p97/UBXD1 Generate Ubiquitylated Proteins That Are Sequestered into Nuclear Envelope Herniations in Torsin-Deficient Cells

• Published in: International journal of molecular sciences 2022-04, Vol.23 (9), p.4627
• Main Authors: Prophet, Sarah M, Naughton, Brigitte S, Schlieker, Christian
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Vesicular Transport - genetics; Adaptor Proteins, Vesicular Transport - metabolism; Adenosine Triphosphatases - metabolism; Autophagy-Related Proteins - genetics; Autophagy-Related Proteins - metabolism; Cell Membrane Structures - metabolism; Dystonia; Dystonia - genetics; Dystonia - metabolism; Dystonia Musculorum Deformans; DYT1; Enzymes; Heat shock; Humans; Mammals; Molecular Chaperones - genetics; Molecular Chaperones - metabolism; Mutation; Nuclear Envelope - metabolism; Nuclear Pore Complex Proteins - metabolism; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Nucleoporins; p97; Phenotypes; Proteins; Sequestering; TorsinA; Ubiquitin; Ubiquitin - metabolism; UBXD1; YOD1
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms23094627

DYT1 dystonia is a debilitating neurological movement disorder that arises upon Torsin ATPase deficiency. Nuclear envelope (NE) blebs that contain FG-nucleoporins (FG-Nups) and K48-linked ubiquitin are the hallmark phenotype of Torsin manipulation across disease models of DYT1 dystonia. While the aberrant deposition of FG-Nups is caused by defective nuclear pore complex assembly, the source of K48-ubiquitylated proteins inside NE blebs is not known. Here, we demonstrate that the characteristic K48-ubiquitin accumulation inside blebs requires p97 activity. This activity is highly dependent on the p97 adaptor UBXD1. We show that p97 does not significantly depend on the Ufd1/Npl4 heterodimer to generate the K48-ubiquitylated proteins inside blebs, nor does inhibiting translation affect the ubiquitin sequestration in blebs. However, stimulating global ubiquitylation by heat shock greatly increases the amount of K48-ubiquitin sequestered inside blebs. These results suggest that blebs have an extraordinarily high capacity for sequestering ubiquitylated protein generated in a p97-dependent manner. The p97/UBXD1 axis is thus a major factor contributing to cellular DYT1 dystonia pathology and its modulation represents an unexplored potential for therapeutic development.