EMBO/SourceData huggingface dataset:
Figure 6Expression of shRNA-resistant LINC00115 WT but not mutant or empty vector (EV) rescued LINC00115 shRNA-inhibited ZNF596 mRNA (A) expression in 1123 GSCs.Expression of shRNA-resistant LINC00115 WT but not mutant or empty vector (EV) rescued LINC00115 shRNA-inhibited ZNF596 protein (B) expression in 1123 GSCs.D. MS2-RIP followed by qRT-PCR for endogenous microRNAs association with ZNF596. 12XMS2 empty vector, ZNF596-5'-UTR-WT-12XMS2, or ZNF596-5'-UTR-mut -12XMS2 with Flag-tagged MS2 were co-transfected into 1123 GSCs.F. Luciferase activity in 1123 GSCs co-transfected with miR-200s and luciferase reporters containing ZNF596 5'-UTR WT, mutant, or empty vector (EV).
Figure 7GSEA of EZH2-targeted signature genes using ranked gene expression changes in 1123 GSCs with ZNF596 sgRNA or a control sgRNA. NES, normalized enrichment score.qRT-PCR analysis of effect of ZNF596 knockout on EZH2 expression. Data information: data are representative of three independent experiments. Error bars, ± SD. *, p < 0.05, **, p < 0.01, ***, p < 0.001, by One-way ANOVAZNF596 knockout impaired EZH2 expression, its downstream H3K27me3, and STAT3 phosphorylation in 1123 and 528 GSCs. Data information , data are representative of three independent experiments. Error bars, ± SD.LINC00115 regulated ZNF596/EZH2/STAT3 signaling. 1123 and 528 GSCs were treated with or without EZH2 inhibitor GSK343 (3 μM) for 6 Data information: data are representative of three independent experiments. Error bars, ± SD.LINC00115 and ZNF596 regulate EZH2 promoter activity. Data information: data are representative of three independent experiments. Error bars, ± SD. , by two-tailed t-testChIP-qPCR analysis of ZNF596 binding with the EZH2 promoter. Data information: data are representative of three independent experiments. Error bars, ± SD. *, p < 0.05, **, p < 0.01, ***, p < 0.001, by One-way ANOVAEZH2 inhibitor GSK343 impaired ZNF596 overexpression-reversed and LINC00115 knockdown-inhibited neuro-like sphere formation. 1123 and 528 GSCs with an inducible ZNF596 shRNA were treated with or without Dox (2 μg/ml) and/or EZH2 inhibitor GSK343 (1 μM) for 7 days. Data information: data are representative of three independent experiments. Error bars, ± SD. by two-tailed t-testGrowth kinetics of subcutaneous xenograft tumor with indicated genetic modifications after treatment with or without Dox and/or GSK343. Tumor-bearing mice (five mice per group) were fed with 10% sucrose water with or without 2 mg/ml Dox and combined with treatment with or without GSK343 (5 mg/kg body weight from Monday to Friday via intraperitoneal injection) for three weeks beginning five days post-xenograft transplantation. Data were from three independent experiments with five mice per group. Data information: *, p < 0.05, **, p < 0.01, ***, p < 0.001 , by two-tailed t-testKaplan-Meier analysis of animal implantation with GSC1123 with indicated modifications. n = 10. Statistical analysis was performed by log-rank test.
Figure 8Representative images of RNAscope for LINC00115 and IHC for ZEB1 and ZNF596 expression in two GBM specimens, Sample #1 (positive) and Sample #2 (negative). Scale bar, 50 μm. Images are representative of two independent experiments.Correlation of detected expression between ZEB1 or ZNF596, and LINC00115 from a separate cohort of a total of 75 paraffin-embedded clinical GBM samples. Statistical analysis was performed by Chi-square test.Kaplan-Meier survival analysis of patients with GBM tumors expressing high or low levels of LINC00115 with high or low levels of ZEB1 or ZNF596 expression. Median survival (in months): LINC00115hi/ZEB1hi, 5.4; LINC00115lo/ZEB1lo, 27.9; LINC00115hi/ZNF596hi, 4.2; LINC00115lo/ZNF596lo, 23.8. Statistical analysis was performed by log-rank test.
