Synovial sarcoma translocation (SYT) encodes a nuclear receptor coactivator.
We previously cloned and characterized a novel RNA-binding motif-containing coactivator, named coactivator activator (CoAA), as a thyroid hormone receptor-binding protein-interacting protein using a Sos-Ras yeast two-hybrid screening system. A database search revealed that CoAA is identical with synovial sarcoma translocation (SYT)-interacting protein. Thus, we hypothesized that SYT could also function ... as a coactivator. Subsequently, we isolated a cDNA encoding a larger isoform of SYT, SYT-long (SYT-L), from the brain and liver total RNA using RT-PCR. SYT-L possesses an additional 31 amino acids in its C terminus compared with SYT, suggesting that these two SYT isoforms may be expressed from two mRNAs produced by alternative splicing of a transcript from a single gene. By Northern blot analysis, we found that SYT-L mRNA is expressed in several human embryonic tissues, such as the brain, liver, and kidney. However, we could not detect SYT-L in adult tissues. Glutathione-S-transferase pull-down studies showed that SYT binds to the C-terminus of CoAA, but not to the coactivator modulator. Both isoforms of SYT function as transcriptional coactivators of nuclear hormone receptors in a ligand- and dose-dependent manner in CV-1, COS-1, and JEG-3 cells. However, the pattern of transactivation was different between SYT and SYT-L among these cells. SYT synergistically activates transcription with CoAA. In addition, SYT activates transcription through activator protein-1, suggesting that SYT may function as a general coactivator. These results indicate that SYT activates transcription, possibly through CoAA, to interact with the histone acetyltransferase complex.
Mesh Terms:
Age Factors, Amino Acid Sequence, Animals, Base Sequence, Binding Sites, COS Cells, Cercopithecus aethiops, Gene Expression Regulation, Developmental, Histone Acetyltransferases, Humans, Intracellular Signaling Peptides and Proteins, Molecular Sequence Data, Neoplasm Proteins, Nuclear Proteins, Nuclear Receptor Coactivator 1, Nuclear Receptor Coactivators, Protein Structure, Tertiary, RNA, Messenger, Repressor Proteins, Transcription Factors
Age Factors, Amino Acid Sequence, Animals, Base Sequence, Binding Sites, COS Cells, Cercopithecus aethiops, Gene Expression Regulation, Developmental, Histone Acetyltransferases, Humans, Intracellular Signaling Peptides and Proteins, Molecular Sequence Data, Neoplasm Proteins, Nuclear Proteins, Nuclear Receptor Coactivator 1, Nuclear Receptor Coactivators, Protein Structure, Tertiary, RNA, Messenger, Repressor Proteins, Transcription Factors
Endocrinology
Date: Sep. 01, 2005
PubMed ID: 15919756
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