Browse
Submit Data
Databases
API
Help

Dataset Information

38 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

The SQSTM1/p62 UBA domain regulates Ajuba localisation, degradation and NF-κB signalling function

ABSTRACT: The LIM-domain containing protein Ajuba and the scaffold protein SQSTM1/p62 regulate signalling of NF-κB, a transcription factor involved in osteoclast differentiation and survival. The ubiquitin-associated domain of SQSTM1/p62 is frequently mutated in patients with Paget’s disease of bone. Here, we report that Ajuba activates NF-κB activity in HEK293 cells, and that co-expression with SQSTM1/p62 inhibits this activation in an UBA domain-dependent manner. SQSTM1/p62 regulates proteins by targeting them to the ubiquitin-proteasome system or the autophagy-lysosome pathway. We show that Ajuba is degraded by autophagy, however co-expression with SQSTM1/p62 (wild type or UBA-deficient) protects Ajuba levels both in cells undergoing autophagy and those exposed to proteasomal stress. Additionally, in unstressed cells co-expression of SQSTM1/p62 reduces the amount of Ajuba present in the nucleus. SQSTM1/p62 with an intact ubiquitin-associated domain forms holding complexes with Ajuba that are not destined for degradation yet inhibit signalling. Thus, in situations with altered levels and localization of SQSTM1/p62 expression, such as osteoclasts in Paget’s disease of bone and various cancers, SQSTM1/p62 may compartmentalize Ajuba and thereby impact its cellular functions and disease pathogenesis. In Paget’s, ubiquitin-associated domain mutations may lead to increased or prolonged Ajuba-induced NF-κB signalling leading to increased osteoclastogenesis. In cancer, Ajuba expression promotes cell survival. The increased levels of SQSTM1/p62 observed in cancer may enhance Ajuba-mediated cancer cell survival.

SUBMITTER: Sultana M

PROVIDER: S-EPMC8568271 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Keap1/Cullin3 Modulates p62/SQSTM1 Activity via UBA Domain Ubiquitination.

Project description:p62/SQSTM1 (p62) is a scaffolding protein that facilitates the formation and degradation of ubiquitinated aggregates via its self-interaction and ubiquitin binding domains. The regulation of this process is unclear but may relate to the post-translational modification of p62. In the present study, we find that Keap1/Cullin3 ubiquitinates p62 at lysine 420 within its UBA domain. Substitution of lysine 420 with an arginine diminishes p62 sequestration and degradation activity similar what is seen when the UBA domain is deleted. Overexpression of Keap1/Cullin3 in p62-WT-expressing cells increases ubiquitinated inclusion formation and p62's association with LC3 and rescues proteotoxicity. This effect is not seen in cells expressing a mutant p62 that fails to interact with Keap1. Interestingly, p62 disease mutants have diminished or absent UBA domain ubiquitination. These data suggest that the ubiquitination of p62's UBA domain at lysine 420 may regulate p62's function and be disrupted in p62-associated disease.

| S-EPMC5395095 | biostudies-literature

SNX27-driven membrane localisation of OTULIN antagonises linear ubiquitination and NF-κB signalling activation.

Project description:BackgroundLinear ubiquitination is a novel type of ubiquitination that plays important physiological roles in signalling pathways such as tumour necrosis factor (TNF) signalling. However, little is known about the regulatory mechanisms of linear ubiquitination, except the well-described enzymatic regulators E3 ligase linear ubiquitin chain assembly complex (LUBAC) and deubiquitinase OTULIN.ResultsPreviously, we identified SNX27, a member of the sorting nexin family protein, as a selective linear ubiquitin chain interactor in mass spectrometry-based ubiquitin interaction screening. Here, we demonstrated that the interaction between the linear ubiquitin chain and SNX27 is mediated by the OTULIN. Furthermore, we found that SNX27 inhibits LUBAC-mediated linear ubiquitin chain formation and TNFα-induced signalling activation. Mechanistic studies showed that, upon TNFα stimulation, OTULIN-SNX27 is localised to membrane-associated TNF receptor complex, where OTULIN deubiquitinates the linear polyubiquitin chain that formed by the LUBAC complex. Significantly, chemical inhibition of SNX27-retromer translocation by cholera toxin inhibits OTULIN membrane localization.ConclusionsIn conclusion, our study demonstrated that SNX27 inhibits TNFα induced NF-κB signalling activation via facilitating OTULIN to localize to TNF receptor complex.

| S-EPMC8314547 | biostudies-literature

p62/SQSTM1 as an oncotarget mediates cisplatin resistance through activating RIP1-NF-κB pathway in human ovarian cancer cells.