Figure 1(left) Luciferase expression in HEK293 cells driven by deletion constructs of POLG proximal promoter. (right) Luciferase expression with mutated CAAT-boxes in POLG promoter. The error bars indicate standard deviation in 3 biological replicates. AU; arbitrary units.Expression pattern driven by 500 bp Polg proximal promoter in E12.5 mouse embryo. LacZ-positive cell populations in the developing midbrain (black arrows), dorsal root ganglia (grey arrows) and motoneuron progenitors (arrowhead) of the neural tube. Somites show some expression (white arrow). Sectioning planes indicated by red lines. Scale bars 100 µm.- (G) POLG enhancer elements are functional in vivo and drive expression in E12.5 transgenic mice. Sectioning planes indicated by red lines. Black line in (E) marks the expression in the dorsal neural tube, whereas rostral and caudal regions lack dorsal expression (black arrows).(H)- (J) Neural tube lacZ expression driven by (H) EE1: immature neuronal precursors (grey arrow), (I) EE2: dorsal neural tube (grey arrow) and dorsal root ganglia (black arrow), and (J) EE3: dorsal neural tube (grey arrow). Scale bars 100 µm. K)- (M) Midbrain lacZ expression, driven by (K) EE1, (L) EE2 and (M) EE3. Black arrow indicates neuronal population from EE1 embryo stained in (N). Scale bars 100 µm. (N) EE1 drives expression in oculomotor complex; immunofluorescent co-staining with antibodies against ISL1/2 (motoneurons of oculomotor complex; red) and β-Gal (green). LacZ-staining of the region in (k); black arrow. Scale bars 50 µm.
Figure 2Sagittal section of adult mouse brain showing lacZ expression driven by EE2. HC, hippocampus.EE2-driven expression in rostral migratory stream (black arrow) and in subventricular zone (white arrow). Scale bar 760 µm.Adult mouse spinal cord, EE2 and (D) EE3 expression pattern. Dorsal horns, laminae I-III (black arrows) and central canal (arrowheads). LacZ staining. Dashed lines in (C) indicates the region of dorsal horn shown in (D), (F) and (G). Inlets in (C) and (E) show POLG immunohistochemistry of dorsal horn and central canal (grey arrow), respectively. Scale bars: 100 µm if not indicated otherwise.(F)-(G) Calbindin (red) and β-Gal (green) expression in interneurons of the dorsal horn laminae I-III of (F) EE2 and (G) EE3 transgenic adult mice. Immunofluorescence. Scale bars 20 µm.
