PIAS-1 is a checkpoint regulator which affects exit from G1 and G2 by sumoylation of p73.
p73 is a recently described member of the p53 family, and, like p53, it undergoes a number of posttranslational modifications. Here we show, by yeast two-hybrid screening, pull-down assays, and coimmunoprecipitation, that p73alpha, -beta, and -gamma bind to the protein inhibitor of activated STAT-1 (PIAS-1) and that this binding stabilizes p73. PIAS-1 also sumoylates p73alpha, although not the C-terminally truncated isoforms p73beta and -gamma, and this requires the RING finger domain of PIAS-1. The DeltaNp73alpha isoform can also bind, and be sumoylated by, PIAS-1. PIAS-1-mediated sumoylation decreases p73 transcriptional activity on several target promoters, such as Bax. p73 is colocalized in the nucleus with PIAS-1, and sumoylated p73 is located exclusively in the nuclear matrix. PIAS-1 is expressed predominantly during S phase, and PIAS-1 overexpression reduces p73-mediated transcription of p21, with a reduction of cells in G(1) and cell cycle reentry. Inhibition of endogenous PIAS-1 by RNA interference reduces the proportion of cells in S phase and induces G(2) arrest. These data suggest that PIAS-1, acting partly through binding and sumoylation of p73, is an important component of the cell cycle machinery.
Munarriz
Eliana
E
Medical Research Council, Toxicology Unit, Hodgkin Building, Leicester University, Lancaster Road, P.O. Box 138, Leicester LE1 9HN, United Kingdom.
Barcaroli
Daniela
D
Stephanou
Anastasis
A
Townsend
Paul A
PA
Maisse
Carine
C
Terrinoni
Alessandro
A
Neale
Michael H
MH
Martin
Seamus J
SJ
Latchman
David S
DS
Knight
Richard A
RA
Melino
Gerry
G
De Laurenzi
Vincenzo
V
D015153:Blotting, Western; D018288:Carcinoma, Small Cell / Q000473:pathology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D016193:G1 Phase; D016195:G2 Phase; D016147:Genes, Tumor Suppressor; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008175:Lung Neoplasms / Q000473:pathology; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D012516:Osteosarcoma / Q000473:pathology; D011233:Precipitin Tests; D050828:Protein Inhibitors of Activated STAT; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D011994:Recombinant Proteins / Q000378:metabolism; D025841:Small Ubiquitin-Related Modifier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D020798:Two-Hybrid System Techniques
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C106529:PIAS1 protein, human; D050828:Protein Inhibitors of Activated STAT; D020033:Protein Isoforms; D011994:Recombinant Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D008156:Luciferases; D005982:Glutathione Transferase