title: Left-right axis asymmetry determining human Cryptic gene is transcriptionally repressed by Snail.
abstract: Establishment of the left-right axis is important for positioning organs asymmetrically in the developing vertebrate-embryo. A number of factors like maternally deposited molecules have emerged essential in initiating the specification of the axis; the downstream events, however, are regulated by signal-transduction and gene-expression changes identifying which remains a crucial challenge. The EGF-CFC family member Cryptic, that functions as a co-receptor for some TGF-beta ligands, is developmentally expressed in higher mammals and mutations in the gene cause loss or change in left-right axis asymmetry. Despite the strong phenotype, no transcriptional-regulator of this gene is known till date.
  
  
  
  Using promoter-analyses tools, we found strong evidence that the developmentally essential transcription factor Snail binds to the human Cryptic-promoter. We cloned the promoter-region of human Cryptic in a reporter gene and observed decreased Cryptic-promoter activation upon increasing Snail expression. Further, the expression of Cryptic is down-regulated upon exogenous Snail expression, validating the reporter assays and the previously identified role of Snail as a transcriptional repressor. Finally, we demonstrate using gel-shift assay that Snail in nuclear extract of PANC1 cells interacts with the promoter-construct bearing putative Snail binding sites and confirm this finding using chromatin immunoprecipitation assay.
  
  
  
  Snail represses the expression of human Cryptic and therefore, might affect the signaling via Nodal that has previously been demonstrated to specify the left-right axis using the EGF-CFC co-receptors.
authors: Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, India.
authors: Kartik
authors: K
authors: Gupta
authors: Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, India.
authors: Vijaya Satish Sekhar
authors: VS
authors: Pilli
authors: Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, India. agk@iitm.ac.in.
authors: Gopala Krishna
authors: GK
authors: Aradhyam
mesh_terms: D001665:Binding Sites; D019521:Body Patterning; D002460:Cell Line; D003001:Cloning, Molecular; D047108:Embryonic Development; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D057809:HEK293 Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D000071250:Snail Family Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: C491268:CFC1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; C000604407:SNAI1 protein, human; D000071250:Snail Family Transcription Factors
keywords: Cryptic; EGF-CFC; Left-right-axis; Snail; Transcription