{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nNUB1 and its splice variant NUB1L function as critical adaptor proteins that regulate protein quality control by specifically binding ubiquitin‐like proteins—most notably NEDD8 and FAT10—and targeting these modifiers and their conjugates for proteasomal degradation. Through direct interactions with NEDD8, NUB1/NUB1L downregulates neddylation and ensures proper turnover of modified proteins. In addition, by associating with key proteasomal components such as p97/VCP and hRpn10, they facilitate not only the recruitment of substrates but also contribute to proteasome gate opening, thereby enhancing the degradation efficiency of misfolded or aberrantly modified proteins."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "7"}]}, {"type": "t", "text": "\n\nDisruption of protein homeostasis is a hallmark of many neurodegenerative disorders, and NUB1 plays a protective role in these settings. Overexpression of NUB1 has been shown to enhance the degradation of mutant Huntingtin (mHTT) and synphilin-1—proteins implicated in Huntington’s disease and alpha-synucleinopathies, respectively—thereby rescuing neurons from toxicity. In parallel, NUB1 modulates tau pathology by interfering with GSK3β recruitment, reducing tau hyperphosphorylation and aggregation, while its accumulation in Lewy bodies underscores its role in the cellular response to abnormal protein deposits."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "8", "end_ref": "11"}]}, {"type": "t", "text": "\n\nBeyond its involvement in neurodegeneration, NUB1 contributes to proper cellular development and homeostasis in other tissues. In the retina, interactions between NUB1 and AIPL1 are essential for photoreceptor formation and survival, with disruptions likely contributing to inherited retinal degenerations such as Leber congenital amaurosis. Furthermore, by binding to linear ubiquitin precursors (e.g., UbC1) via its UBA domain, NUB1 participates in the generation of free ubiquitin—an activity potentially linked to the high demands of spermatogenesis—and it also regulates telomere-associated proteins like TRF1, thus implicating NUB1 in telomere maintenance and cell cycle control."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "12", "end_ref": "16"}]}, {"type": "t", "text": "\n\nPosttranslational modifications further regulate NUB1’s function: Mdm2-mediated di-ubiquitination at a specific lysine residue (K159) and phosphorylation at serine 46 both serve to enhance its capacity to promote proteasomal degradation of neddylated proteins and pathological aggregates. These modifications fine-tune NUB1’s adaptor activity, ensuring an effective cellular response to proteotoxic stress and maintaining protein homeostasis under both physiological and disease conditions."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "17", "end_ref": "19"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Tomoaki Tanaka, Hidenori Kawashima, Edward T H Yeh, et al. 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