High mobility group I (Y) proteins bind HIPK2, a serine-threonine kinase protein which inhibits cell growth.
The HMGI proteins (HMGI, HMGY and HMGI-C) have an important role in the chromatin organization and interact with different transcriptional factors. The HMGI genes are expressed at very low levels in normal adult tissues, whereas they are very abundant during embryonic development and in several experimental and human tumours. In order to isolate proteins interacting with the HMGI(Y) proteins, a yeast two-hybrid screening was performed using the HMGI(Y) protein as bait. This analysis led to the isolation of homeodomain-interacting protein kinase-2 (HIPK2), a serine/threonine nuclear kinase. HIPK2 co-immunoprecipitates with the HMGI(Y) protein in 293T cells. The interaction between HIPK2 and HMGI(Y) occurs through the PEST domain of HIPK2 and it is direct because in vitro translated HIPK2 binds HMGI(Y). We also show that HIPK2 is able to phosphorylate the HMGI(Y) protein by an in vitro kinase assay. In order to understand a possible role of HIPK2 gene in cell growth we performed a colony assay which showed an impressive HIPK2 inhibitory effect on normal thyroid cells. Flow cytometric analysis would indicate the block of cell growth at the G2/M phase of the cell cycle. Since normal thyroid cells do not express detectable HMGI(Y) protein levels, we assume that the HIPK2 inhibitory effect is independent from the interaction with the HMGI(Y) protein.
Pierantoni
G M
GM
Dipartimento di Biologia e Patologia Cellulare e Molecolare, c/o Centro di Endocrinologia ed Oncologia Sperimentale del CNR, Facoltà di Medicina e Chirurgia, Università degli Studi di Napoli Federico II, 80131 Naples, Italy.
Fedele
M
M
Pentimalli
F
F
Benvenuto
G
G
Pero
R
R
Viglietto
G
G
Santoro
M
M
Chiariotti
L
L
Fusco
A
A
D001665:Binding Sites; D001973:Bromodeoxyuridine / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology; D018076:DNA, Complementary / Q000378:metabolism; D005434:Flow Cytometry; D015723:Gene Library; D025741:HMGA1a Protein; D006609:High Mobility Group Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008957:Models, Genetic; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D014176:Protein Biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D020798:Two-Hybrid System Techniques
D002352:Carrier Proteins; D018076:DNA, Complementary; D006609:High Mobility Group Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D025741:HMGA1a Protein; C115114:HIPK2 protein, human; D017346:Protein Serine-Threonine Kinases; D001973:Bromodeoxyuridine