EMBO/soda-nel huggingface dataset:
NRBF2 regulates autophagy and prevents liver injury by modulating Atg14L-linked phosphatidylinositol-3 kinase III activity (2014)
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(a) Brains of the ‘rescued’ mice (Becn1−/−; Becn1EGFP/+) and of control Becn1+/+ littermates were lysed and subjected to immune isolation using an anti-GFP antibody. Proteins bound to anti-GFP antibody were isolated, detected and identified by SDS-PAGE, Coomassie brilliant blue staining and mass spectrometry. Seven bands pulled down by anti-GFP antibody specifically from ‘rescued’ mice lysate are numbered (this is a copy of image from our previous report with modification). (b) Mouse brain lysates were subjected to co-immunoprecipitation (co-IP) followed by WB analysis using the indicated antibodies. (c) Mouse brain lysates were subjected to co-IP by NRBF2 antibody and followed by WB analysis using the indicated antibodies. (d) Gel filtration analysis. The supernatant fraction of mouse brain lysates was subjected to a Superdex 200 HR 10/30 column and each fraction was immunoblotted with the indicated antibodies. Relative amounts of each fraction determined by Odyssey software are plotted. (e) The deficiency of Atg14L impairs the protein interaction between Beclin 1 and NRBF2. NIH3T3 cells were transfected with Atg14L or NRBF2 RNAi for 72 h, respectively, and then were lysed and subjected to IP using Beclin 1 antibody. The immunoprecipitants were immunoblotted using the indicated antibodies. (f) Direct binding between Atg14L and NRBF2. Flag-tagged Atg14L purified from HEK293T cells overexpressing Flag-Atg14L was incubated with GST or NRBF2-GST purified from Escherichia coli. The GST pull-down assay was performed to examine the direct binding between Flag-Atg14L and NRBF2-GST. (g) Proteomic analysis of NRBF2 interaction proteins. Association map shows identified high-confidence candidate interaction proteins (HCIPs). Liquid chromatography coupled to tandem mass spectrometry were performed to analyse the HA antibody-immunoprecipitated complexes derived from TREx-293 cells inducibly expressing HA-tagged NRBF2. Beclin 1, PIK3C3 (Vps34), PIK3R4 (Vps15) and Atg14L were detected as HCIPs in complex with NRBF2. Furthermore, UVRAG was detected with sub-threshold HCIP values. Dotted lines indicate interactions annotated in BIOGRID, MINT and HPRD protein interaction databases. The representative images shown in this figure are from two or three independent experiments.
NRBF2 regulates autophagy and prevents liver injury by modulating Atg14L-linked phosphatidylinositol-3 kinase III activity (2014)
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(a) The schematic map of full-length and truncate NRBF2-CFP. (b) NRBF2 KO MEFs were transfected with CFP, NRBF2-CFP, dMIT-CFP or dCCD-CFP for 48 h. Atg14L-linked Vps34 was pulled down by an anti-Atg14L antibody and subjected to KA. IP products and inputs were immunoblotted using the antibodies indicated. (c) Quantification of IPed Vps34 kinase activity (PI(3)P), Vps34 and Vps15 protein versus IPed Atg14L protein. (Data are shown as mean±s.e.m., P values are indicated on the figures, multiple t-test are followed by Bonferroni correction, n=4 (otherwise indicated, n means number of independent experiments; NS, not significant)). (b) Overexpression of NRBF2 enhances Atg14L-linked Vps34 kinase activity. HEK293T cells were co-transfected with Myc-Vps34-Vps15-His and Flag-Atg14L in the presence of CFP or NRBF2-CFP. Atg14L-linked Vps34 is pulled down by an anti-Flag antibody and subjected to KA (upper panel). IP products and inputs were immunoblotted using the antibodies indicated (upper panel). Quantification of Vps34 kinase activity (lower panel) shows the significant difference between two groups. (Data are shown as mean±s.e.m., P value is indicated on the figures, one sample t-test versus hypothetical mean 1, n=5).
