The transcription factors Slug and Snail act as repressors of Claudin-1 expression in epithelial cells.
Claudin-1 is an integral membrane protein component of tight junctions. The Snail family of transcription factors are repressors that play a central role in the epithelial-mesenchymal transition, a process that occurs during cancer progression. Snail and Slug members are direct repressors of E-cadherin and act by binding to the specific E-boxes of its proximal promoter. In the present study, we demonstrate that overexpression of Slug or Snail causes a decrease in transepithelial electrical resistance. Overexpression of Slug and Snail in MDCK (Madin-Darby canine kidney) cells down-regulated Claudin-1 at protein and mRNA levels. In addition, Snail and Slug are able to effectively repress human Claudin-1-driven reporter gene constructs containing the wild-type promoter sequence, but not those with mutations in two proximal E-box elements. We also demonstrate by band-shift assay that Snail and Slug bind to the E-box motifs present in the human Claudin-1 promoter. Moreover, an inverse correlation in the levels of Claudin-1 and Slug transcripts were observed in breast cancer cell lines. E-box elements in the Claudin-1 promoter were found to play a critical negative regulatory role in breast cancer cell lines that expressed low levels of Claudin-1 transcript. Significantly, in invasive human breast tumours, high levels of Snail and Slug correlated with low levels of Claudin-1 expression. Taken together, these results support the hypothesis that Claudin-1 is a direct downstream target gene of Snail family factors in epithelial cells.
Martínez-Estrada
Ofelia M
OM
Departament de Biologia Cellular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain. ofeliamartinez@ub.edu
Cullerés
Albert
A
Soriano
Francesc X
FX
Peinado
Hector
H
Bolós
Victoria
V
Martínez
Fernando O
FO
Reina
Manuel
M
Cano
Amparo
A
Fabre
Myriam
M
Vilaró
Senén
S
D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism; D002460:Cell Line; D062445:Claudin-1; D004285:Dogs; D015536:Down-Regulation; D004847:Epithelial Cells / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000378:metabolism*
C568108:CLDN1 protein, human; D062445:Claudin-1; D008565:Membrane Proteins; D012097:Repressor Proteins; C000604407:SNAI1 protein, human; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors