Journal: Virulence

Article Title: FGF8-mediated TRIM16 regulation promotes K48-linked ubiquitination and degradation of RIG-I to facilitate Influenza a virus immune evasion

doi: 10.1080/21505594.2026.2677346

Figure Lengend Snippet: FGF8 negatively regulated IFN-β induced by H13N2 infection. (a, B) luciferase reporter assays were used to assess the impact of FGF8 overexpression on IFN-β and ISRE promoter activity in A549 cells infected with H13N2 at an MOI of 1. (C-F) FGF8-overexpressing A549 cells were infected with H13N2 at an MOI of 1. At 12 hours post-infection (hpi), IFN-β levels in the cell supernatant were measured using ELISA (C), and IFN-β mRNA levels were evaluated by RT-qPCR (d). At 24 hpi, the mRNA levels of interferon-stimulated genes MX1 (e) and IFIT1 (f) were assessed by RT-qPCR. (G-J) stable FGF8-knockdown A549 cells were infected with H13N2 at an MOI of 1. At 12 hpi, IFN-β levels in the cell supernatant were quantified by ELISA (G), and IFN-β mRNA levels were evaluated using RT-qPCR (H). At 24 hpi, the mRNA levels of MX1 (i) and IFIT1 (J) were assessed by RT-qPCR. (K and L) Western blot analysis evaluated RIG-I, p-TBK1, and p-IRF3 expression in A549 cells with FGF8 overexpression (L) or knockdown (K) at 12 hours after H13N2 infection (MOI = 1). Band intensities were quantified by densitometric analysis. Statistical analysis was performed using two-tailed unpaired Student’s t-tests, with significance levels of * p < 0.05, ** p < 0.01, and *** p < 0.001.

Article Snippet: To characterize the direct E3 ligase activity of TRIM16 and its specific ubiquitin linkage in a cell-free system, recombinant human UbcH5b (HY- P79449 , MedChemExpress) and RIG-I protein (TP317615, OriGene) were employed as the E2 conjugating enzyme and substrate, respectively.

Techniques: Infection, Luciferase, Over Expression, Activity Assay, Enzyme-linked Immunosorbent Assay, Quantitative RT-PCR, Knockdown, Western Blot, Expressing, Two Tailed Test

Journal: Virulence

Article Title: FGF8-mediated TRIM16 regulation promotes K48-linked ubiquitination and degradation of RIG-I to facilitate Influenza a virus immune evasion

doi: 10.1080/21505594.2026.2677346

Figure Lengend Snippet: FGF8 drives ubiquitin – proteasomal degradation of RIG-I. (a) FGF8 inhibits RIG-I-mediated signaling. A luciferase reporter assay was performed to evaluate the effect of FGF8 overexpression on IFN-β promoter activation induced by RIG-I. (B and C) FGF8 does not affect RIG-I transcription. RIG-I mRNA levels were quantified by RT-qPCR in FGF8-overexpressing A549 cells at 0, 6, and 12 hours post-infection with H13N2 (b) or H1N1 (C) at an MOI of 1. (d) dose-dependent reduction of RIG-I protein. A549 cells were transfected with increasing amounts of Flag-FGF8 plasmid for 24 hours, followed by infection with H13N2 (MOI = 1) for 12 hours. RIG-I protein levels were analyzed by Western blot, and band intensities were quantified by densitometry. (e) FGF8 reduces RIG-I stability. FGF8-overexpressing A549 cells were infected with H13N2 (MOI = 1) and treated with cycloheximide (CHX, 50 µg/mL) for the indicated time periods. Protein levels were analyzed by Western blot, and the relative abundance of HA-RIG-I was quantified to assess protein degradation rates. (F and G) proteasome inhibition restores RIG-I levels. A549 cells infected with H13N2 (f) or H1N1 (G) at an MOI of 1 were treated with DMSO, chloroquine (CQ, 50 µM), or MG132 (10 µM) for 6 hours. RIG-I expression was analyzed by Western blot, with relative protein levels quantified by densitometry. (H and I) FGF8 promotes K48-linked ubiquitination of RIG-I. HEK-293T cells were co-transfected with the indicated plasmids and treated with MG132 for 6 hours. (H) Total ubiquitination of RIG-I was assessed by immunoprecipitation with anti-HA antibody followed by immunoblotting (ib) with anti-Myc. (i) K48- or K63-linked ubiquitination was analyzed using specific ubiquitin mutants. Error bars indicate the mean ± SEM from three independent experiments. Statistical analysis was performed using two-tailed unpaired Student’s t-tests. ns (not significant), * p < 0.05, ** p < 0.01, and *** p < 0.001.

