Transcriptional control of Shh/Ptc1 signaling in embryonic development.
In vivo profiling of signal-directed gene expression patterns is a major bottleneck in studying developmental biology. A signal molecule initiates its specific gene expression pattern through the activation of certain transcription factor (TF); however, tissue heterogeneity often masks this pattern due to intercellular complexity of other signal transduction pathways. To decipher the synergistic regulation of signal-directed gene expression in the tissue level, we report here a unique transcriptional responsive element (TRE) existing in the 5'-upstream promoter regions (5'-UPR) of the genes responding to the Shh/Ptc1 signal transduction pathway during feather placode development in chicken embryos. By locating the TRE homologue and its interactive TF, we were able to reveal the gene expression pattern of the Shh/Ptc1 signaling. We firstly demonstrated that homology profiling of the 5'-UPR of the genes, Gli1, TGF-beta2 and Msx2, responding to the Shh/Ptc1 signaling showed a more than 70% conserved region. Computer alignment of the consensus sequences in the conserved region revealed a 37-nucleotide TRE sequence, containing two regulatory elements homologous to human and mouse Gli-binding sites. Activation of this newly identified Shh/Ptc1-responsive TRE by active Smo signaling in chicken hepatoepithelial carcinoma cells elicited a strong synergistic expression of the Shh/Ptc1-downstream genes. Based on previous bioinformatics and the present experimental findings, we successfully established an in vivo signaling model for the Shh/Ptc1-directed embryonic feather morphogenesis.
Lin
Shi-Lung
SL
Department of Cell and Neurobiology, BMT-403, 1333 San Pablo Street, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA. lins@usc.edu
Chang
Shin-Ju E
SJ
Ying
Shao-Yao
SY
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D002642:Chick Embryo; D016384:Consensus Sequence; D017124:Conserved Sequence; D004797:Enzyme-Linked Immunosorbent Assay; D005241:Feathers / Q000196:embryology; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism; D053823:Hedgehog Proteins; D008113:Liver Neoplasms / Q000235:genetics / Q000473:pathology; D008954:Models, Biological; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D050436:Regulatory Elements, Transcriptional / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D053823:Hedgehog Proteins; C509239:SHH protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D049452:Green Fluorescent Proteins