NRBF2 regulates autophagy and prevents liver injury by modulating Atg14L-linked phosphatidylinositol-3 kinase III activity (2014)
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(a) Starvation-induced long-lived protein degradation is impaired after NRBF2 knockdown. Compared with control (con) siRNA, NRBF2 siRNA decreases long-lived protein degradation (proteolysis rate) in NIH3T3 cells under starvation (ST) condition. This difference is diminished when the starved cells are co-treated with wortmannin (WM, 100 nM). (Data are shown as mean±s.e.m., P values are indicated on the figures, one-way analysis of variance with Dunnett as post hoc test, n=4; NS, not significant). (b) Rapamycin (Rap)-induced autophagy is impaired in the NRBF2 KO cells. The MEFs were treated with (dimethyl sulfoxide) DMSO or 50 μg ml−1 of Rap for 4 h then the cell lysates were immunoprobed with anti-LC3 and anti-p62 antibodies. (c) LC3-II and p62 levels were quantified and normalized with β-actin. Quantification results show that Rap-induced LC3 lipidation (upper) and p62 degradation (lower) were markedly impaired in the NRBF2 KO MEFs. (Data are shown as mean±s.e.m., P values are indicated on the figures, one sample t-test (WT con versus KO con) or unpaired t-test (WT Rap versus KO Rap)). p62 blots quantification, n=6; LC3 blots quantification, n=3). (d,e) The MEFs were subjected to Rap (50 μg ml−1) or starvation (HBSS) treatment then stained with anti-LC3 (d) or anti-WIPI2 (e) antibody. (f) The LC3 and WIPI2 puncta per cell were counted and quantified. (Data are shown as mean±s.e.m., P values are indicated on the figures, independent samples Kruskal–Wallis test followed by pairwise comparisons, n=30 randomly selected cells, a representative result from three independent repeats). (g) NRBF2-CFP stable cells were starved in HBSS for 4 h and then subjected to WIPI2 staining. Under starved condition, NRBF2-CFP forms puncta structures that co-localized with WIPI2. This is a representative image from three independent experiments. (h) The NRBF2 KO MEFs were transfected with CFP, NRBF2-CFP, dMIT-CFP or dCCD-CFP for 24 h and then followed by co-immunostaining with GFP and WIPI2 antibodies. (i) The WIPI2 puncta number per cell in GFP-positive cells were counted and quantified. (Data are shown as mean±s.e.m., P values are indicated on the figures, independent samples Kruskal–Wallis test followed by pairwise comparisons, n=30 randomly selected cells, a representative result from two independent repeats). Scale bars, 20 μm, or length indicated on the figure. CM, culture medium.
NRBF2 regulates autophagy and prevents liver injury by modulating Atg14L-linked phosphatidylinositol-3 kinase III activity (2014)
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(a) NRBF2 KO MEFs display impaired autophagosome acidification. WT and NRBF2 KO MEFs are transiently transfected with mCherry–GFP–LC3B. WT MEFs expressing mCherry–GFP–LC3B contain many red-only puncta along with yellow (presence of both red and green) puncta. The number of both red-only puncta and yellow puncta markedly increases after rapamycin (Rap; 50 μg ml−1, 4 h) or starvation (HBSS, 4 h) treatment, suggesting the increased autophagolysosomes and nascent autophagosomes. In contrast, NRBF2 KO MEFs expressing mCherry–GFP–LC3B contain quite fewer red-only puncta and yellow puncta, even after Rap or starvation treatment. (b) The quantification results show that both the numbers of red-only puncta and percentage of red-only puncta (verses total puncta) in KO MEFs were markedly reduced. (Data are shown as mean±s.e.m., P values are indicated on the figures, Mann–Whitney U-test, n=20 randomly selected cells, a representative result from three independent repeats), indicating both the autophagolysome number and autophagosome acidification rate are reduced in KO cells. Scale bars, 20 μm or 10 μm (amplified regions). (c) Autophagolysome formation is impaired in NRBF2 KO MEFs. WT and NRBF2 KO MEFs were transiently transfected with RFP-LC3 then stained with LAMP2 antibody. The co-localization between RFP-LC3 and LAMP2 are illustrated by line profile. RFP-LC3 puncta recruit much stronger LAMP2 signal in WT MEFs than in NRBF2 KO MEFs (as indicated by white arrows), suggesting the impairment of autophagolysosome formation in KO cells. Scale bars, 20 μm or 10 μm (amplified regions). This is a representative image from three independent experiments. (d) Overexpression of NRBF2 enhances UVRAG-linked Vps34 kinase activity. HEK293T cells were co-transfected with Myc-Vps34-Vps15-His and FLAG-UVRAG, in the presence of CFP or NRBF2-CFP. UVRAG-linked Vps34 was pulled down by an anti-FLAG antibody and subjected to KA. IP products and inputs are immunoblotted using the antibodies indicated. (e) Quantification of Vps34 kinase activity normalized with immunoprecipitated Vps34 shows the significant difference between two groups. (Data are shown as mean±s.e.m., P value is indicated on the figures, one sample t-test versus hypothetical mean 1, n=5).
