-
International Journal of Molecular... Dec 2023Mitochondrial dysregulation, such as mitochondrial complex I deficiency, increased oxidative stress, perturbation of mitochondrial dynamics and mitophagy, has long been... (Review)
Review
Mitochondrial dysregulation, such as mitochondrial complex I deficiency, increased oxidative stress, perturbation of mitochondrial dynamics and mitophagy, has long been implicated in the pathogenesis of PD. Initiating from the observation that mitochondrial toxins cause PD-like symptoms and mitochondrial DNA mutations are associated with increased risk of PD, many mutated genes linked to familial forms of PD, including , , and , have also been found to affect the mitochondrial features. Recent research has uncovered a much more complex involvement of mitochondria in PD. Disruption of mitochondrial quality control coupled with abnormal secretion of mitochondrial contents to dispose damaged organelles may play a role in the pathogenesis of PD. Furthermore, due to its bacterial ancestry, circulating mitochondrial DNAs can function as damage-associated molecular patterns eliciting inflammatory response. In this review, we summarize and discuss the connection between mitochondrial dysfunction and PD, highlighting the molecular triggers of the disease process, the intra- and extracellular roles of mitochondria in PD as well as the therapeutic potential of mitochondrial transplantation.
Topics: Humans; Parkinson Disease; Ubiquitin-Protein Ligases; Mitochondria; DNA, Mitochondrial; Mitophagy
PubMed: 38069350
DOI: 10.3390/ijms242317027 -
Nature Communications Jan 2022Proteolysis-targeting chimaeras (PROTACs) as well as molecular glues such as immunomodulatory drugs (IMiDs) and indisulam are drugs that induce interactions between...
Proteolysis-targeting chimaeras (PROTACs) as well as molecular glues such as immunomodulatory drugs (IMiDs) and indisulam are drugs that induce interactions between substrate proteins and an E3 ubiquitin ligases for targeted protein degradation. Here, we develop a workflow based on proximity-dependent biotinylation by AirID to identify drug-induced neo-substrates of the E3 ligase cereblon (CRBN). Using AirID-CRBN, we detect IMiD-dependent biotinylation of CRBN neo-substrates in vitro and identify biotinylated peptides of well-known neo-substrates by mass spectrometry with high specificity and selectivity. Additional analyses reveal ZMYM2 and ZMYM2-FGFR1 fusion protein-responsible for the 8p11 syndrome involved in acute myeloid leukaemia-as CRBN neo-substrates. Furthermore, AirID-DCAF15 and AirID-CRBN biotinylate neo-substrates targeted by indisulam and PROTACs, respectively, suggesting that this approach has the potential to serve as a general strategy for characterizing drug-inducible protein-protein interactions in cells.
Topics: Adaptor Proteins, Signal Transducing; Biological Assay; Biotinylation; Cell Line, Tumor; DNA-Binding Proteins; Gene Expression Regulation; HEK293 Cells; Hepatocytes; Humans; Immunologic Factors; Intracellular Signaling Peptides and Proteins; Lymphocytes; Neurons; Protein Binding; Protein Interaction Mapping; Proteolysis; Receptor, Fibroblast Growth Factor, Type 1; Substrate Specificity; Sulfonamides; Transcription Factors; Ubiquitin-Protein Ligases
PubMed: 35013300
DOI: 10.1038/s41467-021-27818-z -
Blood Aug 2021Ferroportin (FPN), the body's sole iron exporter, is essential for maintaining systemic iron homeostasis. In response to either increased iron or inflammation,...
