Fig. 6: The ERCC6L2–CtIP condensates protect CtIP from RNF138-mediated ubiquitination and subsequent degradation.

a, Left: Ctrl and ERCC6L2-KO U2OS cells were exposed to 50 μg ml⁻¹ CHX for the indicated time. Right: quantification of CtIP protein levels by densitometry. Data are presented as mean ± s.d. n = 3 biological replicates. b, Immunoblot analysis of CtIP levels in Ctrl and ERCC6L2-KO U2OS cells upon treatment with MG132 (10 μM, 6 h). c–f, Immunoblot analysis of CtIP ubiquitination in Ctrl and ERCC6L2-KO U2OS cells, with untreated (c) or transfected (d and f) with the indicated plasmids (Flag-ER-C, NLS-EGFP-R1, NLS-EGFP-FUS-C). Cells were pretreated with MG132 (10 μM) for 6 h. Quantification of protein levels by densitometry. g, ERCC6L2-KO U2OS cells were exposed to 50 μg ml⁻¹ CHX for the indicated time (left) following transfection with either siNC or siRNF138. Quantification of CtIP protein levels by densitometry (right). Data are presented as mean ± s.d. n = 3 biological replicates. h, Immunoblot analysis of CtIP ubiquitination levels in ERCC6L2-KO U2OS cells transfected with the indicated plasmids and siRNAs. Cells were pretreated with MG132 (10 μM) for 6 h. Quantification of protein levels by densitometry. i, Immunoblot analysis of CtIP ubiquitination levels in U2OS cells transfected with the indicated plasmids. Cells were pretreated with MG132 (10 μM) for 6 h. Quantification of protein levels by densitometry. j, Immunoblot analysis of the interaction between CtIP and RNF138 in U2OS cells following 1,6-hexanediol (1%) treatment. Quantification of protein levels by densitometry. k, Immunoblot analysis of CtIP ubiquitination levels in U2OS cells following 1,6-hexanediol (1%) treatment. Cells were pretreated with MG132 (10 μM) for 6 h. Quantification of protein levels by densitometry. Data are representative of at least three independent experiments (b–f, j and k).

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