NRBF2 regulates autophagy and prevents liver injury by modulating Atg14L-linked phosphatidylinositol-3 kinase III activity (2014)
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(a) The gross anatomical views of representative 4% paraformaldehyde-fixed livers and quantification of liver index. (Data are shown as mean±s.e.m., P values are indicated on the figures, unpaired Student’s t-test, n=3 mice each group). Scale bar, 1 cm. (b) The haematoxylin and eosin (HE) and CD45 staining of 10-month-old WT and NRBF2 KO mice livers. The NRBF2 KO liver shows mild increase of ductular reaction (yellow arrow) and isolated necrosis (red arrows). The necrotic foci were further confirmed by CD45 staining (black arrow). This is a representative image from four mice per genotype. Scale bar, 50 μm. (c) The number of necrotic foci and ductular reaction scores were recorded under bright-field microscope. At least 10 randomly selected fields (10 × ) from each mouse and four mice per genotype were analysed. (Data are shown as mean±s.e.m., P values are indicated on the figures. Ductular reaction scores, unpaired Student’s t-test; necrotic foci, Mann–Whitney U-test, n=4 mice each group). BD, bile duct; CV, central vein; PV, portal vein.
NRBF2 regulates autophagy and prevents liver injury by modulating Atg14L-linked phosphatidylinositol-3 kinase III activity (2014)
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(a) WB analysis shows accumulation of p62 in the liver of NRBF2 KO mice. Liver lysates were immunoprobed with antibodies indicated. p62 protein levels are upregulated in the KO mice liver. (b) The quantification result shows that the p62 level increased more than threefold in the NRBF2 KO mice liver compared with WT mice liver. (Data are shown as mean±s.e.m., P values are indicated on the figures, unpaired Student’s t-test; WT, n=5 mice; KO, n=4 mice). (c) WB analysis shows accumulation of high-molecular weight (HMW) ubiqutin in the liver of NRBF2 KO mice. Insoluble fractions of liver lysates were immunoprobed with an anti-ubiquitin antibody, n=4 mice per genotype. (d) Atg14L-linked Vps34 kinase activity is impaired in the liver of NRBF2 KO mice. Atg14L-linked Vps34 is pulled down by an anti-Atg14L antibody and is subjected to KA. IP products and inputs were immunoblotted using the antibodies indicated. (e) Quantification of IPed Vps34 kinase activity versus IPed Atg14L shows the significant difference between WT and NRBF2 KO mice liver. (Data are shown as mean±s.e.m., P values are indicated on the figure, unpaired Student’s t-test, n=4 mice each group). (f) Focal accumulation of p62 in the liver of NRBF2 KO mice. Liver frozen sections (15 μm in thickness) were stained with an anti-p62 antibody. Focal accumulation of p62 is observed in the KO mice liver but not in the WT mice liver. Scale bars, 100 μm or 20 μm (amplified regions). This is a representative image from four mice per genotype. (g) Accumulated p62 colocalizes with NQO1. Liver frozen sections were double stained with an anti-p62 antibody and an anti-NQO1 antibody. This is a representative image from four mice per genotype. Scale bars, 20 μm.