Ferroportin (FPN), the body's sole iron exporter, is essential for maintaining systemic iron homeostasis. In response to either increased iron or inflammation, hepatocyte-secreted hepcidin binds to FPN, inducing its internalization and subsequent degradation. However, the E3 ubiquitin ligase that underlies FPN degradation has not been identified. Here, we report the identification and characterization of a novel mechanism involving the RNF217-mediated degradation of FPN. A combination of 2 different E3 screens revealed that the Rnf217 gene is a target of Tet1, mediating the ubiquitination and subsequent degradation of FPN. Interestingly, loss of Tet1 expression causes an accumulation of FPN and an impaired response to iron overload, manifested by increased iron accumulation in the liver together with decreased iron in the spleen and duodenum. Moreover, we found that the degradation and ubiquitination of FPN could be attenuated by mutating RNF217. Finally, using 2 conditional knockout mouse lines, we found that knocking out Rnf217 in macrophages increases splenic iron export by stabilizing FPN, whereas knocking out Rnf217 in intestinal cells appears to increase iron absorption. These findings suggest that the Tet1-RNF217-FPN axis regulates iron homeostasis, revealing new therapeutic targets for FPN-related diseases.
Topics: Animals; Carrier Proteins; Cation Transport Proteins; DNA-Binding Proteins; Iron; Iron Overload; Mice; Mice, Knockout; Organ Specificity; Proteolysis; Proto-Oncogene Proteins; Ubiquitin-Protein Ligases; Ubiquitination
PubMed: 33895792
DOI: 10.1182/blood.2020008986 -
Proceedings of the National Academy of... Nov 2021High expression of programmed death-ligand 1 (PD-L1) in cancer cells drives immune-independent, cell-intrinsic functions, leading to resistance to DNA-damaging...
High expression of programmed death-ligand 1 (PD-L1) in cancer cells drives immune-independent, cell-intrinsic functions, leading to resistance to DNA-damaging therapies. We find that high expression of the ubiquitin E3 ligase FBXO22 sensitizes nonsmall cell lung cancer (NSCLC) cells to ionizing radiation (IR) and cisplatin, and that activation of FBXO22 by phosphorylation is necessary for this function. Importantly, FBXO22 activates PD-L1 ubiquitination and degradation, which in turn increases the sensitivity of NSCLC cells to DNA damage. Cyclin-dependent kinase 5 (CDK5), aberrantly active in cancer cells, plays a crucial role in increasing the expression of PD-L1 in medulloblastoma [R. D. Dorand , 353, 399-403 (2016)]. We show in NSCLC cells that inhibiting CDK5 or reducing its expression increases the level of FBXO22, decreases that of PD-L1, and increases the sensitivity of the cells to DNA damage. We conclude that FBXO22 is a substrate of CDK5, and that inhibiting CDK5 reduces PD-L1 indirectly by increasing FBXO22. Pairing inhibitors of CDK5 with immune checkpoint inhibitors may increase the efficacy of immune checkpoint blockade alone or in combination with DNA-damaging therapies.
Topics: A549 Cells; B7-H1 Antigen; Carcinoma, Non-Small-Cell Lung; Cyclin-Dependent Kinase 5; DNA Damage; F-Box Proteins; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms; Medulloblastoma; Phosphorylation; Receptors, Cytoplasmic and Nuclear; Ubiquitin-Protein Ligases; Ubiquitination; Ubiquitins
PubMed: 34795058
DOI: 10.1073/pnas.2112674118 -
Molecular Cell Nov 2021Inhibitors of poly(ADP-ribose) (PAR) polymerase (PARPi) have entered the clinic for the treatment of homologous recombination (HR)-deficient cancers. Despite the success...
Inhibitors of poly(ADP-ribose) (PAR) polymerase (PARPi) have entered the clinic for the treatment of homologous recombination (HR)-deficient cancers. Despite the success of this approach, preclinical and clinical research with PARPi has revealed multiple resistance mechanisms, highlighting the need for identification of novel functional biomarkers and combination treatment strategies. Functional genetic screens performed in cells and organoids that acquired resistance to PARPi by loss of 53BP1 identified loss of LIG3 as an enhancer of PARPi toxicity in BRCA1-deficient cells. Enhancement of PARPi toxicity by LIG3 depletion is dependent on BRCA1 deficiency but independent of the loss of 53BP1 pathway. Mechanistically, we show that LIG3 loss promotes formation of MRE11-mediated post-replicative ssDNA gaps in BRCA1-deficient and BRCA1/53BP1 double-deficient cells exposed to PARPi, leading to an accumulation of chromosomal abnormalities. LIG3 depletion also enhances efficacy of PARPi against BRCA1-deficient mammary tumors in mice, suggesting LIG3 as a potential therapeutic target.