Figure 3The number of distal DNAse I hypersensitive sites (DHSs) of mtDNA maintenance genes and genes in the genomic POLG locus correlating >0.85 with target promoter DHS across 125 cell lines. Abbreviations: TWNK, Twinkle protein; POLG, DNA Polymerase gamma, catalytic subunit; POLG2, DNA Polymerase gamma, accessory subunit; SSBP1, Single stranded DNA binding protein 1; TFAM, mitochondrial transcription factor A; FANCI, Fanconi anemia group I protein; RHCG, Ammonium transporter Rh type C; TICRR, Treslin.Distribution histogram of DHSs for mtDNA maintenance genes.Genomic distribution of POLG DHSs. Black arrow shows a cluster upstream from POLG coding region.Expression of LINC00925 and POLG in different human tissues and cell types. Quantitative PCR amplification of cDNA. Abbreviations: iPS, induced pluripotent stem cell; SH5Y, neuroblastoma line; HepG2, liver hepatocellular carcinoma line; U2OS bone osteosarcoma line. Error bars indicate standard deviation in 3 technical replicates. AU; arbitrary units.Polg and long-non-coding RNA Ai854517 (mouse homologue of human LINC00925) correlate tightly in mouse cerebellar development. Time points: E18, postnatal days 0, 3, 6, 9; three mice per time point. Expression calculated as cap analysis of gene expression (CAGE) hits in the transcription start site (CTSS).Ai854517 and Polg transcripts colocalize in adult mouse brain; in situ hybridization. HC, hippocampus; cerebellar molecular layer (M), Purkinje cell layer (PC), granular cell layer (GC). Scale bars: hippocampus 760 µm, cerebellum 300 µm.Expression levels of MIR9-3 and Ai854517 correlate in mouse cerebellar development. Time points: E18, postnatal day 0, 3, 6, 9; three mice per time point.. Expression calculated as cap analysis of gene expression (CAGE) hits in the transcription start site (CTSS).RNA expressions of MIR9, NR2E2, LDLDRAP1 and MTHFD2 in HEK293 untransfected controls and in cells transfected with pre-MIR9 or scrambled RNA. Shown is mean with standard error of the mean. Statistical testing was performed using 1-way ANOVA with Dunnet's correction for multiple comparisons. Abbreviations: AU; arbitrary units.
Figure 4Spinal cord (C8-level) of MIRAS patient, neurofilament staining. Dorsal columns, especially the gracile, show pallor (star); motoneurons in the anterior horns are preserved (black arrow). Scale bar 1 mm.Oculomotor complex of POLG patient with progressive ophthalmoplegia; midbrain level. Hematoxylin-eosin staining. The whole area shows spongiotic degeneration. Scale bar 50 µm.
figf1(a) Western blotting was performed to determine FoxO1 expression, p62 degradation and LC3-II accumulation in H1299, HCT116 and HeLa cells in response to serum starvation (SS) for 24 h or 0.5 mM H2O2 for 6 h in the presence or absence of E64 and pepstatin A (PEPS A).(b, c) Stable FoxO1 knockdown HCT116 cells, or cells with an empty RNAi plasmid, were incubated in a serum-free medium for up to 36 h (b) or treated with 0.5 mM H2O2 for up to 12 h (c); western blotting was performed to detect changes in FoxO1, p62, LC3-II or β-actin.(d) HCT116 cells were labelled with [3H]leucine for 48 h, washed and incubated for 24 h, before being subjected to serum starvation for 24 h or 0.5 mM H2O2 for 12 h in the presence or absence of 3-MA. At 12 or 24 h after treatment, the relative degradation of long-lived proteins was measured by counting radioactivity. Data in d are means ± s.d. (n = 3). Two asterisks, P 0.01; asterisk, P 0.05; NS, not significant, P > 0.05; Student's t-test.(e) Autophagic vesicles or autophagosomes in HCT116 cells or stable FoxO1-RNAi HCT116 cells, were observed by electron microscopy after 24 h of serum starvation. The bottom picture enlargement showing clearer autophagic vesicles indicated by an arrow. The graph shows a statistical analysis of autophagic vesicles in HCT116 cells with or without knockdown of FoxO1 in response to serum starvation. Data in e are means ± s.d. (n = 3).(f) LC3-immunopositive punctate signals were observed in HCT116 or in stable FoxO1-RNAi HCT116 cells in response to serum starvation for 24 h or 0.5 mM H2O2 treatment. (g) Quantification of LC3-positive punctate cells in f. Data in g are means ± s. d. (n = 3).(h) A rescue experiment using a specific mutated FoxO1 plasmid to validate the activity of FoxO1 in the induction of autophagy in HCT116 cells in the presence or absence of serum, with or without E64 and pepstatin A.
