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. 2013 Apr;93(2):525–569. doi: 10.1152/physrev.00019.2012

Figure 7.

Figure 7.

Summary of TGF-β-dependent and -independent SMAD/SNAIL/SLUG-signalling on claudin expression. Upregulation of SMAD2, SMAD3, SMAD4, SNAIL1 and/or SLUG by TGFβ (upper part), Wnt, β-catenin or HGF (lower part) causes a general downregulation of claudin expression, irrespective of claudin function (tightening or pore-forming, red arrows). Effects are transmitted by different effects on claudin promoters. Inhibition of SMAD2, SMAD3, and/or SMAD4 upregulation (e.g., by SMAD7), or interference with promoter binding, causes claudin upregulation (green arrows). TGF-β may also differentially affect certain claudins in a SMAD-independent way via the MEKK/p38/MAP kinase pathway (blue arrows). Based on References 31, 67, 116, 126, 136, 157, 220, 232, 240, 276, 283, 285, 305, 322, 353, 362, 381, 422. See text for detailed description.