Topics: Animals; BRCA1 Protein; Biopsy; CRISPR-Cas Systems; Cell Line; Cell Nucleus; Cell Proliferation; Chromosome Aberrations; DNA Damage; DNA Ligase ATP; DNA, Single-Stranded; Female; Humans; Lentivirus; MRE11 Homologue Protein; Mammary Neoplasms, Animal; Mice; Mutation; Ovarian Neoplasms; Poly(ADP-ribose) Polymerase Inhibitors; Poly-ADP-Ribose Binding Proteins; RNA, Small Interfering; Transgenes; Triple Negative Breast Neoplasms; Tumor Suppressor p53-Binding Protein 1
PubMed: 34555355
DOI: 10.1016/j.molcel.2021.09.005 -
Experimental & Molecular Medicine Jan 2023Mitochondrial DNA (mtDNA) released through protein oligomers, such as voltage-dependent anion channel 1 (VDAC1), triggers innate immune activation and thus contributes...
Mitochondrial DNA (mtDNA) released through protein oligomers, such as voltage-dependent anion channel 1 (VDAC1), triggers innate immune activation and thus contributes to liver fibrosis. Here, we investigated the role of Parkin, an important regulator of mitochondria, and its regulation of VDAC1-mediated mtDNA release in liver fibrosis. The circulating mitochondrial DNA (mtDNA) and protein levels of liver Parkin and VDAC1 were upregulated in patients with liver fibrosis. A 4-week CCl challenge induced release of mtDNA, activation of STING signaling, a decline in autophagy, and apoptosis in mouse livers, and the knockout of Parkin aggravated these effects. In addition, Parkin reduced mtDNA release and prevented VDAC1 oligomerization in a manner dependent on its E3 activity in hepatocytes. We found that site-specific ubiquitination of VDAC1 at lysine 53 by Parkin interrupted VDAC1 oligomerization and prevented mtDNA release into the cytoplasm under stress. The ubiquitination-defective VDAC1 K53R mutant predominantly formed oligomers that resisted suppression by Parkin. Hepatocytes expressing VDAC1 K53R exhibited mtDNA release and thus activated the STING signaling pathway in hepatic stellate cells, and this effect could not be abolished by Parkin. We propose that the ubiquitination of VDAC1 at a specific site by Parkin confers protection against liver fibrosis by interrupting VDAC1 oligomerization and mtDNA release.
Topics: Mice; Animals; DNA, Mitochondrial; Voltage-Dependent Anion Channel 1; Mitochondria; Ubiquitination; Apoptosis; Ubiquitin-Protein Ligases; Liver Cirrhosis
PubMed: 36658227
DOI: 10.1038/s12276-022-00923-9 -
Nature Communications Oct 2022The cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) plays a critical role in antiviral immunity and autoimmunity. The activity and stability of cGAS are fine-tuned...
The cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) plays a critical role in antiviral immunity and autoimmunity. The activity and stability of cGAS are fine-tuned by post-translational modifications. Here, we show that ariadne RBR E3 ubiquitin protein ligase 1 (ARIH1) catalyzes the mono-ISGylation and induces the oligomerization of cGAS, thereby promoting antiviral immunity and autoimmunity. Knockdown or knockout of ARIH1 significantly inhibits herpes simplex virus 1 (HSV-1)- or cytoplasmic DNA-induced expression of type I interferons (IFNs) and proinflammatory cytokines. Consistently, tamoxifen-treated ER-Cre;Arih1 mice and Lyz2-Cre; Arih1 mice are hypersensitive to HSV-1 infection compared with the controls. In addition, deletion of ARIH1 in myeloid cells alleviates the autoimmune phenotypes and completely rescues the autoimmune lethality caused by TREX1 deficiency. Mechanistically, HSV-1- or cytosolic DNA-induced oligomerization and activation of cGAS are potentiated by ISGylation at its K187 residue, which is catalyzed by ARIH1. Our findings thus reveal an important role of ARIH1 in innate antiviral and autoimmune responses and provide insight into the post-translational regulation of cGAS.
