Regulation of repp86 stability by human Siah2.
Human repp86 is a nuclear protein that is expressed in a tightly limited period of time during the cell cycle and plays an essential role in its progression. Manipulation of repp86 expression by reduction of endogenous repp86 or overexpression of exogenous repp86 results in cell cycle arrest. We found that repp86 interacts with human Siah2, which is a known mediator for proteasomal degradation. Siah2 failed to interact with repp86 lacking the first 67 N-terminal amino acids. Overexpression of Siah2 reduced endogenous and exogenous repp86 at the protein level without affecting its mRNA, as shown by cotransfection and RT-PCR experiments. Furthermore, MG-132--a specific inhibitor of the proteasome--blocked the degradation of repp86 in Siah2 overexpressing cells. Moreover, transiently transfected Siah2 abrogated the mitotic arrest in repp86 overexpressing cells. Our data show that Siah2 is an important mediator of repp86 protein degradation.
Szczepanowski
Monika
M
Department of Pathology, Hematopathology and Lymph Node Registry, Schleswig-Holstein University Hospitals, Campus Kiel, Michaelisstrasse 11, 24105 Kiel, Germany.
Adam-Klages
Sabine
S
Kruse
Marie-Luise
ML
Pollmann
Marc
M
Klapper
Wolfram
W
Parwaresch
Reza
R
Heidebrecht
Hans-Juergen
HJ
D015153:Blotting, Western; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004720:Endonucleases; D005786:Gene Expression Regulation / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014162:Transfection; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D000098563:Seven in Absentia Proteins
D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D044767:Ubiquitin-Protein Ligases; D000098563:Seven in Absentia Proteins; D004720:Endonucleases; C095221:SND1 protein, human; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde