Dataset Information

USP32 regulates non-proteolytic LAMTOR1 ubiquitination and Ragulator function

ABSTRACT: Ubiquitination is among the most prevalent post-translational modifications regulating a great number of cellular functions, and defects in such processes contribute to many diseases. Deubiquitinating enzymes (DUBs) are essential to control the precise outcome of ubiquitin signals. The ubiquitin-specific protease 32 (USP32) differs from all other DUBs as it comprises in addition to its catalytic USP domain and the DUSP domain also multiple EF hands and a C-terminal prenylation site. This unique domain architecture offers various features for the regulation of specific signaling processes by USP32. To better understand the cellular function of USP32, we performed SILAC-based quantitative ubiquitinome analyses to determine potential USP32 substrates. We found proteins involved in endosomal trafficking as well as lysosomal proteins with regulated diGly sites in USP32 knockout (KO) cells.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Permanent Cell Line Cell

SUBMITTER: Florian Bonn

LAB HEAD: Anja Bremm

PROVIDER: PXD024211 | Pride | 2022-12-16

REPOSITORIES: Pride

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Publications

USP32-regulated LAMTOR1 ubiquitination impacts mTORC1 activation and autophagy induction.

Hertel Alexandra A Alves Ludovico Martins LM Dutz Henrik H Tascher Georg G Bonn Florian F Kaulich Manuel M Dikic Ivan I Eimer Stefan S Steinberg Florian F Bremm Anja A

Cell reports 20221201 10

The endosomal-lysosomal system is a series of organelles in the endocytic pathway that executes trafficking and degradation of proteins and lipids and mediates the internalization of nutrients and growth factors to ensure cell survival, growth, and differentiation. Here, we reveal regulatory, non-proteolytic ubiquitin signals in this complex system that are controlled by the enigmatic deubiquitinase USP32. Knockout (KO) of USP32 in primary hTERT-RPE1 cells results among others in hyperubiquitina ...[more]

PMID: 36476874

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Project description:Huntington’s disease is caused by a polyglutamine repeat expansion at the N-terminus of the huntingtin protein which affects the function and folding of the protein, and results in intracellular protein aggregates. Here, we examined whether this mutation leads to altered ubiquitination of huntingtin and other proteins in both soluble and insoluble fractions of brain lysates of the Q175 knock-in Huntington disease mouse model and the Q20 wild-type mouse model. Ubiquitination sites are detected by identification of Gly-Gly (diGly) remnant motifs that remain on modified lysine residues after digestion. We identified K6, K9, K132, K804 and K837 as endogenous ubiquitination sites of soluble huntingtin, with wild-type huntingtin being mainly ubiquitinated at K132, K804 and K837. Mutant huntingtin protein levels were strongly reduced in the soluble fraction while K6 and K9 were mainly ubiquitinated. In the insoluble fraction increased levels of huntingtin K6 and K9 diGly sites were observed for mutant huntingtin as compared to wild type. Besides huntingtin, proteins with various roles, including membrane organization, transport, mRNA processing, gene transcription, translation, catabolic processes and oxidative phosphorylation, were differently expressed or ubiquitinated in wild-type and mutant huntingtin brain tissues. Correlating protein and diGly site fold-changes in the soluble fraction revealed that diGly site abundances of the majority of the proteins were not related to protein fold-changes, indicating that these proteins were differentially ubiquitinated in the Q175 mice. In contrast, both the fold-change of the protein level and diGly site level were increased for several proteins in the insoluble fraction, including ubiquitin, ubiquilin-2, sequestosome-1/p62 and myo5a. Our data sheds light on putative novel proteins involved in different cellular processes as well as their ubiquitination status in Huntington’s disease, which forms the basis for further mechanistic studies to understand the role of differential ubiquitination of huntingtin as well as ubiquitin-regulated processes in Huntington’s disease.

Project description:Ubiquitination is a post-translational modification that has been shown to have a range of effects, such as regulating protein function, protein:protein interactions, protein localization, and protein abundance by targeting proteins for degradation by the 26S proteasome. We have previously shown that the muscle-specific ubiquitin E3 ligase, ASB2, is down-regulated in models of muscle growth and that overexpression ASB2 is sufficient to induce muscle atrophy. To gain insight into the effect of increased ASB2 expression on skeletal muscle mass and function, we used 2-dimensional nano-ultra-high-performance mass spectrometry to investigate ASB2-induced changes to the mouse skeletal muscle proteome, and whether these were associated with changes in protein ubiquitination. The results show that in vivo recombinant adeno-associated viral vector-mediated ASB2β overexpression induces impaired intrinsic force production and progressive muscle atrophy over 12 weeks, while ASB2 knockdown induces mild muscle hypertrophy. ASB2-induced muscle atrophy and dysfunction were associated with the early down regulation of mitochondrial and contractile proteins, and the upregulation of proteins involved in proteasome-mediated protein degradation, protein synthesis and the cytoskeleton/sarcomere. The overexpression ASB2β also resulted in marked changes in protein ubiquitination, however, there was no simple relationship between changes in ubiquitination status and protein abundance. To gain insights into proteins that interact with ASB2, and potential ASB2 targets, in muscle cells, flag-tagged wild type ASB2, and a mutant ASB2 with a deleted C-terminal SOCS box domain (dSOCS) were immunoprecipitated from C2C12 myotubes and subjected to label-free proteomic analysis to determine the ASB2 interactome. ASB2β was found to interact with a range of cytoskeletal and nuclear proteins. When combined with the in vivo ubiquitinomic data, we identified several novel potential ASB2β target substrates that await further investigation. Overall, this study reveals for the first time the complexity of changes to the proteome and ubiquitinome during E3 ligase-mediated skeletal muscle atrophy and dysfunction.

Dataset Information

USP32 regulates non-proteolytic LAMTOR1 ubiquitination and Ragulator function

Publications

USP32-regulated LAMTOR1 ubiquitination impacts mTORC1 activation and autophagy induction.

Similar Datasets

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