A natural antisense transcript regulates Zeb2/Sip1 gene expression during Snail1-induced epithelial-mesenchymal transition

• Published in: Genes & development 2008-03, Vol.22 (6), p.756-769
• Main Authors: Beltran, Manuel, Puig, Isabel, Peña, Cristina, García, José Miguel, Alvarez, Ana Belén, Peña, Raúl, Bonilla, Félix, de Herreros, Antonio García
• Format: Article
• Language: English
• Subjects: 5' Untranslated Regions; Adenocarcinoma - metabolism; Adenocarcinoma - pathology; Blotting, Western; Cadherins - genetics; Cadherins - metabolism; Case-Control Studies; Cell Line; Cells, Cultured; Colon; Colonic Neoplasms - metabolism; Colonic Neoplasms - pathology; DNA Primers; Epithelium - physiology; Gene Expression Regulation, Neoplastic; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Humans; Mesoderm - physiology; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Plasmids; Promoter Regions, Genetic; Repressor Proteins - genetics; Repressor Proteins - metabolism; Research Paper; Reverse Transcriptase Polymerase Chain Reaction; RNA, Antisense - physiology; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; Snail Family Transcription Factors; Transcription Factors - metabolism; Zinc Finger E-box Binding Homeobox 2; Zinc Fingers
• ISSN: 0890-9369; 1549-5477
• DOI: 10.1101/gad.455708

Expression of Snail1 in epithelial cells triggers an epithelial-mesenchymal transition (EMT). Here, we demonstrate that the synthesis of Zeb2, a transcriptional repressor of E-cadherin, is up-regulated after Snail1-induced EMT. Snail1 does not affect the synthesis of Zeb2 mRNA, but prevents the processing of a large intron located in its 5'-untranslated region (UTR). This intron contains an internal ribosome entry site (IRES) necessary for the expression of Zeb2. Maintenance of 5'-UTR Zeb2 intron is dependent on the expression of a natural antisense transcript (NAT) that overlaps the 5' splice site in the intron. Ectopic overexpression of this NAT in epithelial cells prevents splicing of the Zeb2 5'-UTR, increases the levels of Zeb2 protein, and consequently down-regulates E-cadherin mRNA and protein. The relevance of these results is demonstrated by the strong association between NAT presence and conservation of the 5'-UTR intron in cells that have undergone EMT or in human tumors with low E-cadherin expression. Therefore, the results presented in this article reveal the existence of a NAT capable of activating Zeb2 expression, explain the mechanism involved in this activation, and demonstrate that this NAT regulates E-cadherin expression.