罗亚
生物
下调和上调
上皮-间质转换
细胞生物学
鸟嘌呤核苷酸交换因子
基因沉默
MAPK/ERK通路
转化生长因子
SMAD公司
转化生长因子β
癌症研究
信号转导
生物化学
基因
作者
Elsa Papadimitriou,Eleftheria Vasilaki,Christina Vorvis,Dimitrios Iliopoulos,Aristidis Moustakas,Dimitris Kardassis,Christos Stournaras
出处
期刊:Oncogene
[Springer Nature]
日期:2011-10-10
卷期号:31 (23): 2862-2875
被引量:98
摘要
In the present study we analyzed the regulation of the two isoforms of the RhoA-specific guanine nucleotide exchange factor Net1 by transforming growth factor-β (TGF-β) in keratinocytes. We report that short-term TGF-β treatment selectively induced Net1 isoform2 (Net1A) but not Net1 isoform1. This led to upregulation of cytoplasmic Net1A protein levels that were necessary for TGF-β-mediated RhoA activation. Smad signaling and the MAPK/ERK kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway were involved in Net1A upregulation by TGF-β. Interestingly, long-term TGF-β treatment resulted in Net1 mRNA downregulation and Net1A protein degradation by the proteasome. Furthermore, we identified the microRNA miR-24 as a novel post-transcriptional regulator of Net1A expression. Silencing of Net1A resulted in disruption of E-cadherin- and zonula occludens-1 (ZO-1)-mediated junctions, as well as expression of the transcriptional repressor of E-cadherin, Slug and the mesenchymal markers N-cadherin, plasminogen activator inhibitor-1 (PAI-1) and fibronectin, indicating that late TGF-β-induced downregulation of Net1A is involved in epithelial-to-mesenchymal transition (EMT). Finally, miR-24 was found to be implicated in the regulation of the EMT program in response to TGF-β and was shown to be directly involved in the TGF-β-induced breast cancer cell invasiveness through Net1A regulation. Our results emphasize the importance of Net1 isoform2 in the short- and long-term TGF-β-mediated regulation of EMT.
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