Project description:Platinum-based therapeutic strategies have been widely used in ovarian cancer treatment. However, drug resistance has greatly limited therapeutic efficacy. Recently, tolerance to cisplatin has been attributed to other factors unrelated to DNA. p62 (also known as SQSTM1) functions as a multifunctional hub participating in tumorigenesis and may be a therapeutic target. Our previous study showed that p62 was overexpressed in drug-resistant ovarian epithelial carcinoma and its inhibition increased the sensitivity to cisplatin. In this study, we demonstrate that the activity of the NF-κB signaling pathway and K63-linked ubiquitination of RIP1 was higher in cisplatin-resistant ovarian (SKOV3/DDP) cells compared with parental cells. In addition, cisplatin resistance could be reversed by inhibiting the expression of p62 using siRNA. Furthermore, deletion of the ZZ domain of p62 that interacts with RIP1 in SKOV3 cells markedly decreased K63-linked ubiquitination of RIP1 and inhibited the activation of the NF-κB signaling pathway. Moreover, loss of the ZZ domain from p62 led to poor proliferative capacity and high levels of apoptosis in SKOV3 cells and made them more sensitive to cisplatin treatment. Collectively, we provide evidence that p62 is implicated in the activation of NF-κB signaling that is partly dependent on RIP1. p62 promotes cell proliferation and inhibits apoptosis thus mediating drug resistance in ovarian cancer cells.

| S-EPMC5497928 | biostudies-literature

Palmitoylation restricts SQSTM1/p62-mediated autophagic degradation of NOD2 to modulate inflammation.

Project description:The nucleotide-binding oligomerization domain protein 2 (NOD2) senses bacterial peptidoglycan to induce proinflammatory and antimicrobial responses. Dysregulation of NOD2 signaling is involved in multiple inflammatory disorders. Recently, S-palmitoylation, a novel type of post-translational modification, is reported to play a crucial role in membrane association and ligand-induced signaling of NOD2, yet its influence on the stability of NOD2 is unclear. Here we show that inhibition of S-palmitoylation facilitates the SQSTM1/p62-mediated autophagic degradation of NOD2, while S-palmitoylation of NOD2 by ZDHHC5 promotes the stability of NOD2. Furthermore, we identify a gain-of-function R444C variant of NOD2 short isoform (NOD2s-R444C) in autoinflammatory disease, which induces excessive inflammation through its high S-palmitoylation level. Mechanistically, the NOD2s-R444C variant possesses a stronger binding ability to ZDHHC5, which promotes its S-palmitoylation, and restricts its autophagic degradation by reducing its interaction with SQSTM1/p62. Taken together, our study reveals the regulatory role of S-palmitoylation in controlling NOD2 stability through the crosstalk with autophagy, and provides insights into the association between dysfunctional S-palmitoylation and the occurrence of inflammatory diseases.

| S-EPMC9346120 | biostudies-literature

OTUD7B deubiquitinates SQSTM1/p62 and promotes IRF3 degradation to regulate antiviral immunity.

Project description:Deubiquitination plays an important role in the regulation of the crosstalk between macroautophagy/autophagy and innate immune signaling, yet its regulatory mechanisms are not fully understood. Here we identify the deubiquitinase OTUD7B as a negative regulator of antiviral immunity by targeting IRF3 (interferon regulatory factor 3) for selective autophagic degradation. Mechanistically, OTUD7B interacts with IRF3, and activates IRF3-associated cargo receptor SQSTM1/p62 (sequestosome 1) by removing its K63-linked poly-ubiquitin chains at lysine 7 (K7) to enhance SQSTM1 oligomerization. Moreover, viral infection increased the expression of OTUD7B, which forms a negative feedback loop by promoting IRF3 degradation to balance type I interferon (IFN) signaling. Taken together, our study reveals a specific role of OTUD7B in mediating the activation of cargo receptors in a substrate-dependent manner, which could be a potential target against excessive immune responses.Abbreviations: Baf A1: bafilomycin A1; CGAS: cyclic GMP-AMP synthase; DDX58/RIG-I: DExD/H-box helicase 58; DSS: dextran sodium sulfate; DUBs: deubiquitinating enzymes; GFP: green fluorescent protein; IFN: interferon; IKKi: IKBKB/IkappaB kinase inhibitor; IRF3: interferon regulatory factor 3; ISGs: interferon-stimulated genes; MAVS: mitochondrial antiviral signaling protein; MOI: multiplicity of infection; PAMPs: pathogen-associated molecular patterns; SeV: Sendai virus; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; STING1: stimulator of interferon response cGAMP interactor 1; TBK1: TANK binding kinase 1; Ub: ubiquitin; WT: wild-type; VSV: vesicular stomatitis virus.