figf2(a) A Flag-tagged FoxO1(WT), FoxO1(ΔDB), FoxO1(ΔDB3A) or an empty plasmid was individually transfected into GFP-LC3 pre-transfected H1299 cells, and the cellular localization of FoxO1 (upper panels) or GFP-LC3 punctate signals (lower panels) was observed with a confocal microscope. Scale bars, 10 μm. (b) The numbers of punctate GFP-LC3 cells are represented by the ratio of GFP-LC3-labelled punctate cells to overall survived H1299 cells (at least 200 cells were counted). Data in b are means ± s.d. (n = 3).(c) p62 degradation and LC3-II accumulation were evaluated by western blotting in H1299 cells transfected with exogenous FoxO1-expressing plasmids mentioned above.(d) H1299 cells were labelled with [3H]leucine for 48 h, then transfected with a control plasmid or various Flag-FoxO1 plasmids, in the presence or absence of 3-MA or E64 and pepstatin A. Degradation of long-lived proteins was measured at the indicated time, 24 h after transfection. Data in d are means ± s.d. (n = 3).(e) A GFP-tagged FoxO1(3A) or an empty plasmid was co-transfected with a FoxO1-promoter luciferase plasmid into H1299 cells. After 24 h, luciferase reporter activity of FoxO1 was measured. RLU, relative luciferase units. Data are means ± s.d. (n = 3).(f) A set of RNAi-resistant rescue forms of FoxO1 plasmids were transfected into stable FoxO1-RNAi HCT116 cells in the presence or absence of E64 and pepstatin A. Western blotting was performed to detect p62 degradation and LC3-II accumulation.(g) Flag-tagged FoxO1(WT)r, FoxO1(3A)r, FoxO1(3A-NLSm)r, FoxO1(NESm)r or an empty plasmid were individually transfected into GFP-LC3 pre-transfected HCT116 cells (FoxO1-RNAi treated), and the cellular localization of FoxO1 (upper panels) or GFP-LC3 punctate signals (lower panels) were observed with a confocal microscope. (h) The numbers of punctate GFP-LC3 cells are represented by the ratio of GFP-LC3-labelled punctate cells to overall survived HCT116 cells. Data in h are means ± s.d. (n = 3).
figf3(a) Different FoxO1-expressing plasmids, namely FoxO1(WT), FoxO1(3A), FoxO1(ΔDB), FoxO1(ΔDB3A), FoxO1(NESm) and FoxO1(3A-NLSm), were transfected into H1299 cells and cell fractionation was performed to analyse cellular localization (N, nucleus; C, cytoplasm) of these FoxO1 mutants. PCAF is a loading control for nuclear protein, and actin is the loading control for cytoplasmic protein.(b) Quantitative PCR was performed to measure the transactivity of autophagy-related genes in transfected H1299 cells with different FoxO1-expressing plasmids (upper panel) or in stable FoxO1-RNAi or non-RNAi-treated HCT116 cells in response to serum starvation for 24 h or 0.5 mM H2O2 for 12 h (lower panel). All data are means ± s.d. (n = 3).(c) Different FoxO1-mutant-expressing plasmids were transfected into H1299 cells and a ChIP assay was performed to measure the binding activity of these mutated FoxO1 to the p27 promoter.
figf4(a) HCT116 cells were treated with serum starvation for 24 h (upper panels) or 0.5 mM H2O2 for 12 h (lower panels); cytosolic proteins were extracted for co-immunoprecipitation with anti-FoxO1 and probed with anti-acetylated lysine (Ace-lyn). Both bottom panels display cytosolic FoxO1. IP, immunoprecipitation.(b) HCT116 cells were serum-starved for 24 h and the cytosolic proteins were extracted for co-immunoprecipitation with anti-FoxO1 or anti-SIRT2, followed by probing with anti-SIRT2 or anti-FoxO1, respectively (top and middle panels). FoxO1(WT) was also transfected into H1299 cells and the cytosolic protein was extracted, followed by co-immunoprecipitation with anti-FoxO1 and probing with anti-SIRT2 (bottom panels).(c) HCT116 cells were transfected with SIRT2 RNAi plasmid or an empty control plasmid. At 48 h after transfection, the cytosolic lysate was extracted for probing with SIRT2 or FoxO1 (upper panels), or for co-immunoprecipitation with anti-FoxO1, followed by probing with anti-acetylated lysine (lower panels). IB, immunoblot.(d) HCT116 cells were treated with AGK2 for 24 h at different doses, as indicated. The cytosolic lysate was extracted for co-immunoprecipitation with anti-FoxO1, followed by probing with anti-acetylated lysine.