NRBF2 regulates autophagy and prevents liver injury by modulating Atg14L-linked phosphatidylinositol-3 kinase III activity (2014)
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WT and NRBF2 KO MEFs were treated with DMSO, 1 μM thapsigargin (TP) or 1 μM tunicamycin (TN) for 24 or 48 h. (a) Then cells were either imaged under phase-contrast microscope or (b) stained with propidium iodide (PI) and subjected to cell death rate analysis by flow cytometry. The representative images of cell morphology after treatments and quantitative analysis of PI-positive cells rate show marked increase of cell death in the NRBF2 KO MEFs compared with WT MEFs. (Data are shown as mean±s.e.m., P values are indicated on the figure, unpaired Student’s t-test, n=5). Scale bars, 100 μm; Con, control. (c) Re-introducing NRBF2 to NRBF2 KO MEFs reverses the vulnerability of cells to ER stress. NRBF2-CFP stably expressing cells were established in the NRBF2 KO background. Cells were treated with DMSO or 1 μM TP for 24 h then stained with PI and subjected to cell death rate analysis by flow cytometry. The cell death rate in CFP-positive (+) population (NRBF2-CFP expression) and negative (−) population (no NRBF2-CFP expression) were recorded and analysed, respectively. (Data are shown as mean±s.e.m., P values are indicated on the figure, unpaired Student’s t-test, n=3). (d) ER stress inducers trigger caspase-8 and caspase-3 activation in NRBF2 KO MEFs. MEFs were treated with DMSO, 1 μM TP or 1 μM TN for 24 h, and then immunoprobed with indicated antibodies. Marked accumulation of cleaved caspase-8 (C-Cas 8; p43 and p18 units) and cleaved caspase-3 (C-Cas 3) are observed in the NRBF2 KO MEFs but not WT MEFs treated with TP or TN. This is a representative image from three independent experiments. (e) C-Cas 8 preferentially localizes at p62 aggregation foci. MEFs were treated with DMSO or 1 μM TP for 24 h, and then co-stained with an anti-p62 antibody and an anti-cleaved caspase-8 antibody. The C-Cas 8 fluorescence signals are triggered in NRBF2 KO MEFs treated with TP and preferentially localize at p62 aggregation foci. Scale bars, 20 μm. This is a representative image from three independent experiments.
NRBF2 regulates autophagy and prevents liver injury by modulating Atg14L-linked phosphatidylinositol-3 kinase III activity (2014)
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(a) NRBF2 is critical for the assembly of Vps34-Vps15 and Atg14L-Beclin 1 complex. Brain lysate from WT and NRBF2 KO mice were subjected to co-IP by Vps34 antibody and Atg14L antibody. The IP products were subjected to in vitro lipid KA and WB analysis using the indicated antibodies. (b,c) Quantification results shows that Vps34-Vps15 and Atg14L-Beclin 1 complex interactions as well as Atg14L-linked Vps34 kinase activity are markedly impaired in NRBF2 KO mice. (Data are shown as mean±s.e.m., P values are indicated on the figures, unpaired Student’s t-test, n=4 mice in each group; NS, not significant). (d) Overexpression of NRBF2 enhances overall Vps34 kinase activity. HEK293T cells were co-transfected with Myc-Vps34-Vps15-His and CFP, NRBF2-CFP, dMIT-CFP or dCCD-CFP. Total Vps34 was pulled down by an anti-myc antibody and subjected to KA. IP products and inputs are immunoblotted using the antibodies indicated. (e) Quantification of IPed Vps34 kinase activity, Vps15 protein normalized with IPed Vps34 shows that NRBF2-CFP, but not CFP, dMIT-CFP or dCCD-CFP significantly enhance Vps34 kinase activity and Vps34-Vps15 interaction. (Data are shown as mean±s.e.m., P values are indicated on the figures. IPed Vps15/IPed Vps34, one sample t-test versus hypothetical mean 1, Bonferroni correction, n=3; IPed Vps34 kinase activity/IPed Vps34, multiple t-test followed by Bonferroni correction, n=3). (f) Schematic model for the NRBF2 function in autophagy. Top: in WT cells, NRBF2 functions to stabilize Beclin 1-Atg14L, Vps34 and Vps15 proteins in the specific autophagy PI3K-III kinase complex. In NRBF2 KO cells, ~25% Atg14L remains in the complex with Vps34-Vps15; middle and bottom: upon autophagy induction, NRBF2-Atg14L interaction mediates the binding with other components in the cytosol and consequent assembly of a highly active PI3K-III kinase complex at the phagophore, resulting in enhanced autophagy capacity.