| S-EPMC9542415 | biostudies-literature

PDLIM7 Synergizes With PDLIM2 and p62/Sqstm1 to Inhibit Inflammatory Signaling by Promoting Degradation of the p65 Subunit of NF-?B.

Project description:Activation of NF-?B transcription factors is critical for innate immune cells to induce inflammation and fight against microbial pathogens. On the other hand, the excessive and prolonged activation of NF-?B causes massive inflammatory damage to the host, suggesting that regulatory mechanisms to promptly terminate NF-?B activation are important to prevent immunopathology. We have previously reported that PDLIM2, a PDZ-LIM domain-containing protein, is a nuclear ubiquitin E3 ligase that targets the p65 subunit of NF-?B for degradation, thereby suppressing NF-?B activation. Here we show that PDLIM7, another member of LIM protein family, is also a ubiquitin E3 ligase that inhibits NF-?B-mediated inflammatory responses. PDLIM7 directly polyubiquitinates p65 and promotes its proteasomal degradation. Moreover, PDLIM7 heterodimerizes with PDLIM2 to promote synergistic PDLIM2-mediated degradation of p65. Mechanistically, PDLIM7 promotes K63-linked ubiquitination of PDLIM2 and then the proteasome/autophagosome cargo protein p62/Sqstm1 binds to both polyubiquitinated PDLIM2 and the proteasome, thereby facilitating the delivery of the NF-?B-PDLIM2 complex to the proteasome and subsequent p65 degradation. Consistently, double knockdown of PDLIM7 and either PDLIM2 or p62/Sqstm1 results in augmented proinflammatory cytokine production compared to control cells or single knockdown cells. These data delineate a new role for PDLIM7 and p62/Sqstm1 in the regulation of NF-?B signaling by bridging a ubiquitin E3 ligase and the proteasome.

| S-EPMC7417631 | biostudies-literature

circRNA_SLC8A1 promotes the survival of mycobacterium tuberculosis in macrophages by upregulating expression of autophagy-related protein SQSTM1/p62 to activate the NF-κB pathway.

Project description:Macrophages act as the first immune defense line of the host against Mycobacterium tuberculosis (Mtb). A previous study showed that circRNA_SLC8A1 was significantly upregulated in Mtb-infected macrophages, but its regulatory mechanism in anti-tuberculosis infection is unclear. Therefore, this study aimed to investigate the role of circRNA_SLC8A1 in the anti-tuberculosis activity of macrophages. We showed that circRNA_SLC8A1 was upregulated in tuberculosis patients. Moreover, the binding sites of miR-20b-5p on circRNA_SLC8A1 and Sequestosome 1 (SQSTM1/p62) mRNA were predicted by StarBase and verified by the double luciferase reporter gene assay. Next, we found that miR-20b-5p expression was decreased, while SQSTM1 protein expression was increased in a time- and dose-dependent manner in the human macrophage U937 in response to Mtb infection. Furthermore, circRNA_SLC8A1 overexpression vector (circRNA_SLC8A1) or shRNA (sh-circRNA_SLC8A1) and/or miR-20b-5p mimic or inhibitor and/or SQSTM1 overexpression vector (SQSTM1) or small interfering RNA (si-SQSTM1) or its corresponding control were transfected into Mtb-infected macrophages. Results showed that overexpression of circRNA_SLC8A1 or miR-20b-5p inhibitor promoted the secretion of pro-inflammatory factors IL-1β, IL-6, and TNF-α, increased Nitric Oxide (NO) content and inducible nitric oxide synthase (iNOS) expression, inhibited Reactive oxygen species (ROS) production. Cleaved-caspase-3 protein expression, and cell apoptosis, and promoted Mtb survival. Silencing SQSTM1 inhibited secretion of pro-inflammatory factors and activation of the NF-κB pathway. Overexpression of miR-20b-5p blocked the promoting of circ-SLC8A1 on SQSTM1 protein expression. In summary, circRNA_SLC8A1 sponged miR-20b-5p to upregulate SQSTM1/p62 expression and promoted Mtb survival in macrophages through the NF-κB signaling pathway.

| S-EPMC10909944 | biostudies-literature

Crystal structure of the ubiquitin-associated (UBA) domain of p62 and its interaction with ubiquitin.