Article Snippet: To characterize the direct E3 ligase activity of TRIM16 and its specific ubiquitin linkage in a cell-free system, recombinant human UbcH5b (HY- P79449 , MedChemExpress) and RIG-I protein (TP317615, OriGene) were employed as the E2 conjugating enzyme and substrate, respectively.

Techniques: Ubiquitin Proteomics, Luciferase, Reporter Assay, Over Expression, Activation Assay, Quantitative RT-PCR, Infection, Transfection, Plasmid Preparation, Western Blot, Inhibition, Expressing, Immunoprecipitation, Two Tailed Test

Journal: Virulence

Article Title: FGF8-mediated TRIM16 regulation promotes K48-linked ubiquitination and degradation of RIG-I to facilitate Influenza a virus immune evasion

doi: 10.1080/21505594.2026.2677346

Figure Lengend Snippet: Identification of the ubiquitination site on RIG-I targeted by FGF8. (a) diagram illustrating the truncated constructs of RIG-I. (b) HEK-293T cells were co-transfected with specified plasmids and exposed to MG132 for 6 hours. Western blot analysis was conducted to assess the ubiquitination of various RIG-I truncation constructs. (C) Western blot analysis identified the ubiquitination site on RIG-I targeted by FGF8, and band intensities were quantified by densitometry to assess the degradation of each mutant. (d) a dual-luciferase assay was conducted in HEK293T cells co-transfected with specified RIG-I mutants and FGF8 to evaluate the impact of FGF8 on IFN-β promoter activity. Error bars indicate the mean ± SEM from three independent experiments. Two-tailed unpaired Student’s t-tests were used. ns (not significant), * p < 0.05, ** p < 0.01, and *** p < 0.001.

Article Snippet: To characterize the direct E3 ligase activity of TRIM16 and its specific ubiquitin linkage in a cell-free system, recombinant human UbcH5b (HY- P79449 , MedChemExpress) and RIG-I protein (TP317615, OriGene) were employed as the E2 conjugating enzyme and substrate, respectively.

Techniques: Ubiquitin Proteomics, Construct, Transfection, Western Blot, Mutagenesis, Luciferase, Activity Assay, Two Tailed Test

Journal: Virulence

Article Title: FGF8-mediated TRIM16 regulation promotes K48-linked ubiquitination and degradation of RIG-I to facilitate Influenza a virus immune evasion

doi: 10.1080/21505594.2026.2677346

Figure Lengend Snippet: TRIM16 mediated RIG-I degradation and promoted influenza virus replication. (a) Co-immunoprecipitation analysis was performed in cells transfected with Flag-TRIM16 and HA-RIG-I, with or without H13N2 infection (MOI = 1), to verify the interaction. (b) immunofluorescence microscopy showing the localization of TRIM16 (green) and RIG-I (red) in cells infected with H13N2 or mock-infected (NC). Nuclei were stained with DAPI (blue). Note that TRIM16 and RIG-I show diffuse distribution in the NC group but form co-localized puncta (yellow) upon H13N2 infection. Scale bar: 5 μm. (C) in vitro ubiquitination assay to verify the direct E3 ligase activity of TRIM16 using wt and ΔB-Box mutant proteins. (d) in vitro ubiquitination assay to determine the linkage specificity of TRIM16-mediated RIG-I ubiquitination using K48-only and K63-only ubiquitin mutants. (e) bioinformatic analysis using PONDR revealed the presence of intrinsically disordered regions (IDRs) in the FGF8 protein sequence. (f) fluorescence microscopy of A549 cells transfected with EGFP-FGF8 (green). Nuclei were stained with DAPI. Scale bar represents 10 μm. (G) TurboID-based proximity labeling assay was performed in cells expressing FGF8-TurboID. Biotinylated proteins were captured using streptavidin beads, and the pulled-down proteins were analyzed by Western blot to detect the presence of RIG-I and TRIM16. (H and I) validation of TRIM16 knockdown. RT-qPCR (H) and Western blot (i) confirmed the silencing efficiency in A549 cells. (J) control and TRIM16-silenced A549 cells were infected with H1N1 or H13N2 (MOI = 0.5) for 24 hours. Viral protein levels (NP, PB1, PB2) were analyzed by Western blot, and band intensities were quantified by densitometry. (K) RT-qPCR analysis of IFN-β mRNA levels in TRIM16-silenced A549 cells 12 hours post-infection with H13N2 (MOI = 1). (L) Western blot confirmation of TRIM16 overexpression (OE-TRIM16). (M) A549 cells overexpressing TRIM16 were infected with H1N1 or H13N2 (MOI = 0.5) for 24 hours. Viral protein expression was analyzed by Western blot and quantified by densitometry. Error bars indicate the mean ± SEM from three independent experiments. Statistical analysis was performed using two-tailed unpaired Student’s t-tests. ns (not significant), * p < 0.05, ** p < 0.01, and *** p < 0.001.

