Grudzien-Nogalska Ewa, Reed Brent C, Rhoads Robert E
Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA.
Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
J Cell Sci. 2014 May 15;127(Pt 10):2326-38. doi: 10.1242/jcs.144956. Epub 2014 Mar 14.
Downregulation of CPEB1, a sequence-specific RNA-binding protein, in a mouse mammary epithelial cell line (CID-9) causes epithelial-to-mesenchymal transition (EMT), based on several criteria. First, CPEB1 knockdown decreases protein levels of E-cadherin and β-catenin but increases those of vimentin and Twist1. Second, the motility of CPEB1-depleted cells is increased. Third, CID-9 cells normally form growth-arrested, polarized and three-dimensional acini upon culture in extracellular matrix, but CPEB1-deficient CID-9 cells form nonpolarized proliferating colonies lacking a central cavity. CPEB1 downregulates Twist1 expression by binding to its mRNA, shortening its poly(A) tract and repressing its translation. CID-9 cultures contain both myoepithelial and luminal epithelial cells. CPEB1 increases during CID-9 cell differentiation, is predominantly expressed in myoepithelial cells, and its knockdown prevents expression of the myoepithelial marker p63. CPEB1 is present in proliferating subpopulations of pure luminal epithelial cells (SCp2) and myoepithelial cells (SCg6), but its depletion increases Twist1 only in SCg6 cells and fails to downregulate E-cadherin in SCp2 cells. We propose that myoepithelial cells prevent EMT by influencing the polarity and proliferation of luminal epithelial cells in a mechanism that requires translational silencing of myoepithelial Twist1 by CPEB1.
根据多项标准，在小鼠乳腺上皮细胞系（CID - 9）中，序列特异性RNA结合蛋白CPEB1的下调会导致上皮 - 间质转化（EMT）。首先，CPEB1敲低会降低E - 钙黏蛋白和β - 连环蛋白的蛋白水平，但会增加波形蛋白和Twist1的蛋白水平。其次，CPEB1缺失细胞的运动性增加。第三，CID - 9细胞在细胞外基质中培养时通常会形成生长停滞、极化的三维腺泡，但CPEB1缺陷的CID - 9细胞会形成缺乏中央腔的非极化增殖菌落。CPEB1通过与其mRNA结合、缩短其聚腺苷酸尾并抑制其翻译来下调Twist1的表达。CID - 9培养物包含肌上皮细胞和管腔上皮细胞。CPEB1在CID - 9细胞分化过程中增加，主要在肌上皮细胞中表达，其敲低会阻止肌上皮标志物p63的表达。CPEB1存在于纯管腔上皮细胞（SCp2）和肌上皮细胞（SCg6）的增殖亚群中，但其缺失仅在SCg6细胞中增加Twist1，而在SCp2细胞中未能下调E - 钙黏蛋白。我们提出，肌上皮细胞通过一种机制影响管腔上皮细胞的极性和增殖来预防EMT，该机制需要CPEB1对肌上皮Twist1进行翻译沉默。