Topics: Animals; Autoimmunity; Cytokines; DNA; Herpes Simplex; Herpesvirus 1, Human; Immunity, Innate; Interferon Type I; Mice; Nucleotidyltransferases; Tamoxifen; Ubiquitin-Protein Ligases
PubMed: 36217001
DOI: 10.1038/s41467-022-33671-5 -
Nature Oct 2021Transcription-coupled DNA repair removes bulky DNA lesions from the genome and protects cells against ultraviolet (UV) irradiation. Transcription-coupled DNA repair...
Transcription-coupled DNA repair removes bulky DNA lesions from the genome and protects cells against ultraviolet (UV) irradiation. Transcription-coupled DNA repair begins when RNA polymerase II (Pol II) stalls at a DNA lesion and recruits the Cockayne syndrome protein CSB, the E3 ubiquitin ligase, CRL4 and UV-stimulated scaffold protein A (UVSSA). Here we provide five high-resolution structures of Pol II transcription complexes containing human transcription-coupled DNA repair factors and the elongation factors PAF1 complex (PAF) and SPT6. Together with biochemical and published data, the structures provide a model for transcription-repair coupling. Stalling of Pol II at a DNA lesion triggers replacement of the elongation factor DSIF by CSB, which binds to PAF and moves upstream DNA to SPT6. The resulting elongation complex, EC, uses the CSA-stimulated translocase activity of CSB to pull on upstream DNA and push Pol II forward. If the lesion cannot be bypassed, CRL4 spans over the Pol II clamp and ubiquitylates the RPB1 residue K1268, enabling recruitment of TFIIH to UVSSA and DNA repair. Conformational changes in CRL4 lead to ubiquitylation of CSB and to release of transcription-coupled DNA repair factors before transcription may continue over repaired DNA.
Topics: Carrier Proteins; Cryoelectron Microscopy; DNA Helicases; DNA Repair; DNA Repair Enzymes; DNA-Binding Proteins; Humans; Models, Molecular; Multiprotein Complexes; Poly-ADP-Ribose Binding Proteins; RNA Polymerase II; Transcription Elongation, Genetic; Transcription Factor TFIIH; Transcription Factors; Transcription, Genetic; Ubiquitin-Protein Ligases; Ubiquitination
PubMed: 34526721
DOI: 10.1038/s41586-021-03906-4 -
Autophagy Nov 2019Macroautophagy/autophagy is a cellular process in which cytosolic contents are degraded by lysosome in response to various stress conditions. Apart from its role in the...