Article Snippet: To characterize the direct E3 ligase activity of TRIM16 and its specific ubiquitin linkage in a cell-free system, recombinant human UbcH5b (HY- P79449 , MedChemExpress) and RIG-I protein (TP317615, OriGene) were employed as the E2 conjugating enzyme and substrate, respectively.

Techniques: Virus, Immunoprecipitation, Transfection, Infection, Immunofluorescence, Microscopy, Staining, In Vitro, Ubiquitin Proteomics, Activity Assay, Mutagenesis, Sequencing, Fluorescence, Labeling, Expressing, Western Blot, Biomarker Discovery, Knockdown, Quantitative RT-PCR, Control, Over Expression, Two Tailed Test

Journal: Nutrients

Article Title: Sericin’s Potential in Osteoporosis Management: The Roles of L-Serine and D-Serine in Bone Metabolism Regulation

doi: 10.3390/nu17030574

Figure Lengend Snippet: The effect of D-serine administration on osteoclast activation in RAW264.7 cells. ( a ) Treatment with RANKL + M-CSF (R+M) significantly increased the expression of the osteoclast activation marker cathepsin K. Pretreatment with D-serine (50 μM) inhibited R+M-induced osteoclast activation. ( b ) From the results of panel B, compared to the untreated control and D-serine pretreatment groups, the R+M group exhibited significantly higher cathepsin K expression levels (* p < 0.05, ** p < 0.001). ( c ) Results from the TRAP assay indicated that D-serine pretreatment suppressed osteoclast activation (Scale bar: 200 µm). ( d , e ) A concentration-dependent effect of D-serine on cathepsin K expression was observed, with higher concentrations of D-serine resulting in greater inhibition. Compared to the untreated control, R+M, 10 μM D-serine, and 50 μM D-serine treatments significantly increased cathepsin K expression levels (* p < 0.05, ** p < 0.001). However, relative to the R+M group, 50 μM and 100 μM D-serine treatments significantly reduced cathepsin K expression levels (# p < 0.05, ### p < 0.001). Error bars represent the mean ± standard deviation. ( f ) Similar trends were observed in the TRAP activity assay, further confirming the dose-dependent inhibitory effect of D-serine on osteoclast activation (Scale bar: 200 µm).

Article Snippet: To prevent differentiation into osteoclasts, RAW264.7 cells were pretreated with 175 μM D-serine in DMEM for 24 h. For osteoclast differentiation, cells were treated with 50 ng/mL recombinant human-soluble RANK Ligand (RANKL; Oriental Yeast, Tokyo, Japan) and 20 ng/mL recombinant mouse macrophage colony-stimulating factor (M-CSF; R&D Systems, Minneapolis, MN, USA) in α-MEM medium containing 1% P/S for 5 days, with the induction medium being replaced every 2 days.

