The SUMO ubiquitin-protein isopeptide ligase family member Miz1/PIASxbeta /Siz2 is a transcriptional cofactor for TFII-I.
We have shown previously that a TFII-I-related protein, hMusTRD1/BEN, represses transcriptional activity of TFII-I. The repression by hMusTRD1/BEN was hypothesized to occur via a two-step competition mechanism involving a cytoplasmic shuttling factor and a nuclear cofactor required for transcriptional activation of TFII-I. Employing a two-hybrid approach with both yeast genomic and mouse cDNA libraries in parallel, we have identified the RING-like zinc finger containing Miz1/PIASxbeta/Siz2, which is a ubiquitin-protein isopeptide ligase in the SUMO pathway, as the potential nuclear cofactor that interacts with both TFII-I and hMusTRD1/BEN. Our conclusion is based on the following observations. First, the interactions are biochemically confirmed in mammalian cells where Miz1/mPIASxbeta interacts with both TFII-I and hMusTRD1/BEN when these proteins are ectopically co-expressed. Second, co-expression of a nuclear localization signal-deficient mutant of Miz1/mPIASxbeta with wild type TFII-I fails to alter the subcellular localization of the former. Finally, ectopically expressed Miz1/mPIASxbeta augments the transcriptional activity of TFII-I and relieves the repression exerted by a mutant hMusTRD1/BEN that co-localized with TFII-I in the nucleus.
Department of Pathology, Programs in Immunology and Genetics, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Maria Isabel
MI
Tussie-Luna
Bertha
B
Michel
Shweta
S
Hakre
Ananda L
AL
Roy
D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002522:Chlorocebus aethiops; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015723:Gene Library; D051741:Kruppel-Like Transcription Factors; D051379:Mice; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000378:metabolism; D025842:SUMO-1 Protein / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D019473:Transcription Factors, TFII / Q000378:metabolism*; D014162:Transfection; D016335:Zinc Fingers
D017931:DNA Primers; D004268:DNA-Binding Proteins; D051741:Kruppel-Like Transcription Factors; D020033:Protein Isoforms; D025842:SUMO-1 Protein; D029701:Saccharomyces cerevisiae Proteins; C436836:Siz2 protein, S cerevisiae; D014157:Transcription Factors; D019473:Transcription Factors, TFII; C107961:ZBTB17 protein, human