Journal: Redox Biology
Article Title: Inhibition of SDE2 promotes autophagy-dependent ferroptosis in multiple myeloma
doi: 10.1016/j.redox.2026.104007
Figure Lengend Snippet: Molecular interaction between SDE2 and ATG5. (A) Molecular docking prediction illustrating the interaction between ATG5 and SDE2. (B) Box plot showing significantly elevated ATG5 expression in plasma cells from MM patients compared to healthy controls. Data were obtained from the TCGA database. (C) Kaplan–Meier survival analysis of multiple myeloma (MM) patients stratified by combined expression levels of ATG5 and SDE2. (D) Western blot analysis demonstrating the effect of SDE2 knockdown on ATG5 protein levels in OPM-2 and KMS-11 cells. (E–F) Co-immunoprecipitation (Co-IP) assays in KMS-11 cells using antibodies targeting SDE2 to pull down ATG5 (E) and antibodies targeting ATG5 to pull down SDE2 (F), confirming a direct interaction between the two proteins. (G) HEK 293T cells were co-transfected with Myc-tagged ATG5 and Flag-tagged SDE2. Immunoprecipitation using anti-Flag antibodies was followed by immunoblotting with anti-Myc (ATG5) and anti-Flag (SDE2) antibodies, validating the interaction between exogenous SDE2 and ATG5. (H) Western blot analysis of ATG5 degradation in SDE2-overexpressing cells treated with the protein synthesis inhibitor cycloheximide (CHX, 10 μg/mL) in the presence of chloroquine (CQ) or MG132. (I) Western blot analysis showing that treatment with MG132 rescues ATG5 degradation in SDE2-overexpressing cells. (J) Schematic representation of full-length and truncation constructs of SDE2. (K) Co-immunoprecipitation of HA-SDE2 variants with Flag-tagged ATG5 in HEK293T cells. Only full-length and 1–300 aa fragment of SDE2 retained the ability to bind ATG5. (L) Cell lysates from SDE2-overexpressing cells (wild-type, Δ1, and Δ2 mutants) were immunoprecipitated with anti-ATG5 antibodies and immunoblotted with anti-Ub and anti-ATG5 antibodies to assess ATG5 ubiquitination levels. (M) HEK 293T cells were co-transfected with HA-tagged ubiquitin (Ub), Myc-tagged ATG5, and Flag-tagged SDE2 (wild-type and Δ1 mutant). Immunoprecipitation using anti-Myc antibodies was followed by immunoblotting with anti-HA and anti-Myc antibodies, demonstrating that the SDE2 UBL domain mediates ATG5 ubiquitination. (N) Co-IP analysis of the interaction between ATG5 and the SDE2-Δ1 mutant. HEK293T cells were co-transfected with Myc-tagged ATG5 and Flag-tagged SDE2-Δ1 plasmids as indicated. Cell lysates were immunoprecipitated with anti-Flag antibody, followed by immunoblotting with anti-Myc and anti-Flag antibodies. Input blots confirmed protein expression levels. (O) M. SDE2-Δ1 fails to promote ATG5 degradation in KMS-11 cells. Cells were transfected with SDE2-Δ1 and treated with or without the proteasome inhibitor MG132 (10 μM, 6 h). (P) HEK 293T cells were co-transfected with Myc-tagged ATG5, Flag-tagged SDE2, and HA-tagged ubiquitin constructs (wild-type, Lys48-only, or Lys63-only). Immunoprecipitation using anti-Myc antibodies was followed by immunoblotting with anti-HA and anti-Myc antibodies, confirming that SDE2 facilitates Lys48-linked ubiquitination of ATG5. (Q) Western blot analysis showing ATG5 and SDE2 levels in control and SDE2-overexpressing KMS-11 cells co-expressing wild-type ubiquitin (Ub WT) or ubiquitin with a Lys48-to-Arg mutation (Ub Lys48R) after 72 h of culture. ∗P < 0.05; ∗∗P < 0.01; ∗∗∗P < 0.001.
Article Snippet: Ubiquitination Assay Plasmids: HA-tagged ubiquitin plasmids (wild-type: #17608; K48-linked: #17605; K63-linked: #17606) were obtained from Addgene.
Techniques: Expressing, Clinical Proteomics, Western Blot, Knockdown, Immunoprecipitation, Co-Immunoprecipitation Assay, Transfection, Construct, Ubiquitin Proteomics, Mutagenesis, Control
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