Techniques: Activation Assay, Expressing, Marker, Control, TRAP Assay, Concentration Assay, Inhibition, Standard Deviation, Activity Assay

Journal: Nutrients

Article Title: Sericin’s Potential in Osteoporosis Management: The Roles of L-Serine and D-Serine in Bone Metabolism Regulation

doi: 10.3390/nu17030574

Figure Lengend Snippet: Effects of sericin treatment on serum protein expression. IP-HPLC analysis of serum from the sericin-treated groups showed an increased expression of serine racemase and osteogenic proteins, including BMP2, osterix, Runx2, OPG, osteopontin, osteocalcin, and osteonectin, while reducing anti-osteogenic proteins like BMP3, PTH/PTHrP-R, and SOSTDC1. Osteoclastogenesis was inhibited by downregulating RANKL and HSP90. Inflammation and stromal fibrosis were reduced via downregulation of TNFα, NFATc1, TLR2, TLR3, and TGFβ1. These findings highlight sericin’s dual-action effects on bone metabolism and inflammation, supporting its therapeutic potential for osteoporosis.

Article Snippet: To prevent differentiation into osteoclasts, RAW264.7 cells were pretreated with 175 μM D-serine in DMEM for 24 h. For osteoclast differentiation, cells were treated with 50 ng/mL recombinant human-soluble RANK Ligand (RANKL; Oriental Yeast, Tokyo, Japan) and 20 ng/mL recombinant mouse macrophage colony-stimulating factor (M-CSF; R&D Systems, Minneapolis, MN, USA) in α-MEM medium containing 1% P/S for 5 days, with the induction medium being replaced every 2 days.

Techniques: Expressing

Journal: bioRxiv

Article Title: UBE2G1 Governs the Destruction of Cereblon Neomorphic Substrates

doi: 10.1101/389098

Figure Lengend Snippet: UBE2D family proteins redundantly promote the ubiquitination of GSPT1 (A) Sequence alignment of human UBE2D family proteins using Clustal W 2.1. Note that the amino acid sequence identity among all 4 family proteins is close to 90%. (B) In vitro ubiquitination of GSPT1 MBP fusion protein by recombinant CRL4CRBN complex in the presence of UBE2G1, UBE2D1, UBE2D2, or UBE2D3, alone or in combination. Recombinant protein products as indicated were incubated with or without 80 μM CC-885 in the ubiquitination assay buffer at 30 °C for 2 hours, and then analyzed by immunoblotting. SE, short exposure; LE, long exposure

Article Snippet: Purified recombinant human Ube1 E1 (E-305), UbcH5a/UBE2D1 (E2-616-100), UbcH5b/UBE2D2 (E2-622-100), UbcH5c/UBE2D3 (E2-627-100), wild-type ubiquitin (U-100H), K48R ubiquitin (UM-K48R-01M), and K48-only ubiquitin (UM-K480-01M) were purchased from R&D systems.

Techniques: Sequencing, In Vitro, Recombinant, Incubation, Ubiquitin Assay, Western Blot

Journal: bioRxiv

Article Title: UBE2G1 Governs the Destruction of Cereblon Neomorphic Substrates

doi: 10.1101/389098

Figure Lengend Snippet: (A) Schematic showing the design of dual-gRNA directed CRISPR screen of E2s regulating the CM-induced degradation of ePL-tagged IKZF1 in 384-well array format. (B) Chemiluminescent measurement of ePL-IKZF1 protein expression level in U937-Cas9_ePL-IKZF1 parental cells or cells expressing UBE2G1-specfic sgRNA alone or in combination with non-targeting or UBE2D3-specific sgRNA. Cells were treated with POM at the indicated concentrations for 16 hours. Data are presented as mean ± SD (n = 4). (C) Immunoblot analysis of U937-Cas9 parental cells or cells expressing non-targeting sgRNA, UBE2G1-specific sgRNA, UBE2D3-specfic sgRNA, or both UBE2G1 and UBE2D3 sgRNAs. Cells were treated with POM at the indicated concentrations for 16 hours. SE, short exposure; LE, long exposure.

Article Snippet: Purified recombinant human Ube1 E1 (E-305), UbcH5a/UBE2D1 (E2-616-100), UbcH5b/UBE2D2 (E2-622-100), UbcH5c/UBE2D3 (E2-627-100), wild-type ubiquitin (U-100H), K48R ubiquitin (UM-K48R-01M), and K48-only ubiquitin (UM-K480-01M) were purchased from R&D systems.

