoaki Kahyo, Yoshio Hashizume, Daita Kaneda, Mitsutoshi Setou
Format: Article
Language:English
Published: MDPI AG 2024-10-01
Series:Neurology International
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Online Access:https://www.mdpi.com/2035-8377/16/6/89
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Summary:Background/Objectives: UBL3 (Ubiquitin-like 3) is a protein that plays a crucial role in post-translational modifications, particularly in regulating protein transport within small extracellular vesicles. While previous research has predominantly focused on its interactions with α-synuclein, this study investigates UBL3’s role in Huntington’s disease (HD). HD is characterized by movement disorders and cognitive impairments, with its pathogenesis linked to toxic, polyglutamine (polyQ)-expanded mutant huntingtin fragments (mHTT). However, the mechanisms underlying the interaction between UBL3 and mHTT remain poorly understood. Methods: To elucidate this relationship, we performed hematoxylin and eosin (HE) staining and immunohistochemistry (IHC) on postmortem brain tissue from HD patients. Gaussia princeps-based split-luciferase complementation assay and co-immunoprecipitation were employed to confirm the interaction between UBL3 and mHTT. Additionally, we conducted a HiBiT lytic detection assay to assess the influence of UBL3 on the intracellular sorting of mHTT. Finally, immunocytochemical staining was utilized to validate the colocalization and distribution of these proteins. Results: Our findings revealed UBL3-positive inclusions in the cytoplasm and nuclei of neurons throughout the striatum of HD patients. We discovered that UBL3 colocalizes and interacts with mHTT and modulates its intracellular sorting. Conclusions: These results suggest that UBL3 may play a significant role in the interaction and sorting of mHTT, contributing to the understanding of its potential implications in the pathophysiology of Huntington’s disease.
ISSN:2035-8377