Ubiquitin accumulation in autophagy-deficient mice is dependent on the Nrf2-mediated stress response pathway: a potential role for protein aggregation in autophagic substrate selection. (2010)
Figure 1.

Accumulation of Ub in autophagy-deficient brain. Ub profile from the 1% Triton X-100–soluble and –insoluble fraction of autophagy-deficient brain homogenates captured with P2UBA resin. (A) Age-matched control Atg7 littermates (Atg7flox/+;nestin-Cre:p62+/−; denoted +) at 6 wk (open circles; n = 4) or Atg7 KO (Atg7flox/flox;nestin-Cre:p62+/−; denoted −) at 6 wk (closed diamonds; n = 3) are shown. (B) Control Atg5 littermates (Atg5flox/+;nestin-Cre; denoted +) at 16 (open circles; n = 4) and 26 wk (open diamonds; n = 3) or Atg5 KO (Atg5flox/flox;nestin-Cre; denoted −) at 16 (closed circles; n = 4) and 26 wk (closed diamonds; n = 3) are shown. Each symbol represents one animal. *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.005.
Ubiquitin accumulation in autophagy-deficient mice is dependent on the Nrf2-mediated stress response pathway: a potential role for protein aggregation in autophagic substrate selection. (2010)
Figure 2.

Suppressed accumulation of Ub in Atg7-/p62-deficient brains. (A and B) Quantitative mass spectrometry analysis of P2UBA captured total (A) and isopeptide-linked (B) Ub from the soluble and insoluble fractions of autophagy-deficient brains. Age-matched control Atg7 littermates (Atg7flox/+:nestin-Cre:p62+/−; denoted +) at 6 wk (open circles; n = 4), p62 KO (Atg7flox/flox:p62−/−; denoted −) at 6 wk (closed circles; n = 3), Atg7 KO (Atg7flox/flox:nestin-Cre:p62+/−; denoted −) at 6 wk (closed diamonds; n = 3), or Atg7-/p62-DKO (Atg7flox/flox:nestin-Cre:p62−/−) at 6 wk (closed triangles; n = 3) are shown. Each symbol represents one animal. *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.005.
Ubiquitin accumulation in autophagy-deficient mice is dependent on the Nrf2-mediated stress response pathway: a potential role for protein aggregation in autophagic substrate selection. (2010)
Figure 3.

Suppressed accumulation of Ub in Atg7-/Nrf2-deficient livers. (A and B) Quantitative mass spectrometry analysis of P2UBA captured p62 (A), total (A), and isopeptide-linked (B) Ub from the soluble and insoluble fraction of autophagy-deficient livers (28 d after pIpC injection). Control littermates (F/F or F/F:Nrf2+/−; denoted +; open circles; n = 4), Nrf2 KO (F/F:Nrf2−/−; denoted −; closed circles; n = 4), Atg7 KO (F/F:Mx1 or F/F:Mx1:Nrf2+/−; denoted −; closed diamonds; n = 6), or Atg7-/Nrf2-DKO (F/F:Mx1:Nrf2−/−; closed triangles; n = 6) are shown. Each symbol represents one animal. **, P ≤ 0.01; ***, P ≤ 0.005.
Ubiquitin accumulation in autophagy-deficient mice is dependent on the Nrf2-mediated stress response pathway: a potential role for protein aggregation in autophagic substrate selection. (2010)
Figure 4.

