F-box protein complex FBXL19 regulates TGFβ1-induced E-cadherin down-regulation by mediating Rac3 ubiquitination and degradation.
F-box protein complex FBXL19 regulates TGFβ1-induced E-cadherin down-regulation by mediating Rac3 ubiquitination and degradation.
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DOI：
10.1186/1476-4598-13-76
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发表时间：
2014-04-01
期刊：
影响因子：
37.3
通讯作者：
Zhao Y
中科院分区：
文献类型：
--
作者：
Dong S;Zhao J;Wei J;Bowser RK;Khoo A;Liu Z;Luketich JD;Pennathur A;Ma H;Zhao Y
Rac 3是一种小的GT3多功能蛋白，调节细胞粘附、迁移和分化。它被认为是乳腺癌中的癌基因;然而，它在食管癌中的作用及其稳定性的调节尚未研究。F-box蛋白是Skp 1-Cullin-1-F-box（SCF）E3泛素连接酶的主要亚基，其识别泛素化和蛋白酶体降解的特定底物。最近，我们发现SCFFBXL 19靶向Rac 1和RhoA，从而调节Rac 1和RhoA的泛素化和降解。在这里，我们展示了FBXL 19在调节Rac 3位点特异性泛素化和稳定性中的作用。TGFβ1表达与食管癌预后不良有关。TGFβ1可降低多种上皮来源的癌症中肿瘤抑制因子E-钙粘蛋白的表达。我们研究了FBXL 19介导的Rac 3降解在TGFβ1诱导的食管癌细胞E-cadherin下调中的作用。通过免疫印迹和免疫共沉淀法测定FBXL 19调节的内源性和过表达Rac 3稳定性。以食管癌细胞系OE 19和OE 33为研究对象，采用免疫印迹和免疫染色方法，观察TGFβ1对食管癌细胞系E-cadherin表达的影响。FBXL 19的过表达通过相互作用和多聚泛素化Rac 3降低内源性和过表达的Rac 3表达，而FBXL 19的下调抑制Rac 3降解。Rac 3内的赖氨酸166被鉴定为泛素化受体位点。在N端截短的FBXL 19变体导致Rac 3降解增加;然而，在C端截短的FBXL 19变体失去了与Rac 3相互作用并泛素化Rac 3蛋白的能力。此外，我们发现Rac 3在TGFβ1诱导的食管癌细胞E-cadherin下调中起关键作用。FBXL 19过表达可减弱TGFβ1诱导的E-cadherin下调和食管癌细胞伸长表型。这些数据共同揭示了FBXL 19通过调节Rac 3的稳定性作为Rac 3的拮抗剂发挥作用，并调节TGFβ1诱导的E-cadherin下调。本研究将为调节TGFβ1信号通路从而抑制食管肿瘤的发生提供一种新的治疗策略。
Rac3 is a small GTPase multifunctional protein that regulates cell adhesion, migration, and differentiation. It has been considered as an oncogene in breast cancer; however, its role in esophageal cancer and the regulation of its stability have not been studied. F-box proteins are major subunits within the Skp1-Cullin-1-F-box (SCF) E3 ubiquitin ligases that recognize particular substrates for ubiquitination and proteasomal degradation. Recently, we have shown that SCFFBXL19 targets Rac1 and RhoA, thus regulating Rac1 and RhoA ubiquitination and degradation. Here, we demonstrate the role of FBXL19 in the regulation of Rac3 site-specific ubiquitination and stability. Expression of TGFβ1 is associated with poor prognosis of esophageal cancer. TGFβ1 reduces tumor suppressor, E-cadherin, expression in various epithelial-derived cancers. Here we investigate the role of FBXL19-mediated Rac3 degradation in TGFβ1-induced E-cadherin down-regulation in esophageal cancer cells. FBXL19-regulated endogenous and over-expressed Rac3 stability were determined by immunoblotting and co-immunoprecipitation. Esophageal cancer cells (OE19 and OE33) were used to investigate TGFβ1-induced E-cadherin down-regulation by Immunoblotting and Immunostaining. Overexpression of FBXL19 decreased endogenous and over-expressed Rac3 expression by interacting and polyubiquitinating Rac3, while down-regulation of FBXL19 suppressed Rac3 degradation. Lysine166 within Rac3 was identified as an ubiquitination acceptor site. The FBXL19 variant with truncation at the N-terminus resulted in an increase in Rac3 degradation; however, the FBXL19 variant with truncation at the C-terminus lost its ability to interact with Rac3 and ubiquitinate Rac3 protein. Further, we found that Rac3 plays a critical role in TGFβ1-induced E-cadherin down-regulation in esophageal cancer cells. Over-expression of FBXL19 attenuated TGFβ1-induced E-cadherin down-regulation and esophageal cancer cells elongation phenotype. Collectively these data unveil that FBXL19 functions as an antagonist of Rac3 by regulating its stability and regulates the TGFβ1-induced E-cadherin down-regulation. This study will provide a new potential therapeutic strategy to regulate TGFβ1 signaling, thus suppressing esophageal tumorigenesis.
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影响因子：
3.8
作者：
Gest C;Joimel U;Huang L;Pritchard LL;Petit A;Dulong C;Buquet C;Hu CQ;Mirshahi P;Laurent M;Fauvel-Lafève F;Cazin L;Vannier JP;Lu H;Soria J;Li H;Varin R;Soria C
通讯作者：
Soria C
影响因子：
3.9
作者：
Engers, R.;Ziegler, S.;Gabbert, H. E.
通讯作者：
Gabbert, H. E.
影响因子：
4.8
作者：
Haataja, L;Groffen, J;Heisterkamp, N
通讯作者：
Heisterkamp, N
影响因子：
11.2
作者：
Onder, Tamer T.;Gupta, Piyush B.;Weinberg, Robert A.
通讯作者：
Weinberg, Robert A.
DOI：
10.1038/nsb0297-147
发表时间：
1997-02-01
期刊：
NATURE STRUCTURAL BIOLOGY
影响因子：
--
作者：
Hirshberg, M;Stockley, RW;Webb, MR
通讯作者：
Webb, MR