The transcription factor basic transcription element-binding protein 1 is a direct thyroid hormone response gene in the frog Xenopus laevis.
Several genes have been identified that are activated or repressed by thyroid hormone in tadpole tissues during metamorphosis of the frog Xenopus laevis. One rapidly and strongly induced gene encodes the Xenopus homolog of basic transcription element-binding protein 1 (xBTEB1), an SP1-related transcription factor. xBTEB1 has similar DNA-binding activity and transcriptional activation properties as mammalian BTEB1. The thyroid hormone-dependent regulation of xBTEB1 was investigated using a modified electrophoretic mobility shift assay to scan genomic DNA for receptor-binding sites. Due to the tetraploid X. laevis genome, xBTEB1 is duplicated, and thyroid hormone regulates both copies. A consensus thyroid hormone response element (TRE) lies far upstream of the transcriptional start site of both genes. The TRE is nested within a 200-bp region of high sequence conservation between these two genes that duplicated millions of years ago. The TRE acts as a strong response element in transfection assays using a heterologous promoter or its native context. Thus, one of the earliest thyroid hormone-induced genes in tadpoles is a transcription factor regulated through an evolutionarily conserved TRE. xBTEB1 is predicted to play an important role in downstream gene regulation leading to the growth and remodeling of tissues at metamorphosis.
Section of Neurobiology, Physiology, and Behavior, University of California, Davis, California 95616-8519, USA. jdfurlow@ucdavis.edu
J David
JD
Furlow
Akira
A
Kanamori
D000818:Animals; D001665:Binding Sites; D015139:Blotting, Southern; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D015723:Gene Library; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000032:analysis; D011993:Recombinant Fusion Proteins; D020218:Response Elements; D015183:Restriction Mapping; D013963:Thyroid Hormones / Q000494:pharmacology*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D029867:Xenopus Proteins / Q000235:genetics* / Q000378:metabolism; D014982:Xenopus laevis / Q000235:genetics*
D018076:DNA, Complementary; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D013963:Thyroid Hormones; D014157:Transcription Factors; D029867:Xenopus Proteins; C465392:xBTEB1 protein, Xenopus; D004247:DNA; D005982:Glutathione Transferase