https://blog.superhyydl.org/tags/usp14/Recent content in USP14 on Superhyydl's BlogHugozh-cnTue, 01 Sep 2026 00:00:00 +0000https://blog.superhyydl.org/reading/usp14-competitively-binds-to-fbxw7-to-stabilize-mtdh/Tue, 01 Sep 2026 00:00:00 +0000https://blog.superhyydl.org/reading/usp14-competitively-binds-to-fbxw7-to-stabilize-mtdh/<h2 id="一句话亮点">一句话亮点</h2> <p>这篇文章发现USP14通过和E3泛素连接酶FBXW7“抢座位”来稳定MTDH蛋白，进而激活NF-κB信号，同时推动头颈鳞癌的转移和化疗耐药——而且这个机制在临床样本里确实和淋巴结转移及不良预后挂钩。</p> <h2 id="背景痛点">背景/痛点</h2> <p>头颈鳞癌（HNSCC）的预后一直不怎么好，主要麻烦在于它特别容易转移，而且对化疗（顺铂、紫杉醇）很容易耐。MTDH这个蛋白在很多癌种里都被证实能促进EMT、维持肿瘤干细胞特性，还和耐药密切相关。Wang团队之前已经发过好几篇文章证实MTDH在头颈鳞癌里通过多种机制（比如调控VEGF、AKT、NF-κB）促癌。</p> <p>但问题来了：MTDH这个蛋白本身没有典型的配体结合口袋或者酶活性中心，传统的“直接抑制蛋白功能”的策略很难走通。那不如换个思路——既然肿瘤里MTDH蛋白水平异常高，能不能从“它为什么不会被降解”这个角度切入？这就是整篇文章的逻辑起点。</p> <h2 id="推理链分步拆解">推理链分步拆解</h2> <h3 id="1-mtdh是靠蛋白酶体降解的那谁在保护它">1. MTDH是靠蛋白酶体降解的，那谁在保护它？</h3> <p>他们首先用一个很基础但必须做的实验确定了MTDH的降解途径：MG132（蛋白酶体抑制剂）处理能让MTDH蛋白明显累积，而CQ（溶酶体抑制剂）没什么效果。这就把方向锁死在蛋白酶体-泛素系统上了。</p> <p>然后他们用Flag-MTDH做亲和纯化+质谱，筛到了好几个可能和MTDH结合的去泛素化酶（DUB），其中USP14的评分最高。Co-IP和免疫荧光共定位进一步确认了它俩确实能拉到一起，在细胞质里有明显的共定位（Pearson系数&gt;0.76，挺高的了）。</p> <p>@方法论点评：先确定降解途径（蛋白酶体vs溶酶体），再用质谱无偏筛选互作蛋白，最后用Co-IP和共定位交叉验证——这是鉴定新底物-酶关系的经典“三步走”，每一步都在排除假阳性。</p> <p><img alt="Fig. 1：MTDH is degraded via the proteasome and interacts with USP14. (A–D). Fadu and HN8 cells were exposed to MG132 or CQ under concentration- gradient conditions (A and C) or time-course conditions (B and D) to evaluate changes in MTDH protein abundance after different treatments. The accompanying quantification shows the densitometric ratio of each target band relative to GAPDH at the indicated concentrations or time points. (E) Schematic overview of the strategy used to screen MTDH-interacting proteins in Fadu cells is shown at the Top. Candidate deubiquitinases potentially associated with MTDH were identified by mass spectrometry analysis, as shown at the bottom. (F) HEK293T cells were transfected with Flag–MTDH or HA-USP14 for 48 h, followed by collection of cell lysates for immunoprecipitation analysis. (G and H) Coimmunoprecipitation assays were performed to examine the endogenous interaction between MTDH and USP14 in Fadu and HN8 cells. (I) Immunofluorescence staining was used to visualize the subcellular colocalization of MTDH and USP14. (J) Line- scan profiling and Pearson’s correlation coefficient analysis were conducted using ImageJ along randomly selected lines from panel I. (K) HEK293T cells were cotransfected with HA-MTDH together with vectors encoding Flag-tagged full-length USP14 or the indicated USP14 truncation mutants. Cell lysates were immunoprecipitated with anti-Flag antibody and analyzed by immunoblotting with the indicated antibodies. (L) HEK293T cells were cotransfected with HA-USP14 and vectors expressing Flag-tagged full-length MTDH or the indicated MTDH truncation mutants. Lysates were subjected to anti-Flag immunoprecipitation, followed by immunoblotting with the indicated antibodies." loading="lazy" src="https://blog.superhyydl.org/images/reading/usp14-competitively-binds-to-fbxw7-to-stabilize-mtdh/figure-01.png"></p>