Project description:p62/SQSTM1/A170 is a multimodular protein that is found in ubiquitin-positive inclusions associated with neurodegenerative diseases. Recent findings indicate that p62 mediates the interaction between ubiquitinated proteins and autophagosomes, leading these proteins to be degraded via the autophagy-lysosomal pathway. This ubiquitin-mediated selective autophagy is thought to begin with recognition of the ubiquitinated proteins by the C-terminal ubiquitin-associated (UBA) domain of p62. We present here the crystal structure of the UBA domain of mouse p62 and the solution structure of its ubiquitin-bound form. The p62 UBA domain adopts a novel dimeric structure in crystals, which is distinctive from those of other UBA domains. NMR analyses reveal that in solution the domain exists in equilibrium between the dimer and monomer forms, and binding ubiquitin shifts the equilibrium toward the monomer to form a 1:1 complex between the UBA domain and ubiquitin. The dimer-to-monomer transition is associated with a structural change of the very C-terminal end of the p62 UBA domain, although the UBA fold itself is essentially maintained. Our data illustrate that dimerization and ubiquitin binding of the p62 UBA domain are incompatible with each other. These observations reveal an autoinhibitory mechanism in the p62 UBA domain and suggest that autoinhibition plays a role in the function of p62.

| S-EPMC3173063 | biostudies-literature

Regulation of FN1 degradation by the p62/SQSTM1-dependent autophagy-lysosome pathway in HNSCC.

Project description:Epithelial-mesenchymal transition (EMT) is involved in both physiological and pathological processes. EMT plays an essential role in the invasion, migration and metastasis of tumours. Autophagy has been shown to regulate EMT in a variety of cancers but not in head and neck squamous cell carcinoma (HNSCC). Herein, we investigated whether autophagy also regulates EMT in HNSCC. Analyses of clinical data from three public databases revealed that higher expression of fibronectin-1 (FN1) correlated with poorer prognosis and higher tumour pathological grade in HNSCC. Data from SCC-25 cells demonstrated that rapamycin and Earle's balanced salt solution (EBSS) promoted autophagy, leading to increased FN1 degradation, while 3-methyladenine (3-MA), bafilomycin A1 (Baf A1) and chloroquine (CQ) inhibited autophagy, leading to decreased FN1 degradation. On the other hand, autophagic flux was blocked in BECN1 mutant HNSCC Cal-27 cells, and rapamycin did not promote autophagy in Cal-27 cells; also in addition, FN1 degradation was inhibited. Further, we identified FN1 degradation through the lysosome-dependent degradation pathway using the proteasome inhibitor MG132. Data from immunoprecipitation assays also showed that p62/SQSTM1 participated as an autophagy adapter in the autophagy-lysosome pathway of FN1 degradation. Finally, data from immunoprecipitation assays demonstrated that the interaction between p62 and FN1 was abolished in p62 mutant MCF-7 and A2780 cell lines. These results indicate that autophagy significantly promotes the degradation of FN1. Collectively, our findings clearly suggest that FN1, as a marker of EMT, has adverse effects on HNSCC and elucidate the autophagy-lysosome degradation mechanism of FN1.

| S-EPMC7736930 | biostudies-literature

Insights into degradation mechanism of N-end rule substrates by p62/SQSTM1 autophagy adapter.

Project description:p62/SQSTM1 is the key autophagy adapter protein and the hub of multi-cellular signaling. It was recently reported that autophagy and N-end rule pathways are linked via p62. However, the exact recognition mode of degrading substrates and regulation of p62 in the autophagic pathway remain unknown. Here, we present the complex structures between the ZZ-domain of p62 and various type-1 and type-2 N-degrons. The binding mode employed in the interaction of the ZZ-domain with N-degrons differs from that employed by classic N-recognins. It was also determined that oligomerization via the PB1 domain can control functional affinity to the R-BiP substrate. Unexpectedly, we found that self-oligomerization and disassembly of p62 are pH-dependent. These findings broaden our understanding of the functional repertoire of the N-end rule pathway and provide an insight into the regulation of p62 during the autophagic pathway.

| S-EPMC6098011 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data