Techniques: CRISPR, Expressing, Western Blot

Journal: bioRxiv

Article Title: UBE2G1 Governs the Destruction of Cereblon Neomorphic Substrates

doi: 10.1101/389098

Figure Lengend Snippet: UBE2G1 catalyzes the ubiquitin chain assembly on GSPT1 pre-conjugated with ubiquitin (A) Sequence alignment of human UBE2G1, human UBE2G2 and human CDC34 using Clustal W 2.1. The acidic loops indispensable for the assembly of K48-linked ubiquitin chains are highlighted with red, and the catalytic cysteines are highlighted with blue. (B) Immunoblot analysis of 293T parental or UBE2G1-/- cells transduced with lentiviral vectors expressing FLAG-tagged UBE2G1 wild-type or C90S mutant, or FLAG-tagged UBE2D3 wild-type or C85S mutant. Cells were treated with CC-885 at the indicated concentrations for 4 hours. Note that overexpression of wild-type FLAG-UBE2G1 or FLAG-UBE2D3 partially rescued the GSPT1 degradation defect caused by UBE2G1 deficiency, while overexpression of catalytically-dead mutant FLAG-UBE2G1-C90S or FLAG-UBE2D3-C85S further blocked the degradation of GSPT1. (C) In vitro ubiquitination of GSPT1 by CRL4 CRBN with or without CC-885 and indicated E2 variants. Consistent with results observed with bacterial recombinant UBE2G1 and UBE2D3 proteins, FLAG-UBE2G1 and FLAG-UBE2D3 proteins purified from human cells acted in concert to promote the ubiquitination of GSPT1.

Article Snippet: Purified recombinant human Ube1 E1 (E-305), UbcH5a/UBE2D1 (E2-616-100), UbcH5b/UBE2D2 (E2-622-100), UbcH5c/UBE2D3 (E2-627-100), wild-type ubiquitin (U-100H), K48R ubiquitin (UM-K48R-01M), and K48-only ubiquitin (UM-K480-01M) were purchased from R&D systems.

Techniques: Sequencing, Western Blot, Transduction, Expressing, Mutagenesis, Over Expression, In Vitro, Recombinant, Purification

Journal: bioRxiv

Article Title: UBE2G1 Governs the Destruction of Cereblon Neomorphic Substrates

doi: 10.1101/389098

Figure Lengend Snippet: (A-D) In vitro ubiquitination of IKZF1 (A and C) and GSPT1 (B and D) MBP fusion proteins by recombinant CRL4CRBN complex. Recombinant protein products as indicated were incubated with or without 80 μM POM (A and C) or 80 μM CC-885 (B and D) in the ubiquitination assay buffer containing 80 mM ATP at 30°C for 2 hours, and then analyzed by immunoblotting. (E) Sequential in vitro ubiquitination of GSPT1 by recombinant CRL4CRBN complex. MBP-GSPT1 recombination protein was incubated with Ube1, UBE2D3, Cul4-Rbx1, DDB1-cereblon, Ubiquitin, ATP and CC-885 in the ubiquitination assay at 30 °C for 4 hours. After purification over size-exclusion chromatography, pre-ubiquitinated MBP-GSPT1 protein was then incubated with Ube1, DDB1-cereblon, Ubiquitin, ATP and UBE2G1 with or without CC-885 or Cul4A-Rbx1 in the ubiquitination assay at 30 °C for 2 hours, followed by immunoblot analysis. (F) Schematic showing the sequential ubiquitination of CRBN neomorphic substrates by UBE2D3 and UBE2G1.

Article Snippet: Purified recombinant human Ube1 E1 (E-305), UbcH5a/UBE2D1 (E2-616-100), UbcH5b/UBE2D2 (E2-622-100), UbcH5c/UBE2D3 (E2-627-100), wild-type ubiquitin (U-100H), K48R ubiquitin (UM-K48R-01M), and K48-only ubiquitin (UM-K480-01M) were purchased from R&D systems.