figf5(a, b) H1299 cells were transfected with an empty control plasmid or with the Flag-FoxO1(WT) plasmid. At 24 h after transfection, the cytosolic lysate was extracted for co-immunoprecipitation with anti-FoxO1, followed by probing with anti-mTOR, Beclin 1, Vps34 or Atg1 (a) and with Atg3, Atg4, Atg10, Atg7 or LC3 (b).(c) H1299 cells were co-transfected with Myc-Atg7, with Flag-FoxO1(WT) or with an empty control plasmid. At 24 h after transfection, the cytosolic lysate was extracted for Flag with anti-Flag, followed by probing with anti-Myc.HCT116 cells were serum-starved for 24 h (d)and the cytosolic lysate was extracted for co-immunoprecipitation with anti-FoxO1, followed by probing with anti-Atg7(e) Different Myc-tagged FoxO1 fragments and Flag-tagged Atg7 were co-transfected into H1299 cells, and the cytosolic lysate was extracted for co-immunoprecipitation with anti-Myc, followed by probing with anti-Flag.(f) HCT116 cells were transfected with an empty control plasmid, an SIRT2(WT)-expressing plasmid or an SIRT2(168A)-expressing plasmid. At 24 h after transfection, cells were serum-starved for 24 h, and the cytosolic lysate was extracted for co-immunoprecipitation with anti-FoxO1, followed by probing with anti-Atg7.HCT116 cells weretreated with AGK2 for 24 h (g), and the cytosolic lysate was extracted for co-immunoprecipitation with anti-FoxO1, followed by probing with anti-Atg7
figf6(a) HCT116 cells or stable FoxO1-RNAi HCT116 cells were treated with a non-specific RNAi control or SIRT2-RNAi, and LC3-II accumulation or p62 degradation was detected in the presence or absence of E64 and pepstatin A.(b) HCT116 cells or stable FoxO1-RNAi HCT116 cells were treated with 10 μM AGK2 for 24 h, in the presence or absence of E64 and pepstatin A. Changes in FoxO1, p62 and LC3-II were determined by western blotting (upper panels), or the formation of LC3 punctate signals was observed (lower panels). HCT116 cells were treated with 10 μM AGK2 for 24 h and the formation of LC3 punctate signals was observed. Quantification of the ratio of LC3 punctate cells to overall HCT116 cells is shown in the lower right panel. Data are means ± s.d. (n = 3).(c) H1299 cells were transfected with Flag-FoxO1(WT), SIRT2(WT) or SIRT2(168A). At 24 h after transfection, the cell lysate was extracted and immunoblotted with anti-Flag, anti-SIRT2, anti-LC3, anti-p62 or anti-β-actin..(d) HCT116 cells were transfected with a control plasmid, a SIRT2(WT)-expressing plasmid or a SIRT2(168A)-expressing plasmid. At 24 h after transfection, the cells were subjected to serum starvation for 24 h. The cell lysate was extracted and immunoblotted with anti-SIRT2, anti-LC3, anti-p62 or anti-β-actin.(e) H1299 cells were transfected with Myc-Atg7, Flag-FoxO1(WT) or mutated Flag-FoxO1(KR). At 24 h after transfection, the cytosolic lysate was extracted for co-immunoprecipitation with anti-Myc, followed by probing with anti-Flag.(f) H1299 cells were transfected with a control plasmid, Flag-FoxO1(WT), Flag-FoxO1(K262R), Flag-FoxO1(K265R), Flag-FoxO1(K274R) or Flag-FoxO1(KR). At 24h after transfection in the presence or absence of E64 and pepstatin A and immunoblotted, the cell lysate was extracted and immunoblotted with anti-Flag, anti-LC3, anti-p62 or anti-β-actin.(g) Left: H1299 cells were co-transfected with GFP-LC3, Flag-FoxO1(WT) or Flag-FoxO1(KR). The formation of GFP-LC3-labelled punctate signals was observed 24 h after transfection. Right: quantification of the ratio of GFP-LC3-labelled punctate cells to overall survived H1299 cells. Data in g are means ± s.d. (n = 3). Scale bars, 25 μm (b), 10 μm (g).