Nrf2 transcription factor–binding sites are enriched among Ub-associated genes. (A) Enrichment of predicted transcription factor (TF)–binding sites in the promoter region (−5,000 to 300) of Ub-associated genes versus its representation genome wide. The top 10 most enriched transcription factor–binding sites predicted among Ub-associated genes are labeled, with their enrichment scores (or −Log10–transformed Benjamini–Hochberg-adjusted p-values) plotted against its occurrence. (B) Elevated Ub mRNA levels from Atg5-deficient brains. Total RNA was extracted from control Atg5 littermates (Atg5flox/+;nestin-Cre) at 16 wk or Atg5 KO (Atg5flox/flox;nestin-Cre) at 16 wk (n = 4 for each genotype; **, P ≤ 0.01) and the amount of transcript from Ubc, Ubb, Uba52, and Uba80 genes was quantified using real-time RT-PCR and normalized to actin. Error bars indicate SEM. au, arbitrary unit. (C) Gene expression analysis of Ub-associated Nrf2 targets mapped to mouse orthologues. Probes detecting transcripts exhibiting differential expression (Benjamini–Hochberg-adjusted P < 0.05) in at least one of the four comparisons are shown. Heat map represents Log2 (fold changes) with respect to either wild type (WT) or Atg7 KO (as indicated). Labels show the symbol, RefSeq (accession numbers from the NCBI Nucleotide database), gene probe name, and the gene row and gene column (i.e., array coordinates).
Ubiquitin accumulation in autophagy-deficient mice is dependent on the Nrf2-mediated stress response pathway: a potential role for protein aggregation in autophagic substrate selection. (2010)
Figure 6.

Flow cytometry assay to quantify selective autophagy. (A) Diagram of the bicistronic reporter construct. Ribosomes are recruited to both the 5′ end of the bicistronic construct to translate the test fusion protein fused to GFP and at the IRES to translate the stable, nonaggregating reference protein chFP. The test protein is either htt exon 1 with a nonpathogenic poly-Gln repeat htt(Q25) fused to GFP or htt with an expanded poly-Gln tract, htt(Q47)-GFP, which promotes aggregation. (B) The addition of dox for 96 h decreased autophagy in the bicistronic stably expressing cell lines similar to the parental line, m5-7, as measured by the decreased levels of phosphatidylethanolamine-modified LC3 (LC3-II). (C) Western blot (WB) analysis of the accumulation of htt(Q)-GFP after autophagy shutoff. At steady-state (t = 0 h), the levels of both htt(Q25)-GFP and htt(Q47)-GFP were virtually undetectable. After autophagy shutoff, there was a robust increase in the level of htt(Q47)-GFP, as detected by GFP Western blot, whereas there was very little or no detectable increase in htt(Q25)-GFP, GAPDH, LDH, or chFP. (D) Quantitative flow cytometry time course analysis measuring selective autophagy in live cells. The ASI is the ratio of the relative increase in green and red fluorescence, as assessed by two-color flow cytometry, in response to dox. In control experiments, the ASI of two soluble, nonaggregating proteins, htt(Q25)-GFP and chFP, was 1. In contrast, the ASI of the aggregation-prone protein, htt(Q47)-GFP, compared with chFP after autophagy shutoff (+dox; 100 h) was 2. Data represent three independent experiments performed on different days. **, P ≤ 0.01; ***, P ≤ 0.005. (E) Flow cytometry time course analysis of cell death at different time points after autophagy shutoff (+dox). The degree of cell death correlated directly with increased htt(Q47)-GFP levels after autophagy shutoff and was significantly enhanced in cells expressing htt(Q47)-GFP compared with htt(Q25)-GFP (***, P ≤ 0.005). Data represent three independent experiments performed on different days. (F) AQUA using heavy isotope–labeled GFP standard in addition to the routine Ub standards after P2UBA pull-down of soluble and insoluble lysates from htt(Q)-GFP-IRES-chFP bicistronic expressing cells before (−dox) and after autophagy shutoff (+dox). The experimental GFP peptide was only detected in two of the four experiments, and the data shown are representative of these. In the other two experiments, the experimental GFP peptide was below the threshold of detection. (D–F) Error bars indicate SEM. *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.005.