Interaction of the stress protein p8 with Jab1 is required for Jab1-dependent p27 nuclear-to-cytoplasm translocation.
p8 is an 80 amino-acid polypeptide identified because of its remarkable over-expression in the stressed pancreas. This protein, apparently devoid of enzymatic activity, is a powerful regulator of several intracellular pathways, suggesting that it has to interact with several molecular partners to modulate their activity. We used two-hybrid screening of a pre-transformed human testes cDNA library to identify some of these partners. One of them was the multifunctional protein Jab1, its interaction with p8 being confirmed by His6-pull down and co-immunoprecipitation assays. In addition, we could show that the two proteins co-localized in the cell. Our functional data demonstrate that Jab1 requires direct interaction with p8 to induce the translocation of p27 from nucleus to cytoplasm and its subsequent degradation. Experiments showing that the knock-down of p8 expression results in a strong inhibition of Jab1 activity confirmed that the mechanism by which Jab1 promotes cell growth by decreasing p27 level is p8-dependent.
Malicet
Cédric
C
INSERM U.624, Stress Cellulaire, 163 Avenue de Luminy, Case 915, Parc Scientifique et Technologique de Luminy, 13288 Marseille Cedex 9, France.
Hoffmeister
Albrecht
A
Moreno
Silvia
S
Closa
Daniel
D
Dagorn
Jean-Charles
JC
Vasseur
Sophie
S
Iovanna
Juan L
JL
D021581:Active Transport, Cell Nucleus; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D000075686:COP9 Signalosome Complex; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D049109:Cell Proliferation; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D015723:Gene Library; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics; D020798:Two-Hybrid System Techniques
D051792:Basic Helix-Loop-Helix Proteins; D000075686:COP9 Signalosome Complex; D050760:Cyclin-Dependent Kinase Inhibitor p27; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D010447:Peptide Hydrolases; D034741:RNA, Small Interfering; C491643:NUPR1 protein, human; C501488:COPS5 protein, human