figf7(a) H1299 cells were transfected with a control plasmid, Flag-FoxO1(WT), Flag-FoxO1(3A), Flag-FoxO1(ΔDB) or Flag-FoxO1(ΔDB3A), in the presence or absence of 10 mM 3-MA (upper panel) or in the presence or absence of 50 μM Z-VAD-fmk (lower panel); cells were stained with propidium iodide (PI) 48 h after transfection. PI-stained (dead) cells were counted by flow cytometry and the percentage cell loss was calculated.(b) FoxO1(WT) or Flag-FoxO1(ΔDB) was transfected into H1299 cells; 48 h later the autophagic vesicles were observed under an electron microscope. Enlarged images (right) show clearer autophagic vesicles indicated by arrows. Scale bars, 2 μm.(c) 48 h cells with or without Atg5 RNAi were transfected with FoxO1(WT), and cell death was determined by staining with PI at 48 h after transfection. Data in c are means ± s.d. (n = 3).(d) The stable Atg5 knockdown H1299 cells was further transfected with a control plasmid, Flag-FoxO1(WT), or Flag-FoxO1(ΔDB), and the percentage cell loss was quantified by flow cytometry at 48 h after transfection. Data in d are means ± s.d. (n = 3).
figf8(a) Stable H1299 cells with or without Atg7 knockdown were transfected with a control plasmid (group 1), Flag-FoxO1(ΔDB) (group 2) or Flag-FoxO1(ΔDB-3A) (group 3); 107 cells were then injected into 18 nude mice, with 6 mice per group. Seven weeks later the mice were killed and the tumours were weighed and analysed (bottom graph). Group 1: tumour weights were 1.22 ± 0.78 g (without Atg7 RNAi) and 1.31 ± 0.43 g (with Atg7 RNAi), P = 0.426. Group 2: tumour weights were 0.49 ± 0.18 g (without Atg7 RNAi) and 0.80 ± 0.20 g (with Atg7 RNAi), P = 0.017. Group 3: tumour weights were 1.00 ± 0.40 g (without Atg7 RNAi) and 1.10 ± 0.36 g (with Atg7 RNAi), P = 0.500. Data are means ± s.d. (n = 6).(b) Expression levels of FoxO1 and Atg7 conjugate in mice tumours were determined by western blotting.(c) HCT116 cells (107) or stable FoxO1-knockdown HCT116 cells (107) were injected into the left or right hind legs of three nude mice. Six weeks later the mice were killed and the tumours were weighed and analysed (bottom graph). Tumour weights were 0.08 ± 0.10 g (without FoxO1 RNAi) and 0.48 ± 0.06 g (with FoxO1 RNAi), P = 0.020. Data are means ± sd. n = 3.(d) Protein was extracted from one paired colon tumour (T) or adjacent normal tissue (N) from one patient, and western blotting was performed to detect changes in FoxO1 or p62.(e) Proteins were extracted from 16 paired samples from patients for western blotting with anti-FoxO1 or with anti-p62 antibody. Protein bands were scanned with a phosphorimager and relative band intensity was normalized to the β-actin band. FoxO1 of normal tissue, 0.37; FoxO1 of tumour tissue, 0.10; P = 0.001, two-sided t-test. p62 of normal tissue, 0.32; p62 of tumour tissue, 1.00; P = 0.009, two-sided t-test. Data in e are means ± s.d. (n = 16).