Techniques: In Vitro, Recombinant, Incubation, Ubiquitin Assay, Western Blot, Purification, Size-exclusion Chromatography

Journal: bioRxiv

Article Title: UBE2G1 Governs the Destruction of Cereblon Neomorphic Substrates

doi: 10.1101/389098

Figure Lengend Snippet: (A and B) 293T parental and UBE2G1-/-;UBE2D3-/- (clone 4) cells were transiently transfected with plasmids expressing cereblon, V5-tagged IKZF1 and 8xHis-Ub with or without UBE2G1, UBE2D3 or both. (C) 293T parental and UBE2G1-/- (clone 13) cells were transiently transfect with plasmids expressing cereblon, IKZF1-V5, 8xHis-Ub with or without UBE2G1 wild-type or C90S mutant. In (A), (B) and (C), 48 hours after transfection, cells were treated with MG-132 (10 μM) and POM at the indicated concentrations for additional 8 hours. Ubiquitinated protein products enriched with magnetic nickel sepharose were subjected to immunoblot analysis. Immunoblot analysis of whole cell extracts showing equal input proteins is shown in .

Article Snippet: Purified recombinant human Ube1 E1 (E-305), UbcH5a/UBE2D1 (E2-616-100), UbcH5b/UBE2D2 (E2-622-100), UbcH5c/UBE2D3 (E2-627-100), wild-type ubiquitin (U-100H), K48R ubiquitin (UM-K48R-01M), and K48-only ubiquitin (UM-K480-01M) were purchased from R&D systems.

Techniques: Transfection, Expressing, Mutagenesis, Western Blot

Journal: bioRxiv

Article Title: UBE2G1 Governs the Destruction of Cereblon Neomorphic Substrates

doi: 10.1101/389098

Figure Lengend Snippet: Input protein levels for the in vivo ubiquitinaiton studies corresponding to (A) Total input for . Immunoblot analysis of 293T parental and UBE2G1-/- ; UBE2D3-/- (Clone 4) cells transfected to produce 8xHis-Ubiquitin, cereblon and IKZF1-V5. (B) Total input for . Immunoblot analysis of 293T parental and UBE2G1-/-;UBE2D3-/- (Clone 4) cells transfected to produce 8xHis-Ubiquitin, CRBN, IKZF1-V5 with or without UBE2G1 and/or UBE2D3. (C) Total input for . Immunoblot analysis of 293T parental and UBE2G1-/- (Clone 13) cells transfected to produce 8xHis-Ubiquitin, CRBN, IKZF1-V5 with or without UBE2G1 wildtype or C90S mutant. In (A), (B) or (C), 48 hours after transfection, cells were treated with 10 μM MG132 and POM at the indicated concentrations for additional 8 hours.

Article Snippet: Purified recombinant human Ube1 E1 (E-305), UbcH5a/UBE2D1 (E2-616-100), UbcH5b/UBE2D2 (E2-622-100), UbcH5c/UBE2D3 (E2-627-100), wild-type ubiquitin (U-100H), K48R ubiquitin (UM-K48R-01M), and K48-only ubiquitin (UM-K480-01M) were purchased from R&D systems.

Techniques: In Vivo, Western Blot, Transfection, Mutagenesis

Journal: bioRxiv

Article Title: UBE2G1 Governs the Destruction of Cereblon Neomorphic Substrates

doi: 10.1101/389098

Figure Lengend Snippet: UBE2D family proteins redundantly promote the ubiquitination of GSPT1 (A) Sequence alignment of human UBE2D family proteins using Clustal W 2.1. Note that the amino acid sequence identity among all 4 family proteins is close to 90%. (B) In vitro ubiquitination of GSPT1 MBP fusion protein by recombinant CRL4CRBN complex in the presence of UBE2G1, UBE2D1, UBE2D2, or UBE2D3, alone or in combination. Recombinant protein products as indicated were incubated with or without 80 μM CC-885 in the ubiquitination assay buffer at 30 °C for 2 hours, and then analyzed by immunoblotting. SE, short exposure; LE, long exposure

Article Snippet: Purified recombinant human Ube1 E1 (E-305), UbcH5a/UBE2D1 (E2-616-100), UbcH5b/UBE2D2 (E2-622-100), UbcH5c/UBE2D3 (E2-627-100), wild-type ubiquitin (U-100H), K48R ubiquitin (UM-K48R-01M), and K48-only ubiquitin (UM-K480-01M) were purchased from R&D systems.

Techniques: Sequencing, In Vitro, Recombinant, Incubation, Ubiquitin Assay, Western Blot