The human tumor suppressor arf interacts with spinophilin/neurabin II, a type 1 protein-phosphatase-binding protein.
The INK4a gene, one of the most often disrupted loci in human cancer, encodes two unrelated proteins, p16(INK4a) and p14(ARF) (ARF) both capable of inducing cell cycle arrest. Although it has been clearly demonstrated that ARF inhibits cell cycle via p53 stabilization, very little is known about the involvement of ARF in other cell cycle regulatory pathways, as well as on the mechanisms responsible for activating ARF following oncoproliferative stimuli. In search of factors that might associate with ARF to control its activity or its specificity, we performed a yeast two-hybrid screen. We report here that the human homologue of spinophilin/neurabin II, a regulatory subunit of protein phosphatase 1 catalytic subunit specifically interacts with ARF, both in yeast and in mammalian cells. We also show that ectopic expression of spinophilin/neurabin II inhibits the formation of G418-resistant colonies when transfected into human and mouse cell lines, regardless of p53 and ARF status. Moreover, spinophilin/ARF coexpression in Saos-2 cells, where ARF ectopic expression is ineffective, somehow results in a synergic effect. These data demonstrate a role for spinophilin in cell growth and suggest that ARF and spinophilin could act in partially overlapping pathways.
Vivo
M
M
Department of Genetics, General and Molecular Biology, University of Naples "Federico II," via Mezzocannone 8, Napoli 80134, Italy.
Calogero
R A
RA
Sansone
F
F
Calabrò
V
V
Parisi
T
T
Borrelli
L
L
Saviozzi
S
S
La Mantia
G
G
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002384:Catalysis; D020134:Catalytic Domain; D002455:Cell Division; D002478:Cells, Cultured; D005091:Exons; D017353:Gene Deletion; D016158:Genes, p53 / Q000235:genetics; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000737:chemistry; D011233:Precipitin Tests; D011485:Protein Binding; D054645:Protein Phosphatase 1; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014407:Tumor Cells, Cultured; D025803:Tumor Suppressor Protein p14ARF; D020798:Two-Hybrid System Techniques; D000099273:Neurabins
D005982:Glutathione Transferase; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D011506:Proteins; D012333:RNA, Messenger; D025803:Tumor Suppressor Protein p14ARF; D000099273:Neurabins