Figure 1(B) Time course of SUMO-1 modification of His-tagged HTTex1p (25Q)-purified proteins (WT, K6R, K9R, K6,9R, K6,9,15R, and S13,16D) was performed in vitro. SUMOylation was visualized using anti-His antibody. WT HTTex1p is SUMOylated within 16 min, K6R or K9R mutations delay SUMOylation, and combined mutations (K6,9R or K6,9,15R) greatly reduce SUMOylation. Mutations that mimic phosphorylation (S13,16D) alter kinetics of SUMO-1 modification with SUMO modification observed beginning by 4 min.
Figure 2(A) qRT-PCR analysis of SUMO-modifying proteins and enzymes in cortex and striata of WT mice at 12 weeks. Relative expression for all the SUMO enzymes is normalized to mouse β-actin.(B and C) qRT-PCR of SUMO mRNAs from 12-week-old WT and R6/2 mouse cortex (B) and striatum (C). SUMO enzyme mRNAs are differentially expressed in R6/2 versus control with statistically significant increases in SENP1 (p = 0.01), SENP3 (p = 0.02), and SUMO-1 (p = 0.003) in cortex and SENP1 (p = 0.02), SENP6 (p = 0.04), PIAS3 (p = 0.007), SUMO-1 (p = 0.02), and SUMO-2 (p = 0.02) in striatum. Samples were analyzed in quadruplicate and normalized to mouse β-actin. Data are shown as R6/2 expression relative to WT levels set at 1 for each enzyme with ± SD (n = 4). *p < 0.05. n.s., not significant.(D and E) Western blot analysis of SUMO-2 in 14-week R6/2 cortex (D) and striatum (E) versus aged-matched controls. SUMO-2 is upregulated in R6/2 striatum versus control (p = 0.026; n = 4). Protein is normalized to α-tubulin and quantitated using ImageJ.
Figure 3(A) HeLa cells transfected with His-tagged HTTex1p (46Q) or 46QP-K6,9,15R (3R) along with GFP-SUMO-1 or GFP-SUMO-2, lysed under denaturing conditions, and nickel purified (Ni-NTA). Unmodified HTT-46Q is indicated by the arrow and SUMO-modified HTT by the boxed region. The lysine mutant (3R) serves as a negative control. Ni-NTA represents nickel-purified His-tagged HTT, and WC TCA represents 10% of the whole-cell lysate expression of HTT and myc-actin (transfection control). HTT is modified by SUMO-1 (left) and SUMO-2 (right).(B) SUMO isopeptidases (SENP1, SENP2, SENP3, SENP5, and SENP6) modulate SUMO-modified HTT when overexpressed together with HTT (46QP-H4 or 3R) and SUMO-1 (GFP-SUMO-1). SENP1, SENP2, and SENP6 decrease HTT SUMOylation. Graph depicts quantitation of western blot using the Odyssey Infrared Imaging System (LI-COR) to calculate the ratio of HTT purified versus the HTT modified by SUMO multiplied by 100.(C) Titration of SUMO-1. Denaturing nickel purification of HTTex1p (46QP-H4) following transfection with decreasing amounts of SUMO-1 reduces the amount of SUMO-modified HTT to undetectable levels. The Ni-NTA blot displayed in the gray scale shows purified HTTex1 and SUMO-modified HTTex1 using HTT antibody. Note that 0.5 μg of SUMO-1 (¼ the amount of SUMO-1 cDNA ) was used for identifying the SUMO-1 E3 ligase for HTTex1p. Graph depicts quantitation of western blot using the Odyssey Infrared Imaging System to calculate the ratio of HTT purified versus the HTT modified by SUMO multiplied by 100. Note that all experiments were performed in triplicate, and a representative figure is shown.