Definition of the DNA-binding site repertoire for theDrosophilatranscription factor SNAIL

Abstract

The Drosophila gene snail (sna) which encodes a zinc finger protein is essential for dorsal-ventral pattern formation in the developing embryo. We have defined a repertoire of SNAIL (SNA) binding sites using recombinant SNA proteins to select specific binding sequences from a pool of random sequence nucleotides. The bound sequences which were selected by multiple rounds of gel retardation and amplification by the polymerase chain reaction (PCR) were subsequently cloned and sequenced. The consensus sequence, 5'G/A A/t G/A A CAGGTG C/t A C 3', with a highly conserved core of 6 bases, CAGGTG, shares no significant homology with known binding sequences of other Drosophila zinc finger proteins. However, the CAGGTG core is identical to the core motif of aHLH (helix-loop-helix) binding sites. The strongest SNA binding is obtained with sequences containing this core motif whereas reduced binding is seen for sequences with canonical CANNTG HLH motifs. Interestingly, SNA binding is detected in the promoter region of the snail gene. Transient expression in co-transfection experiments using a SNA binding element (SBE) linked to a heterologous promoter indicates that SNA has the ability to function as a transcription activator.

A ubiquitin ligase, skeletrophin, is a negative regulator of melanoma invasion

“…Although typical Snail binding site consisted of a 5 0 -CAGGTG-3 0 core motif, previous studies also indicated that the zinc-finger transcriptional factor, Snail, could bind to the 5 0 -CAAGTG-3 0 element (Mauhin et al, 1993). Therefore, Figure 2 Representative examples of MSP analyses in invasive malignant melanoma, non-invasive melanoma and benign nevi and their expression of skeletrophin protein.…”

“…Although the typical Sail-binding element, the E-box, is composed of a 5 0 -CAGGTG-3 0 core motif, Snail can also bind to 5 0 -CAAGTG-3 0 . Mauhin et al (1993) demonstrated that Snail strongly bound to the canonical E-box, whereas it moderately bound the 5 0 -CAAGTG-3 0 element.…”

A conserved role for Snail as a potentiator of active transcription

“…4A, ''Dorsal-like''), as expected from the known role of Dorsal in activating neuroectodermal enhancers that are repressed by Snail (for review, see Chopra and Levine 2009). While the Snail CAGGTG motif (from Jaspar) (Mauhin et al 1993) is not enriched in either cobound set, an alternative Snail motif with an adenine preference at position 6 (CAGGTA) is enriched in both the activated and repressed CRMs (Fig. 4A, ''alternative Snail motif'').…”

Snail, a transcriptional regulator, represses nephrin expression in glomerular epithelial cells of nephrotic rats

“…However, we found five E-box motifs in the segment C1 to which Snail could potentially bind according to literature (Figure 3c). 27 All five E-box motifs may be necessary for the association between Snail and nephrin gene.…”

“…Transcriptional repression of these molecules occurs through the consensus DNA-binding site for Snail and this site has been reported as the E-box motif (5 0 -CA(C/G)(C/G)TG-3 0 ). 27 Snail plays a central role in regulating epithelial functions and is critical for triggering epithelial to mesenchymal transition (EMT) in embryonic development, carcinogenesis, and cancer metastasis. 28 In this study, we examined the involvement of Snail in the transcriptional regulation of nephrin using a rat nephrosis model.…”