Macroautophagy/autophagy is a cellular process in which cytosolic contents are degraded by lysosome in response to various stress conditions. Apart from its role in the maintenance of cellular homeostasis, autophagy also involves in regulation of cell cycle progression under nutrient-deprivation conditions. However, whether and how autophagy is regulated by the cell cycle especially during mitosis remains largely undefined. Here we show that WIPI2/ATG18B (WD repeat domain, phosphoinositide interacting 2), an autophagy-related (ATG) protein that plays a critical role in autophagosome biogenesis, is a direct substrate of CUL4-RING ubiquitin ligases (CRL4s). Upon mitosis induction, CRL4s are activated via neddylation, and recruit WIPI2 via DDB1 (damage specific DNA binding protein 1), leading to polyubiquitination and proteasomal degradation of WIPI2 and suppression of autophagy. The WIPI2 protein level and autophagy during mitosis could be rescued by knockdown of or treatment with MLN4924/Pevonedistat, a selective inhibitor of CRLs, via suppression of NAE1 (NEDD8 activating enzyme E1 subunit 1). Moreover, restoration of WIPI2 rescues autophagy during mitosis and leads to mitotic slippage and cell senescence. Our study thus discovers a novel function of CRL4s in autophagy by targeting WIPI2 for polyubiquitination and proteasomal degradation during mitosis. : ACTB, actin beta; ATG, autophagy-related; AMPK, AMP-activated protein kinase; AURKB/ARK2, aurora kinase B; BafA1, bafilomycin A; CCNB1, cyclin B1; CDK1, cyclin dependent kinase 1; CHX, cycloheximide; CQ, chloroquine; CRL4s, CUL4-RING ubiquitin ligases; DDB1, damage specific DNA binding protein 1; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; GFP, green fluorescent protein; GST, glutathione S-transferase; MAP1LC3B/LC3B, microtubule associated protein 1 light chain 3 beta; STK11/LKB1,serine/threonine kinase 11; MTORC1/MTOR complex 1, mechanistic target of rapamycin kinase complex 1; NAE1, NEDD8 activating enzyme E1 subunit 1; NOC, nocodazole; RING, really interesting new gene; RBX1, ring-box 1; SA-GLB1/β-gal, senescence-associated galactosidase beta 1; TSC2, TSC complex subunit 2; TUBA, tubulin alpha; WIPI2, WD repeat domain, phosphoinositide interacting 2.
Topics: Autophagy; Cellular Senescence; Cyclopentanes; DNA-Binding Proteins; HEK293 Cells; HeLa Cells; Humans; Leupeptins; Membrane Proteins; Mitosis; NEDD8 Protein; Phosphate-Binding Proteins; Proteasome Endopeptidase Complex; Protein Binding; Pyrimidines; Signal Transduction; Ubiquitin; Ubiquitin-Activating Enzymes; Ubiquitin-Protein Ligases; Ubiquitination
PubMed: 30898011
DOI: 10.1080/15548627.2019.1596484 -
Nature Mar 2024Cyclic GMP-AMP synthase (cGAS) senses aberrant DNA during infection, cancer and inflammatory disease, and initiates potent innate immune responses through the synthesis...
Cyclic GMP-AMP synthase (cGAS) senses aberrant DNA during infection, cancer and inflammatory disease, and initiates potent innate immune responses through the synthesis of 2'3'-cyclic GMP-AMP (cGAMP). The indiscriminate activity of cGAS towards DNA demands tight regulatory mechanisms that are necessary to maintain cell and tissue homeostasis under normal conditions. Inside the cell nucleus, anchoring to nucleosomes and competition with chromatin architectural proteins jointly prohibit cGAS activation by genomic DNA. However, the fate of nuclear cGAS and its role in cell physiology remains unclear. Here we show that the ubiquitin proteasomal system (UPS) degrades nuclear cGAS in cycling cells. We identify SPSB3 as the cGAS-targeting substrate receptor that associates with the cullin-RING ubiquitin ligase 5 (CRL5) complex to ligate ubiquitin onto nuclear cGAS. A cryo-electron microscopy structure of nucleosome-bound cGAS in a complex with SPSB3 reveals a highly conserved Asn-Asn (NN) minimal degron motif at the C terminus of cGAS that directs SPSB3 recruitment, ubiquitylation and cGAS protein stability. Interference with SPSB3-regulated nuclear cGAS degradation primes cells for type I interferon signalling, conferring heightened protection against infection by DNA viruses. Our research defines protein degradation as a determinant of cGAS regulation in the nucleus and provides structural insights into an element of cGAS that is amenable to therapeutic exploitation.
Topics: Animals; Humans; Mice; Cell Nucleus; Cryoelectron Microscopy; Degrons; DNA Virus Infections; DNA Viruses; DNA, Viral; Immunity, Innate; Innate Immunity Recognition; Interferon Type I; Nuclear Proteins; Nucleosomes; Nucleotidyltransferases; Proteasome Endopeptidase Complex; Protein Stability; Proteolysis; Substrate Specificity; Ubiquitin; Ubiquitin-Protein Ligases; Ubiquitination
PubMed: 38418882
DOI: 10.1038/s41586-024-07112-w